Power supply for the foundry. Schemes of power supply of the workshop (enterprise) Layout of electrical equipment in the mechanical workshop

Electrical networks are used for transmission and distribution electrical energy to shop consumers of industrial enterprises. Energy consumers are connected through intrashop substations and distribution devices using protective and starting devices.

Electric networks of industrial enterprises are carried out internal (workshop) and external. External voltage networks up to 1 kV are of very limited distribution, since at modern industrial enterprises the power supply of shop loads is produced from intra-shop or attached transformer substations.

The choice of electrical networks radial power schemes are characterized by the fact that from a power source, for example, from transformer substation, depart lines supplying directly powerful electrical receivers or separate distribution points, from which smaller electrical receivers are fed by independent lines.

Radial circuits provide high reliability of power supply to individual consumers, since accidents are localized by turning off the automatic switch of the damaged line and do not affect other lines.

All consumers can lose power only in case of damage on the PTS busbars, which is unlikely. As a result of a fairly reliable design of cabinets of these PTS.

Main power circuits are widely used not only to power many electrical receivers of one technological unit, but also to compare a large number of small receivers that are not connected by a single technological process.

Trunk circuits allow you to abandon the use of a bulky and expensive switchgear or shield. In this case, it is possible to use the transformer-trunk block scheme, where bus ducts (bus ducts) manufactured by the industry are used as the supply line. Trunk circuits made by busbars provide high reliability, flexibility and versatility of workshop networks, which allows technologists to move equipment inside the workshop without significant installation of electrical networks.

Due to the uniform distribution of consumers within the mechanical repair shop, as well as low cost and ease of use, the main power supply scheme is selected.

The location of the main equipment is shown in the diagram (Fig. 1).

We carry out all types of student work

coursework

The electrical load is calculated jointly for working and emergency lighting. The initial data for the calculation are given in Table 8. Table 8 - Lighting load parameters of the workshop. Active replaceable powers of working, kW, and emergency, kW, lighting are determined by the formula. For = 0.83. Reactive replaceable powers of working, kvar, and emergency, kvar, lighting are determined by the formula (2) ...

Power supply of the machine shop for mass production (abstract, term paper, diploma, control)

Introduction
1. General part
1.3 Reliability category of shop power supply
2. Special part
2.3 Calculation of the electrical load of the power equipment of the workshop
2.8.4 Calculation and selection of pipes

Introduction

One of the most urgent tasks in our country is the systematic development of its economic complex. In conditions market economy The main factor in increasing the efficiency of the national economy is not the individual achievements of science and technology, but the high scientific and technological level of the entire production complex. This level is determined primarily by the state of engineering as an industry. In this regard, the most acute issues related to the improvement, reorganization, development and modernization of the industry as a whole and each enterprise separately. In turn, any modernization of industrial machine-building enterprises, or the creation of new ones, sets the priority task of organizing a full-fledged, economical and efficient power supply for production facilities, including machine tools.

This course project discusses some experience in designing the power supply of a separate section of a machine shop for serial production, intended for serial production of products for a heavy engineering plant.

The course project consists of general and special parts. The general part deals with the basic data of the premises, equipment, etc., necessary for the calculations. In a special part, the methods and directly the calculations themselves for organizing the power supply of the section of the machine-building workshop are given.

power supply machine shop network

1. General part

1.1 Characteristics of the premises of the workshop

The mass production machine shop (MCSP) is divided into the following sections:

machine department;

transformer substation (TP);

repair site;

household premises;

milling section;

grinding area;

ventilation.

In the premises of the machine department, the main production activities of the MCSP, the processing of blanks and parts, are carried out. The machine shop is a dry room with a normal environment, temperature environment does not exceed 30 °C, there is no chemically active environment, flammable and explosive substances. The degree of protection of the shell of electrical equipment is IP 44.

The characteristics of the sites in terms of environmental conditions, technological purpose, the presence of fire and explosion hazard zones are given below in Table 1.

Table 1 - Characteristics of the premises of the workshop

Site name	Technological purpose	Environmental conditions		Degree of protection of the shell

	transformation of electricity and its transmission to consumers	normal	flammable, class P1
machine department		dry with normal environment	fire hazardous class P-2a
milling section	processing of metal parts on machine tools	dry with normal environment	fire hazardous class P-2a
sharpening section	processing of metal parts on machine tools	dry with normal environment	fire hazardous class P-2a
repair site	processing of metal parts	dry with normal environment	fire hazardous class P-2a
	storage of tools, fixtures, materials, finished products	dry with normal environment,	fire hazardous class P-2a
ventilation	supply of clean air and exhaust of polluted air	normal	missing
household premises	Solution org. questions, rest of workers	dry with normal environment,	fire hazardous, class P-2a

1.2 Analysis of shop electrical consumers

This workshop uses electrical equipment that has the following technological purposes:

metalworking equipment (turning, milling machines etc.);

handling equipment (overhead crane);

metalworking machines (grinding, drilling, turning, grinding, milling, bolt-cutting, thread-cutting machines);

woodworking machinery;

household appliances (refrigerator, electric stove);

welding equipment (welding transformer, welder's table);

sanitary equipment (fans);

Electrical consumers are connected to a three-phase voltage of 380 V (fans, machines), to a single-phase voltage of 220 V (refrigerator) and a single-phase voltage of 380 V (welding transformer, electric stove). The rest of the electrical equipment operates in a continuous mode.

Most of the electrical receivers are connected to a three-phase voltage of 380 V (metalworking, handling equipment), except for single-phase electrical receivers of 220 V (emery, grinding machines, magnetic flaw detector) with a frequency of 50 Hz. The electrical consumers of the workshop operate both in long-term mode (metal-working equipment) and in intermittent mode (handling equipment).

The category of power supply reliability is the ability of the electrical system to provide the enterprise and individual facilities with electricity of the proper quality without emergency interruptions. With regard to ensuring the reliability of power supply, power receivers (EP) are divided according to the rules for the installation of electrical installations (PUE) into three categories.

Category 1 - it includes electrical consumers, the interruption in the power supply of which can cause a threat to human life, damage to expensive equipment, mass defective products, etc. Consumers of this category are powered by two independent sources of electricity. Power supply interruption is allowed for the period of automatic switching from one source to another.

Category 2 - this category includes electrical consumers, a break in the power supply of which can cause a massive underproduction and downtime of workers, disruption of the life of urban and rural residents. Consumers are fed from two independent sources. When one power source fails, switching to another power source is carried out by a mobile operational team or operational personnel.

Category 3 - this category includes electrical consumers that do not belong to the 1st and 2nd categories. Consumers of this category are powered by a single source of electricity, and a break in their power supply is allowed for a period of not more than a day.

For power receivers of this category, interruptions in power supply are allowed for the time required to turn on the backup power by the on-duty personnel or the mobile operational team. In the presence of a centralized reserve, it is allowed to supply power consumers of category II with one transformer, because a break in power supply can cause a massive underproduction and downtime for workers.

1.4 Design input

To perform the power supply of the workshop, it is necessary to indicate the main indicators of the workshop, the load parameters of the workshop and the technical parameters of the electrical consumers, which are entered in tables 2, 3 and 4, respectively.

Table 2 - Main indicators of the workshop

Name	Units	Value

Continuation of table 2
2. Workshop height, H
3. The number of use of the maximum load, T m
4. Generator power, S G
5. Inductive resistance of the generator, X G	about. e.
6. The length of the high voltage line, l
7. Power system power factor,
8. Ground resistance,
9. Aggressiveness of soil towards steel
10. Protection response time, t h

Table 3 - Workshop load parameters

Name	Units	Value
1. Installed capacity of power equipment;
2. Utilization rate
3. Power factor
4. Effective number of power consumers
5. Maximum coefficient

7. Installed power of work lighting
8. Demand factor
9. Power factor

11. Installed power of emergency lighting
12. Demand factor
Continuation of table 2
13. Power factor

Table 4 - Technical parameters of electrical consumers

ES name	No. according to the plan	Quantity, pcs	Power,

1. Carousel-milling machine
2. Tool-grinding 1-phase.
3. Emery machine 1 phase.
4. Supply fan
5. Exhaust fan
6. Planer
7. Surface grinder
8. Longitudinal milling machine
9. Threading machine
10. Turret lathe
11. Semi-automatic milling	21, 22, 23, 24, 25, 26,27, 28
12. Gear hobbing machine
13. Semiautomatic gear hobbing
14. Overhead crane PV = 60 % Withosc=0,92

2. Special part

2.1 Choice of method and scheme of power supply of distribution networks

A distribution network is a network from distribution cabinets to electrical consumers.

Distribution cabinet (SHR) is an electrical device that serves to receive and distribute electricity between electrical consumers, as well as to protect them from emergency conditions. Distribution cabinets are installed, as a rule, in the center of loads, as well as in places that do not interfere with the technological process and are convenient for operation and repair. In this workshop, distribution cabinets are located near the walls.

There are 3 schemes for the implementation of distribution networks.

The radial scheme (Figure 1) is a distribution network power supply scheme in which the power consumer receives power through its own separate line. Thus, if one supply line fails, the remaining electrical consumers continue to receive power. However, with such a scheme, a large number of starting-protective equipment and cable products are used.

Figure 1 - Radial diagram of the distribution network

The main circuit (Figure 2) is a distribution network power supply scheme in which several electrical consumers are powered from one line.

Figure 2 - Main distribution network diagram

A mixed scheme (Figure 3) is a power supply scheme for distribution networks, in which power consumers receive electricity both through radial and main schemes.

Figure 3 - Mixed distribution network scheme

Connecting electrical consumers to distribution cabinets in machine shop It is produced both according to radial and mixed schemes of distribution networks.

This course project uses a radial distribution network.

To connect electrical consumers, both open (in structures, in boxes) and hidden (in floor preparation pipes) electrical wiring are used. The wiring method depends on technological process, environmental conditions, the presence of dust, a chemically active environment, zones of explosion and fire hazard. For example, the electrical wiring in the ventilation chamber is carried out openly in a box to protect the wiring from process dust.

2.2 Calculation of the electrical load of the switch cabinet using the ordered diagram method

The electrical load for the workshop is power equipment and electric lighting. The calculation of the electrical load is an important element in the design of workshops, enterprises, sites. Depending on the calculated power, the number and power of power transformers, the brand and cross-section of the high and low voltage supply lines, as well as the type of start-protective devices of distribution cabinets are selected.

An example of the calculation of power equipment for a distribution cabinet (SR) No. 1 (according to the plan) is given.

Initial data are selected from table 4 and entered in table 5

According to the reference data, the values of ki, cosц, tgц are found and are entered in table 5

Table 5 - Data of electrical consumers connected to ШР1

No. according to the plan	Technology name
	Semi-automatic milling
	Semi-automatic milling
	Semi-automatic milling
	Semi-automatic milling
	Semi-automatic milling
	Gear hobbing machine
	Semiautomatic gear hobbing
	Semiautomatic gear hobbing

The layout of the switch cabinet is shown in Figure 4.

Figure 4 - Schematic diagram of ShR1

All EPs belong to the same technological group.

The active replaceable power Rcm, kW, is determined by the formula Rcm \u003d ku x? Рн1…8 (1)

Rcm=0.12×81.5 = 9.78 kW Reactive power Qcm, kvar, is determined by the formula

Qcm \u003d Rcm x tgc (2)

Qcm= 9.78×2.30 =22.494 kvar = Rcm (3)

rsm? = 9.78 kW

Qcm? = Qcm (4)

Qcm? = 22.494 kvar The weighted average value of the function tgц is determined by the formula

tgcsrv = Qcm? / rsm? (5)

tgcrv = 22.494 / 9,78 = 2,3

The total average shift power ShR1 Scm?, kVA, is determined by the formula

Scm? =v 9.78 I + 22.494I = 24.53 kVA

coscrv = Rcm? / Scm? (7)

coscrv = 9.78/24.53 = 0.399

The total installed power E P Ru?, kW, connected to ShR1, is determined by the formula Ru? =? Pn1+ Pn2+ Pn3+ Pn4+ Pn5+ Pn6+ Pn7+ Pn8 (8)

RU? = 9.5+9.5+9.5+9.5+9.5+10+12+12 = 81.5 kW

The weighted average value of the utilization factor is determined by the formula

kUav = Rcm? / RU? (9)

kUav = 9.78/81.5 = 0.12

The effective number of EP nef, pcs, is determined by the formula

6642, 25

nef = 839.25 = 7.91

According to the values of nef and k and av, the value of the coefficient of maximum km is found

km = f (nef; kUav) (11)

km \u003d f (7.91; 0.12) \u003d 2.59

Active design power ШР1 Рр kW, is determined by the formula Рр = km x Rcm? (12)

Рр = 2.59 × 9.78 = 25.33 kW Reactive calculated power ШР1 Qр, kvar, is determined by the formula

Qp \u003d 1.1 x Qcm ?, because nef<10, nэф = 7,91 (13)

Qр = 1.1×22.494 = 24.7434 kVAr Total reactive power ШР1 Sр, kVA, is determined by the formula

Sp =v 25.33 I + 24.7434 I = 35.41 kVA Rated current ШР1, A, is determined by the formula

Ir = 35.41 / 1.73 × 380 = 53.86 A The electric power supply with the highest starting current is selected. For ShR1, this is EP13 (Semi-automatic gear hobbing). Its rated current, A, is found by the formula

In1= 1.73×380×0.4×0.83 = 54.98 A Starting current of a given EA, A, is determined by the formula

where is the start factor (for).

In1 \u003d 6 × 54.98 \u003d 329.88 A Peak current ШР1, A, is calculated by the formula

Ipeak \u003d 53.86 + 329.88 - 0.12 × 54.98 \u003d 377.1424 A The calculation data are entered in table 6.

Table 6

Active replaceable total power of power equipment, kW, is determined by the formula

P cm Force = 710 × 0.3 = 213 kW The weighted average value of the mathematical function of the power equipment is determined corresponding to

at = 0.7 = 0.9 (20)

Reactive replaceable total power of power equipment, kvar, is determined by the formula

Qcm? force = 213 × 1.02 = 217.26 kvar Active rated power of power equipment, kW, is determined by the formula Pp force = P cm Y force x km force (12)

Рр forces = 213 × 1.3 = 276.9 kW The reactive rated power of power equipment, kvar, is determined by the formula

QР forces = 217.26 kvar The total rated power of power equipment, kVA, is determined by the formula

Sp force = v 276.9 І + 217.26 І = 351.96 kVA Rated current of power equipment, A, is determined by the formula

Ip = 351.96 / 1.73 × 380 = 535.38 A ) respectively

In strength \u003d 1.73 × 380 × 0.8 × 0.83 \u003d 27.49 A

In1 = 6 × 27.49 = 164.94 A Peak current of power equipment, A, is determined by formula (27)

I peak force \u003d 535.38 + 164.94 - 0.12 × 27.49 \u003d 697.0212 A

2.4 Calculation of working and emergency lighting of the workshop

The electrical load is calculated jointly for working and emergency lighting. The initial data for the calculation are given in table 8

Table 8 - Shop lighting load parameters

Active replaceable power of working, kW, and emergency, kW, lighting are determined by the formula

Pcm RO \u003d 0.9 × 54 \u003d 48.6 kW

Pcm AO = 1×11 = 11 kW The weighted average values of the mathematical function of working and emergency lighting are determined by the corresponding values

Reactive replaceable powers of working, kvar, and emergency, kvar, lighting are determined by the formula (2)

Qcm RO \u003d 48.6 × 0.48 \u003d 23.33 kvar

Qcm AO = 11×0 = 0 kvar Active design power of working, kW, and emergency, kW, lighting are determined by the formula

Pr RO = Pcm RO = 48.6 kW

Pr AO = Pcm AO = 11 kW Reactive design power of working, kvar, and emergency, kvar, lighting are determined by the formula

Qr RO \u003d Qcm RO (31)

Qr RO \u003d Qcm RO \u003d 23.33 kvar

Qр AO = Qcm AO = 0 kVAr The total design power of the working, kVA, and emergency, kVA, lighting is determined by the formula (14)

Sp RO \u003d v 48.6 I + 23.33 I \u003d 53.9 kVA

Sp RO \u003d v 11 I + 0 I \u003d 11 kVA The rated currents of the working, A, and emergency, A, lighting are determined by the formula (15)

Ir RO \u003d 1.73 × 0.38 \u003d 81.67 A

Ir RO \u003d 1.73 × 0.38 \u003d 16.67 A The total active replaceable power of working and emergency lighting, kW, is determined by the formula

Pcm? sv \u003d 48.6 + 11 \u003d 59.6 kW The total installed power of working and emergency lighting, kW, is determined by the formula

Pу sv = 54 + 11 = 65 kW Total reactive replaceable power of working and emergency lighting, kvar, are determined by the formula

(34) Qcm? sv = 23.33 + 0 = 23.33 kvar Active rated power of working and emergency lighting, kW, are determined by the formula

Pr sv = 59.6 kW Reactive rated power of working and emergency lighting, kvar, are determined by the formula

Qr sv \u003d 23.33 kvar

2.5 Reactive power compensation

The operation of alternating current machines and devices, based on the principle of electromagnetic induction, is accompanied by a process of continuous change by changing the magnetic flux in their magnetic circuits and stray fields. Therefore, the power flow supplied to them must contain not only the active component P, but also the reactive component of the inductive nature Q, necessary to create magnetic fields, without which the processes of energy conversion, the type of current and voltage are impossible.

Reactive power compensation can be performed both naturally (reducing reactive power consumption) and artificially (installing reactive power sources) in ways.

2.5.1 Calculation of the electrical load of the shop before compensation

The calculation of the total electrical load of the workshop is carried out on the basis of the data of the calculation of the electrical load on the low voltage side of the PTS and the calculation of the electrical load of the electric lighting of the workshop, which are given in table 9

Table 9 - Parameters of electrical loads of power equipment and electric lighting of the workshop

The active installed capacity of the workshop, kW, is determined by the formula

Pу shop = 710 + 54 = 764 kW Active replaceable total power of the shop, kW, is determined by the formula

(38) P cm? shop = 196 +59.6 = 255.6 kW Reactive replaceable total power of the shop, kvar, is determined by the formula

Qcm? workshop = 217.26 + 23.33 = 240.59 kvar The total shift power of the workshop, kVA, is determined by the formula (6)

Scm workshop =v 255.6 І + 240.6І = 351.03 kVA The weighted average value of the workshop power factor is determined by the formula (7)

soscsrv shop = 255.6 / 351.03 = 0.73

The weighted average value of the mathematical function of the workshop is determined by the formula (5)

tgcsrv workshop = 240.6 / 255,6 = 0,941

The active design power of the workshop, kW, is determined by the formula

— coefficient of mismatch of the maximum load for active power.

P p shop \u003d 0.95 x (276.9 + 59.6) \u003d 319.7 kW The reactive design power of the shop, kvar, is determined by the formula

Qр workshop = 0.98 x (217.26 + 23.33) = 235.78 kVAr The total rated power of the workshop, kVA, is determined by the formula (14)

Scm shop \u003d v 319.7 I + 235.78 I \u003d 397.24 kVA The rated current of the shop, A, is determined by the formula (15)

Ir workshop = 397.24 / 1.73 × 380 = 604.26 A The peak current of the workshop, A, is determined by the formula (18)

Ipeak shop \u003d 604.26 + 329.88 - 0.12 × 54.98 \u003d 930.54A

2.5.2 Calculation and selection of a complete condensing unit

To select the power and type of complete capacitor units, the calculation data of the electrical load of power equipment and electric lighting of the workshop are used, which are given in table 10

Table 10 - Parameters of the electrical load of the shop

The weighted average of a mathematical function is determined by is determined by the value of the function

The desired power value of the KKU, kvar, is determined by the formula

QKKU zhel \u003d 255.6 x (0.941 - 0.36) \u003d 148.5 kvar

The power value of the KKU is selected - 150 kvar, since 150 kvar ‹ 240.59 kvar.

The reactive replaceable total power of the shop after compensation, kvar, is determined by the formula

Qcm? shop PC = 240.59 - 150 = 90.59 kvar Total replaceable total power of the shop after compensation, kVA, is determined by the formula (6)

Scm? shop PC = v 255.6І + 90.59І = 271.18 kVA The weighted average value of the power factor of the shop after compensation is determined by the formula

(45) soscav PC = 255.6/ 271.18 = 0.942

The obtained values are compared with the value

0.942? 0.94 - true This means that a CCGT with a rated power of 150 kvar is selected, and its technical data are entered in table 11

Table 11 - Technical parameters of the CCU

The rated current of the KKU, A, is determined by the formula

In KKU = 150 / (1.73 × 0.38) = 288.17 A The reactive design power of the workshop after compensation, kvar, is determined by the formula

Qcm? shop PC = 235.78 - 150 = 85.78 kvar The total design power of the shop after compensation, kVA, is determined by the formula (14)

Sp workshop PC = v 319.7І + 85.78І = 331.01 kVA The rated current of the workshop after compensation, A, is determined by formula (15) A, by formula (25)

Ir shop PC = 331.01/ (1.73 × 0.38) = 503.51A Peak current of the shop after compensation, A, is determined by the formula (18)

Ipeak shop PC = 503.51 + 329.88 - 0.12 × 54.98 = 826.79 A

2.6 Calculation and selection of the number and power of power transformers

In the mechanical workshop of serial production, there are electrical consumers of the first and second categories of power supply reliability.

The consumer of the first category includes emergency lighting of the workshop, and the consumer of the second category - the working lighting of the workshop.

The initial data for the calculation and selection of the number and power of power transformers are given in table 12

Table 12 - Initial data for the calculation and selection of the number and power of power transformers

The weighted average value of the mathematical function is determined by the corresponding value

The reactive replaceable total power of the workshop after compensation, kvar, is determined by the formula (21)

Qcm? workshop PK = 255.6 × 0.035 = 8.95 kvar Total replaceable total power of the workshop after compensation, kVA, is determined by the formula (6)

S cm? shop PC = v 255.6І + 8.95І = 255.77 kVA The reactive design power of the shop after compensation, kvar, is determined by the formula (22)

Qr shop PC = 8.95 kvar Total rated power on the low voltage side, kVA, is determined by the formula (14)

S p workshop PC = v319.7І + 8.95І = 319.83 kVA Active, kW, and reactive, kvar, power losses in the power transformer and in high-voltage lines, kW, are determined by the formulas

P T \u003d 0.02 × 319.83 \u003d 6.4 kW

Q T \u003d 0.1 × 319.83 \u003d 31.98 kvar

R P= 0.03×319.83 = 9.6 kW Total rated power on the high voltage side, kVA, is determined by the formula

S p HV = v (319.7 + 6.4 + 9.6) I + (8.95 + 31.98) I = 338.19 kVA The calculated power of the power transformer, kVA, taking into account the load factor, is determined by the formula

- allowable load factor, which, with the predominance of consumers Category III reliability of power supply, equal to 0.92

S Т1 = 338, 19/ 0.92 = 367.59 kVA Select the nearest higher standard power transformer power value, kVA

The actual value of the load factor is determined and compared with the value of the allowable load factor

in Tf = 338, 19/400 = 0.85

Comparable, provided

0.92 > 0.85 - correct The value of the load curve fill factor, determined by the formula

The number of use of the maximum load, h, is determined by the formula

According to the values \u200b\u200band, as well as the curves of the multiplicity of permissible loads of transformers, the coefficient of permissible overload is determined

The calculated power of the power transformer, kVA, taking into account, is determined by the formula

ST2 \u003d 297.73 / 1.02 \u003d 297.73 kVA Taking into account the values \u200b\u200bof ST1 and ST2 The standard value of the power transformer power is selected and its technical data are entered in table 13

Table 13 - Technical data of the power transformer

Losses, kW	Dimensions

		140 010 801 900

The active calculated total power of consumers of the I and II categories of power supply reliability, kW, is determined by the formula

The reactive calculated total power of consumers of the I and II categories of power supply reliability, kvar, is determined by the formula

The total rated power of consumers of the I and II categories of reliability of power supply, kVA, is determined by the formula (14)

The percentage of consumers of the I and II categories of reliability of power supply,%, is determined by the formula

Since the percentage of consumers of the I and II categories of power supply reliability does not exceed 30%, then 1 power transformer is selected with redundancy on the low side from the nearest workshop transformer substation.

2.7 Calculation and selection of protective equipment

Start-up equipment are called devices designed for switching and protecting electrical networks from overloads and short circuits. These devices include circuit breakers, magnetic starters and fuses.

Circuit breakers are used to automatically open electrical circuits during overloads and short circuits, with unacceptable voltage drops, as well as for infrequent manual switching on of circuits.

Magnetic starters are designed to start motors and protect against overloads.

Fuses are designed to protect circuits from short circuit modes and, occasionally, from overloads.

Below is a diagram of a switch cabinet with protective devices installed in it, supply and distribution networks (Figure 5).

Figure 5 - Schematic diagram of ShR1

2.7.1 Fuse selection FU1

The rated current of the electric consumer, A, is determined by the formula (16)

The starting current of the electric consumer, A, is determined by the formula (17)

The desired value of the fuse-link current of the fuse installed in the box, A, is determined by the formula

where is the coefficient of starting conditions: with a difficult start = 1.6; with light = 2.5.

By value, a larger standard value of the current of the fuse fuse, A, is selected, provided

A fuse of type PN - 2 - 150 is selected; .

According to the reference data, the type of fuse is determined, which are entered in table 14

Table 14 - Technical data of box 1I

2.7.2 Selecting the type of fuses installed in switch cabinets

The choice of fuse types installed in the switch cabinet is considered using the FU1 fuse as an example.

The rated current of the consumer, A, which is protected by a fuse, is determined by the formula (25)

The starting current of the consumer, A, which is protected by a fuse, is determined by the formula (17)

The desired value of the fuse fuse current, A, is determined by the formula (63)

By value, a larger standard value of the fuse fuse link current, A, is selected, subject to (64)

The types of other fuses are determined similarly.

Calculation data are entered in table 15

Table 15 - Technical data of the fuses installed in ШР1









Table 15 continued

2.7.3 Selection of enclosure types

The choice of distribution cabinets is made according to the number of fuses, their rated currents, and the degree of protection. The technical data of the ShR1 cabinet are entered in table 16

Table 16 - Technical data of switch cabinet ШР1

2.8 Calculation and selection of distribution networks

A distribution network is a network from distribution cabinets to electrical consumers. Electrical consumers are connected to the SR by means of wires or cables, the totality of which is electrical wiring. Electrical wiring can be open (suspensions, trays, boxes, etc.), or hidden, in which cables or wires are laid hidden in the cable channels of walls and ceilings or in floor preparation pipes.

2.8.1 Selection of cross-sections of conductors for continuous current

To connect electrical consumers to ШР1, hidden laying of cables in floor preparation pipes at a temperature of 25ºС is used. The wiring is made with a VVG brand cable with three phase and one neutral conductors. The cable cores are made of copper, the insulation and sheath are made of polyvinyl chloride, there is no protective cover. The choice of cable sections is considered on the example of one of the sections of the distribution network from ShR1 - section 18N-1.

The rated current connected by this cable, the consumer, A, is determined by the formula (25)

According to the reference data, the nearest higher value of the continuous-admissible current, A, to the rated current of the EA is determined

- the condition is satisfied

In accordance with the value, the VVG cable 31.5 + 11.5 mm² is selected.

The selection of the conductor cross-sections of the remaining sections of the distribution network from ШР2 is carried out in a similar way.

Table 17 - Data for the selection of cross-sections of conductors of the distribution network

site name							Mark, section, mm2
							VVG 31.5+11.5
							VVG 31.5+11.5
							VVG 31.5+11.5
							VVG 31.5+11.5

							VVG 31.5+11.5
							VVG 31.5+11.5
							VVG 31.5+11.5

2.8.2 Checking the selected sections of conductors for compliance with protective devices

The distribution network from ШР1 is protected by fuses installed in the distribution cabinet.

To perform a check, you need to know the following parameters:

protection factor, the value of which is determined from the reference data for a particular protective device (for fuses, since the network does not require overload protection);

operating current of the protective device, A - for fuses, the value is equal to the value of the fuse-link current, A;

value of continuous current, A.

The algorithm for checking the selected sections of conductors for compliance with protective devices is given on the example of one of the sections of the distribution network - section 21-H1.

The condition must be met

- the condition is satisfied

Therefore, the selected cable section corresponds to the protective device. Checking for compliance with other selected sections of conductors is carried out similarly. The verification data are entered in table 17.

2.8.3 Checking the selected conductor cross-sections for allowable voltage loss

Voltage loss is the algebraic difference between the voltage of the power source and the voltage at the connection point of the consumer. The sum of allowable voltage losses of the supply and distribution networks should not exceed 3%.

To determine the voltage loss of a given distribution network, the voltage loss is determined in the section from switch cabinet No. 1 to the most remote consumer, that is, in section 34-H1.

Resistivity, determined by the formula

- specific conductivity, (for copper).

Specific reactance, determined from the reference data ().

The calculated value of voltage loss,%, is determined by the formula

The resulting calculated value, %, is compared with the allowable value for distribution networks, %, provided

- the condition is satisfied

2.8.4 Calculation and selection of pipes

For hidden laying of conductors in floor preparation pipes, steel (electric-welded or water-gas), PVC, polyethylene and polypropylene pipes are used. The choice of pipe material depends on the environmental and process conditions. So, for example, when laying wiring, it is recommended to use steel pipes in explosive and fire hazardous areas of premises, PVC pipes - when laying on non-combustible bases, and polyethylene and polypropylene pipes - only on fireproof bases.

To connect electrical consumers to switch cabinet No. 2, pipe laying of cables of the VVG brand using PVC and steel pipes is used. Pipes are laid at a depth of 0.3 m from the level of the clean floor. Steel pipes are used to carry out the exit of the cable from the floor, as it needs protection from mechanical damage. The cable connection from the steel pipe to the electrical consumer is carried out using a flexible input.

To perform pipe laying of electrical wiring, it is necessary to draw up a special project document "Pipe Procurement List", which indicates the marking of the route, the material and diameter of the pipes, the beginning and end of the route, sections of pipe blanks.

Table 18 - Pipe procurement list

			Sections of the pipe route

					0,5−90?-6,1−120?-0,5
					0,5−90?-1,6−90?-2,7−135?-7,5−135?2−120?-0,3
					0,5−90?-3−135?-4,7
					0,5−90?-2,6−120?-7,4
					0,5−90?-1,6−90?-3,3−135?-5,1−135?-2,8−90?-0,4
					0,5−90?-1,6−90?-3,4−135?-1,5
					0,5−90?-9,4−120?-0,6
					0,5−90?-9,4−120?-0,6

Then a pipe summary is performed, indicating the pipe material and diameter in ascending order: Polyvinyl chloride pipe TU6 - 0.5.1646 - 83 Sh 20 mm = 71.6 m Gas-welded steel pipe GOST 10 704- - 76 Sh 20 mm = 7.7 m

2.9 Choice of location and type of complete transformer substation

Complete transformer substation (KTP - for indoor and KTPN - for outdoor installation) - a substation consisting of transformers and complete switchgear units (KRU or KRUN), supplied assembled or fully prepared for assembly.

Power transformers are divided into dry, oil and non-combustible liquid filled dielectric.

By location on the territory of the facility, the following transformer substations (TS) are distinguished:

separately standing at a distance from buildings;

attached, directly adjacent to the main building from the outside;

built-in, located in separate rooms inside the building, but with transformers rolled out;

intrashop, located inside industrial buildings with

placement of electrical equipment directly in the production or

a separate closed room with the roll-out of electrical equipment to the workshop.

2.10. Selection of the power supply scheme and calculation of supply networks with voltage up to 1 kV

The supply network is the network from the switchgear of the transformer substation to distribution cabinets, lighting panels, and powerful electrical consumers.

The supply network of the workshop is shown in Figure 9.

Figure 9 - Scheme of power supply of the mains

Data for calculation are given in table 19

Table 19 - Data of rated and peak currents of the supply network

2.10.1 Calculation and selection of types of nominal parameters of circuit breakers

Circuit breakers are used in the power supply network to protect them from emergency operation (overloads, short circuits, etc.). The algorithm for selecting the type and nominal parameters of automatic switches is considered on the example of a machine.

The condition must be met

The desired value of the operating current of the thermal element, A, is determined by the formula

The desired value of the current of the magnetic release, A, is determined by the formula

The condition must be met

where is the standard value of the operating current of the thermal element, the value of which is determined from the reference data.

The standard value of the current of the magnetic release, A, is determined by the formula

where k is the cutoff factor, the value of which is determined from the reference data.

The condition must be met

According to the reference data, the type and rating parameters of the circuit breaker are determined. The types of other circuit breakers are defined similarly. The calculation data are entered in table 20.

Table 20 - Type and ratings of circuit breakers

cabinet type

Machine name

designations

Breaker type

Load type

1.25-Ipeak BUT

Highway

linear

2.10.2. Calculation and selection of supply networks with voltage up to 1 kV

The supply networks of this workshop are carried out with cables of the ANRG brand.

An example of the selection of the cross section of the supply line cable is considered on the example of section M1. This section is made with an ANRG brand cable applied openly in the air on cable hangers at a temperature of 25ºC. The selection of the section is made according to the long-term permissible current. Data for selection are given in table 19.

According to the reference data, the nearest higher value of the continuous-admissible current, A, is determined, provided

- the condition is satisfied

In accordance with the value, an ANRG 3120+135 mm2 cable is selected.

The selection of the sections of the remaining cables of the supply network is carried out in a similar way.

The selected cable section is checked for compliance with the protective device - the QF2 circuit breaker (according to Figure 9).

The condition must be met

- the condition is satisfied

Therefore, the selected cable section corresponds to the protective device.

The calculated value of voltage loss is determined,%, according to the formula (68)

- resistivity, the value of which is determined by the formula (67)

- specific reactance, the value of which is determined from reference data (for a cable line up to 1 kV,).

The value of a mathematical function is determined by the corresponding value

The resulting calculated value, %, is compared with the allowable value for distribution networks, %, provided that the condition is met

Therefore, the selected cable section satisfies the requirements.

2.11 Calculation selection of the high voltage supply network

The high-voltage cable is designed to transmit electricity from the central distribution substation (CRS) to the transformer substation (TS). The choice of brand and section of the high-voltage cable depends on the laying conditions, environmental conditions and corrosion.

To connect a complete transformer substation, a high-voltage cable of the AAP2LShVU brand is used, that is, a cable with aluminum conductors, improved paper insulation, and an aluminum sheath.

Armor made of flat metal. The cable is laid in the ground in a trench one at a time. The cable length is 0.9 km. The soil is aggressive towards steel.

The selection of the cable section is made according to the long-term permissible current and the economic current density.

The value of the current flowing through the high side of the transformer, A, is determined by the formula

According to the reference data, the nearest greater value of the continuous-admissible current, A, to the current is determined

In this case, the condition

- the condition is satisfied

In accordance with the value, the cable AAP2LShVU 310 mm2 - 6kV is selected.

The desired value of the cable cross-section is determined by the economic current density, mm2, according to the formula

where - economic density, the value of which is determined from the table

From among the standard values of cable cross-sections, the nearest greater to the value, mm2, is selected, provided

Therefore, the cable m. AAP2LShVU 335 mm2 - 6 kV is selected.

From the found values of the cable cross-sections for continuous current and economic current density, a larger one is selected

Therefore, the cable AAP2LShVU 335 mm2 - 6kV is selected.

The calculated value of voltage loss,%, is determined by the formula (68)

where is determined by formula (67)

determined according to reference data (for a cable line of 6 kV and a cable cross section of 35 mm2).

The value of a mathematical function is determined by the corresponding value

The resulting calculated value, %, is compared with the allowable value for supply networks, % - the condition is met

Therefore, the selected cable section satisfies the requirements.

Then the calculated value of the total voltage loss in the power supply networks is determined,%, according to the formula

The resulting calculated value, %, is compared with the allowable total value for distribution, supply networks and high-voltage lines, % is correct.

2.12 Calculation and selection of a grounding device

For grounding devices, you can use both natural (water and other metal pipes, except for pipelines with combustible substances), and artificial ground electrodes (steel rods driven into the ground and interconnected by a steel strip).

To ground the electrical equipment of the KTP of this workshop, artificial ground electrodes are used - steel bars hammered into the ground and interconnected by a horizontal ground conductor (strip steel) laid at a depth of 0.6 m. The initial data for the calculation are given in table 21

Table 26 - initial data for the calculation and selection of a grounding device

Earth fault current, A, is determined by the formula

The calculated resistance of the grounding device is determined, Ohm

In accordance with the PUE, the value of the resistance of the grounding device, Ohm, is determined, common for high and low voltage installations

Since the earth electrode is made of round steel with a diameter of 20 mm and a length of 5 m each, its resistance is determined by the formula

Since the length of the vertical grounding conductors l and the distance between them a are 5 m, the screening coefficient is determined by the formula

Then, the number of grounding conductors n, pcs, is determined by the formula

Since pcs, it is necessary to take into account the resistance of the horizontal ground electrode

The length of the horizontal strip, m, is determined by the formula

The required resistance of vertical grounding conductors, Ohm, is determined by the formula

The specified number of vertical ground electrodes, pcs, is determined by the formula

List of sources used

1. Barybin Yu. G., Krupovich V. N. Handbook for the design of power supply. - M .: Energy, 1990

2. Barybin Yu. G., Fedorov L. E. Reference book on the design of electrical networks and electrical equipment. - M .: Energy, 1990

3. Konyukhova E. A. Power supply of objects. - M .: Publishing house "Mastery"; graduate School, 2001

4. Lipkin B. Yu. Power supply of industrial enterprises. - M .: Higher school, 1990

5. Postnikov N. P. Power supply of industrial enterprises. - M .: Stroyizdat, 1990

6. Rules for the installation of electrical installations (PUE). — M.: Energoatomizdat, 2002

7. Sibikin Yu. D., Yashkov V. A. Power supply of enterprises and installations oil industry. - M .: OAO Publishing House Nedra, 1997

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INTRODUCTION

Modern energy is characterized by the increasing centralization of the production and distribution of electricity. To ensure the supply of electricity from power systems to industrial facilities, installations, devices and mechanisms, power supply systems consisting of networks with voltage up to 1000V and above and transformer, converter and distribution substations are used. To transmit electricity over long distances, ultra-long-distance power lines (TL) with high voltage are used: 1150 kV AC and 1500 kV DC. In modern multi-span industrial workshops, packaged transformer substations (KTS), packaged distribution units (KRU), power and lighting busbars, switching, protection, automation, control, accounting, and so on are widely used. This creates a flexible and reliable power supply system, as a result of which the cost of electrical supply of the workshop is significantly reduced.

The purpose of this diploma project is to design the power supply of a mechanical repair shop with minimal capital and operating costs and ensure high safety. The main consumers of electrical energy are industrial enterprises. They consume more than half of all energy generated in our country.

The relevance of this graduation project lies in the fact that the commissioning of new enterprises, the expansion of existing ones, the growth of power supply, the widespread introduction of various types of electrical technologies in all industries put forward the problem of their rational power supply.

At present, the electric power industry of Russia is the most important life-supporting industry of the country. It includes more than 700 power plants with a total capacity of 215.6 MW.

The distribution system of such a large amount of electricity in industrial enterprises must have high technical and economic indicators and be based on the latest achievements of modern technology. Therefore, the power supply of industrial enterprises should be based on the use of modern competitive electrical equipment.

Based on the argument about the relevance of the chosen topic, it is possible to determine the target orientation of the work.

The purpose of the graduation project: to give a brief description of the mechanical repair shop for electrical loads, mode of operation, type of current, supply voltage and make a calculation of electrical loads for the selection of electrical equipment of the substation.

The Mechanical Repair Shop (RMS) is designed to repair and adjust electromechanical equipment that is out of order. It is one of the workshops of a metallurgical plant that smelts and processes metal. The RMC has two sections in which the electrical equipment necessary for repair is installed: turning, planing, milling, drilling machines, etc. ESN from the main step-down substation (GPP). The distance from the GPP to the TP is 3.3 km, and from the power system (ESN) to the GPP is 14 km. The voltage at the GPP is 10kV. Number of shifts - 2. Consumers of the shop have 2nd and 3rd category of ESN reliability.

1. GENERALPART

1.1 Briefcharacteristictechnolologicalprocessproduction

Repair and mechanicalshop

The mechanical repair shop is structural unit enterprises, headed by the foreman and subordinate to the chief mechanic.

The repair and mechanical shop performs work to ensure the normal functioning of the repair and maintenance service related to the repair, modernization of equipment and molds, the manufacture of spare parts produced in accordance with the approved annual, monthly schedules.

The head of the mechanical repair shop is appointed and dismissed by the director.

Persons with higher technical education and work experience in engineering and technical positions in the field of equipment repair for at least three years or secondary specialized education and work experience in managerial positions for equipment repair for at least five years are appointed to the position of head of the mechanical repair shop.

The head of the mechanical repair shop in his work is guided by the orders and instructions of the ministry, administration, orders of the director, orders of the chief engineer and chief mechanic, as well as repair manuals and this regulation.

Head of the mechanical repair shop:

manages the production and economic activities of the workshop for the repair, modernization of equipment and molds, manufacturing non-standard equipment and tools, as well as the manufacture of spare parts and maintenance equipment and molds, buildings and structures of the mechanical repair shop;

participates in the development of current and long-term plans for the repair of equipment and forms, buildings, structures, as well as work plans for individual services, organizes the development and communication to the executors of tasks and repair schedules;

ensures the implementation planned assignments on time, the rhythmic work of the workshop, increasing the productivity of repair workers, reducing the cost of repairs when high quality repair work, the efficient use of fixed and working capital, maintaining the correct balance between the growth of labor productivity and wages;

carries out work on the introduction of scientific organization of labor, improvement of the organization of production, its technology, mechanization and automation production processes, prevention of marriage, improvement of product quality, use of reserves to increase labor productivity and profitability of production, reduce labor intensity and production costs;

organizes planning, accounting and reporting on production activities work on the development and strengthening of economic accounting, the improvement of labor rationing, the correct application of forms and systems of wages and financial incentives, generalization and dissemination of advanced methods and techniques of labor, the development of rationalization and invention;

ensures the technically correct operation of equipment and other fixed assets and the implementation of their repair schedules, safe and healthy working conditions, as well as the timely provision of benefits to employees on working conditions;

together with public organizations organizes socialist competition, conducts educational work in the collective.

1.2 Characteristicsconsumerselectricity,categorieselectricity supply

Characteristics of electricity consumers and the definition of the category of power supply. The power supply of the object can be carried out from its own power plant, energy system in the presence of its own power plant.

The requirements for the reliability of power supply from power sources are determined by the power consumption of the facility and its type.

Receivers of electrical energy in relation to ensuring the reliability of power supply are divided into several categories. The first category is electrical receivers, the interruption of power supply of which can lead to a danger to people's lives, significant economic damage, damage to expensive equipment, disruption of a complex technological process, and mass product defects. From the composition of power receivers of the first category, a special group (zero category) of power receivers stands out, the uninterrupted operation of which is necessary for an accident-free shutdown of production in order to prevent a threat to human life, explosions, fires and damage to expensive equipment.

The second category is electrical receivers, the interruption of power supply of which leads to massive undersupply of products, mass downtime of workers and mechanisms. The permissible interval of the duration of a power outage for power consumers of the second category is not more than 30 minutes.

The third category - all other electrical receivers that do not fit the definition of the first and second categories. Power receivers of the first category should be provided with electricity from two independent power sources, when one of them is disconnected, switching to the backup should be carried out automatically. According to the definition of the PUE, independent power sources are those on which voltage is maintained when it disappears from other sources that feed these power consumers.

According to the PUE, two sections or busbar systems of one or two power plants or substations can be classified as independent sources, subject to the following conditions: - each section or busbar system is powered by independent sources. - bus sections are not interconnected or have a connection that automatically turns off when one of the bus sections fails to operate normally. For the power supply of power receivers of a special group, an additional third power source should be provided, the power of which should ensure an accident-free shutdown of the process.

It is recommended to provide power receivers of the second category from two independent power sources, switching can not be carried out automatically. The power supply of power receivers of the third category can be carried out from one source, provided that the power supply interruptions necessary for the repair and replacement of damaged equipment do not exceed one day. The electrical equipment of the mechanical repair shop belongs to categories 2 and 3 and can be powered from one source, provided that power supply interruptions do not exceed one day. The choice of the type of current, voltage and scheme of internal power supply. Purpose of electrical networks. Electrical networks are used to transmit and distribute electrical energy to shop consumers of industrial enterprises.

Energy consumers are connected through intrashop substations and distribution devices using protective and starting devices.

Electric networks of industrial enterprises are carried out internal (workshop) and external. External voltage networks up to 1 kV are very limited in distribution, tk. at modern industrial enterprises, shop loads are powered from in-shop or attached transformer substations.

The choice of electrical networks radial power circuits are characterized by the fact that from the power source, for example, from a transformer substation, lines depart directly to power powerful electrical receivers or separate distribution points, from which smaller electrical receivers are fed by independent lines.

Radial schemes provide high reliability of power supply to individual consumers, because. accidents are localized by switching off the circuit breaker of the damaged line and do not affect other lines. All consumers can lose power only if there is a fault on the PTS busbars, which is unlikely. Owing to rather reliable design of cases of these PTS. Main power circuits are widely used not only to power many electrical receivers of one technological unit, but also to compare a large number of small receivers that are not connected by a single technological process.

Trunk circuits made by busbars provide high reliability, flexibility and versatility of workshop networks, which allows technologists to move equipment inside the workshop without significant installation of electrical networks. Due to the uniform distribution of consumers within the mechanical repair shop, as well as low cost and ease of use, the main power supply scheme is selected.

1 .3 Choicekind,voltage

Three-phase networks are made three-wire for voltages over 1000V and four-wire - up to 1000V. The neutral wire in a four-wire network ensures the equality of phase voltages with uneven loading of phases from single-phase power consumers.

Three-phase networks for a voltage of 380 / 220V (in numerators - linear, in denominators - phase) allow you to power three and single-phase installations from one transformer. Electrical networks are carried out mainly on a three-phase alternating current system, which is the most appropriate, since electricity can be transformed in this case. With a large number of single-phase electrical receivers, single-phase branches are carried out from three-phase networks.

1. 4 Classificationpremisesonexplosively- andfire departmentsecurity

The fire-fighting measures provided for in the design of buildings and installations depend primarily on the fire or explosion hazard of the industries located in them and individual premises. Premises and buildings as a whole are divided according to the degree of fire or explosion hazard into five categories in accordance with ONTP-24.

Category A - these are rooms in which flammable liquids with a flash point of vapors of 28 o C and below or combustible gases are used in such quantities that they can form an explosive mixture with air, the explosion of which will create a pressure of more than 5 kPa (for example, gasoline warehouses ).

Category B - these are rooms in which combustible fibers or dust passing into a suspended state, as well as flammable liquids with a vapor flash point of more than 28 o C are emitted in such an amount that the mixture they form with air during an explosion can create a pressure of more than 5 kPa ( shops for the preparation of hay flour, sacking and grinding departments of mills and grits, fuel oil facilities of power plants and boiler houses).

Category B - these are premises in which solid combustible substances are processed or stored, including those emitting dust or fibers that are unable to create explosive mixtures with air, as well as flammable liquids (sawmill, carpentry and compound feed shops; shops for the primary dry processing of flax, cotton ; feed kitchens, grain cleaning departments of mills; closed coal warehouses, warehouses of fuel and lubricants without gasoline; electrical switchgear or substations with transformers).

· Category G - these are premises in which fuel is burned, including gas, or non-combustible substances are processed in a hot, red-hot or molten state (boiler rooms, forges, engine rooms of diesel power plants).

Category D - these are premises in which non-combustible substances are in a practically cold state (pumping irrigation stations; greenhouses, except for those heated by gas, shops for processing vegetables, milk, fish, meat).

The categories of fire hazard productions to a large extent determine the requirements for design and planning solutions for buildings and structures, as well as other issues of ensuring fire and explosion safety. They meet the standards process design or special lists approved by ministries (departments). Guidelines for this can serve as "Instructions for determining the category of production for explosive, explosive and fire hazard" (SN 463-74) and "Methodology for categorizing chemical industry production for explosive, explosion and fire hazard".

The conditions for the occurrence of a fire in buildings and structures are largely determined by the degree of their fire resistance (the ability of a building or structure as a whole to resist destruction during a fire). Buildings and structures according to the degree of fire resistance are divided into five degrees (I, II, III, IV and V). The degree of fire resistance of a building (structure) depends on the flammability and fire resistance of the main building structures and on the spread of fire through these structures.

By flammability, building structures are divided into fireproof, slow-burning and combustible. Fireproof structures are made of non-combustible materials, slow-burning - from slow-burning or from combustible, protected from fire and high temperatures by fireproof materials (for example, a fire door made of wood and covered with asbestos sheet and roofing steel).

fire resistance building structures are characterized by their fire resistance limit, which is understood as the time in hours after which they lose their bearing or enclosing capacity, that is, they cannot perform their normal operational functions.

The loss of bearing capacity means the collapse of the structure.

Loss of enclosing capacity - heating of a structure during a fire to temperatures, the excess of which can cause spontaneous ignition of substances located in adjacent rooms, or the formation of through cracks or holes in the structure, through which combustion products can penetrate into neighboring rooms.

The fire resistance limits of structures are established empirically.

To do this, a life-size sample of the structure is placed in a special furnace and at the same time it is subjected to the required load.

The time from the start of the test to the appearance of one of the signs of loss of bearing or enclosing capacity is considered the fire resistance limit. The limiting heating of a structure is an increase in temperature on an unheated surface by an average of more than 140 o C or at any point on the surface by more than 180 o C compared to the temperature of the structure before testing, or more than 220 o C regardless of the temperature of the structure before the test.

Figure 1 - Layout plan of the electrical equipment of the mechanical repair shop

Unprotected metal structures have the lowest fire resistance limit, and reinforced concrete structures have the highest.

The required degree of fire resistance of industrial buildings of industrial enterprises depends on the fire hazard of the industries located in them, the floor area between the fire walls and the number of storeys of the building. The required degree of fire resistance must correspond to the actual degree of fire resistance, which is determined according to the tables of SNiP P-2-80, containing information on the fire resistance limits of building structures and the limits of fire propagation through them.

For example, the main parts of buildings of I and II degrees of fire resistance are fireproof and differ only in the fire resistance limits of building structures. In buildings of the I degree, the spread of fire through the main building structures is not allowed at all, and in buildings of the II degree, the maximum limit of the spread of fire, which is 40 cm, is allowed only for internal load-bearing walls (partitions). The main parts of buildings of the V degree are combustible.

The limits of fire resistance and the spread of fire for them are not standardized.

2. SPECIALPART

2 .1 Initialdataforcalculation

2. Short circuit currents on the GPP buses 10.5 kA.

3. The length of the cable line from the GPP to the TP is 3.3 km.

5. Installed lighting power 90 kW.

6. The data of electrical receivers of the workshop are given in table 1.

Table 2.1

Shop electrical receiver data

		Nom. power, kWt
Rotary lathe
lathe
Milling machine
Drilling machine
Induction furnace

Fan
Welding rectifier
Overhead crane at duty cycle = 25%

2.2 Calculationelectricalloads

The calculation of electrical loads is the first and one of the most important design stages, because based on the results of such a calculation, in the future, the power of compensating devices, power transformers, converters, electrical equipment of substations is selected, the sections of current-carrying parts (wires, cables, tires) are determined, the protection of electrical installations is calculated, etc. There should be no errors in the calculation. Overestimation of the design capacity will lead to large additional costs; understatement - to equipment failure, false alarms of protection, etc. The correct definition of the calculated electrical loads ensures that the equipment will operate economically, reliably, and energy losses will be minimal.

2 .2. 1 Calculationelectricalloadsmethodorderlydiagrams

This method allows you to determine the calculated electrical loads with the smallest error, therefore it is the main one for calculating loads. Rated power of electrical receivers without taking into account the lighting load (according to Table 2.1)

In the presence of intermittent duty motors, their rated power is reduced to continuous duty

where P pass - nameplate power (according to the task), kW;

PV - duration of inclusion, in relative units.

The total rated power of electrical receivers of the workshop

Average active and reactive power for the most loaded shift

where K and - the utilization factor of a group of electrical receivers of one operating mode;

P n - rated power of electrical receivers, kW.

We write out from Appendix 1.1 the values \u200b\u200bof K and and cos in table 2.2

Table 2.2

The values of K and and cos

Names of electrical receivers	Qty. PCS	power, kWt
Rotary lathe
lathe
Milling machine
Drilling machine
Induction furnace

Fan
Welding rectifier
Overhead crane

The values of tg c are determined by the formula

Group utilization rate

The effective number of power receivers n e is such a number of power receivers of the same power that are homogeneous in operating mode, which gives the same value of the calculated load as a group of power receivers that are different in operating mode and power.

According to diagrams or tables. 2.13 determine the coefficient of the maximum.

At k u = 0.4 and n e = 14, the maximum coefficient k m = 1.32 according to .

Estimated power of the lighting load

where X.o. - coefficient of demand for lighting load;

pH.o. - installed power of electric lighting, kW

According to X.o. = 0.85.

By order

Estimated active and reactive loads of a given group of electrical receivers

2. 3 Choicecompensatingdevices

If compensating devices are not installed, then all the rated power is transferred to the power receivers from the power plant

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Figure 2 - Transmission of electricity without the use of CH

If compensating devices with a total power Q ku are connected to the substation buses or terminals of a group of power receivers, then less reactive power will be transmitted from the power plant, and therefore less apparent power.

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Figure 2.1 - electricity using CHP

With a decrease in the transmitted total power from the value of S p to S p ", the power factor cos increases.

On the busbars of the substation, the power factor must be within cos n = 0.92 ... 0.95. If the calculated power factor cos p is less than the standard cos n, it is necessary to install a compensating device.

Power of compensating devices:

tg p - corresponds to the calculated power factor;

tg n - corresponds normative coefficient power.

When choosing the power of compensating devices, a 10-15% reserve should be provided to ensure acceptable voltage deviations in post-accident modes.

In low voltage networks, it is not recommended to split the required power of capacitor banks to a value of less than 30 kvar due to the increase in unit costs for disconnecting equipment, measuring instruments and other equipment per installed kilovolt-ampere of the battery.

2. 3.1 Calculationcompensatingdevices

Estimated power factor

The calculated power factor is less than the standard, so it is necessary to install compensating devices.

Power compensating devices

From Appendix No. 2, we select for two sections of the LV busbars two banks of static capacitors of the UKM-0.4-20-180UZ type with a capacity of 180 kvar. each.

Reactive power transmitted from the power plant

Apparent power transmitted from the power plant

Examination:

We accept for installation unregulated batteries of static capacitors with a connection diagram according to fig. 2.3.

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Figure 2.2 Scheme for connecting capacitor banks to U = 0.38-0.66 kV through a switch and a fuse

2.4 Choicenumbersandpowerpowertransformers

The choice of the number and power of power transformers is made in the following order:

1. The number of transformers is determined based on the required degree of power supply reliability, i.e. taking into account the category of electrical receivers.

2. Options for the power of power transformers are outlined, based on the calculated power of the substation and a number of rated powers of transformers (Table 2.3).

Table 2.3

Rated power of transformers

3. Options are compared in terms of technical indicators, taking into account the permissible overload of transformers in operating and emergency modes.

4. Economic indicators are determined by options. The most economical option is applied to execution.

2.4.1 Choicenumbersandpowerpowertransformers

The loads of the mechanical repair shop belong to category II consumers. Therefore, two power transformers must be installed at the substation.

Active power losses in transformers

Reactive power losses

Apparent power loss

Full design power transmitted from the GPP to the TP of the shop

Power transformers

The value of K s is taken depending on the category of power receivers according to the degree of reliability of power supply. For workshops with a predominant load of category II with a two-transformer substation with possible redundancy -.

We accept the value of K s \u003d 0.75

Single transformer power

where n is the selected number of transformers.

We choose two transformers of the TM-400/10 type with a power of 400 kVA, which has the technical data given in table 2.4.

Table 2.4

Transformer technical data

We check the selected transformers according to the actual load factor:

Kzdeist? Kzprin

2.5 Choiceschemeelectricalconnectionssubstations

Schemes of workshop TP are determined by the characteristics of electrical receivers and schemes of inter-shop and intra-shop distribution of energy.

Schemes with blind connection of the transformer to the supply line (Fig. 4.1) are used:

* in the absence of receivers with voltage over 1000V;

* with radial power supply according to the block diagram, the line is a transformer.

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Figure 2.4 Scheme of blind connection of the transformer to the supply line

Switching devices at the high voltage input must be installed in the following cases:

* when powered by a power source administered by another operating organization.

* when removing the power source from the substation by 3-5 km;

* when powered by overhead lines;

* if a disconnecting device is needed according to the conditions of protection, for example, for the effect of gas protection on a load switch (Fig. 2.5);

* in the main power supply circuits, a disconnector or a load switch with fuses is installed in order to selectively turn off the transformer if it is damaged (Fig. 2.6);

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Figure 2.5 Scheme of connecting a transformer to a line through a load switch

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Figure 2.6 Scheme of connecting the transformer to the main line

* when a more reliable power supply is required, when substation transformers are often turned off and on; when short-circuit currents are high and the switching capacity of the fuses is not enough to disconnect in the event of a short circuit.

The non-partitioned busbar system is used when supplying one line and non-responsible consumers of the III reliability category (Fig. 4.1, 4.2, 4.3, 4.4).

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Picture. 2.7 - Scheme of connecting the transformer to the line through the oil circuit breaker

The presence of consumers of category II requires sectioning the tires with a normally open switch or disconnector (Fig. 4.5). Each section is powered by a separate line. The sectional apparatus is switched on when the bus voltage fails and the HV supply line is disconnected.

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Figure 2.8 - Scheme of electrical connections of the substation of the mechanical repair shop

2.6 Calculationhigh voltagefeedinglines

The conductors of electrical networks from the current passing through them, according to the Joule-Lenz law, heat up. Excessively high heating temperature of the conductor can lead to premature wear of the insulation, deterioration of contact connections and fire hazard. Therefore, the maximum allowable values for the heating temperature of the conductors are set depending on the brand and material of the conductor insulation. The current flowing through the conductor for a long time, at which the highest long-term permissible heating temperature of the conductor is established, is called the maximum permissible heating current I add. Its value depends both on the brand of wire or cable, and on the laying conditions and ambient temperature. To select the cross-sections of the cores of cables and wires for heating, the rated current is determined and, according to the tables given in,, the standard cross-section corresponding to the nearest higher current is determined.

Section selection condition

where I p - design current, A;

K correction - correction factor for laying conditions.

With two cables laid side by side, the K correction values are taken according to

The values of K correction for ambient temperature at ground temperature other than +15°C and at air temperature other than +25°C are taken according to .

2. 6 .1 Calculationhigh voltagefeedinglines

Current flowing through the cable line in normal mode

where K z is the load factor of the transformer.

U n - rated voltage on the high side, kV;

S T - transformer power, kVA.

Taking into account the expansion of the capacity of the workshop, we accept the rated current equal to

According to the table, we accept a three-core power cable with aluminum conductors of the ASB brand - 3x16 (A - aluminum core; paper insulation; C - lead sheath; B - armored with two steel tapes with an outer jute cover).

2.7 Calculationcurrentsshortclosures

We draw up a calculation scheme (Fig. 2.9).

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Figure 2.9 - Calculation scheme

According to the design scheme, we draw up an equivalent circuit (Fig. 2.10).

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Picture. 2.10-Equivalent Circuit

We choose the basic conditions:

For point K 1

For point K 2

For point K 1

For point K 2

We determine the resistance of the network elements.

System power

System resistance in relative units

Cable line resistance in relative units

With the power of transformers, active resistance is taken into account

where r is the relative active resistance of the transformer windings, referred to the rated power.

Relative active resistance of the transformer windings (with the power of transformers)

In our case, the rated power of the transformer is 400 kVA, so the active resistance of the transformer is taken into account.

Resulting resistances up to point K 1

Resulting resistances up to point K 2

Short circuit currents and power for point K 1

Effective value of the initial short-circuit current

When (), the periodic component of the short circuit current does not change and the effective values

Surge short circuit current

where K y is the shock coefficient.

where T a is the time constant.

Short circuit power

We determine the currents and short circuit power for point K 2

Initial current at the moment of short circuit

According to table 2.5, we accept for the LV side of a 400 kVA transformer,

Table 2.5

Ku values

The calculation data are summarized in Table 2.6.

Table 2.6

Calculation data are summarized

2.8 Choiceelectrical equipmentsubstations

The general requirement for the electrical equipment of a substation is to ensure normal operation and its resistance to the effects of short-circuit currents.

2.8 .1 Choiceelectrical equipmentsubstationson thesideVN

Checking the cable cross-section for the action of short-circuit currents

The high-voltage supply lines selected in section 5 must be checked for the thermal effect of short-circuit currents.

Minimum cable cross-section for thermal stability for a three-phase short circuit.

where C - coefficient; for cables with a voltage of 6-10 kV with copper conductors C = 140, with aluminum conductors C = 95, for aluminum tires C = 95, for copper tires C = 170;

t pr - reduced time, s.

Reduced time

t pr \u003d t pr.p. +t pr.a. , (2.31)

where t pr.p. - time of the periodic component of the short-circuit current, s;

t pr.a. - time of the aperiodic component of the short-circuit current, s;

The value of t pr.p. is determined from the curves t pr.p. = () depending on the actual short-circuit current flow time t.

t \u003d t s + t off (2.32)

where t C - protection time, s;

t off - the time of operation of the switching equipment, s;

According to the assignment, the protection action time (according to the conditions of selectivity) t c = 0.5 s, the operation time of the GPP oil circuit breakers t off = 0.14 s.

t = 0.5 + 0.14 = 0.64 s

and t = 0.64 with t pr.p. = 0.5 s according to .

The time of the aperiodic component of the short-circuit current at a real time t< 1 с не учитывается.

In general

In our case

t pr \u003d t pr.p. = 0.5 s

For the ASB-3x16 cable, the coefficient C = 95, at I = 0.85kA = 850A

The selected cross-section of the cable cores is 16 mm 2 > 6.35 mm 2, therefore, the ASB - 3x16 cable satisfies the calculated current of thermal resistance to short-circuit currents.

2.8 .2 Choiceswitchesloads

In section 4, a decision was made to install load break switches with fuses on the HV side of the substation.

Conditions and data for selection are given in Table 2.7.

Table 2.7

Fuse switch-disconnector data

We select the VNPu-10 / 400-10zUZ load switch in accordance with the PKT101-10-31.5-12.5UZ fuses with the rated current of the cartridge I n.p = 31.5A > I p = 24A and the rated breaking current I off = 12, 5kA. When choosing fuses for breaking capacity, the conditions and must be met.

In our case

2.8 .3 Choiceelectrical equipmentsubstationson thesideHH

Tire selection

The switchgear busbars are selected according to the rated current and checked for a short circuit mode.

Tire Selection Conditions

where I n - long-term permissible tire load current, A

where k 1 - correction factor, when the tires are horizontal k 1 = 0.92;

k 2 - coefficient for multi-band tires;

k 3 - correction factor at ambient temperature other than +25C.

Estimated current according to the formula (5-2)

We select aluminum painted single-strip tires 60x8mm in size, having a permissible current of 1025A when placed vertically.

When the tires are flat

To check tires for dynamic stability, we determine the calculated load

where l is the distance between the support insulators, cm;

a is the distance between the axes of the phases, see

According to the assignment, l \u003d 50 cm; a = 10 cm.

Moment of resistance of tires when installed flat

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Picture. 2.11 - Flat tire arrangement

Maximum bending moment with more than 2 spans

bending stress

Tire test condition for dynamic stability:

The highest allowable bending stress G add is

for copper tires 130MPa;

for aluminum busbars 65MPa.

5.5MPa< 65МПа, следовательно по электродинамической устойчивости шины проходят.

To check the tire for thermal stability, the minimum cross section is determined by the formula

The section of the selected tires is 50x5 = 250 mm 2 >71 mm 2, therefore, the tire passes in terms of thermal resistance.

2.8 .4 Choiceautomaticswitches

Circuit breakers are selected according to rated voltage, rated current and switching capacity.

We select a three-pole circuit breaker type BA53-41.

Table 2.8

Circuit breaker data

2. 8 .5 Choiceknife switches

Knife switches are selected according to the rated voltage and current and checked for electrodynamic and thermal resistance to short-circuit currents.

We choose a three-pole knife switch of the P2115 series.

Table 2.9

Breaker data

For the R2115 knife switch, according to I t calc = 500 kA at t k = 1 s.

3. MOUNTINGELECTRICAL EQUIPMENT

3.1 Appointment,device,classificationelectricaldevices

Electrical devices (EA) are called electrical devices designed to control the flow of energy and information, as well as the modes of operation, control and protection of technical and electrical systems and their components.

One of the main features of the classification of EA is their operating (nominal) voltage, according to which they are divided into low (up to 1000 V) and high (over 1000 V) voltage devices.

Low voltage devices mainly perform the functions of switching and protecting electrical circuits and devices (circuit breakers, contactors, starters, relays, knife switches and batch switches, control buttons, toggle switches and other devices) and regulating the parameters of technical objects (stabilizers, voltage regulators, power and current, amplifiers, sensors of various variables).

High voltage devices are divided into switching (switches, load switches, disconnectors), measuring (measuring current and voltage transformers, voltage dividers), compensating (shunt reactors), complete switchgears.

According to their design, the devices are divided into electromechanical, static and hybrid. The main feature of electromechanical devices is the presence of moving parts in them, for example, a contact system for switching devices. Static devices are built using semiconductor and magnetic elements and devices (diodes, transistors, thyristors and other semiconductor devices, magnetic amplifiers, etc.). Hybrid devices are a combination of electromechanical and static devices. Electrical devices are also classified:

* according to the value of operating currents - low-current devices (up to 5A) and high-current devices (over 5A);

* by the nature of the current - direct and alternating current devices;

* according to the frequency of the operating voltage - devices with normal (up to 50 Hz) and increased (from 400 to 10,000 Hz) voltage frequency.

Manual control devices include low-power command devices - buttons, control keys and various command devices (commander controllers), with the help of which the switching of electrical control circuits and the supply of control commands to the EA are carried out.

Control buttons. Control buttons differ in size - normal and small-sized, in the number of NO and NC contacts, in the shape of the pusher, in the magnitude and type of current and voltage, in the degree of protection from environmental influences. Two, three or more buttons mounted in one housing form a push-button station. On fig. 3.1, a is shown a conditional image of single-circuit buttons with closing (SBI button) and opening (SB2 button) contacts. The contacts of buttons and other electrical devices on the diagrams are depicted in the so-called normal state, when they are not subjected to mechanical, electrical, magnetic or any other impact. Double circuit pushbuttons have both pairs of pins shown with a single drive.

Figure 3. Conditional images: a - control buttons; b - control key; c - electrical contacts

Control keys (universal switches). These devices have two or more fixed positions of the control handle and several make and break contacts. On fig. 3.1, b shows a switch with three fixed positions of the handle. In the middle position of the handle (position 0), contact SM1 is closed, which is indicated by a dot in the diagram, and contacts SM2 and SM3 are open. In position 1 of the key, contact SM2 closes and SM1 opens, in position 2, vice versa. On fig. 3.1, in shows making and breaking contacts.

Controllers (commanders) are devices for switching several low-power (load current up to 16 A) electrical circuits controlled by a handle or pedal with several positions. Their electrical circuit is depicted similarly to the circuit of control keys and switches.

Manually operated power switching devices include knife switches, packet switches, controllers and circuit breakers.

Knife switches are simple switching devices designed for non-automatic infrequent closing and opening of power electrical circuits of direct and alternating current with voltage up to 500V and current up to 5000A. They differ in the amount of switched current, the number of poles (switched circuits), the type of handle drive and the number of its positions (two or three).

Package switches are a kind of knife switches, characterized in that their contact system is recruited from separate packages according to the number of poles (switched circuits). The package consists of an insulator, in the grooves of which there is a fixed contact with screw terminals for connecting wires and a spring moving contact with a spark extinguishing device.

A variety of knife switches are switch-disconnectors with various types of drive - lever, with a central handle, driven by a flywheel or rod.

Controllers are multi-position electric devices with manual or foot drive for direct switching of power circuits, mainly electric motors. There are two types of power controllers: cam and magnetic.

Cam controllers are characterized by the fact that the opening and closing of their contacts is provided by cams mounted on the drum, which are rotated using a handle, handwheel or pedal. Due to the profiling of the cams, the necessary switching sequence of the contact elements is ensured.

Magnetic controllers are a switching device, which includes a controller and power electromagnetic devices - contactors. The controller with the help of its contacts controls the coils of the contactors, which already switch the power circuits of the engines with their contacts. The service life of magnetic controllers under the same conditions is significantly higher than that of cam controllers, which is determined by the high switching capacity and wear resistance of electromagnetic contactors.

Magnetic controllers have found their main application in the electric drive of crane mechanisms, the operation of which is characterized by a high frequency in...

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1 Brief description of the electrical receivers of the workshop according to the mode of operation and the category of uninterrupted power supply

The workshop houses fans, pumps, machine tools, overhead cranes, automatic lines, conveyors, arc welding machines and electric furnaces and resistance. The list of electrical equipment located in the workshop, its installed capacity, quantity are given in Table 1.1.

There are consumers in the workshop with long-term and intermittent (PKR) modes of operation.

PKR is a mode in which the temperature rises during the switch-on time, decreases during the pauses, however, the heating during the cycle of this electric receiver does not reach a steady temperature, and during the pause the temperature does not reach the ambient temperature.

Duration of inclusion for anti-ship missiles:

where t< 10 мин - среднее время цикла.

Electric motors of overhead cranes and arc welding machines operate in the PKR (this mode is shown in Figure 1 (b));

Long-term mode is a mode in which the temperature of the ED increases exponentially and after a certain time reaches a steady value.

EP of continuous operation are characterized by the inclusion factor:

Electric drives of pumps, fans and machine tools operate in continuous mode.

Table 1.1 - List of electrical loads of the shop

	Name of the mechanism or unit		Rust, kW
	Milling machine
	lathe
	Automatic line
	Fan

	Automatic line
	arc welding machine
	Induction oven
	Electric resistance furnace
	Overhead crane
	Conveyor

The foundry shop must be classified as category I consumers, the interruption in the power supply of which can lead to a danger to human life or significant material damage associated with equipment damage, mass product defects or a long-term disruption of a complex technological production process.

Consumers of electrical energy of category I must have two power sources and ATS (automatic transfer switch) on the sectional switch.

2 Selection of the voltage of the workshop network and the power supply system for the power load and lighting

The workshop network can be made for voltages of 220 and 380 AT.

Voltage 660 V should be used in enterprises where there are a large number of electric motors in the power range of 200 - 600 kW. Switching the power supply of electrical consumers from 380 V to 660 V reduces the cost of building a low-voltage cable network by about 30% and reduces the loss of electricity in this network by 1.3-1.4 times. The introduction of a voltage of 660 V provides a reduction capital costs relative to the total cost of electrical installations of a standing enterprise by 0.5-1.5%.

In the workshop under consideration, the maximum power of the electric motor is 75 kW, so the efficiency of introducing a voltage of 660 V is negligible.

For the installed consumers of electricity in the workshop, the main supply voltage is 380 V. The lighting is supplied with a voltage of 220 V.

Thus, 380/220 V is selected as the main voltage in the shop.

Lighting and power loads will be powered by common workshop transformers 10/0.4 kV.

3 Selection of electric motors, starting and protective equipment

According to the PUE, for driving mechanisms that do not require speed control, regardless of their power, it is recommended to use synchronous or asynchronous electric motors with a squirrel-cage rotor. Usually, engines of the same series are selected for one workshop.

We choose asynchronous motors with a squirrel-cage rotor of the AIR series with a voltage of 380 V, since they are simple in design, cheap and do not require speed control.

The AIR series covers the range of nominal powers from 0.06 to 400 kW. Engines are available for speeds of 3000, 1500, 1000, 750, 600 and 500 rpm.

The motors of this series are intended for general use in industry in moderate climates, in non-explosive environments that do not contain aggressive gases and vapors that destroy metals and insulation, and conductive dust. AIR series motors are designed to operate on AC mains with a frequency of 50 Hz. They can be operated with mains voltage deviations from the nominal within -5 - +10% and frequency deviations of 2.5% from the nominal value.

For the crane, we accept asynchronous motors of the 4MTF series (with a phase rotor), 4MTKF (with a squirrel-cage rotor). These are intermittent duty motors. Used on heavy duty cranes. The main operating mode PV 25%.

Conditions for choosing electric motors:

The choice of starting and protective equipment is made according to the expression (3.2):

where is the rated current of the release, A;

Rated current of the electric motor, A.

The values given in the catalogs for asynchronous electric motors are interconnected by the following dependencies:

where - rated power, kVA;

Rated current, A;

Rated power, kW;

Rated power factor;

Efficiency at rated load and parameters

Types of engines and their technical characteristics are given in table 3.1.

Table 3.1. - Choice of motors for electrical receivers

EP name

Qty.

R,

Motor data

engine's type

u,

h,

lathe

Milling machine

Automatic line

Fan

Automatic line

bridge-howl

cargo lifting

movement carts

movement crane

Conveyor

AIR180M2U3

Asynchronous

Unified Series (Interelectro)

Binding to installation and mounting dimensions

Rotation axis height, mm

Installation dimension along the length of the bed

Number of poles

Modification with built-in temperature protection

Let's choose an electric motor, starting and protective equipment for a lathe, P=18kW.

From choose HELL AIR180S4 with Pn=18.5 kW; cos=0.85; =90%;

n =1500 rpm.

Calculate by expression (3.5):

.

We will use the products of the German company ABB as starting and protective equipment. All products are manufactured and tested according to the latest national and international standards. Surpass existing analogs in technical characteristics, functionality, switching capability, ease of operation and installation.

The selected equipment provides the following types of protection:

Protection of motors is carried out by automatic switches of the MS series. ABB motor protection circuit breakers of the MS series are designed to protect motors from short circuits and overheating of the winding.

-- response characteristic MS corresponds to characteristic D, which allows the machine not to respond to inrush currents.

-- smooth adjustment of the thermal setting allows you to more accurately adjust the machine to the required current value in order to prevent overload and burnout of the motor.

-- the terminals are protected from accidental contact, and the monobloc design guarantees maximum operational safety.

-- fastening of the automatic machine is carried out on a DIN rail.

-- Depth of protection of the motor can be increased by separately supplied quick-mounted elements -- Shunt release and undervoltage relay.

-- can be used as conventional circuit breakers in switchgears of wide application with inductive nature of consumer circuits.

Due to the fact that the circuit breakers have an adjustable trip setting, there is no need to duplicate them with thermal relays.

We enter the results in table 3.2.

Table 3.2 - Selection of protection and control equipment

Name of technological equipment.	Electric motors or electrical receivers	Defense apparatus	Manadgement Department
		Power Рnom, kW	rated current	quantity p, pcs.	Switch	circuit breaker rated current	rated current of the release	Contactor, starter	rated current according to AC-3, In, A

lathe
Milling machine
Automatic line
Fan

Automatic line
arc welding machine
electric furnace resistance
Load lifting
Before. carts
Before. crane
Induction. bake
Conveyor

4 Calculation of electric lighting

4.1 Selection of the lighting system and lighting of the workshop

electrical receiver power supply workshop voltage

In a given foundry, casting is processed on metal-cutting milling and turning machines; work on such equipment is classified as high precision(category IIIb), and most operations should be performed under combined lighting.

The minimum illumination under combined lighting for the category of visual work IIIb is 1000 lux. At the same time, the illumination from general lighting in the combined system is 300 lux.

All places in a given workshop have local lighting.

When choosing light sources for general lighting, the height of the room, the environment, and the category of the room are taken into account. Since the foundry shop is a room of medium height (according to the task h = 10m), the most economical is the installation of DRI lamps. This light source corresponds to a lamp type GSP.

The nature of visual work and environmental conditions allow the use of enclosed luminaires with a degree of protection IP50 and higher.

We choose fixtures such as GSP 51 "Hermes" production

Characteristics of the lamp GSP 51 Hermes:

-- rated voltage 220 V;

-- Degree of protection: IP54 (dust-splash-proof);

-- light sources: - metal halide ellipsoid lamp (DRI), E40 base (power 250-400 W);

-- installation type: suspended;

-- climatic version U1.

The shop also has an emergency lighting system. The lowest illumination of working surfaces of industrial premises to the territory of enterprises requiring maintenance in emergency mode should be 5-10% of the illumination of working lighting with a general lighting system. To create a uniform distribution of illumination over the entire area of the workshop, we accept a uniform placement of lamps. Luminaires are arranged in rows parallel to the longitudinal axis of the workshop. To reduce the pulsations of the light flux, we install three lamps at each point.

Emergency lighting is carried out with incandescent lamps with NSP lamps.

4.2 Selecting the type and power of the light source

Initial data:

- shop length a = 168 m;

- workshop width b = 96 m;

- shop height hц = 10 m;

- lighting system voltage U = 220 V;

- minimum illumination ERAB = 300 lx.

4.2.1 Working lighting calculation

Because workshop height of 10 m, it is advisable to use high-pressure mercury lamps of the DRI 400-5 type with lamps GSP51-400-001 / 003 with KSS D.

We arrange the lamps in a checkerboard pattern, while in order to reduce the pulsations of the light flux characteristic of using this type of lamp, we install 2 lamps at each point.

Luminaire suspension height: HP = h - hС,

where h is the height of the workshop, m;

h` = 1.8 - distance from the luminaire to the ceiling (overhang), m

HP \u003d 10-1.8 \u003d 8.2 m.

Estimated workshop area: S = L b = 168 96 = 16128 m2

We plan the number of lamps: pcs.

The ratio of the flux falling on the illuminated surface to the entire flux of the lamps is called the Ki utilization factor. The dependence of Ki on the area of the room, height and shape is taken into account by the room index i.

Room index:

,

where S - workshop area, m2;

L - workshop length, m;

b - workshop width, m.

With i \u003d 7.45 and sweat \u003d 0.5, st \u003d 0.5, sex \u003d 0.3, we have Ki \u003d 0.95.

Luminous flux of one lamp:

lm

where KZ = 1.5 - safety factor for auxiliary premises with a normal environment and premises of residential and public buildings for fluorescent lamps;

KI=0.95 - utilization factor of the lighting installation;

n=161 - approximately selected number of lamps in the workshop;

z=1.15 - correction factor taking into account the ratio between Emin and Emax.

We choose the DRI 400-5 lamp, because it is the most powerful lamp installed in GSP luminaires.

We accept the luminous flux of the DRI lamp 400-5 Fl \u003d 35000 Lm.

We adjust the number of lamps in the workshop:

We accept n = 252 lamps.

We finally accept GSP51-400-001/003 lamps with DRI 400-5 lamps with a power of one lamp of 400 W with a luminous flux of 35,000 Lm. We draw up the final plan of the workshop, on which we apply lamps and power supply networks for working lighting.

With the number of DRI 400-5 lamps equal to 252, the following illumination is created in the workshop:

Thus, this number of lamps creates the required illumination.

4.2.2 Calculation of emergency lighting

Emergency lighting is 5-10% of the working

Eav = 30 lux; Ki=0.95; Kz=1.3; Fl=18600 lm.

PCS.

We accept 40 lamps. We choose an incandescent lamp G215-225-1000 with a lamp NSP-17. Lamp luminous flux Fl=18600 lm.

OK

Thus, this number of lamps creates the required emergency lighting.

4.3 Selection of cables supplying lighting boards

The condition for choosing the cable section has the form:

IP< IД.Д, (4.1)

where IP - rated current, A;

ID.D - permissible long-term current load on the cable. For non-explosive areas

ID.D = IN.D, (4.2)

where IN.D - long-term permissible current for cables under normal laying conditions, .

4.3.1 Selecting the cable supplying the work light box

We select the cable that feeds the working lighting shield of the main room of the forge shop.

The design load of the internal lighting of the RR building is determined by the installed lighting capacity of the switchgear and the demand factor kС:

PP \u003d RU * kС, (4.3)

The installed power of the switchgear is determined by summing the power of the lamps of all stationary lamps, while to take into account losses in the ballasts of gas-discharge lamps, we multiply the DRI by 1.1:

RU \u003d n * RL * 1.1,

where n is the number of lamps, pcs.

RL - rated lamp power, W.

k c = 0.9 ,

RU = 2524001.1 = 110440W,

PP \u003d 1104400.9 \u003d 99396 W,

QP \u003d PP * tg c \u003d 99396 * 1.44 \u003d 143130.24 VAr,

where tg = 1.44 for DRI lamps.

,

We determine the estimated current for the selection of wires:

,

where Unom \u003d 380 V is the rated voltage of the network.

Choose a cable brand AVVG.

We accept a five-core wire AVVG (5x120 mm2) with In.d = 295 A.

4.3.2 Selecting the cable supplying the emergency lighting panel

Determine the installed power of the lamps:

Ru = 401000 = 40000 W.

Determine the calculated load:

PP \u003d Ru Ks \u003d 40000 0.9 \u003d 36000 W,

where Kc \u003d 0.9.

Qr \u003d Рr tg c \u003d 36000 0.33 \u003d 11880 var,

where tg = 0.33 for incandescent lamps.

Determine the total power of working lighting:

.

We determine the estimated current for the selection of wires:

,

We accept AVVG cable (5x25mm2) five cores.

In.d \u003d 70 A\u003e IP \u003d 57.59A

The calculation results are summarized in Table 4.1.

Table 4.1 - Selection of cables for lighting boxes

4.4 Selecting the power supply of the lighting installation

Electric lighting is powered from transformers common for lighting and power loads with a low voltage of 0.4 kV (network voltage 380/220 V).

AVVG wire is used to power the lamps.

We use compact switchboards to distribute power for working and emergency lighting, as well as to protect networks from short circuit currents. For emergency and outgoing work lighting lines, we use ABB modular circuit breakers. As the introductory working lighting switch, we choose the ABB TMAX modular circuit breaker.

The power supply circuit of the lighting installation is shown in Figure 4.1.

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The lighting network of the workshop provides for the presence of one group shield, to which lamps are connected by group lines. In the event of an emergency termination of the operation of the working lighting, emergency lighting is provided, which ensures the possibility of continuing work and the safe evacuation of people from the workshop.

Emergency lighting fixtures automatically turn on when the working lighting is turned off in an emergency.

Work lighting is controlled by automatic switches installed on the group panel. For ease of operation and safety of repair work and replacement of individual elements of the electric lighting circuit, it is necessary to provide for the possibility of turning off the group shield. This function is performed by a switch.

4.5 Selecting the type and location of the group shield, network layout and its implementation

For emergency equipment and working lighting as lighting boards we use ABB type SRN boards with a mounting plate. They are easy to use and have compact geometric dimensions. They have a degree of protection IP 65.

4.5.1 Selection of work lights

Working lighting fixtures are divided into 8 rows (figure 4.2).

In row 1 - 10 lamps are connected to phase A B C

in row 2 - 11 lamps are connected to phase A, B-11, C-10

in row 3- 11 lamps are connected to phase A, B-10, C-11

in row 4- 10 lamps are connected to phase A, B-11, C-11.

in row 5- 11 lamps are connected to phase A, B-11, C-10

in row 6- 11 lamps are connected to phase A, B-10, C-11

in a row. 7 - 10 lamps are connected to phase A, B-11, C-11

in row 8 - 10 lamps are connected to phase A B C;

We determine the calculated power of phase A in one row of fixtures:

Рнбз = Рl n ks,

where Рl is the power of one lamp, W;

kc = 1.1 - correction factor for the power consumption of ballasts.

Rnbz \u003d 400 11 1.1 \u003d 4840 W.

Determine the rated current

where UФ = 220 V - phase voltage;

сosц = 0.8 - for DRI lamps.

For working lighting, we select the wire AVVG 5x6, with Inom \u003d 32 A. We use circuit breakers to distribute electricity and protect networks from short circuit currents. The number of circuit breakers on feeders is 8 three-pole. Switches on outgoing lines S203 32A In.v. = 32A.

4.5.2 Selection of emergency lighting fixtures

We determine the calculated power of the most loaded phase in one row.

In row 1 - 2 lamps are connected to phase A B, 1 lamp is connected to phase C

in row 2 - for phase A -2, B-1, C-2;

in row 3 - for phase A-1, B-2, C-2;

in row 4 - for phase A-2, B-2, C-1.

in row 5 - for phase A-2, B-1, C-2;

in row 6 - for phase A-1, B-2, C-2;

in row 7 - for phase A-2, B-2, C-1.

in row 8 - for phase A-2, B-1, C-2;

Thus, phase A is the busiest.

Rnbz \u003d? Rl n,

where RL is the power of one lamp, W;

n - number of fixtures per phase, pcs;

RNBZ=1000*2=2000 W.

Determine the rated current for the most loaded phase

where UФ=220 V - phase voltage;

Cosц=0.95 - for incandescent lamps.

For emergency lighting, choose the cable AVVG 5 * 2.5 with Inom = 23A.

We use circuit breakers to distribute electricity and protect networks from short circuit currents. Estimated load current: IP=57.59 A.

Number of switches on feeders - 8 three-pole. Switches on outgoing lines S203 10A In.in.= 10A. \u003d 63 A.

The selected equipment is summarized in Table 4.2.

Table 4.2 - Lighting conductors and group shields

Room (type of lighting)	group shield	conductor
		Feeder switches	Introductory switch

Main (working)	SRN6420
Main (emergency)	ABB Europa

The layout of the fixtures is shown in Figure 4.2.;

The plan shows:

- Lamp GSP18-400-07 with lamps DRI 400-5 working lighting

- Luminaire NSP-17 with incandescent lamp G 215-225-1000 emergency lighting

- Work lighting board

- Emergency lighting board

- Mains and emergency working lighting

5 Calculation of electrical loads

5.1 Calculation of the welding load using the effective power method

We calculate according to the formula:

, (5.1)

where S nom is the power of the welding transformer (from the task), kVA;

PV - duration of inclusion,%;

We find active and reactive loads:

, (5.2)

where cos c = 0.5, whence tg c = 1.73

Pr.d.s. = 91.40.5 = 45.7 kW;

Qr.d.s. \u003d 45.71.73 \u003d 79.06 kvar

We calculate the current:

, (6.3)

5.2 Calculation of the electrical loads of the induction furnace

where cos c = 0.95, whence tg c = 0.32

R.p \u003d 70 0.95 \u003d 66.5 kW;

Qi.p. \u003d 66.50.32 \u003d 21.28 kvar (5.3)

5.3 Calculation of electrical loads by the method of ordered diagrams

We break all electrical receivers into groups with similar characteristics. For each group of power consumers, we determine the active load according to the formulas:

(5.4)

(5.5)

For receivers operating in anti-ship missiles:

, (5.6)

The calculation results are shown in Table 5.1.

Table 5.1 - Calculation of the average load for the maximum loaded shift

Name	Col	PNOM,	KI,

lathe
Milling machine
Automatic line
Fan

Automatic line
Electric resistance furnace
Overhead crane (5 t)
Conveyor

(5.7)

where n is the number of all electrical receivers;

. (5.8)

since nef>10, then the maximum coefficient

. (5.9)

(5.10)

Full design load

. (5.11)

Estimated current:

. (5.12)

5.4 Distribution of load on busbars

We will distribute the electrical receivers of the workshop along the busbars. The calculation is carried out according to the formulas:

Average shift load:

(5.17)

(5.18)

where n is the number of electrical receivers in the group;

K - the number of groups of electrical receivers;

Ki.i - coefficient of use of electrical receivers;

Рnom i - rated power of electrical receivers of the i-th group;

tgцi - power factor of electrical receivers.

We find the group utilization factor:

, (5.19)

where ni is the number of power receivers in the group.

Effective number of power receivers:

. (5.20)

Determine the maximum coefficient:

(5.21)

Estimated peaks of active and reactive load:

(5.22)

Full design load

. (5.23)

Estimated current:

. (5.24)

The results of the distribution of power receivers along the busbars are shown in Table 5.2. The layout of the workshop with the location of the busbars is shown in Figure 5.2.

Table 5.2 - Distribution of electrical receivers by ShRA

busbar

Name of the electrical receiver

lathe

Fan

Automatic line

Conveyor

lathe

Milling machine

Fan

Electric resistance oven

Conveyor

Overhead crane

lathe

Milling machine

Automatic line

Milling machine

Fan

arc welding machine

lathe

Milling machine

Automatic line

Fan

Overhead crane

Figure 5.2 - Plan of the workshop with the location of busbars

5.4 Selection of distribution busbars

The choice of busbars is carried out according to the condition:

Ip< Iном, (5.25)

where Ir - rated current, A;

Inom - rated current of the busbar, A.

For example, let's choose a distribution busbar for ShRA-1:

The rated current of the first group of electrical receivers is Ir = 120.77A.

We use the Zucchini bus duct - the best option for creating power lines at almost any facility. It is easily and quickly mounted from ready-made factory modules, as a designer is assembled by an installer who has undergone minimal instruction. The Zucchini busbar is a self-supporting structure, on which the necessary electrical fittings are immediately installed. The main advantages of Zucchini busbars are: fire safety, small size, possibility of multi-channel use, long service life. Busbar for small and medium power distribution, dimensions 39x97 mm, rated current 160A with taps on both sides, casing - PE conductor.

Standard degree of protection IP40 (IP55 - with optional accessories).

This range includes: end feed units, 3-, 2-, 1-meter and non-standard custom straights, horizontal/vertical corners, tap-off units with isolation/protection devices (fuses, circuit breakers) and mounting accessories (brackets).

Choosing a MINI SBARRA distribution busbar trunking with a rated current

Inom = 160 A.

Ir = 120.77 A< Iном = 160А.

The condition is met, therefore, the busbar is correctly selected. The choice of busbars is summarized in Table 5.3.

Table 5.3 - Selection of busbars

Groups of electrical consumers	Busway type	Cable
		AVVG (4x120)
		AVVG (4x120)
		AVVG (4x120)
		AVVG (4x120)
		AVVG (4x120)

5.5 Branches to electrical receivers

The section of the power network that feeds a separate power receiver is called a branch. We carry out branches to power receivers from busbars with an APV cable in a pipe, for arc welding machines - with an AVVG cable (according to the PUE in industrial premises if there is a danger of mechanical damage in operation, the laying of unarmored cables is allowed provided that they are protected from mechanical damage). We select the section of wires and cables according to the condition of permissible heating:

Ir< Iдд, (5.26)

where Idd is the permissible continuous current load on the wire (cable), A

Idd = Kp Ind = 1 Ind (5.27)

For branches to individual long-term power consumers, we take the rated current of the power consumer as the rated current:

Inom. ep Ind (5.28)

For example, let's choose the wires that feed the pump P = 8.5 kW:

We select a four-wire AR wire (4x2.5) with Ind \u003d 19 A. We carry out a check according to the condition Inom. ep Ind:

Inom. ep = 16.9A Ind = 19 A,

the wire passes through the long-term permissible heating current. We summarize the selected wires in table 5.4.

Table 5.4 - Selection of wires and cables to consumers

	Electrical receivers		Cable brand
	lathe
	Milling machine
	Automatic line
	Fan

	Automatic line
	arc welding machine
	electric furnace resistance
	induction oven
	Conveyor

5.4 Choice of trolley lines

We choose a trolley line for an overhead crane with an intermittent operation with a lifting capacity of 5 tons. Three motors with a phase rotor from the MTF series are installed on the crane. Usually no more than two engines are in operation at the same time. We accept the most difficult mode, when the two most powerful crane engines with a rated power of 12 kW and 7.5 kW are simultaneously in operation.

Motor parameters: 1 = 83.5%, cos 1 = 0.73, Рnom1 = 12 kW, 2 = 77%,

cos 2 \u003d 0.7, Рnom2 \u003d 7.5 kW.

Active power:

Reactive power:

Estimated current of one crane:

We choose the trolley busbar ShTR4 - 100 with Inom = 100 A.

6 Selection of the number and power of shop transformers

Because according to the composition and nature of the load of electrical consumers, the workshop belongs to the first category in terms of uninterrupted power supply, it is necessary to install a two-transformer substation.

The power of transformers of the TP of the shop is determined by the formula:

where Sp.ts - total design capacity of the workshop, kVA;

n is the number of transformers, pcs.;

w - load factor of transformers.

We accept W = 0.8 (for consumers of the first category in terms of uninterrupted power supply).

where Рмц, Qмц - maximum calculated (active and reactive) power load of the workshop, kW, kvar;

Рro, Qro - calculated (active and reactive) lighting power, kW, kvar;

Rsv, Qsv - calculated (active and reactive) power of welding installations, kW, kvar;

Maximum calculated power load of the workshop:

Rmts = 596.47 kW,

Qmts \u003d 309.95 kvar.

Estimated lighting power:

Рro = 135.39 kW,

Qro = 155.01 sq.

Estimated power of welding installations:

Рsv = 112.2 kW,

Qsv \u003d 100.34 kvar.

Total design capacity of the workshop:

Workshop transformer power:

Based on Str, we select two transformers TMZ - 630/10.

Table 6.1.- Reference data of transformers.

Transformer type	Voltage, kV	Losses, kW

Actual load factor:

The selected TP is located in the workshop. The substation, in addition to two transformers, contains input cabinets for a voltage of 10 kV and complete distribution cabinets, with the help of which a switchgear circuit with a voltage of 0.4 kV is assembled.

7 Selecting the power supply scheme

Let's consider the problem of internal power supply of the workshop, namely: the location of the transformer substation TP-10/0.4 kV; type of supply network 0.4 kV and its design. First, it is necessary to evaluate internal environment workshop (its aggressive effect on electrical equipment and networks) and the type of production carried out in this workshop (explosion and fire hazard). According to the instructions, the environment inside the workshop is normal, production is mechanical. This production belongs to the first category of uninterrupted power supply. To power the power load of the workshop, on the basis of this, the main power supply scheme is selected, because busbar trunkings are designed for normal environment.

Power supply is carried out by main, distribution and trolley busbars.

Advantages, disadvantages and features of using the backbone network scheme:

The main circuit is convenient for the ability to connect electrical equipment at any point in the network - it does not require disconnecting all receivers as with a radial circuit;

In the technical design, the main circuit is open, clear and simple (since SHMA are laid over structures, unlike cable lines, which can be laid both along structures and along communications, in cable channels) - that is, hidden wiring is eliminated;

However, when using SMA, a large consumption of metal occurs;

The use of SHMA requires special designs and the very execution of busbars is carried out according to special connection schemes in order to reduce power and voltage losses;

Main busbars are made for high currents (up to 3200 A).

The 10 kV power input must be carried out taking into account the following factors:

By the shortest distance from the GPP to the workshop;

Depending on the type and design of the factory network for 10 kV (radial - cable, main - current conductors);

Depending on the internal layout of the workshop and the location of the equipment.

We accept the input of power through the column on the plan of the workshop, the distance from which to the GPP is the shortest - A7. The power supply scheme of the workshop is shown in Figure 7.1.

Figure 7.1 - Scheme of power supply of electric receivers of the shop

8 Calculation of the required compensating power, selection of compensating equipment and its placement in the workshop network

The transfer of reactive power causes additional costs for increasing the cross-section of conductors of networks and the power of transformers, and creates additional losses of electricity. In addition, voltage losses increase due to the reactive component, which is proportional to the reactive load and inductive resistance, which reduces the voltage quality of electricity.

Therefore, it is important to compensate for reactive loads and increase the power factor in the power supply systems of the enterprise. Compensation means the installation of local sources of reactive power, which increases the capacity of networks and transformers, as well as reduces power losses.

Phase angle tangent before reactive power compensation:

, (8.1)

where Qr.ts, Rr.ts - active and reactive power of the shop, kW, kvar;

The total power of the compensating device:

, (8.2)

where tgce = 0.35 is the power factor set by the system, o. e

Qku \u003d 844.06 (0.669 - 0.35) \u003d 269.25 kvar

As sources of reactive power, we use complete capacitor units with their placement on the main busbars.

We install a VARNET capacitor unit manufactured by Tavrida-Electric for each main bus duct:

VARNET-NS-, with a total capacity of 2x130 kvar = 260 kvar.

9 Refinement of calculated loads and power of transformers, taking into account reactive power compensation

9.1 Clarification of the power of transformers, taking into account compensation

Estimated reactive load after installation of complete capacitor units:

, (9.1)

.

We recalculate the total rated power:

(9.2)

We determine the calculated power of the transformer:

Taking into account the compensation, we choose the transformer TMZ - 630/10. Passport data of the transformer are given in table 7.1.

Load factor:

9.2 Selection of trunking

After clarifying the calculated loads and power of transformers, taking into account compensation, we select the main busbars according to the rated current of the transformer.

(9.5)

We use ZUCCHINI MR series trunking. The main advantages are speed, ease of installation, reliability.

We choose the ZUCCHINI MR series trunking. Rated current 1000 A.

In this way, the busbar trunking passes the current test.

10 Selection of power cables

The cable line through which the transformer substation receives power is laid in the ground. We choose a cable for a voltage of 10 kV brand AASHv a cable with aluminum conductors, an aluminum sheath, impregnated paper insulation with a three-core PVC hose.

The choice of cross-sections of 10 kV cable cores is made according to three criteria:

1) By heating;

2) According to the economic current density;

3) By thermal resistance to short-circuit currents.

10.1 Selection of the cable section for heating

The main condition for choosing a cable for heating

Ir Id.d. (10.1)

where Id.d - long-term permissible current load on the cable, A;

Ir - rated current, A.

According to the PUE, the conductors must meet the requirements for the maximum allowable heating, taking into account not only normal, but also post-accident modes, modes after repair. Since the workshop two-transformer substation receives power through two cables, and when one of them is disconnected (in repair or post-emergency modes), the load of the other increases, then

.

We accept a three-core cable AAShv 3x16 mm with Id.d = 75 A.

Ip = 48.55 A< Iд.д = 75 А.

10.2 Selection of the cable section according to the economic current density

We determine the economic current density for the AASHv cable, depending on the duration of use of the maximum load according to the PUE. At ТМ from 3000 to 5000 h/year for an enterprise operating in three shifts:

jek \u003d 1.4 A / mm2.

Economical section:

Fek = Ir / jek, (10.2)

where Iр is the estimated current of the line, which is taken from the conditions of normal operation and when determining it, the increase in current in the line during accidents or repairs in any network element is not taken into account.

Fek = 27.74 / 1.4 = 19.81 mm2

The nearest standard section is 16 mm2.

10.3 Selection of cable cross-section according to thermal resistance

The cross section that ensures the thermal resistance of the conductor to short-circuit current is determined by the expression:

where b - design coefficient (for cables with aluminum conductors b = 12);

I? - steady short-circuit current, kA;

tav - possible time of current passage through the cable (the sum of the time of the relay protection and the time of opening the circuit breaker), taken from the task.

The nearest larger section is 120 mm2.

Based on the calculations for the power supply of the workshop two-transformer substation, we accept two cables of the AAShv brand 3x120 mm2.

11 Mapping protection selectivity

We are building a selective protection map for the most electrically remote electrical receiver - a pump motor with a power of 30 kW.

11.1 Calculation of three-phase short-circuit currents

The design scheme and the equivalent circuit are shown in Figures 11.1 and 11.2. We determine the resistance of the circuit elements.

Figure 11.1 - calculation diagram of the pump power supply

Figure 11.2 - pump power supply equivalent circuit

11.1.1 Determining the resistance of circuit elements

We determine the inductive resistance of the system, reduced to the 0.4 kV side.

, (11.1)

We determine the active and inductive resistances of a high-voltage cable line with a length of l \u003d 200 m and S \u003d 3x120 mm2:

, (11.2)

, (11.3)

where R0 is the specific active resistance of the high-voltage cable line;

X0 - specific reactance of a high-voltage cable line;

L is the length of the high-voltage cable line.

We determine the active resistance of the transformer TMZ-630/10:

Determine the impedance of the transformer:

Determine the reactance of the transformer:

We determine the active and inductive resistance of the main bus duct, l = 24 m:

RSHMA \u003d R0 l \u003d 0.034 24 \u003d 0.816 mOhm; (11.7)

HSHMA \u003d X0 l \u003d 0.016 24 \u003d 0.384 mOhm. (11.8)

where R0 is the specific active resistance of the main bus duct;

X0 - specific reactance of the main bus duct;

l is the length of the main bus duct.

We determine the active and inductive resistance of the distribution busbar, l = 35 m:

RSHRA \u003d R0 l \u003d 0.23 35 \u003d 8.05 mOhm; (11.9)

XShRA \u003d X0 l \u003d 0.23 35 \u003d 8.05 mOhm. (11.10)

where R0 is the specific active resistance of the distribution busbar;

X0 - specific reactance of the distribution busbar;

l is the length of the distribution busbar.

We determine the active and inductive resistance of the supply wire

AVVG (4x2.5), l = 8 m:

Rcl \u003d R0 l \u003d 9.81 8 \u003d 78.48 mOhm; (11.11)

Xcl \u003d X0 l \u003d 0.096 8 \u003d 0.768 mOhm. (11.12)

where R0 is the specific active resistance of the supply cable;

X0 - specific reactance of the supply cable;

l is the length of the supply cable.

Transitional resistance according to are taken equal to:

RA1 =3 0 mΩ - contact resistance for point K1;

RA2 \u003d 25 mOhm - contact resistance for point K2;

RA3 \u003d 15 mOhm - transition resistance for point K3.

The calculation of the initial effective value of the periodic component of the current of a three-phase short circuit without taking into account the resistance of the electric arc is carried out according to the formula:

where Unom is the average rated line voltage in the network, kV;

RУ, ХУ - total active and inductive resistances up to the short circuit point without taking into account the resistance of the electric arc, mOhm.

The results of calculations of the total resistances are summarized in Table 11.1.

Table 11.1 - Determination of the total resistance of the network to the short circuit point. and short-circuit current without arc resistance

11.2 Calculation of single-phase short-circuit currents

In an electrical network with a voltage of up to 1000 V, a single-phase short circuit means a short circuit between the phase and neutral conductors in the power supply circuit. Therefore, the magnitude of the single-phase fault current depends on the magnitude of the phase voltage and the resistance of the “phase-zero” loop from the workshop transformer to the calculated short circuit point. Equivalent circuit for calculating single-phase short circuit shown in figure 11.3

The calculation of single-phase short-circuit currents is carried out according to the expression:

Where Unom is the rated voltage of the network;

Rt.f-0, Xt.f-0 - resistance of step-down transformers to the current of a single-phase short circuit, mOhm;

Rns.f-0, Hns.f-0 - total resistance of the low-voltage network to the current of a single-phase short circuit, mOhm;

Rp - contact resistance (see clause 11.1).

Figure 11.3 - equivalent circuit for calculating a single-phase short circuit.

Determination of the resistance of circuit elements:

Resistance of the power transformer TMZ-630/10 to the current of a single-phase short circuit:

Rt.f-0 = 10.2 mOhm; XT.F-0 = 40.5 mOhm.

Resistance of the main bus duct to the current of a single-phase short circuit:

Rsp.ph-0 = 0.085 mOhm/m; Hud.f-0 \u003d 0.013 mOhm / m;

Rshma f-0 = Rud.f-0 l;

Khshma f-0 = Hud.f-0 l; (11.15)

Rshma f-0 = 0.085 24 = 2.04 mOhm; Khshma f-0 \u003d 0.013 24 \u003d 0.312 mOhm.

Resistance of the distribution busbar to the current of a single-phase short circuit:

Rsp.ph-0 = 0.45 mOhm/m; Hud.f-0 \u003d 0.45 mOhm / m;

R shra f-0 = Rud.f-0 l;

Khshra f-0 = Hud.f-0 l; (11.16)

R shra f-0 = 0.45 35 = 15.75 mOhm; Xshra f-0 = 0.45 35 = 15.75 mOhm.

Resistance of the four-wire wire AVVG (4x2.5) to the current of a single-phase short circuit:

Rsp.ph-0 = 25 mOhm/m;

Hud.f-0 \u003d 0.2 3mOhm / m;

R cl f-0 = Rud.f-0 l;

Hcl f-0 = Hud.f-0 l; (11.17)

R cl f-0 \u003d 25 8 \u003d 200 mOhm; Xcl f-0 \u003d 0.23 8 \u003d 1.84 mOhm.

The calculation of single-phase short-circuit currents is summarized in Table 11.2.

Table 11.2 - Determination of the total resistance of the network to the short circuit point. and short-circuit current without arc resistance

11.3 Protection selectivity map

We perform the check on the example of connecting a pump (see Figure 11.1).

We select circuit breakers from.

1) Circuit breaker QF1:

Rnom = 8.5 kW, Inom = 16.9 A.

Inom. off > Inom, (11.18)

Based on the normal mode condition, we select the circuit breaker of the MS325-20 series, Inom=25 A, Inom. r. = 16-25 A.

Ico = 10 Inom. rasts. = 10 25 = 250A; tco = 0.02 s;

ISO< IК1(3), Iсо < IК1(1), (11.20)

Let's determine the setting current:

I6 = 6 Inom. p \u003d 6 18 \u003d 108A; t6 = 8 s; (11.21)

Isp = 1.35 Inom. rasts. = 1.35 18 = 24.3 A; tsp = 6000 s; (11.23)

Sensitivity factor to currents of single-phase K1:

where Inom. off - rated current of the circuit breaker;

Inom. rass. - rated current of the release;

Isp - circuit breaker operation current in the overload zone;

tsp - circuit breaker operation time in the overload zone;

I6 - setting current;

t6 - setpoint operation time;

Iso - cutoff actuation current;

tco - cutoff response time.

We enter the switch data in table 11.3.

2) Circuit breaker QF2:

Irab \u003d 156 A.

Inom. off > Irab

We select the ABB switch Tmax T1, Inom = 160 A, Inom. R. = 160 A.

Let's determine the cutoff operation current:

Ico = 5 Inom. rast. = 5 160 = 800A; tco = 0.05 s;

ISO< IК1(3), Iсо < IК1(1).

Let's determine the setting current:

I6 = 6 Inom. rasts. = 6 160 = 960 A; t6 = 4 s.

Let's determine the tripping current of the circuit breaker in the overload zone:

Isp = 1.25 Inom. rasts. = 1.25 160 = 200 A; tsp = 1000 s;

Sensitivity factor to currents of single-phase K2:

We enter the circuit breaker data in table 11.3

3) Circuit breaker QF3:

Rated current:

We select the switch ABB Emax E1B 1000 Inom = 1000 A, Inom. R. = 1000 A.

Let's determine the cutoff operation current:

Ico = 3 Inom. dist. = 3 1000 = 3000A; tco = 0.1 s;

Let's determine the setting current:

I6 = 6 Inom. rasts.= 6 1000 = 6000 A; t6 = 4 s

Let's determine the tripping current of the circuit breaker in the overload zone:

Isp = 1.25 Inom. rasts. = 1.25 1000 = 1250 A; tsp = 1000 s;

Sensitivity factor to single-phase short circuit currents:

Breaker type	I nom. off, A	I nom. rasts., A	Overload zone	Sixfold current zone	Cutoff zone

Figure 11.4 shows the construction of a pump protection selectivity map.

12 Selection of the equipment of the switchgear cell at the GPP

The 10 kV distribution point is located at the enterprise's GPP and serves to distribute energy between workshops and individual large consumers available at the plant, as well as to perform switching and protective functions. Control and measuring devices (in the form of ammeters, voltmeters, counters), protective equipment in the form of automata, fuses and control devices (relays, automation, alarms, as well as current transformers) are also located on the switchgear, therefore, when choosing the type of switchgear cells and their equipment, be attentive to their parameters, since the reliability of this equipment plays important role in the power supply system of the entire enterprise.

Distribution point 10kV is carried out using switchgear cabinets. We will select switchgear cabinets for connecting two lines to them, going to the transformer substation of the designed workshop. A significant difference in the choice of switchgear are switching resources, labor costs for the operation of the switches and their own time of switching on and off the switches. The switchgear cell with all equipment is selected and checked according to the following indicators:

a) rated voltage

Unom Unetwork; (12.1)

b) rated current

Inom Icalc; (12.2)

c) dynamic stability

isp.sp. isp.calc; (12.3)

d) thermal stability

Itherm.st. I; (12.4)

e) breaking capacity

Iout.nom. I. (12.5)

RU-10 kV GPP is performed using switchgear cabinets. We will select switchgear cabinets for connecting two lines to it, which go to the transformer substation of the workshop.

Surge current is defined by the expression:

where I” - short-circuit current on the power supply buses;

ku - shock coefficient.

where ia,t is the aperiodic component of the short circuit current;

tk = tcv + trz = 0.07 + 0.3 = 0.37 s - short-circuit off time;

tsv=0.07 - own time of switching off the circuit breaker;

trz=0.3 - relay protection operation time (as per task).

Ta=0.1 s is the decay time constant of the aperiodic component of the short circuit current.

Thermal pulse current short circuit:

We select 2 cabinets (for connecting two outgoing lines) of the KRU-104M series, Unom = 10.5kV, Inom.cabinet = 630 A with built-in vacuum circuit breakers VVE-10-31.5 / 630U3 and with current transformers of the TLK-10U3 type.

We will issue the choice of devices in the form of table 12.1.

Table 12.1 - Selection of switchgear cell equipment

Name and type of device	Estimated data	Selection condition	Specifications	Condition check
	Unetwork =10 kV	Network? Unom	Unom = 10.5 kV Inom = 630 A	10 kV< 10,5 кВ 51 A< 630 А
BB/TEL-10-20/630U3 switch	Unetwork =10 kV	Network? Unom VC? Iterm tterm	Unom = 10 kV Inom = 630 A idin = 80 kA Iterm2 tterm = 31.5x3=2977A2 s	10 kV = 10 kV 51 A< 630 А 63 kA< 80 кА 160A2 s< 2977 А2·с
Current transformer	Unetwork =10 kV	Network? Unom VC? Iterm tterm	Unom = 10 kV Inom = 100 A idin = 81 kA Iterm2 tterm = 1.52 3 \u003d 2977A2 s	10 kV = 10 kV 51 A< 100 А 63 kA< 81 кА 160A2 s< 2977 А2·с

13 Calculation of power quality indicators

Electric energy generated by power sources and intended for the operation of electrical receivers must have such quality indicators that determine the reliability and efficiency of their operation. Qualitative indicators of electricity are normalized by state standards; these standards are oriented to the technical conditions for the operation of electrical receivers manufactured by the industry.

The calculation is made for such power quality indicators as voltage deviation and voltage non-sinusoidality. Calculation is necessary in order to establish how these indicators correspond to the standards established for them. Normalization of indicators is necessary due to negative impact for the operation of other electrical receivers:

Voltage deviation is created during their work by any electrical receivers, tk. a change in the group load schedule during the day leads to a change in the voltage losses of the elements of electrical networks. Voltage deviation can lead to a change in the performance of a given installation or unit, to a defective product in a given installation or unit, to a change in the consumption of active and reactive power, to a change in active power losses, as well as to a change in the service life of the power receiver itself and the insulation of the conductors that feed it ;

Voltage fluctuations are created during their operation by electrical receivers with pulsed and sharply variable operating modes (electric welding installations, arc furnaces). Voltage fluctuations have the greatest effect on lighting and on various electronic equipment(PC, TVs, etc.). Voltage fluctuations have practically no effect on electric motors and electrotechnological installations, because the duration of the oscillations is small. Voltage fluctuation affects relay protection;

Calculation of the power of electrical energy receivers

The load power on the supply network largely depends on the type of production. For example, the equipment of the metal-cutting machine shop of a metalworking plant, with the same number of devices, consumes much more power than the machines of a woodworking shop. Thus, the power supply of the mechanical workshop of heavy engineering requires a more rigorous approach regarding the choice of the number and capacity of converter substations and power lines.

When designing, the daily work schedule of consumers should be taken into account, and the average power consumption during peak hours should be the basis for calculations. If we take into account the total power of consumers, then most of the time the substation transformers will operate in an underloaded mode, which will lead to unnecessary financial costs for servicing the supply equipment.

It is believed that the optimal mode of operation of the transformer should be 65 - 70% of the rated power.

The required section of the power supply lines is also selected taking into account the average power consumption, since the allowable current density, heating and power losses have to be taken into account.

Similarly, at this stage, the characteristics of the consumption of the reactive component of power must be taken into account, for rational use compensators. Incorrect placement and parameters of compensators will lead to energy overruns, incorrect accounting, and, most importantly, to increased losses and load on power lines.

This task is posed primarily where there are many powerful consumers with inductive loads. The most common example is induction motors, which are found in most machine tools.

Second stage of design

The choice of the type of distribution network is partly determined by the characteristics of the equipment according to the categorization of the receivers. There are three categories according to the requirements for power supply reliability:

The first category - a power outage leads to a safety hazard, accidents, a complete disruption of the technological process. This category includes a large number of machine-building and metal-working equipment, as well as mass production enterprises based on a conveyor, for example, a machine-building profile.
The second category is a violation of the production cycle, interruptions in the production of products that do not lead to serious economic consequences. Most industries fall into this category. Here you can specify the equipment of the mechanical repair shop (RMC).
The third category includes consumers with more forgiving power requirements than the first two categories. This includes most production equipment sewing workshop, and some metal products workshops.

Equipment belonging to the first category requires the design of power supply, taking into account the mutual redundancy of several (usually two) sources of external electrical supply.

The optimal combination of power supply reliability at minimal cost is achieved the right choice power supply systems in accordance with the categorization of the equipment and the location of the equipment on the area of the production workshop.

In most cases, the most rational is a combined trunk scheme with concentrated loads. The equipment of a forging shop or a welding shop has its own characteristics in terms of energy consumption and requires the laying of separate supply lines, and the power supply of the machine-assembly shop, on the contrary, can be performed according to the main scheme. And when several production lines are installed in the workshop, then several supply lines are indispensable. The same must be taken into account when calculating the power supply of the tool shop.

Separate power lines are laid for the lighting and ventilation system, whether it is an electrical project for a woodworking plant or an electrical project for an aircraft factory of an aviation enterprise.

The final stage

Based on the data of previous calculations, an electrical project is drawn up, consisting of several sets of documents. First, a working draft is developed, which in the process of performing work can be adjusted depending on local conditions and at the end of the work will differ from the calculated one. One of the main documents in the design of power supply is a single-line power supply diagram of the workshop. A drawing of a single-line diagram allows you to quickly navigate the intricacies and features of the power supply of the workshop.

Summing up

Designing the power supply system of a separate workshop or a whole plant is one of the most important activities, the implementation of which is possible only by specialized organizations that have the right to such work. It makes no sense to waste time developing the project yourself. No matter how it is executed competently and accurately, it still will not receive approval from energy sales organizations. By ordering standard project intra-shop power supply schemes up to 1000 V or more from a licensed organization, you can not worry about the safety and legality of all activities for the construction and operation of electrical equipment. Finished project will have all the necessary approvals and approvals, starting from the sketch and ending with fully corrected documentation when the facility is put into operation.

You can order a project at Mega.ru. The company's website has many articles that reveal the essence and subtleties of design, with examples of projects. Particular attention should be paid to the article, which explains in detail what are the stages of an electrical project.

But still, much more information of interest can be obtained by contacting the company directly for advice. The section indicates how you can contact our specialists and get answers to all questions.

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Consumers of electrical energy of category I must have two power sources and ATS (automatic transfer switch) on the sectional switch.

2 Selection of the voltage of the workshop network and the power supply system for the power load and lighting

R,

u,

h,

bridge-howl

AIR180M2U3

Asynchronous

Unified Series (Interelectro)

Binding to installation and mounting dimensions

Rotation axis height, mm

Installation dimension along the length of the bed

Number of poles

Modification with built-in temperature protection

Let's choose an electric motor, starting and protective equipment for a lathe, P=18kW.

From choose HELL AIR180S4 with Pn=18.5 kW; cos=0.85; =90%;

n =1500 rpm.

Calculate by expression (3.5):

.

The selected equipment provides the following types of protection:

Protection of motors is carried out by automatic switches of the MS series. ABB motor protection circuit breakers of the MS series are designed to protect motors from short circuits and overheating of the winding.

-- response characteristic MS corresponds to characteristic D, which allows the machine not to respond to inrush currents.

-- smooth adjustment of the thermal setting allows you to more accurately adjust the machine to the required current value in order to prevent overload and burnout of the motor.

-- the terminals are protected from accidental contact, and the monobloc design guarantees maximum operational safety.

-- fastening of the automatic machine is carried out on a DIN rail.

-- Depth of protection of the motor can be increased by separately supplied quick-mounted elements -- Shunt release and undervoltage relay.

-- can be used as conventional circuit breakers in switchgears of wide application with inductive nature of consumer circuits.

Due to the fact that the circuit breakers have an adjustable trip setting, there is no need to duplicate them with thermal relays.

We enter the results in table 3.2.

Table 3.2 - Selection of protection and control equipment

rated current

circuit breaker rated current

rated current of the release

rated current

electric furnace

4 Calculation of electric lighting

4.1 Selection of the lighting system and lighting of the workshop

electrical receiver power supply workshop voltage

In a given foundry, casting is processed on metal-cutting milling and turning machines; work on such equipment is classified as high precision(category IIIb), and most operations should be performed under combined lighting.

The minimum illumination under combined lighting for the category of visual work IIIb is 1000 lux. At the same time, the illumination from general lighting in the combined system is 300 lux.

All places in a given workshop have local lighting.

The nature of visual work and environmental conditions allow the use of enclosed luminaires with a degree of protection IP50 and higher.

We choose fixtures such as GSP 51 "Hermes" production

Characteristics of the lamp GSP 51 Hermes:

-- rated voltage 220 V;

-- Degree of protection: IP54 (dust-splash-proof);

-- light sources: - metal halide ellipsoid lamp (DRI), E40 base (power 250-400 W);

-- installation type: suspended;

-- climatic version U1.

Emergency lighting is carried out with incandescent lamps with NSP lamps.

4.2 Selecting the type and power of the light source

Initial data:

- shop length a = 168 m;

- workshop width b = 96 m;

- shop height hц = 10 m;

- lighting system voltage U = 220 V;

- minimum illumination ERAB = 300 lx.

4.2.1 Working lighting calculation

Because workshop height of 10 m, it is advisable to use high-pressure mercury lamps of the DRI 400-5 type with lamps GSP51-400-001 / 003 with KSS D.

We arrange the lamps in a checkerboard pattern, while in order to reduce the pulsations of the light flux characteristic of using this type of lamp, we install 2 lamps at each point.

Luminaire suspension height: HP = h - hС,

where h is the height of the workshop, m;

h` = 1.8 - distance from the luminaire to the ceiling (overhang), m

HP \u003d 10-1.8 \u003d 8.2 m.

Estimated workshop area: S = L b = 168 96 = 16128 m2

We plan the number of lamps: pcs.

The ratio of the flux falling on the illuminated surface to the entire flux of the lamps is called the Ki utilization factor. The dependence of Ki on the area of ​​the room, height and shape is taken into account by the room index i.

Room index:

,

where S - workshop area, m2;

L - workshop length, m;

b - workshop width, m.

With i \u003d 7.45 and sweat \u003d 0.5, st \u003d 0.5, sex \u003d 0.3, we have Ki \u003d 0.95.

Luminous flux of one lamp:

The ratio of the flux falling on the illuminated surface to the entire flux of the lamps is called the Ki utilization factor. The dependence of Ki on the area of the room, height and shape is taken into account by the room index i.