Shekhovtsov “Electrical and electromechanical equipment. Book: V. P. Shekhovtsov “Electrical and electromechanical equipment Ground resistance meter F4103-M1

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Electrical and electromechanical equipment

1. Give the concept of demand coefficient. Determine substation capacity using the demand coefficient method

power substation lightning rod

demand coefficient - the ratio of the combined maximum load of energy receivers to their total installed capacity.

The most widely used method for determining the power of mine substations is the demand coefficient method. The initial values for determining the electrical loads of substations are the installed and connected power of the receivers. Installed power (kW) is the rated power of all receivers powered from a given transformer substation, with the exception of backup ones and those operating only during repair shifts. For electric motors, the installed power corresponds to their rated shaft power indicated on the plate. Connected power (kW) is the power consumed by receivers when operating with a rated load, i.e. connected power is equal to installed power divided by efficiency. receiver:

Thus, the power of the substation (transformer) is determined by the connected power of the current collectors. However, due to the fact that the power of each electric motor is selected with a certain margin for the operation of the machine and the average load of the working machine is usually lower than the maximum, and all pantographs do not operate simultaneously, then when determining the electrical loads to select the power of the substation transformer, it is necessary to take into account the simultaneous operation coefficient of pantographs and their coefficient downloads. The simultaneity coefficient is the ratio of the rated power of simultaneously switched on receivers at a given moment to the total power of receivers connected to a given transformer, where URodn is the rated total power of simultaneously switched on receivers, kW; URust - total installed power of all pantographs, kW. The load factor is the ratio of the actual power supplied by the pantograph (on the shaft) at a given moment to its rated power

Pf - actual power on the electric motor shaft, kW; Rnom - rated power of the electric motor, kW. Due to the complexity of determining the two indicated coefficients, they are replaced by one that takes into account non-simultaneous operation and incomplete loading of electric motors. This coefficient is called the coefficient of simultaneous use of connected power or the demand coefficient ks. The demand coefficient is the ratio of the stable maximum load of receivers to their total connected power. Sustained maximum load is defined as a load lasting at least 30 minutes. Thus, the demand coefficient is, in hidden form, the product of the stable maximum values of the simultaneity and load coefficients. Since the determination of load and simultaneity factors is based on the rated (net) power of the receivers, when calculating loads the efficiency should also be taken into account. receivers?dv and networks?s. Therefore, the demand coefficient is usually understood as the product

Based on the value of the demand coefficient, the design load (kW) URust is the total installed power of a group of electric motors homogeneous in operating mode (or technological characteristics), kW. Electrical loads based on installed power and demand factor are calculated in the following sequence: 1) all electrical receivers planned for installation are grouped according to technological characteristics (processes) - cleaning and preparatory work, near-mine yard, etc. Electrical receivers are also grouped by voltage; 2) determine the total installed capacities of electrical receivers within groups by technological processes (and workshops) and by the voltage accepted for the corresponding groups; 3) calculate active, reactive and total electrical loads for underground sections, groups, technological processes, as well as total loads for groups of electrical receivers with the same voltage - Rcalc - active design power of a group of receivers, kW; ks is the demand coefficient for a given group of receivers, taken from reference data.

Qp - reactive calculated power of the group's current collectors, kvar tgts - corresponds to cost for a given group of receivers (determined from reference materials)

Where Sp is the total design power of a given group of pantographs, kVA. The found power values are entered into the calculation table and the design load (kVA) of the substation is determined by the formula

where kу.м is the coefficient of participation in the load maximum, taking into account the discrepancy in the time of load maximums of individual groups of receivers. Accepted based on reference data. In the absence of data, ku.m = 0.8h0.95 is accepted; URcalc - the sum of the calculated active loads of individual groups of receivers, kW; УQp - the sum of the calculated reactive loads of individual groups of receivers, kvar. The weighted average cosс is determined by tgс from the formula

The values of demand and capacity coefficients for groups of main consumers of coal and mining mines are given in Appendix. 2.1; values of the coefficients of participation in the maximum load for individual groups of electrical receivers in mines - in appendix. 2.2, The demand coefficient for the extraction areas of coal mines is 0.5--0.7, for iron ore mines 0.4--0.6. According to the demand coefficient method, the design power (kVA) of the transformer of the local mobile substation for coal mines. According to the demand coefficient method, the design power (kVA) of the transformer of the local mobile substation for coal mines

For a group of electrical receivers in the production and development faces of coal mines, according to App. 2.1, take 0.6--0.7 (for flat seams - 0.6, for steep ones - 0.7). The demand coefficient here is determined according to the formulas proposed by Tsentrogiproshakht. When using complexes with powered roofing and automatic electrical blocking of the start sequence of electric motors included in the complex for cleaning work, the demand coefficient.

Recently, taking into account operating experience and survey data of electrical loads of local transformer substations, when choosing the power of a substation to power a treatment or preparation site, it is generally accepted that the calculated power of the transformer obtained from expression (2.10) is overestimated. Therefore, when choosing a transformer, the calculated power of the transformer is proposed, determined by formula (2.10) using the method | demand coefficient, divide the coefficient of the possible use of mine substations in the areas, equal to 1.25, and, based on the resulting refined calculated power Sktp, select the rated power of the transformer substation.

However, according to the existing methodology, the rated power of a transformer substation is selected according to the calculated power determined using the demand coefficient method. This is what should guide you when solving the problems presented here. A transformer mobile substation, the rated power of which is equal to or greater than the calculated one, is accepted for installation on the site.

A substation with a rated transformer power less than the calculated one can be accepted if the difference between the calculated and rated power of the substation transformer does not exceed 5%.

2. Give the concept of overvoltage. Describe the design and operation of rod and cable lightning rods

Under normal conditions, the voltage in electrical installations is close to the nominal one and does not exceed it by more than 10%. However, short-term increases in voltage, called overvoltages, are possible. Depending on the cause of their occurrence, they are divided into switching and atmospheric. Their consequence may be a breakdown of the insulation of electrical installations, followed by a short circuit and disconnection of electrical receivers. The main type of overvoltage from which electrical installations must be protected is overvoltage caused by atmospheric phenomena, and primarily by thunderstorms.

The cause of a thunderstorm is a thundercloud, which is formed from tiny drops of water - water dust. By rising air currents, water dust rises to the upper layers of the atmosphere and forms clouds. Along the way, the drops become electrified due to friction with the air, and the lower part of the cloud becomes negatively charged. In turn, the earth, as the second plate of a kind of huge capacitor, receives a positive charge. The electric field strength between a thundercloud and the ground is on average 10 kV/m, but in places where there are sharp-pointed objects on the ground, the intensity increases and a glow may even be observed due to the so-called corona discharge.

If the electric field strength exceeds the electrical strength of air 25 ... 30 kV/cm, then conditions are created for the formation of lightning. There are different types of lightning: linear, ball. From the point of view of possible damage to electrical installations, linear lightning between the cloud and the ground is of interest.

Rice. Dependence of voltage on time during atmospheric overvoltage.

Approximately 50% of linear lightning consists of 3...4 repeated discharges or more - up to 40. The intervals between discharges range from thousandths to hundredths of a second. The first discharge is usually the strongest. Each discharge consists of a pre-discharge process and the discharge itself. The pre-discharge process is a stepwise breakdown of air, called a leader, moving in steps of 50 ... 100 m and stopping at 10 ... 100 x. The leader's advancement speed is about 1000 km/s. When the leader reaches the ground or the counter leader from the ground to the cloud, the main discharge rushes along the formed channel at a speed of 50 ... 150 thousand km/s.

The length of linear lightning, which is a huge spark, is usually hundreds and thousands of meters, and even tens of kilometers between clouds.

The lightning current rapidly increases to 30 ... 40 kA. Lightning with a current intensity of hundreds of kiloamperes has been recorded, but they are rare and are taken into account only when protecting particularly critical objects.

During the discharge, the channel temperature in the air reaches 20,000 °C. At the same time, the air quickly expands and seems to explode, which causes a dazzling light pulse and thunderclaps.

A lightning discharge has the form of an aperiodic pulse or voltage wave. Voltage rises quickly to maximum U max, which is called overvoltage amplitude, and then decreases relatively slowly. The time t 1 during which the lightning voltage increases from zero to the amplitude value is called wave front. Time t 2 from started process until the voltage decreases equal to 50% of the amplitude on the falling part of the pulse or wave is called wavelength. For the average characteristic of a lightning pulse or wave, determine t 1 = 1,67 VA, and t 2 = OS, and straight O.D. pass through points on the pulse curve equal to 0.30 U max and 0.90 U max. The wave front is t 1 = 1.2 μs and the wavelength is t 2 = 50 μs.

The maximum voltage of linear lightning is hundreds of thousands and even millions of volts, that is, its power is enormous, however, due to the fact that the duration of lightning is negligible (tens of microseconds), the amount of energy released is insignificant. Total charge, carried by lightning is usually 20 ... 100 coulombs. Thunderstorms are an extremely common phenomenon. Since they are mainly thermal in nature, the number of thunderstorm hours per year as one moves north, as a rule, decreases. In the middle zone, the thunderstorm season begins in May and ends in October. Winter thunderstorms are extremely rare.

The most severe consequences occur with a direct lightning strike on the affected object. This is, first of all, the impact of the amplitude of the overvoltage wave, which reaches millions of volts and practically breaks through any insulation. In addition, lightning splits wooden posts and traverses of power transmission line supports, destroys stone and brick buildings, causes fires, etc.

Electrostatic and electromagnetic fields associated with the main lightning discharge induce voltages on the line wires passing near the strike site, reaching hundreds of thousands of volts. This induced impulse or wave travels at close to the speed of light along all electrically connected lines and causes damage in the weakest insulated areas, sometimes several kilometers away from the lightning strike.

Lightning rods consist of a load-bearing part (support), an air terminal, a down conductor and a grounding conductor. There are two types of lightning rods: rod and cable. They can be free-standing, isolated or not isolated from the protected building or structure.

Rice. Types of lightning rods and their protection zones:

a - single rod; b - double rod; c - antenna; 1 - lightning rod; 2 - down conductor, 3 - grounding

Rod lightning rods are one, two or more vertical rods installed on or near the protected structure. Cable lightning rods - one or two horizontal cables, each fixed to two supports, along which a down conductor connected to a separate grounding conductor is laid; The supports of the cable lightning rod are installed on the protected object or near it. Round steel rods, pipes, galvanized steel cable, etc. are used as lightning rods. Down conductors are made of steel of any grade and profile with a cross-section of at least 35 mm2. All parts of lightning rods and down conductors are connected by welding.

3. Explain how to monitor the serviceability of protective grounding using the M-416 meter

Protective grounding is an intentional electrical connection to ground or the equivalent of metallic non-current-carrying parts that may become live due to a short circuit to the frame.

The task of protective grounding- eliminating the danger of electric shock in case of touching the housing and other non-current-carrying metal parts of an electrical installation that is energized.

The principle of grounding is to reduce the voltage between the energized housing and the ground to a safe value.

Grounding devices after installation work and are periodically tested at least once a year according to the program of Electrical Installation Rules. According to the test program, the resistance of the grounding device is measured.

The resistance of the grounding device, to which the neutrals of generators or transformers or terminals of single-phase current sources are connected, at any time of the year should be no more than 2, 4, 8 Ohms, respectively, at line voltages of 660, 380, and 220 V of a three-phase current source or 380, 220 and 127 V single-phase current source.

Measurements of the resistance of the grounding device circuit are carried out using a grounding meter M416 or F4103-M1.

Description of the M416 grounding meter

M416 grounding meters are designed to measure the resistance of grounding devices, active resistances and can be used to determine soil resistivity (s). The measuring range of the device is from 0.1 to 1000 Ohm and has four measurement ranges: 0.1 ... 10 Ohm, 0.5 ... 50 Ohm, 2.0 ... 200 Ohm, 100 ... 1000 Ohm. The power source is three 1.5 V dry galvanic cells connected in series.

Ground resistance meter F4103-M1

The F4103-M1 grounding resistance meter is designed to measure the resistance of grounding devices, soil resistivity and active resistance both in the presence of interference and without it with a measurement range from 0-0.3 Ohm to 0-15 Kom (10 ranges).

The F4103 meter is safe.

When working with the meter in networks with voltages above 36 V, it is necessary to comply with the safety requirements established for such networks. The accuracy class of the F4103 measuring device is 2.5 and 4 (depending on the measurement range).

Power supply - element (R20, RL20) 9 pcs. Operating current frequency - 265-310 Hz. The time to establish the operating mode is no more than 10 seconds. The time to establish the readings in the "MEAS I" position is no more than 6 seconds, in the "MEAS II" position - no more than 30 seconds. The duration of continuous operation is not limited. The standard mean time between failures is 7250 hours. Average service life - 10 years Operating conditions - from minus 25 ° C to plus 55 ° C. Overall dimensions, mm - 305x125x155. Weight, kg, no more than - 2.2.

Before carrying out measurements with the F4103 meter, it is necessary, if possible, to reduce the number of factors causing additional error, for example, install the meter almost horizontally, away from powerful electric fields, use power supplies of 12±0.25V, take into account the inductive component only for circuits whose resistance is less 0.5 Ohm, determine the presence of interference, and so on. Interference alternating current are detected by the swing of the arrow when rotating the PDST knob in the "MEAS" mode. Impulse (jump-like) interference and high-frequency radio interference are detected by constant non-periodic oscillations of the needle.

The procedure for measuring the resistance of the protective grounding loop

1. Install batteries into the ground meter.

2. Set the switch to the “Control 5 Shch” position, press the button and rotate the “reochord” knob until the indicator needle is set to the zero scale mark.

3. Connect the connecting wires to the device, as shown in Figure 1, if measurements are made with the M416 device, or Figure 2, if measurements are made with the F4103-M1 device.

4. Deepen additional auxiliary electrodes (ground electrode and probe) according to the diagram in Fig. 1 and 2 to a depth of 0.5 m and connect the connecting wires to them.

5. Set the switch to position “X1”.

6. Press the button and rotate the “reochord” knob to bring the indicator needle closer to zero.

7. Multiply the measurement result by a factor.

Connecting the M416 device for measuring ground loop resistance

Connection of the F4103-M1 device for measuring the resistance of the ground loop: a - connection diagram; b - ground loop

Bibliography

1. http://electricalschool.info/

2. Guiding technical material. RTM 12.25.006-EO. 1972

3. P.L. Svetlichny “Handbook of coal mine power engineers” M. “Nedra” 1975

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In the discipline “Electrical and electromechanical equipment”

Content

electrical machine equipment

1. Typical interlocking connections in machine control circuits

To perform a work cycle in automatic machine control circuits, there must be a relationship between different operating modes of the same mechanism or between individual machine mechanisms. In machines of various types and modifications, some typical relationships can be noted, designed to implement the following modes.

a) Setting up and operating modes of the machine.

In operating mode, the machine drive operates for a long time or repeatedly for short periods, which is determined by the performance of production operations. Adjustment operations are carried out to test individual components of the machine, to check the correct installation of the workpiece and tool. This mode is characterized by short-term switching on of an unloaded drive at low angular speeds of the motor (if the drive speed is regulated).

For long-term mode (Fig. 1, a), the KnP button is pressed, the contactor KL receives power, which turns on the motor D with the main contacts, and at the same time the KnP button is blocked by the closing contact, so after a short press this button can be released.

Rice. 1. Schematic diagram of the relationship between setup and operating modes

For the adjustment mode, a two-contact KnTolch button is used. When this button is pressed, its opening contact unlocks the KnP button, and through the normally open contact the CL contactor receives power and the motor is turned on, which will run for the duration of the action on the KnPolch button.

By briefly pressing this button, you can force the engine to operate in pulse mode with an average angular velocity significantly lower than the nominal one. The relationship between the setup and operating modes can be achieved by introducing an intermediate relay RP (Fig. 1, b), replacing the two-contact KnTolch button.

Similar schemes for obtaining the adjustment mode are used in drives with multi-speed asynchronous motors, as well as in DC drives controlled by the G-D or TP-D system.

b) Limiting movements and precise stopping of machine mechanisms.

Used to avoid collisions between individuals. moving elements or to prevent machine components from leaving normal engagement with the leading link of the kinematic chain. For example, in surface grinding, longitudinal planing and other machines, the path made by the table is limited by limit switches, which are switched by stops located on the table. In Fig. 2, a shows a diagram for shutting off the rotation drive of the workpiece of a cylindrical grinding machine when the wheel leaves the grinding zone.

Rice. 2. Schemes for turning off the engine when the movement of the mechanism is limited: a - for driving the rotation of the product of a cylindrical grinding machine; b - for hydraulic feed drive of an aggregate machine

In such machines, the translational movement of the grinding head is usually carried out by a hydraulic drive. In the initial position of the mechanism, the contact of the limit switch VK opens and the motor D automatically turns off. For intensive braking of the wheel drive, an electromechanical brake EMT is used. It should be noted that hydraulic devices allow you to simply ensure that the feed mechanism operates on a rigid stop, and then change the direction of its movement.

In Fig. 2, b shows a schematic diagram of the control of the hydraulic feed drive of the machine.

When approaching the extreme position, the mechanism stops at a hard stop, the limit switch VK is triggered and the time relay PB begins counting the duration of stopping at the stop. After the set time delay has expired, the intermediate relay RK is turned on and a pulse is given to turn on the electromagnet EmN, which switches the hydraulic drive to retract the mechanism to its original position, controlled by the VKI switch.

c) Coordination of the operation of individual drives.

In large machines, there is often no mechanical connection between the individual working bodies, so there is a need for a certain sequence of putting them into operation, and also the order of turning off the main drive and the feed drive must be observed, lubricant must be supplied in a timely manner, etc. So, in metal-cutting machines having a separate feed drive, in order to avoid tool breakage, the main drive must be turned on first. When a shutdown command is received, on the contrary, the main drive must stop after the feed drive has stopped. The specified sequence of operation of the drives is provided by the diagram shown in Fig. 3.

Rice. 3. Scheme for coordinating the operation of the main drive and the feed drive of the machine

The priority of switching on the main drive here is ensured by introducing the closing contact of the KG contactor into the circuit of the CP contactor coil. When the feed drive is not working, the contactor of the main drive KG is turned off without a time delay after pressing the KnS1 button.

To turn off the main drive while the feed drive is running, press the KnS1 button for a long time. In this case, the intermediate relay RP loses power, the CP contactor is de-energized and the feed motor D2 is turned off.

The main drive with motor D1 will turn off after some time, determined by the setting of the time relay PB, the coil of which is connected in parallel with the coil of the gearbox contactor. When you briefly press the KnS1 button, the RP relay will turn on again, and if by this moment the PB relay has not worked, then the main drive will not turn off after the feed drive is turned off.

2. Electrical equipment of automatic lines

The electrical equipment of automatic lines consists of a large number of motors, electromagnets, contactors and magnetic starters, buttons and control switches, limit switches, various relays: time, pressure and speed, blocking, intermediate, etc.

All electrical equipment must be very reliable and have a long service life, therefore non-contact electrical devices and electronic elements are actively used.

The basic principle of constructing control schemes for automatic lines is control as a function of the path. This control allows you to control the relative position of parts and tools at any time and is the most reliable. The command for subsequent actions is given when the previous action has already been completed (finished). For this purpose, position switches and switches are used.

Limit switches are usually installed on stationary components of machine tools and mechanisms, and the action on their pin or lever is carried out by the moving stop of the mechanism when it reaches a certain point on the path. All automatic machine lines have a developed alarm system.

When calculating the engine power, we assume that the rated speed of the engine corresponds to the reverse speed of the table (the highest speed of the mechanism), because Single-zone speed control is adopted, downward from the rated speed. We focus on the choice of a D series motor, designed for rated operating mode S1 and having forced ventilation.

Equivalent static force per cycle:

Estimated engine power:

K z - safety factor (let’s take K z = 1.2);

z pN - efficiency of mechanical transmissions under operating load.

After all the calculations, we select the engine.

Draw and describe the control circuit of a universal boring machine.

The main components of the feed drive control system are:

Microcontroller Somatic S7-300;

Processing unit PCU 50;

Monitor for displaying information;

Main Drive Module;

Machine panel and 3.5" disk drive;

Field PG programmer;

Peripherals;

Analog and digital sensors;

Power supply/regeneration and power supply SITOP 20A.

The Simatic S7-300 microcontroller includes the following modules:

The central processor module CPU 314 is required for receiving, processing and issuing data to the controller modules;

The NCU 570 module is required to control the main motion drive, as well as to connect the operator panel, control panel and auxiliary devices;

Expansion module FM-354, required to expand the capabilities of the S7-300 controller;

The input/output module consists of the SM-331 module for receiving signals from analog sensors and the SM-321 module for receiving signals from discrete sensors;

SITOP 20 power supply to provide power to all controller modules.

The PCU 50 processing unit is used to process data received from the S7-300 controller, in particular the control of the main movement motor; data exchange with the operator console and machine panel. This unit is powered by a 24V DC power supply SITOP 20 A

The main drive module includes the main drive motor itself, a pulse width modulation (PWM) module, and a speed sensor.

A power supply/recuperation unit is used to power the main motion motor, which ensures a stable supply voltage to the motor, and when it is braked, excess energy is returned to the network.

Control system diagram

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Introduction

electrical equipment mechanical shop repair

General industrial mechanisms play an important role in the national economy of the country. They are the main means of mechanization and automation of various production processes. Therefore, the level of industrial production and labor productivity largely depend on the equipment of production with general industrial mechanisms and on their technical perfection.

The tasks assigned to general industrial mechanisms determine the wide variety of their electric drives, which differ both in power range (from fractions of a kilowatt to several thousand kilowatts) and in complexity (from an unregulated squirrel-cage induction motor to complex controlled electromechanical systems). For mechanisms of the class under consideration, almost all existing types of AC and DC electric drives are used.

General industrial mechanisms include a large class of working machines that are used in a wide variety of sectors of the national economy: industry, agricultural production, construction, and transport. In most cases, these mechanisms serve the main production of various industries. These include cranes, passenger and freight elevators, escalators, various conveyors, fans, pumps, metal processing and wood processing machines.

General industrial mechanisms are widespread. For their electric drives, 70... 75% of the produced asynchronous motors and more than 25% of the generated energy are used.

In everyday life, many electrical appliances and mechanisms are used that make household work easier. Mechanisms of household appliances include washing machines, vacuum cleaners, mixers, electric beaters, coffee grinders, etc. The range of these mechanisms is constantly expanding.

The production of a whole range of new appliances has been mastered, such as highly comfortable vacuum cleaners and universal kitchen machines. The technical level of household appliances is largely determined technical level electrical equipment with which they are equipped.

Specialists involved in the operation, maintenance and repair of electrical and electromechanical equipment must be well acquainted with mechanical equipment, technology, and understand the electrical circuit of a particular mechanism. All this requires engineering and technical personnel to study the theoretical foundations of electric drives, control of electric drives, as well as special courses, one of which is “Electrical and electromechanical equipment of general industrial mechanisms and household appliances.”

1.Characteristics of the machine shop

The machine shop is built of brick. Heating is provided from the boiler room. Its area is 171 m2: length A - 19 m; width B - 9 m; height H - 4 m. On this area there is a machine for processing metal by pressure and machines for processing metal by cutting. Crank press, drilling machine, sharpening machine and others. The workshop has 8 windows and 2 doors. There are fans installed in each window. The lighting fixtures are represented by LSP series lamps with fluorescent lamps. The lamps are suspended from the ceiling. External lighting at the entrance to the workshop is provided by NSPO 02-200-021 lamps. The lighting wiring is made using VVG 3x2.5 cable.

The power supply (connection of electrical equipment to the power source) is made with a PV wire in steel pipes laid in a concrete floor and concreted. For an electric trolley, the flexible wiring is located on a cable and is movable. Cable for electric trolley KG 3x2.5+1x1.5mm2, flexible cable for general purpose. Designed for connecting mobile mechanisms to electrical networks with a voltage of 660 V AC. The grounding line inside the building is made of a round steel hoist with a cross-section of at least 100 mm2. The branch from the main to the electrical installations is made with round steel with a diameter of at least 5 mm2. Connection of electrical equipment is carried out through the PR-11 distribution point, next to which the OSCHV-6 lighting panel is installed. Figure 1 shows a plan for the placement of electrical equipment in a mechanical workshop with power supply to it from PR-11. Figure 2 shows a general view of the crank press with its main elements.

Table 1 - electrical and electromechanical equipment of the workshop.

Name of EEO (type)	Motor TYPE	Electric Motor Power	Quantity

1 Crank press.
2 Drilling machine

3 Sharpening machine
4 Compressor
5 Electric trolley
6 Telfer
7 Exhaust fan
8 Fans
9 Blower fan

11 Distribution device PR-11

Figure 1 - Layout plan for electrical equipment in the mechanical workshop.

Switchgear PR-11.

Lighting board OSCHV-6

Branch box.

The wiring is flexible.

Workplace.

Ground loop.

Crank press and blower fan.

Drilling machine.

Sharpening machine.

Compressor.

Electric trolley.

Telfer.

Exhaust fan.

Fan.

2.Selection of lighting distribution points

We select the lighting board OSHV-6 for 6 groups (modules). With single-lane circuit breakers with a thermal release current of 63A.

1st 2nd and 3rd group we connect working lighting.

4th group we turn on the emergency lighting.

Group 5: turn on the sockets.

6th group reserve

At the input of the OSCHV-6 lighting board there is a three-phase circuit breaker with a 50A thermal release.

Figure 2. Schematic diagram of the lighting board OSHCHV-6.

Table 3 - Selection of feeder circuit breakers.

	Circuit breakers			Number of poles

3. Calculation of workshop lighting

Calculation of illumination is carried out using the luminous flux utilization coefficient method

Workshop size:

A = 18 m - length of the workshop,

B = 8 m - width of the workshop,

H = 4 m - workshop height.

Based on the type of work performed, we select the standardized illumination from reference table 6.2. (OK).

We accept lux for lighting with fluorescent lamps.

For consecration we accept NSP 02 lamps with incandescent lamps or LPO lamps with fluorescent lamps.

We determine the estimated height of the lamp above the working surface.

where is the height of the working surface from the floor, - for fluorescent lamps, the height of the overhang of the lamp.

Determine the distance between the lamps.

m, take 4 m.

Determine the number of rows.

Determine the number of lamps in a row.

We accept 4 lamps.

Determine the total number of lamps.

Determine the room index.

The ceiling and walls in the workshop are light, so we take the reflection coefficient from the ceiling of the walls and the working surface:

Reflection of light from the ceiling,

Reflection of light from the walls, - reflection of light from the working surface.

By type of lamp, coefficient and index we determine the coefficient of luminous flux utilization

We determine the luminous flux of one lamp.

Safety factor - coefficient of illumination unevenness.

According to (L5), we select a lamp with a larger nearby luminous flux.

Lamp type LB 40 lm.

We determine the actual illumination.

According to calculations, the actual illumination is approximately equal to the calculated one, which means we leave the number of lamps at 16.

According to SNiP, deviation of illumination is allowed within limits, since the actual illumination is within the permissible value, then we install 4 lamps in a row.

We determine the large installed power of lamps in the lamp workshop in the workshop.

W - for luminaires with one lamp,

W - for luminaires with two lamps,

where is the power of one lamp, N is the number of lamps.

We carry out the layout of lamps in the workshop according to the calculation.

Figure 3 - Lighting diagram of the machine shop

We determine the number of emergency lighting lamps, which is allowed 5 - 10% of the working number of lamps, one lamp.

Emergency lighting in the workshop we use one lamp with fluorescent lamps, and outside at the entrance to the workshop we install an NSP-02 lamp with an incandescent lamp and connect it to a separate group on the switchboard.

According to operating conditions, we divide the lamps into 3 groups.

We determine the current of one incandescent lamp:

We determine the current of one fluorescent lamp:

we accept cosс = 0.9.

We determine the current of one group of lamps:

We choose the lighting board OSCHV-6 for 6 groups. With one power circuit breaker with a thermal release current of 4 A.

1st and 2nd group - connect working lighting,

3rd group - a step-down transformer is connected,

4th group - connection of emergency lighting,

5th and 6th groups - reserve.

At the input of the OSCHV-6 lighting board there is a 3-phase circuit breaker with a 25 A thermal release.

Figure 4 - Lighting board OSCHV-6

Figure 5 - Single-line diagram of the lighting board OSHCHV-6

4.Maintenance and repair of electrical equipment

Operation of electrical equipment is technical activities carried out during work and repairs carried out between work.

Maintenance is one of the means of maintaining reliable and uninterrupted operation of machines and mechanisms throughout the entire period of operation. The performance of electrical equipment during operation is maintained by technical maintenance and smooth preventative repairs. The frequency of technical maintenance and routine repairs is determined mainly by the conditions in which the equipment operates and its design. The introduction of a system of smooth preventive repairs determines rational operation and ensures that electrical equipment is maintained in good condition, fully operational and at maximum performance. Current repair is the main type of repair that ensures the durability and trouble-free operation of electrical equipment by cleaning, checking, replacing wearing parts and setting up equipment. Overhaul includes all current repair operations and complete replacement parts and mechanisms, for AC electric motors, replacement of stator windings of armatures, DC machines, phase rotors, as well as checking and, if necessary, replacing the rotor shaft, etc.

Maintenance of the equipped mechanical workshop is carried out according to schedules. The schedule for current and major repairs is left for a period of one year.

5. Maintenance of electric lighting installations

When servicing lighting electrical installations, you need to know that in normal operation in electric lighting networks, the voltage should not decrease by more than 2.5% and increase by more than 5% of the rated voltage of the lamp. For some of the most distant emergency and outdoor lighting lamps, a voltage reduction of 5% is allowed. In emergency mode, a voltage reduction of 12% for incandescent lamps and 10% for fluorescent lamps is allowed. Frequency of voltage fluctuations in lighting networks:

if the deviation from the nominal value is 1.5%, it is not limited;

from 1.5 to 4% - should not be repeated more than ten times in 1 hour;

more than 4% - allowed once every 1 hour.

These requirements do not apply to local lighting lamps.

All maintenance work on lamps is carried out with the voltage removed. Checking the level of illumination at control points of premises during inspections of lighting installations is carried out at least once a year. The serviceability of the circuit breakers that turn off and turn on electric lighting installations is checked once every 3 months (during the daytime).

The serviceability of the emergency lighting system is checked at least once a quarter.

Checking stationary equipment and electrical wiring of working and emergency lighting for compliance of the currents of releases and fuse-links with the calculated values is carried out once a year.

Measuring loads and voltage at individual points of the electrical network and testing the insulation of stationary transformers with a secondary voltage of 12-40 V is carried out at least once a year.

Maintenance of lamps is carried out using floor devices and devices that ensure the safety of workers: stairs (with a lamp suspension height of up to 5 m); stationary and trailed bridges towed by cranes.

Lamp replacement is carried out individually, when one or more lamps (up to 10%) are replaced with new ones, or in a group way, when all lamps in the installation are simultaneously replaced with new ones after a certain time interval. In foundries and forges, DRL type lamps are subject to group replacement after 8000 hours of operation. In mechanical, assembly, and tool shops, when using LB-40 lamps as light sources, group replacement is carried out after 7000 hours (every row). In calculations with sufficient natural light, the annual number of hours of use of lighting installations is assumed to be 2100 hours for two-shift operation, 4600 hours for three-shift operation, and 5600 hours for three-shift continuous operation.

In case of insufficient natural light during two-shift work, the number of hours of use of lighting installations is 4100 hours; with three shifts - 6000 hours; with continuous three-shift work - 8700 hours.

Serviceable lamps removed during group replacement can be used in auxiliary rooms.

Lamps are replaced individually if the installation is made with incandescent lamps, lamps with 30 fluorescent lamps or 15 DRL lamps.

Cleaning of general lighting fixtures for workshops of machine-building enterprises is carried out in the following periods: foundries - once every 2 months; forging, thermal - once every 3 months; instrumental, assembly, mechanical - once every 6 months.

Maintenance of electric lighting networks is performed by specially trained personnel. As a rule, cleaning of fixtures and replacement of burnt-out lamps is carried out during the daytime, removing tension from the area. If it is impossible to remove the voltage from an electrical installation with a voltage of up to 500 V, work under voltage is allowed. In this case, adjacent current-carrying parts are protected with insulating pads, work with tools with insulated handles, wearing safety glasses, a hat and buttoned up sleeves, standing on an insulating stand or wearing dielectric galoshes.

In the workshops of industrial enterprises, cleaning and maintenance of high-lying lighting equipment is carried out by a team of at least two electricians, and the work performer must have qualification group III. Both performers must be allowed to climb. When working, take precautions against getting under voltage, falling from a height, or accidentally starting the crane.

In outdoor lighting networks under voltage, it is allowed to clean fixtures and change burnt-out lamps from telescopic towers and insulating devices, as well as on wooden supports without grounding slopes, on which the lamps are located below the phase wires. The older of the two persons must have qualification group III. In all other cases, the work is carried out along with disconnecting and grounding at the work site all wires of the lines located on the support.

Defective mercury and fluorescent lamps, since they contain mercury, the vapors of which are poisonous, are handed over to the manufacturer or destroyed in specially designated places.

6.Technology for installing electrical wiring in plastic pipes

Open and hidden electrical wiring in pipes require the expenditure of scarce materials and are labor-intensive to install. Therefore, they are used mainly when it is necessary to protect wires from mechanical damage or protect the insulation and cores of wires from destruction when exposed to aggressive environments.

The use of polymer pipes for electrical wiring increases their reliability in aggressive environments and reduces the likelihood of electrical networks shorting to ground.

Vinyl plastic pipes are used for open and hidden laying on fireproof and non-combustible bases indoors and outdoors, as well as for hidden laying on combustible bases over an asbestos layer of at least 3 mm or along a plaster strip with a thickness of at least 5 mm, protruding from each side of the pipe at least by 5mm, followed by plastering the pipe with a layer of at least 10mm. Polyethylene and polypropylene pipes used only for hidden installation on fireproof bases in floor underlays and foundations for equipment. Vinyl plastic, polyethylene and polypropylene pipes are not used in explosive areas.

The diameter of the pipes is selected depending on the number and diameter of the wires laid in them, as well as the number of bends in the pipe along the route between the traction or branch boxes. To determine the diameter of the pipes, first determine the complexity group (I, II or III) for laying wires in them, depending on the length of the section of the pipe route, the number and angles of bends in the section. Then the internal diameter of the pipe D is determined depending on the number of wires, their outer diameter and the difficulty group of laying the wires.

General rules for installing pipes for electrical wiring.

When installing pipes, both open and hidden, as a rule, preliminary preparation of pipes is performed. At the installation site, only the assembly of the pipe route elements is performed. Pipe procurement is carried out according to design drawings, pipe procurement sheets or according to sketches made by installers based on design drawings of plans and sections of electrical wiring or according to measurements of the pipe route in situ at the installation site.

The pipe procurement list for each pipe indicates: number (marking), diameter, estimated length, end points of the beginning and end of the pipe along the route, as well as the length of straight pipe sections between the ends or intersection points of the pipe axial lines at bending points and the values of bending angles in degrees .

When preparing pipes, normalized rotation angles (90, 120, 135°) and pipe bending radii (400, 800 and 1000 mm) are used. A bending radius of 400 mm is used for pipes laid in ceilings, for vertical pipe outlets and in confined spaces, and 800 and 1000 mm are used when laying pipes in monolithic foundations and when laying cables with single-wire conductors in pipes.

When preparing curved pipes, it is necessary to determine the length of their workpiece, as well as the starting bending points when working with a manual pipe bender or the middle bending points when working with mechanized pipe benders.

It is recommended to prepare complex electrical pipe wiring units with a large number of pipes placed in different planes in a small area using a prototype method. With this method, a life-size model of the electrical installation being installed is reproduced on a special platform, the axes are drawn building structures and placement of technological equipment, fix the places where pipes lead to equipment and electrical devices. After this, the pipe elements are prepared, laid and marked on the model. The pipes prepared on the model are disassembled into easy-to-transport units and individual elements, transported and reassembled at the installation site. When installing and preparing electrical wiring, as a rule, they use factory products - branch and duct boxes, complex units of pipe electrical wiring with a large number of pipes placed in different planes in a small area, it is recommended to prepare using a prototype method.

Before laying pipes at the installation site, the location of the axes and marks of the premises, technological and electrical equipment to which the pipe wiring is connected are established. They check the presence of openings, holes and grooves in walls and ceilings for laying pipes, embedded parts in building structures, and also establish the location of expansion and settlement joints. After this, the pipe electrical wiring route is marked, branch and duct boxes, current collectors and equipment are installed, and the places where the electrical wiring is connected to them are specified. If several pipes are laid in parallel along a common route, they are usually combined into single-layer packages or multilayer blocks, which are manufactured according to drawings at the oil extraction plant and delivered ready-made to the installation site. To make it possible and convenient to connect multilayer blocks to each other, the ends of individual pipes in the block are arranged in steps so that the pipes of each subsequent layer are 100 mm shorter.

In horizontal sections, pipes are laid with a slope so that they do not

Figure 6 condensing moisture has accumulated and is not

water bags were created. In the lowest places (for example, when going around columns), it is recommended to install pull-out boxes. Before backfilling soil, concreting floors and foundations, the quality of pipe connections, the reliability of their fastening and the continuity of grounding circuits are checked and an inspection report for hidden work is drawn up.

To avoid crushing and destruction of pipes over long sections when backfilling soil and concreting foundations, supports made of bricks, concrete blocks or lightweight structures are installed under them. In places where hiddenly laid pipes intersect sedimentary and expansion joints, as well as when moving from foundations to the ground, in order to avoid destruction or collapse, sleeves and cases are put on the pipes, and when laid open, compensators are installed (Figure 10.1).

Figure 7 straight sections, 50 m with one pipe bend, 40 m with two pipe bends and 20 m with three pipe bends.

When bringing hidden polymer pipes from foundations and grouts into the room, use sections or elbows of thin-walled steel pipes or protect them from mechanical damage with a box (Figure 10.2). The length of the pipe sections between the drawer boxes (boxes) should not exceed: 75 m for laying plastic pipes for tightening wires and cables in them must be done in accordance with the working drawings at an air temperature not lower than minus 20 and not higher than plus 20 ° C.

In foundations, plastic pipes (usually polyethylene) should be laid only on horizontally compacted soil or a layer of concrete. In foundations up to 2 m deep, the installation of polyvinyl chloride pipes is allowed. In this case, measures must be taken against mechanical damage during concreting and backfilling of soil.

The fastening of openly laid non-metallic pipes must allow their free movement (movable fastening) during linear expansion or contraction due to changes in ambient temperature. The distances between the installation points of movable fasteners for horizontal and vertical installation should be for pipes with an outer diameter of 20, 25, 32, 40, 50, 63, 75 and 90 mm, respectively, 1000, 1100, 1400, 1600, 1700, 2000, 2300 and 2500 mm .

The thickness of the concrete mortar above the pipes (single and blocks) when they are monolithic in floor preparations must be at least 20 mm. Where pipe routes intersect, a protective layer of concrete mortar between the pipes is not required. In this case, the depth of the top row must satisfy the above requirement. If, when crossing pipes, it is impossible to ensure the required depth of pipes, they should be protected from mechanical damage by installing metal sleeves, casings or other means in accordance with the instructions in the working drawings.

Protection against mechanical damage at the intersection of electrical wiring laid in the floor in plastic pipes with intra-shop transport routes with a concrete layer of 100 mm or more is not required. The exit of plastic pipes from foundations, floor grouts and other building structures should be made with sections or bends of polyvinyl chloride pipes, and, if mechanical damage is possible, with sections of thin-walled steel pipes.

The connection of plastic pipes must be made: polyethylene pipes - by a tight fit using couplings, hot casing into a socket, couplings made of heat-shrinkable materials, welding; polyvinyl chloride - tight fit in a socket or using couplings. Connection by gluing is allowed.

When preparing polyethylene pipes for electrical wiring, work is carried out on cutting the pipes: and chamfering, bending and connecting pipes, assembling and marking the blanks. Polyethylene pipes are cut on pendulum circular saws, using round flat saws without teeth set with thickness decreasing towards the center of the disk.

Figure 8 - diameter of the bent pipe. The pipe, heated at the bend until softened, is inserted into the rotary sector clamp located above the water, which is rotated to the required angle, fixed on the scale. When the sector is rotated, the pipe is immersed in water and cooled.

For small volumes of work on the preparation of light pipes, pipes are cut using hand scissors or a knife. Chamfering at an angle of 45° is carried out using cone cutters or ribs. Bending of polyethylene pipes is carried out using special devices consisting of a tank filled with water and a removable rotary sector and a pressure roller with semicircular grooves of appropriate dimensions mounted in it.

Bending of pipes preheated to softening can also be done on a bending device mounted on a marking table or on a manual pipe bender, in which the sector and pressure roller are cast from aluminum or made from hard wood. Low-density polyethylene pipes of small diameters with a bending radius equal to six or more outer diameters of the pipes can be bent without preheating (Figure 9).

When working on the device, in order to avoid crushing the pipes, a piece of metal hose, a spiral wire or a heat-resistant rubber hose with a diameter 1-2 mm smaller than the internal diameter of the pipe is inserted inside them. In both cases, the place where the pipes are bent is cooled with a stream of water after bending is completed. Polyethylene pipes bend 20-25° more than a given angle, since due to the elasticity of the pipes they straighten somewhat after bending.

Figure 9 them for 0.5-- 1.5 min heated to 120-- 130 °C

The pipes are heated in heating gas or induction furnaces or cabinets. Pipes made of low-density polyethylene are heated to 100 °C, and high-density polyethylene pipes are heated to 120-130 °C. The duration of heating of pipes in furnaces is 1.5-3 minutes, depending on the diameter and wall thickness of the pipes. High-density polyethylene pipes are also heated by immersing glycerin or glycol, and low-density pipes in boiling water. To smoothly change the temperature of the liquid, 20-25% water is added to glycerin.

To connect pipes, polyethylene couplings are used, as well as couplings with a socket and corner connecting elements (Figure 10.4).

When connecting polyethylene pipes without couplings to each other and to connect them to boxes and pipes, sockets are pressed out at the ends of the pipes. Pressing out the sockets is carried out on a mandrel or on a special device (Figure 10.5). In both cases, the ends of the pipes are preheated as indicated above, and the extruded socket is cooled with water, and then removed from the mandrel.

Figure 10.

In the same way, sockets are pressed out on sections of pipes to obtain couplings. The length of the part of the socket into which the pipe slides is taken equal to the outer diameter of the pipe.

To obtain a welded joint of polyethylene pipes, a special heating tool is used with electric or gas heating of the head, on which the elements to be welded are melted.

The optimal heating temperature for the tool head is considered to be 220--250°C for high-density polyethylene and 280--320°C for low-density polyethylene. The head temperature is regulated using an automatic controller or a laboratory autotransformer. Temperature is measured using a thermocouple.

The process of welding polyethylene pipes is as follows. A welded coupling or socket is placed on a mandrel preheated to the required temperature, and the end of the welded pipe is inserted into the sleeve (Figure 10.1). After melting, the parts to be welded are removed from the tool and immediately connected to each other. The welded joint is left motionless until completely cooled. The duration of melting of parts is 3-15 s and is set during experimental welding, while the pipes should not be heated to the entire thickness of the wall in order to avoid loss of shape.

Figure 10.1 of polyethylene pipes can be made using polyethylene or rubber pipes into which the ends of the connected pipes are inserted with a tight fit.

The method of connecting pipes by hot casing of sockets is also used; in this case, the pipe to be connected is tightly inserted into the socket until it stops, then the socket is heated with warm air to 100-120 ° C. When cooled, the polyethylene of the socket tends to return to its original shape and compresses the pipe tightly. If greater mechanical strength and tightness are not required, the connection

Plastic boxes are used for electrical wiring in polyethylene pipes, but metal ones can also be used. The connection of pipes to boxes is carried out by tightly fitting the ends of the pipes onto the nozzles using couplings and specially made ones. The method of connecting metal duct boxes with polymer pipes using the hot molding method ensures a sealed connection of pipes with boxes without the use of pipes and bushings (Figure 10.7 and 10.8). To obtain such a connection, at the preheated end of the polymer pipe, using a special textolite mandrel with a steel restrictive ring, two corrugations are made in two steps - one from the outside, the other from the inside of the box wall with a tight compression. At the same time, due to the properties of thermoplastic deformation of polymer materials, the required joint density is ensured.

Figure 10.7 0.7--0.8 m. When laying several pipes in the walls, they are pre-secured with wooden slats or wire. To maintain distances between

Polyethylene pipes, parts and blanks are stored on horizontal racks in enclosed spaces at a distance of at least 1 m from heating devices. At the installation site, polyethylene pipes are laid at temperatures from -20 to +20C. When laying pipes, they should be protected from the ingress of molten metal during welding.

During installation, the boxes are first secured, and then the pipes are laid.

The pipes are laid with wooden slats. When concreting floors and foundations with pipes embedded in them, you should ensure the safety of the pipes and their connections. The ends of the pipes are closed with plugs, and the boxes are closed with lids. Upon completion of plastering and concrete work, the lids of the boxes are removed to facilitate evaporation

Figure 10.8 Accumulated condensate.

7.Scheduled preventive maintenance of equipment

In order to ensure reliable operation of equipment and prevent malfunctions and wear, enterprises periodically carry out scheduled preventive maintenance of equipment (PPR). It allows you to carry out a number of works aimed at restoring equipment and replacing parts, which ensures economical and continuous operation of the equipment.

The rotation and frequency of scheduled preventive maintenance (PPR) of equipment is determined by the purpose of the equipment, its design and repair features, dimensions and operating conditions.

Equipment is stopped for scheduled maintenance while it is still in working order. This (scheduled) principle of bringing equipment out for repairs allows for the necessary preparation for stopping the equipment - both from the service center specialists and from the customer’s production personnel. Preparation for scheduled preventive maintenance of equipment consists of identifying equipment defects, selecting and ordering spare parts and parts that should be replaced during repairs.

An algorithm for carrying out scheduled preventive maintenance of equipment is being developed to ensure uninterrupted operation of production during the repair period. Such preparation allows for the full scope of repair work to be carried out without disrupting the normal operation of the enterprise.

Scheduled preventive maintenance of equipment at the following stages of repair:

1. Between-repair phase of maintenance

The between-repair stage of equipment maintenance is carried out mainly without stopping the operation of the equipment itself.

The between-repair stage of equipment maintenance consists of:

· systematic cleaning of equipment;

· systematic lubrication of equipment;

systematic inspection of equipment;

· systematic adjustment of equipment operation;

· replacement of parts with a short service life;

· elimination of minor faults and defects.

The maintenance period between repairs is prevention in other words. The maintenance period between repairs includes daily inspection and maintenance of equipment. The maintenance period between repairs must be properly organized in order to:

· radically extend the period of operation of the equipment;

· reduce and speed up costs associated with scheduled repairs.

The maintenance period between repairs consists of:

· tracking the condition of the equipment;

· implementation of rules of proper operation by workers;

· daily cleaning and lubrication;

· timely elimination of minor breakdowns and regulation of mechanisms.

The maintenance period between repairs is carried out without stopping the production process. The maintenance phase between repairs is carried out during breaks in the operation of the units.

2. Current stage of scheduled maintenance

The current stage of preventive maintenance is often carried out without opening the equipment, temporarily stopping the operation of the equipment. The current stage of scheduled preventive maintenance is to eliminate breakdowns that appear during operation. The current stage of scheduled preventive maintenance consists of inspection, lubrication of parts, cleaning and elimination of identified equipment breakdowns.

The current stage of scheduled preventative maintenance precedes the capital one. At the current stage of preventive maintenance, important tests and measurements are carried out, leading to the identification of equipment defects at an early stage of their occurrence. Having assembled the equipment at the current stage of scheduled maintenance, it is adjusted and tested.

Decree on the suitability of equipment for further work made by repairmen, based on a comparison of test results at the current stage of scheduled maintenance with existing standards and the results of past tests. Testing of equipment that cannot be transported is carried out using electrical mobile laboratories.

In addition to scheduled preventive maintenance, work outside the plan is carried out to eliminate any defects in the operation of equipment. These works are carried out after the entire working life of the equipment has been exhausted. To eliminate the consequences of accidents, emergency repairs are carried out, which require immediate shutdown of the equipment.

3. Middle stage of scheduled maintenance

The middle stage of scheduled preventive maintenance is intended for partial or complete restoration of used equipment.

The middle stage of scheduled preventative maintenance consists of disassembling equipment components to view, clean parts and eliminate identified defects, change parts and assemblies that wear out quickly and that do not ensure proper use of the equipment until the next major overhaul. The middle stage of scheduled maintenance is carried out no more than once a year.

The middle stage of scheduled maintenance includes repairs in which regulatory and technical documentation establishes the cyclicity, volume and sequence of repair work, regardless of the technical condition in which the equipment is located.

The entire complex of scheduled preventive maintenance consists of the following items:

· planning preventive maintenance of equipment;

· preparation of equipment for scheduled maintenance;

· carrying out scheduled preventive maintenance of equipment;

· Carrying out activities related to scheduled preventative repairs and maintenance of equipment.

The middle stage of scheduled maintenance ensures that the operation of the equipment is maintained normally, and there is little chance of equipment failure.

4. Major renovation

Major repairs of equipment are carried out by opening the equipment. Overhaul of equipment consists of checking the equipment with a meticulous examination of the “internals”, testing, measurements, and elimination of identified breakdowns. Overhaul of equipment ensures restoration of original technical characteristics and modernization of equipment is carried out.

Major repairs of equipment are carried out only after the overhaul period. Before major overhaul of equipment, meticulous preparation is carried out:

drawing up a list of certain works;

· drawing up work schedules;

· carrying out preliminary inspection and verification;

· preparation of documentation;

· preparation of tools, spare parts;

· implementation of fire prevention and safety measures.

Overhaul of equipment consists of:

· replacement or restoration of worn parts;

· modernization of some parts;

· performing preventive measurements and checks;

· Carrying out work to eliminate minor damage.

Defects that are discovered during equipment inspection are eliminated during subsequent major overhaul of the equipment. Breakdowns that are emergency in nature are eliminated immediately.

A specific type of equipment has its own frequency of scheduled preventive maintenance, which is regulated by the Technical Operation Rules.

Activities under the PPR system are reflected in the relevant documentation, with strict consideration of the availability of equipment, its condition and movement. The list of documents includes:

1. Technical passport for each mechanism or its duplicate

2. Equipment registration card (appendix to the technical passport)

3. Annual cyclical schedule for equipment maintenance work

4. Annual plan and estimate for equipment overhaul

5. Monthly equipment repair plan-report

6. Acceptance certificate for major repairs

7. Shift log of technological equipment malfunctions

8. Extract from the annual PPR schedule.

Based on the approved annual PPR schedule, a nomenclature plan is drawn up for major and current repairs, broken down by months and quarters.

Before starting major or current repairs, it is necessary to clarify the date of equipment delivery for repairs.

The annual PPR schedule and tables of initial data are the basis for drawing up an annual budget plan, which is developed twice a year. The annual amount of the estimate plan is divided into quarters and months depending on the period of major repairs according to the PPR schedule for a given year.

8. Maintenance of workshop electrical networks with voltage up to 1000 V

The frequency of inspections of the workshop electrical networks is established by local instructions depending on operating conditions, but at least once every 3 months. Measurements of current loads, temperature of electrical networks, and insulation tests are usually combined with overhaul tests of switchgears to which the electrical networks are connected. When inspecting the workshop, special attention is paid to breaks, increased sag of wires or cables, mastic leaks on cable funnels, etc. Using a hair brush, clean the wires and cables from dust and dirt, as well as the outer surfaces of pipes with electrical wiring and branch boxes.

Check for good contact of the grounding conductor with the grounding loop or grounding structure; detachable connections disassembled, cleaned to a metallic shine, assembled and tightened. Damaged permanent connections are welded or soldered.

Wires and cables are inspected, damaged areas of insulation are restored by wrapping them with cotton tape or PVC tape. The insulation resistance is measured with a 1000 V megohmmeter; if it is less than 0.5 MΩ, the wiring sections with low resistance are replaced with new ones.

The insulators and rollers are inspected, the damaged ones are replaced with new ones. The fastening of the insulators and rollers is checked by shaking. Weakly installed insulators are removed, after first freeing the wire from the fastening. They wrap tow impregnated with red lead onto the hooks (pins), then screw on the insulators and secure the wire to the bottom. The loosely installed rollers are secured. Inspect the anchor devices for the end fastening of the cable wiring to the building elements, tensioning devices and the cable. Corroded areas are cleaned with a steel brush or sandpaper and coated with enamel.

Open the covers of the branch boxes. If there is moisture or dust inside the box, on the contacts and wires, check the condition of the seals on the box cover and on the inputs to the box. Seals that have lost their elasticity and do not ensure the tightness of the boxes are replaced. Inspect the terminals and the wires connected to them. Connections that have traces of oxidation or melting are disassembled.

They check the sag, which for cable and string wiring should be no more than 100-150 mm for a span of 6 m, and for a span of 12 m - 200 = 250 mm. If necessary, areas with a large amount of sag are tightened. The tension of the steel cables is carried out to the minimum possible sag. In this case, the tension force should not exceed 75% of the breaking force allowed for a given section of the cable.

Depending on the installation methods, the cooling conditions for the wires change. This leads to the need for a differentiated approach to determining permissible current loads.

Long-term permissible current loads on wires with rubber, olivinyl chloride insulation are determined from the condition of heating the conductors to a temperature of 65? C at an ambient temperature of 25? C. Loads on wires laid in boxes, as well as in trays, are taken as on conductors laid in pipes.

9. Occupational health and safety

Electricians who have passed the test of knowledge of these technical rules are allowed to operate and repair electrical wiring.

safety and other regulatory technical documents(rules and instructions for technical operation, fire safety, use of protective equipment) for the installation of electrical installations within the limits of the requirements for the relevant position, having a qualification group of at least three and having undergone on-the-job training. The electrical service manager is responsible for safety during maintenance and repair.

Electricians must have basic protective equipment for voltage installations up to 1000 V: dielectric gloves, tools with insulated handles, portable grounding and voltage indicators. Additional equipment: dielectric rubber galoshes: mats, insulating stands and posters.

Before using protective equipment, an external inspection should be carried out, paying attention to the date of their inspection.

When carrying out repair and maintenance work, it is necessary to strictly observe safety rules for operating electrical machines.

The order to carry out the work is given by the head of the electrical technical service of the farm or a person replacing him with qualifications of at least IV group.

When maintaining electrical installations, electrical personnel (electricians) carry out the following technical measures:

1. Turn off the electrical installation and take measures to prevent erroneous and spontaneous switching on by removing the switch handle or locking the switchgear door.

2. Prohibiting posters are hung on the manual drive and remote control keys: “Do not turn on people working”, “Do not turn on work on the line”

3. Check that there is no voltage on the current-carrying parts that should be grounded; if there is none, then we apply it.

4. Inclusion of grounding knives or portable grounding installations.

5. Fencing the workplace by posting warning posters:

“Stop the tension”, “Grounded”, “Work here”, “Get in here”.

6. Proceed with inspection and repair of electrical equipment.

After inspection and repair, remove the poster, apply voltage, check the work for Idling. We hand over the inspected, corrected machine or electrical equipment to the work manager, who makes a note in the work log.

We carry out maintenance of electrical installations according to the schedules of the maintenance system.

When working with a power tool, it must satisfy the following basic requirements:

a) quickly switch on and off from the network, preventing spontaneous switching on and off;

b) be safe to operate and have live parts inaccessible to accidental contact.

The voltage of the portable power tool must be:

a) not higher than 220 V in rooms without increased danger;

b) not higher than 36 V in rooms with increased danger (departments of repair shops with the presence of ammonia, hydrogen, acetylene, acetone and other flammable vapors and gases in the air). If it is impossible to ensure the operation of a power tool with a voltage of 36 V, a power tool with a voltage of up to 220 V is allowed, but with the mandatory use of protective equipment (gloves) and reliable grounding of the power tool body.

The body of the power tool must have a special clamp for connecting the ground wire with the distinctive sign “3” or “Ground”.

Plug connections intended for connecting power tools and hand-held electric lamps must have inaccessible live parts and, if necessary, have a grounding contact. Plug connections (sockets, plugs) used for voltage 12 and 36

V, in their design, must differ from conventional plug connections intended for voltages PO and 220V, and do not include the possibility of plugging 12 and 36 V plugs into 110 and 220V plug sockets. Plug connections for 12 and 36 V must have a color that is sharply distinguishable from the color of plug connections for PO and 220 V.

Sheaths of cables and wires must be inserted into the power tool and firmly secured to avoid breaking and abrasion.

Hand-held portable lamps must be used for a voltage of 12V in the usual design, with their housings grounded.

In explosive premises (workshops for the repair of compression refrigerator units, absorption refrigerator units, impregnation departments of electric motor repair shops, etc.), portable lamps must be used at 12V voltage in an explosion-proof design, with their housings grounded.

Connecting portable lamps for voltages of 12 and 36V to the transformer can be done tightly or using a plug; in the latter case, a corresponding plug socket must be provided on the transformer casing on the 12 or 36 V side.

Monitoring the safety and serviceable condition of power tools and hand-held electric lamps must be carried out by a specially authorized person. Power tools must have a serial number and be stored in a dry place. Checking for the absence of short circuits to the housing and the condition of the insulation of the wires, the absence of a break in the grounding wire of power tools and hand-held electric lamps, as well as the insulation of step-down transformers and frequency converters must be carried out with a megger at least once a month by a person with a qualification of at least group III.

Power tools, step-down transformers, hand-held electric lamps and frequency converters are carefully checked by external inspection; Attention is drawn to the serviceability of grounding and insulation of wires, the presence of exposed live parts and the compliance of the tool with operating conditions.

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6. Sokolov B.A. Installation of electrical installations: for a wide range of electrical engineers / B.A. Sokolov, N.B. Sokolova - 3rd ed. reworked and additional - M.: Energoatomizdat, 1991. - 592 p.

7. Sokolov E.M. Electrical and electromechanical equipment. General industrial mechanisms and household appliances: textbook. allowance / E.M. Sokolov. - M.: Masterstvo, 2001. - 224 p.

8. Kharkuta K.S. Workshop on electricity supply to agriculture / K.S. Kharkuta, S.V. Yanitsky., E.V. Lyash. - M.: Agropromizdat, 1992. - 223 pp. (Textbooks and teaching aids for technical school students).

9. Tsigelman I.E. Power supply of civil buildings and municipal enterprises: educational for technical schools / I.E. Tsigelman. - M.: Higher. school, 1982. - 368 p.

Posted on Allbest.ru

Author	Book	Description	Year	Price	Book type
E. M. Sokolova		@ @	2013	1141	paper book
E. M. Sokolova	Electrical and electromechanical equipment. General industrial mechanisms and household appliances	The electrical equipment of cranes, hoists, conveyors, fans, pumps and compressors, which make up a group of general industrial mechanisms, is considered. The characteristics of electrical machines and... - @Academia, @(format: 60x90/16, 224 pages) @ Secondary vocational education @ @	2013	220	paper book
Shekhovtsov V.P.	Electrical and electromechanical equipment: Textbook for secondary vocational education institutions	- @ @(format: 70x100/16, 407 pages) @ @ @	2004	447	paper book
E. M. Sokolova	Electrical and electromechanical equipment. General industrial mechanisms and household appliances	The electrical equipment of cranes, hoists, conveyors, fans, pumps and compressors, which make up a group of general industrial mechanisms, is considered. The characteristics of electrical machines and... - @Academy, @(format: 60x90/16, 224 pages) @ Secondary vocational education @ @	2013	1184	paper book
Sokolova E.M.	Electrical and electromechanical equipment. General industrial mechanisms and household appliances. Textbook. Federal State Educational Standard	The textbook can be used when mastering the professional PM module. 01 Organization of maintenance and repair of electrical and electromechanical equipment (MDK. 01.02) for... - @Unknown, @(format: 60x90/16, 224 pages) @ @ @	2014	766	paper book

Shekhovtsov “Electrical and electromechanical equipment. Book: V. P. Shekhovtsov “Electrical and electromechanical equipment Ground resistance meter F4103-M1

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