Technological map of electric motor repair

Table 5 - Technology of repair of electric motors

	Repair operations	Explanation
1. Coil insulation	Insulation of coils of cable paper or taffeta tape in two layers with overlap	Under a press, the coil is given the desired size, impregnated with GF-95 varnish and baked at 100 ° C for 10 hours in an oven
2. Making new coils	Winding the coil onto the template using manual or motor-driven cups	A layer of electrical cardboard 0.5 mm thick is pre-wound on the template
3. Stripping the insulation using the wire of the damaged coil	Loosening insulation by firing in a furnace at 450-500o C.	The wire is cleared of traces of insulation
4. Insulation of the multilayer outer winding of round wire	Covering each new layer with cable paper, which isolates the coils and corbels laid at the ends of the template	The belt is made of electrical cardboard in the form of a strip with a thickness equal to the diameter of the wire. The belt is fixed with a tape 25 mm wide and placed at the end of the template
5. Connection of windings	Connection of wires with a cross section of up to 40 mm2 by soldering, large cross-section - with special pliers	For soldering, solder is used - Phosphorite bronze or silver solder PSR45, PSr70, powdered borax, rosin
6. Making a cylindrical inner winding from a rectangular wire	In the manufacture of a single-layer coil, the turns are fixed with a keeper tape, forming an octal binding. With multilayer coils, this is not done.	In places of transition from one layer to another, to protect the insulation, a strip of pressboard is laid, the width of which is 4-5 mm greater than the width of the coil
7. Production of disk (selection) winding	Production of a winding by winding a separate each disk and connecting the disks by soldering or winding the winding in one step	In the first case, a round or square wire is used, in the second - a rectangular one.
8. Impregnation and drying of manufactured windings	Immerse the winding in glyptal varnish until all air bubbles are completely released. Lifting the winding over the bath for 20 minutes and after the varnish has run off, placing it in a drying oven for 4 hours at 100 ° C	If the varnish forms a hard, glossy and elastic film, drying is considered complete.

Technological map of repair of windings of an asynchronous motor

Before repairing the windings, it is necessary to accurately determine the nature of the fault. Often, serviceable electric motors are sent for repair, normally operating as a result of damage to the mains, drive mechanism, or incorrect labeling of drives.

The basis of the armature winding of DC machines is the section, i.e. part of the winding enclosed between two collector plates. Several winding sections are usually combined into a coil, which is placed in the grooves of the core.

When appointing repairs, it should be remembered that for electric motors with a power of up to 5 kW with a two-layer winding, if it is necessary to replace at least one coil, it is more profitable to rewind the stator completely. For electric motors with a power of 10 ... 1000 kW with a winding of round wire, one or two coils can be replaced by the pulling method without lifting intact coils.

The main phase of the winding of AC machines is the coil, i.e. a set of wires, which is shaped, convenient for laying in the grooves of the core, spaced from each other by the value of the pitch of the winding. One or more adjacent coils belonging to the same phase and located under one pole form a coil group. The coil group in the case of soft windings is wound entirely with one or more parallel wires. In some cases, the entire winding phase is wound.

Table 6 - Technological map of repair of windings of an asynchronous motor

Operations	Execution sequence	Applied equipment, tools
1. Dismantling the stator winding	The end parts of the coils and the connecting wires are released from fastening after annealing the stator, the connections between the coils and phases are cut, the wedges are pushed down and knocked out of the stator grooves. The winding of their grooves is removed, the grooves are cleaned, blown and wiped	Devices for mounting stator windings and cleaning grooves
2. Insulation blank and sleeve of the motor stator slots	Install the stator on the tilter, measure the length of the groove. They make a template, cut their pressboard sleeves, belts and other insulating material. Install sleeves and lay belts	Stator chisel
3. Winding the stator coils on a winding machine	The coil is unpacked, the diameter of the wire is measured, the coil is installed on the turntable, the wires are fixed in the wiring, the dimensions of the coil turn are determined. The template is installed, the coil group is wound, the wire is cut off, the wound coil is tied in two places and removed from the template.	Micrometer, universal gauge, winder
4. Laying the coils in the stator	The coils are placed in the grooves of the stator. Gaskets are installed between the coils in the grooves and frontal parts. Seal the wires in the grooves and straighten the frontal parts. They fix the coils in the grooves with wedges, insulate the grooves of the coils with varnished cloth and keeper tape
5. Assembling the stator winding circuit	The ends of the coils are cleaned and connected according to a given scheme. Weld by electric welding (solder) the joints. The lead ends are prepared and attached, the joints are isolated, the winding is shrouded and the frontal projections are straightened. Check the correct connection and insulation	File, knife, pliers, hammer, electric arc soldering iron, megger, test lamp
6. Drying and impregnation of the stator winding (rotor, armature) with varnish	The stator is loaded into the drying chamber using a lifting mechanism. Unloaded from the chamber after drying the winding. The stator winding is impregnated in the bath, the varnish is allowed to drain after impregnation, the stator is loaded into the chamber again and dried. The stator is removed from the chamber and the varnish smudges from the active part of the magnetic circuit are removed with a solvent	Drying chamber
7. Covering the frontal parts of the winding with electroenamel	Cover the frontal parts of the stator winding with electroenamel	Brush or spray gun

1.4 Technological map of repair and maintenance of an asynchronous motor with a squirrel-cage rotor

Name and content of works	Equipment and fixtures	Technical requirements
External inspection of an electrical machine, including control, protection, ventilation and cooling systems.		Compliance with technical data sheets for operation and electrical diagrams.
Visual check of the condition of the grounding conductor; checking the condition of the ground loop.	Hammer, shovel	Lack of anti-corrosion coating, loose fastening, mechanical damage are not allowed.
Check for the absence of extraneous noise.		Extraneous noise is not allowed.
Cleaning accessible parts from dirt and dust.	White spirit, rags, metal brush, sweeping brush.
Inspection of the connection elements of the engine with the driven mechanism.		Cracks at the seams, breaks, distortions, loosening of threaded connections are not allowed.
Checking the connection and reliability of the seal of the input cables, the technical condition and tightness of the inlet boxes and sealed inlet couplings; checking the condition of seals, surfaces and parts providing explosion protection; explosion-proof cable and wire entries.	Set of locksmith's probes No. 1 Set of tools set of screwdrivers Set of heads.	The roughness of the working surface Rd is not more than 1.25 microns.
Checking the fastening of the electric drive to the frame (valve).	Set of tools. Set of heads.	Loose fasteners are not allowed.
Inspection of the state of start-up and control equipment (PRA).
Purging the stator and rotor with compressed air.	Compressor.
Checking the insulation resistance of the windings; drying if necessary.	500V megger.	The insulation resistance must not be less than 0.5 MΩ.
Checking the pairing of parts that ensure tightness.	Set of bench probes No. 1. A set of tools, a set of screwdrivers. Set of heads, sealant.	The clearances are specified in the instruction manual.
Checking the presence of lubrication in the bearings of the electric motor, (if there is a grease fitting, replenishment).	CIATIM grease - 221, syringe for pressing grease.

	Set of tools. Screwdriver Set.
	Brush, paint (tablet).
Inspection, cleaning and tightening of contact connections.	Set of tools. Grinding fabric skin according to GOST 5009-82.	Distortions, the presence of oxide, weakening of contact connections are not allowed.
Revision of automatic switch assemblies.	Set of tools. Screwdriver Set.
Checking the presence of cable markings, inscriptions and symbols on the casing, if necessary, restoration.	Brush, paint (tablet).	Lack of marking and inscriptions are not allowed.

Security measures

The electric motor must be de-energized, the AB is turned off, grounding is installed, posters are hung out. Apply portable grounding to the input ends of the electric motor cable. Secure the work site. Work with PPE. Work with trusted instruments and tested power tools and fixtures.

The composition of the brigade

An electrician for the repair of electrical equipment with an electrical safety group of at least the third. Electrician for the repair of electrical equipment with the third electrical safety group.

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INTRODUCTION

1. GENERAL

1.1 Production and energy characteristics of the aggregate

1.2 The main electromechanical equipment of the aggregate

1.3 Levels and structure of energy consumption of the unit

2. Special part

2.1 Organization of operation of electrical equipment of the aggregate

2.2 Types and features of operational work

2.3 Types of repair of electrical equipment

2.4 Installation of equipment

2.5 Types of repair of electrical equipment

2.6 Maintenance

2.7 Maintenance

2.8 Overhaul

2.9 Typical motor failures and their consequences

2.10 The actual annual fund of the engine and the structure of the repair cycle

3. Organizational and technological part

3.1 Determining the required overhaul time and the size of the repair team

3.2 Drawing up a list of spare equipment and materials necessary for operation

4. safety precautions

4.1 Safety measures during the repair and operation of an asynchronous motor with a squirrel-cage rotor 4A200M3U3

Conclusion

LIST OF USED LITERATURE

INTRODUCTION

Increasing the efficiency of production of products and services requires the production of an enterprise to organize the efficient use of various resources, including energy, for this it is necessary, in particular, to ensure the uninterrupted operation of electrical equipment. To do this, it is necessary to establish an effective system of equipment operation.

The relevance of the course work lies in the knowledge of the rules for organizing the maintenance of the electric motor, and makes it possible to carry out the smooth operation of the equipment.

The purpose of the course project is to determine the feasibility of a major overhaul of an asynchronous motor. To do this, you need to solve some problems:

Drawing up the production and energy characteristics of the workshop;

Indicate the features of the main electromechanical equipment of the workshop;

Determining the levels and structure of power consumption of the shop;

Consideration of individual stages of operational work;

Calculation of the actual annual fund of the engine and scheduling of the engine shutdown;

Drawing up a technological map of the engine overhaul;

Calculation of time for overhaul of the engine, the number of the brigade;

Consideration of labor protection and safety issues.

1. GENERAL

1.1 Production and energy characteristics of the aggregate

The pumping station (PS) is designed for land reclamation. On the National Assembly there is a machine room, a repair area, an aggregate, a welding post, service, amenity and auxiliary premises. The National Assembly receives electricity from the power plant via overhead transmission line-35.

The distance from the power plant to its own transformer substation (TS) is 5 km. The TP is located outside the PS at a distance of 10 km.

Consumers of electricity in terms of reliability of power supply belong to categories 1, 2 and 3.

The number of operating schemes - 3. The main consumer is 5 powerful automated pumping units. The frame of the building and the transformer substation is constructed from blocks-sections 6 m long each. Dimensions of the building NS A x B x H = 42 x 30 x7 m.

The layout of the power supply on the territory of the pumping station is shown in drawing 1. In the course project, an aggregate unit is considered.

1.2 The main electromechanical equipment of the aggregate

The main consumers of the aggregate are ED HV and ED gate valves. In the aggregate room, AD 4A200M2U3 37.0 kW is used as an EM HV. This 4A series electric motor is manufactured with closed blowers. The shaft speed is 3000 rpm.

Execution: HELL with a squirrel-cage rotor, the drive of mechanisms of the main application in the conditions (U) of a temperate climate and (3) category of placement. The electric motor can operate at temperatures from -40 to +40°C and relative humidity up to 98% at 25°C. AD is designed for a frequency of 50 Hz, a voltage of 380 V.

Depending on the method of making the rotor winding of an induction motor, the latter are divided into two large groups: motors with a squirrel-cage winding on the rotor and motors with a phase winding on the rotor or motors with slip rings. Motors with a squirrel-cage winding on the rotor are cheaper to manufacture, reliable in operation, have a rigid mechanical characteristic, i.e. when the load changes from zero to the rated speed, the machine speed decreases by only 2-5%.

The disadvantages of these motors include the difficulty of implementing smooth speed control over a wide range, a relatively small starting torque, as well as large starting currents, 5-7 times higher than the rated current.

Motors with slip rings do not have these disadvantages, however, their rotor design is much more complicated, which leads to an increase in the cost of the motor as a whole. Therefore, they are used in case of difficult start-up conditions and, if necessary, smooth speed control over a wide range.

An asynchronous electric motor has a fixed part - a stator, on which a winding is located that creates a rotating magnetic field, and a movable part - a rotor, in which an electromagnetic moment is created, which drives the rotor itself and the actuator.

The stator and rotor cores are made from insulated sheets of electrical steel, usually 0.5 mm thick. The stator and rotor sheets have grooves in which the stator and rotor windings are placed. During the casting process, both winding rods located in the grooves and short-circuiting rings located outside the rotor core are formed. The rings can be provided with ventilation blades to improve motor ventilation and heat dissipation from the rotor winding. The lack of insulation of the rotor winding ensures good heat dissipation from the winding to the core.

Motors with a squirrel-cage winding on the rotor have a number of designs according to the shape of the grooves on the rotor. The shape of the rotor slots is selected depending on the requirements for the starting characteristics of the engine.

The most rational for single-cage rotor slots are trapezoidal oval slots. The rotor is called deep-groove if the height of the rotor groove exceeds the penetration depth of the magnetic field. In cases where high values of starting torque are required, a double cage rotor is used, and the grooves in this case can alternate. The grooves can be closed or semi-closed. Closing rings in the case of cast double cages are made common to both cages.

The design of an asynchronous motor is shown in Figure 1.

Figure 1 - Asynchronous motor

General view of an asynchronous motor: bearings - 1 and 11, shaft - 2, end shields - 3 and 9, paws - 4, rotor - 5, stator - 6, cap - 7, ribs - 8, fan - 10

There is an air gap between the rotor and the stator of an induction motor. When choosing an air gap, conflicting trends are encountered.

However, with a small air gap, additional losses in the surface layer of the stator and rotor, additional moments and engine noise increase. Due to the increase in losses, the efficiency decreases. Therefore, in modern series of asynchronous motors, the air gap is chosen somewhat larger than required for mechanical reasons.

To protect the pump from going into a faulty state, the engine is connected to protection, control and alarm sensors. connecting the motor to the power network using a control, protection and signaling network as shown in drawing 3.

1.3 Levels and structure of energy consumption of the unit

The structure of power consumption levels of the aggregate is shown in Figure 2.

Figure 2 - Scheme of levels and structure of energy consumption of the aggregate

The division of the power supply system by voltage up to 1 kV and above is traditional in accordance with the electric power industry. However, this division does not take into account that the electric power supply system up to 1 kV and above is also multi-stage, hierarchical. A more detailed connection diagram of the HV ED and the rest of the equipment of the pumping station is shown in drawing 2.

Theoretically and practically, the following levels of the power supply system should be distinguished:

First level - apparatus, mechanism, installation, unit technologically or territorially connected and forming a single product with a certain nameplate capacity; food on one line;

Second level - distribution points and switchboards with voltage up to 1 kV AC and up to 1.5 kV DC, control panels, power cabinets, input distribution devices, installations.

2. SPECIAL PART

2.1 Organization of operation of electrical equipment of the aggregate

The operation of the equipment must be carried out in accordance with the requirements of the Rules for Technical Operation (PTE), the Rules for Industrial (Industrial) Safety (PPB), GOST and SNiP, which set out the main organizational and technical requirements for the operation of equipment. All regulatory technical documents for the operation of equipment in force at the enterprise must comply with the requirements of these documents.

Regardless of the departmental affiliation and forms of ownership of enterprises (state, joint-stock, cooperative, individual, etc.), when using equipment for the production of products and the provision of services, the enterprise must organize the correct operation of the equipment, which largely determines its serviceability throughout the entire service life.

Proper operation of the equipment includes:

Development of job and production instructions for operational and operational-repair personnel;

Correct selection and placement of personnel;

Training of all personnel and checking their knowledge of the rules of operation, industrial safety, job and production instructions;

Exclusion of equipment performance of work that adversely affects the environment;

Organization of reliable accounting and objective analysis of violations in the operation of equipment, accidents and taking measures to establish the causes of their occurrence;

Compliance with the instructions of the federal authorities.

In the joint operation of equipment, an agreement is concluded between the lessor and the lessee, which stipulates specific responsibilities for maintaining the equipment at their disposal in good condition, the procedure for its use and repair.

Direct operation of the equipment is carried out by operational personnel at the location of the equipment.

Heads of subdivisions subordinate to operational and operational-repair personnel must have technical training in the relevant equipment, provide professional guidance and control over the work of personnel subordinate to them. The list of positions of engineering and technical personnel is approved by the head of the enterprise.

Persons under the age of 18 are not allowed to work at power plants. Interns of universities and technical schools are not allowed to work independently. They may only be in the workplace under the supervision of a person with appropriate technical training.

Prior to being appointed to independent work or when transferring to another job (position), as well as during a break in work for more than one year, personnel must undergo a medical examination and on-the-job training.

At the end of the training, the knowledge of employees should be tested, after which they are assigned the appropriate safety group.

After checking the knowledge, each employee must undergo an internship at the workplace lasting at least two weeks under the guidance of an experienced employee, after which he can be allowed to work independently. by workshop.

Checking knowledge of the rules, job descriptions and production instructions in accordance with applicable standards is carried out:

Primary - before admission to independent work;

The next one - once a year for operational and operational and maintenance personnel, once every three years for engineering and technical personnel;

Extraordinary - in case of violation by the employee of the rules and instructions, at the request of the heads of the energy departments, the OGE or Federal Supervision.

Persons who have not passed the knowledge test are re-tested no earlier than 2 weeks and no later than 1 month from the date of the last test.

A person who receives an unsatisfactory mark at the third knowledge test is suspended from work; the contract with him should be terminated due to his insufficient qualifications.

The knowledge of engineering and technical personnel is checked by commissions with the participation of the territorial inspector of the Federal Supervision, the rest of the personnel - by commissions, the composition of which is determined by the head of the enterprise. The result of the knowledge test is recorded in a log of a certain form and signed by all members of the commission.

Personnel who successfully passed the knowledge test are issued a certificate of the established form.

The use of equipment at the workplace must be carried out in accordance with the requirements of the manufacturer's instructions given in the operation manual (passport) of the relevant equipment. In the absence of factory documentation, equipment operating instructions must be developed directly at the enterprise.

The operating instructions must contain the following information:

The procedure for accepting and handing over shifts, stopping and starting equipment, conducting maintenance;

Enumeration of measures to ensure uninterrupted, reliable and efficient operation of the equipment;

Enumeration of characteristic faults in which the equipment must be stopped;

The procedure for stopping equipment in emergency situations, a list of blocking and signaling devices that turn off equipment in case of an accident;

Requirements for industrial safety, industrial sanitation and fire prevention measures.

If there is a "Instruction for the workplace", developed in accordance with applicable standards, then the preparation of operating instructions is not required.

Depending on the nature of production, the type and purpose of equipment, it can be assigned to operational and operational-repair personnel, who are obliged to:

Comply with the established mode of operation of the equipment;

Stop the equipment immediately if there are signs of malfunctions leading to equipment failure or endangering the health or life of people;

Using instrumentation, visually and aurally, monitor the correct operation of the equipment;

Avoid overloads, eliminate the harmful effects of operating equipment on building structures, increased vibrations, temperature effects, etc.;

Control the circulation of the lubricant, the degree of heating of the bearings.

The main task of the operational personnel of the workshop is to ensure the smooth operation of the equipment through constant and full continuous and full maintenance. He bears personal responsibility for breakdowns and equipment failures caused by his fault.

It is allowed to use operational and operational-repair personnel for work on switching technological schemes, preparing equipment for repair, as well as when carrying out all types of repair and maintenance work.

The workshop foreman is obliged to help the operating personnel improve their production skills in operation, accident prevention and prevention of premature equipment wear.

The workshop foreman monitors compliance by the operating personnel with the instructions for operating equipment, protective devices and devices, keeps records of scheduled and unscheduled repairs, accidents and breakdowns, participates in the preparation of accident reports and the development of recommendations for their prevention, and provides technical supervision over the conservation of unused equipment.

The transfer of equipment from shift to shift is made against receipt in the shift log. When a shift is handed over, the shift log for detecting defects shall record failures and malfunctions that occurred during the shift, including those eliminated.

Responsibility for improper operation of the equipment, all the more that led to failures and accidents, is borne by the direct culprits in accordance with applicable law.

2.2 Types and features of operational work

The main types of operational work include:

Reception - initial inspection of the equipment in order to determine its completeness and, if necessary, accessories. It is carried out by an appointed commission, consisting of technical and financial specialists of the enterprise;

installation - in large volumes is carried out by a specialized organization, in small enterprises by specialists;

commissioning - the last stage before operation, usually carried out by third-party specialists with the involvement of the operating personnel of the enterprise, ends with a control run of all equipment within 72 hours;

equipment operation;

· storage;

write-off.

The operation of the equipment includes: maintenance, current and major repairs. These types of work are described in more detail in subsequent sections of this course work.

2.3 Acceptance of equipment

Acceptance of equipment received from manufacturers at the enterprise is carried out by commissions. For the main equipment, the chairman of the commission is the chief engineer - deputy head of the enterprise, the members are the chief power engineer, the chief accountant and the head of the unit for equipment ownership, as well as representatives of the Federal Supervision for the acceptance of equipment for hazardous industries.

The rest (minor) equipment is accepted by the commission, whose members are well acquainted with the device and operation of the received equipment.

The commissions are responsible for strict and precise compliance with the equipment acceptance rules, including:

Identification of external defects;

Verification of the actual completeness of equipment and technical documentation;

Keeping equipment intact;

Checking the quality of manufactured equipment and materials.

Enterprises are required to comply with the rules of admission, including the conduct of incoming control. In case of violation of the requirements listed above for the acceptance of equipment, consumer enterprises are deprived of the right to eliminate defects by the manufacturer and compensate for losses incurred by the consumer.

Acceptance of equipment, consisting of checking the availability of technical documentation and completeness of delivery, as well as identifying external defects that do not require disassembly of the equipment.

Terms and procedure for acceptance of equipment in terms of quality, rules for calling a representative of the manufacturer, the procedure for drawing up an act of acceptance of equipment and presenting claims to the supplier and transport organization for the supply of products that do not comply with GOST in terms of quality, completeness, packaging, packaging and labeling, specifications and drawings, are determined by the current regulatory legal acts.

When receiving equipment, it must be ensured that it is properly unloaded from railway platforms and wagons, trucks and other modes of transport. For this purpose, at the place of receiving the equipment, permanent mechanized means must be equipped or special unloading means must be preliminarily arranged and delivered for temporary use.

Personnel unloading arriving equipment must be prepared to work to keep the equipment intact and prevent breakdowns or damage that could adversely affect the operation of the equipment during operation.

Equipment transfer and acceptance certificates, fully executed and signed by all members of the commission, are transferred to the accounting department of the enterprise for balance accounting, where an inventory number is assigned.

An inventory number can be assigned to equipment both by object and by a group of equipment included in the inventory object.

The inventory object of fixed assets is:

Object with all fixtures and fittings;

A separately structurally isolated object intended for

to perform certain independent functions;

A separate complex of structurally articulated objects, which is a single whole and designed to perform a specific job.

A complex of structurally articulated objects is one or more objects of the same or different purposes, having common devices and accessories, common control, mounted on the same foundation, as a result of which each object included in the complex can perform its functions only as part of the complex, and not independently.

2.4 Installation of equipment

Installation of equipment is the last pre-operational period when obvious and partially hidden defects in the manufacture and assembly of equipment can be identified and eliminated. Installation work must be carried out in such a way as not to increase the number of hidden defects remaining in the equipment. Serious attention should be paid to the composition of the preparatory work, which is crucial both for the timely and high-quality installation of equipment, and for its future efficient operation. .

For equipment, the installation of which must be carried out or completed only at the place of use, the work must be carried out in accordance with the special instructions for installation, start-up, adjustment and running-in of the product at the place of use.

Machine-building plants are obliged to apply this instruction to the supplied equipment. The implementation of this instruction will prevent the possibility of an increase in hidden defects in the equipment, as well as identify and eliminate obvious and partially hidden defects in the manufacture and assembly of equipment.

The installation process includes work, the quality of which can only be checked before the start of subsequent work. In this case, the acceptance of the work performed, provided for by the section of the instruction "Commissioning of the assembled product", is carried out by issuing an intermediate acceptance with drawing up an act for the so-called hidden work and attaching it to the final acceptance documentation, if the instruction does not provide for a control opening of the assembly unit.

Installation and dismantling of equipment should be carried out by specialized teams of the enterprise or specialized commissioning organizations.

Acceptance of the installed equipment and its transfer into operation are documented by the act of acceptance and transfer of fixed assets.

In the act of delivery of the installed equipment, it is required to state in detail the procedure for the start-up (testing), regulation, running-in and registration of delivery.

When describing the start-up (testing) during the acceptance of the installed equipment, the following should be indicated:

Provision of launch, procedure for inspection and preparatory operations before launch;

The procedure for checking the serviceability of the components of the equipment and its readiness for launch;

The procedure for turning on and off the equipment; evaluation of launch results.

When describing the work on regulation, you should specify:

The sequence of adjustment operations, methods of regulation of individual components of the equipment, regulation limits, applied instrumentation, tools and fixtures;

Requirements for the condition of the equipment during its regulation (on the move or when stopped, etc.);

The procedure for setting up and regulating equipment for a given mode of operation, as well as the duration of operation in this mode.

In the description of the equipment running-in work, the following should be indicated:

The order of the break-in mode;

The procedure for checking the operation of equipment during running-in; requirements for compliance with the running-in regime of equipment and the running-in of its parts, the running-in duration;

Parameters measured during running-in and changes in their values.

When describing the work on registration of the acceptance of the installed equipment, the following should be indicated:

Data of control openings of separate parts of the equipment;

Results of the final integrated testing and regulation;

Data in the attached installation drawings, diagrams, reference and other technical documentation;

Installed equipment warranties.

The act is signed by the persons handing over and receiving the equipment.

2.5 Types of repair of electrical equipment

Repair is a set of measures to restore the working or serviceable condition of an object or restore its resource. Repair is carried out if it is impossible or impractical to replace them with new similar ones.

There are such types of repair as: current and capital.

Current repair (T) is a repair carried out to restore the operability of equipment and consists in the replacement and (or) restoration of its individual components.

Depending on the design features of the equipment, the nature and scope of the work performed, current repairs can be divided into the first current repair (T 1), the second current repair (T 2), etc. The list of mandatory works to be performed during current repairs must be determined in the repair documentation of the power department (subdivision).

Overhaul (K) is a repair performed for the complete or close to complete restoration of the equipment resource, with the replacement or restoration of any of its parts, including the basic ones (the basic one is understood as the main part of the equipment intended for assembling and installing other components on it). The post-repair resource of the equipment should be at least 80% of the resource of new equipment.

2.6 Maintenance

The norms and typical scope of maintenance work are considered on the example of an asynchronous electric motor 4A200M2U3 37.0 kW. The norm of maintenance of the electric motor is the number of hours allotted for maintenance.

Maintenance for all types of electrical machines in operation includes unscheduled and scheduled maintenance operations.

During maintenance, the following work is carried out:

Minor repairs that do not require a special stop of the machine and are carried out during breaks in the operation of technological installations in order to timely correct minor defects, including: tightening contacts and fasteners; brush change; adjustment of traverses, devices that provide output parameters of generators, umformers and converters; protection adjustment; wiping and cleaning the accessible parts of the machine (external surfaces, rings, manifolds, etc.);

Day-to-day monitoring of the implementation of the PTE and instructions of manufacturers, in particular,

Control of load, temperature of bearings, windings and housing, and for machines with a closed ventilation system - temperature of incoming and outgoing air;

Lubrication control; checking the absence of abnormal noises and hum, as well as the absence of sparks on the collectors and rings;

Daily monitoring of grounding serviceability;

Shutdown of electric machines in emergency situations; participation in acceptance tests after installation, repair and adjustment of electrical machines and their protection and control systems.

Methods, strategies and organizational forms of repair.

Scheduled repairs are the main type of management of the technical condition and restoration of equipment life. Scheduled repairs are implemented in the form of current and major repairs of equipment.

2.7 Maintenance

One of the sources when carrying out a typical scope of current repairs is a typical nomenclature. A typical range of work during the current repair of an asynchronous electric motor with a squirrel-cage rotor includes all maintenance operations:

Partial disassembly of the electric motor;

Checking the correct operation and fastening of the fan;

Turning the necks of the rotor shaft and repairing the "squirrel cage" (if necessary);

Clearance check;

Change of flange gaskets and lubrication of rolling bearings;

Replacement of worn out rolling bearings, washing of plain bearings and, if necessary, their refilling;

Restoration of sharpenings at electric motor shields;

Assembly of the electric motor with testing at idle and in operation;

Checking the machine's fastenings and the serviceability of grounding;

The norm between current repairs is 4320 hours. In more detail, the norms for current repairs are indicated in the technological map.

2.8 Overhaul

One of the sources when carrying out a typical scope of overhaul work is a typical nomenclature. A typical range of work during the overhaul of an asynchronous electric motor with a squirrel-cage rotor includes all current repair operations and, in addition:

Revision and, if necessary, overhaul of the cable line and switching devices, control circuits of this electric motor

Complete disassembly of the electric motor with complete or partial replacement of windings; turning the necks of the shaft or replacing the rotor shaft;

Rotor balancing; fan and flange replacement;

Assembling the electric motor and testing it under load;

The norm between overhauls of the electric motor is 51840 hours. In more detail, the norms for current repairs are indicated in the technological cards.

2.9 Typical malfunctions of electric motors and their consequences

This section lists typical faults in asynchronous motors. The data are summarized in table 1.

Table 1 - Technical malfunctions of blood pressure

Malfunction		Remedy
when connected to the network, the rotor (armature) is stationary	there is no voltage at the input terminals of the machine or it is too low	check the supply line, repair the damage and supply the rated voltage
when connected to the network, the rotor is stationary, strong buzzing, intense heating	damaged bearing; rubbing of the rotor on the stator; jammed shaft of the working mechanism	disconnect the motor shaft from the mechanism shaft and turn on the motor again; if the motor shaft remains stationary, remove the motor and send it in for repair
stop running engine	power supply interrupted, motor protection tripped	find and eliminate a break in the supply circuit find out the cause of the protection operation (motor overload, mains voltage has changed significantly), eliminate it and turn on the engine
the engine does not reach the required speed, it overheats	motor overloaded bearing failed	remove the overload replace the bearing
engine is overheating	the motor is overloaded the mains voltage is increased or decreased the ambient temperature is increased the ventilation of the motor is disturbed (the air supply channels to the fan are clogged, the surface of the motor is dirty)	eliminate the overload find and eliminate the cause of voltage deviation from the nominal eliminate the cause and lower the temperature to an acceptable value clean the ventilation ducts for air supply to the fan and eliminate contamination of the motor surface
engine operation is accompanied by a strong buzz, smoke appeared	there was a short circuit of the turns of some coils of the stator winding; short circuit of one phase	send engine for repair
severe engine vibration	the balance of the motor fan wheel or other element mounted on the motor shaft is out of balance	eliminate the imbalance of the fan or other element installed on the motor shaft
bearing overheats, noise is heard	bearing and grease in it are contaminated. worn bearing. the alignment of the shafts of the engine and the working machine is violated	remove grease from the bearing, flush it and put in new grease. replace the bearing. to align the shafts
the motor is not disconnected from the network when the "stop" button is pressed	"Stuck" contacts of the magnetic starter	turn off the motor with a circuit breaker and replace the magnetic starter
when plugged in, the motor runs erratically	the power contacts of the magnetic starter do not create a stable connection	replace magnetic starter
destruction of the legs of the machine at the points of their attachment to the body	very strong machine vibration. misalignment of the articulated shafts of the engine and the working machine	identify unbalanced rotating elements and balance them disconnect the shafts and realign them
destruction of sockets in the housing for fastening end shields	too much vibration. bearing destroyed	eliminate the causes of vibration. replace the bearing
loosening of the bearing in the endshield	too much radial load on the output end of the shaft, which led to wear of the bearing seat in the shield. very large machine vibration	reduce the radial load and replace the motor; use a motor of a different size, capable of withstanding the existing radial load without destruction. eliminate the causes of severe vibration and replace the motor

2.10 The actual annual fund of work of an asynchronous motor with a squirrel-cage rotor 4A200M2U337.0 kW,structure of the repair cycle (scheduling of maintenance work)

Scheduled preventive maintenance (PPR) is a set of organizational and technical measures for supervision, maintenance and all types of repairs, which are carried out periodically according to a predetermined plan.

Due to this, premature wear of equipment is prevented, accidents are eliminated and prevented.

The PPR system includes the following types of technical repairs: maintenance (TO), current repairs (T), overhaul (K)

The data of the annual work fund of AD 4A200M2U3 37.0 kW are shown in Table 2. And also, on the basis of the annual work fund, a scheduled preventive maintenance (PPR) was drawn up.

Table 2 - Duration of the repair and overhaul period for a year

The work schedule of the National Assembly is three shifts. This is 24 hours a day, or 8640 hours a year. What is the actual annual fund of the engine.

3. ORGANIZATIONAL AND TECHNOLOGICAL PART

3.1 Determining the required overhaul time and the size of the repair team

Electrician for the repair of electrical equipment (ERE):

Rank 2;

Rank 3;

Rank 4;

Rank 5;

Washer Rank 1 (M1);

Electrician-wrapper and insulator for the repair of electrical machines (EOI):

Discharge 1 (power up to 40 kW);

Category 2 (power over 40 kW).

Table 3 - Technological map of the overhaul

		Norm of time per hour	Rank of work
External inspection and establishment of the main technical characteristics of the electric motor before disassembly	make an external inspection of the motor. write down the main electrical characteristics of the electric motor and register it. take a tag, stamp the registration number on it and hang it on the engine
Cleaning the motor before disassembly	blow out the motor with compressed air. wipe the motor before disassembly.
Disassembly of a squirrel-cage motor	install the electric motor in the workplace. unfasten and remove the outer bearing caps and end shields. Remove the rotor from the stator. remove the retaining rings and press the bearings off the motor shaft. remove the inner bearing caps. unfasten and remove the terminal board cover, disconnect the motor winding leads, remove the terminal board. Label motor parts.
Washing and wiping of parts and assemblies of the electric motor after disassembly	rinse, wipe the parts and components of the electric motor after disassembly. put them on the rack.
Fault detection and drawing up a list of defects	inspect the rotor (armature) and stator (inductor) to detect mechanical damage. check winding integrity and insulation resistance. identify parts to be replaced, restored and adjusted, determine the nature and degree of wear of parts and assemblies. check for interturn short circuit in the winding of the rotor (armature), stator and pole coils, compile a table of measurements. draw up a list of defects indicating the scope of work.
Dismantling the stator (rotor) winding circuit	Load the stator with a hoist into the annealing furnace. unload the stator from the furnace after annealing the winding insulation. release from fastening the frontal parts of the sections and connecting wires after annealing. cut the connections between coils and phases upset the wedges and remove them from the stator slots. remove the winding from the grooves. clean the grooves, blow and wipe.
Insulation blank and sleeve of stator (rotor) slots	install the stator in the workplace. measure the length and width of the groove and make a template. cut the sleeves with lever scissors into grooves with a fit in place and with their preliminary compression on the mandrel. lay and fasten the belts.
Winding the stator (rotor) section on a winding machine	unpacking the coil, measuring the wire with a micrometer and installing the coil on the rack; installation of a wire in a leash; determination of the size of the coil of the section (fitting on the grooves); installation of the template and removal of the template stator (rotor); setting the counter to zero section; start and stop of the machine; a piece of wire with wire cutters; ligation of the section in two places after winding the coil; removing a section from a template.
Laying sections in the stator (rotor)	lay the sections in the stator slots. install gaskets between the sections in the grooves and frontal parts. seal the wires in the grooves, tie and straighten the frontal parts. fasten the sections in the grooves with wedges. isolate the ends of the coils with varnished cloth and keeper tape.
Installation of the stator (rotor) winding circuit	strip the ends of the sections and connect them according to the scheme. solder joints. prepare and connect the lead ends. Isolate connections. put bandages on the connection of the circuit and straighten the frontal flights. check the correctness of the connections, measure the value of the insulation resistance.
The imposition of a bandage on the rotor of the electric motor	prepare the wire for the bandage. prepare and install insulation under the bandage. put a wire bandage on the rotor, fix and solder.
Drying, impregnation of the stator (rotor) winding with varnish, drying after impregnation.	Load the stator into the drying chamber using a lifting mechanism. unload the stator (rotor) from the drying chamber after drying the winding. load the stator (rotor) into a bath of impregnating varnish. unload the stator (rotor) from the bath after impregnation. load the stator (rotor) into the drying chamber using a lifting mechanism. unload the stator (rotor) from the drying chamber after drying. remove the varnish from the active part with a solvent.
Coating of the frontal parts of the stator (rotor) winding.	install the stator (rotor) on the workplace. cover the frontal parts of the winding with electro-enamel. remove the stator (rotor) and lay it on a rack.
Rotor balancing	install a half-coupling on the end of the rotor and fix it. adjust the distance between the supports of the device and install the rotor on these supports. Connect the half-coupling of the balanced rotor with the half-coupling of the drive and fasten. adjust the position of the rotor in the fixture. balance the rotor. remove the rotor from the tool supports.
Assembly of an electric motor with a squirrel-cage rotor.	install the inner bearing caps on the motor rotor shaft. press the bearings onto the rotor shaft while hot. put grease in the bearings and install the fixing rings. install the rotor in the stator. install and secure end shields and outer bearing caps. connect the output ends of the motor winding, install and fix the terminal board, install the terminal board cover and fix it. check the correct assembly of the electric motor.
Motor painting	Paint, then move the electric motor to the workplace or transfer to the rack.

According to the time standards, 10% of the time is allocated for auxiliary work not related to the repair of the ED.

3.2 Drawing up a list of materials required for engine overhaul

To repair an asynchronous motor with a squirrel-cage rotor 4A200M2U3 37.0 kW, you must have the right amount of materials and spare parts, for this the exact cost for repairing this electric motor is calculated. All data are entered in table 4.

Table 4 - list of necessary materials for repairs

Material name	Price per one.	For 100 people/hour	The cost of materials in the KR
Bandage wire, kg
Fasteners, kg
Tin-lead solder, kg
Copper wire, winding, kg
Electrical insulating tape, kg
Keeper tape, kg
Lakotkan, kg
Linoxin tubes, m
Electrical insulating varnish, kg
Enamels, primer, kg
Grease lubrication kg
Kerosene dehydrated, kg
Cleaning materials, kg

4. SAFETY

4.1 Safety measures during the repair of an asynchronous motor with a squirrel-cage rotor 4A200M2U3 37.0 kW

When loading and unloading electric motors, it is necessary to use serviceable, reliable and proven mechanisms and slings. Each inventory sling must have a tag indicating the period for checking it and the permissible load. Mechanisms used in the installation of electric motors (cranes, winches, hoists, blocks).

The cable is attached to the electric motor to the eyelets (lifting rings), into which a steel rod or special figure-eight hooks are passed. Before slinging, it is necessary to check whether the eyelets are securely screwed into the motor housing.

It is prohibited to stay under the lifted load and leave the lifted load unattended. Trained workers who have permission to perform these works are allowed to work on the management of mechanisms, as well as to slinging loads. Electricians who do not have these permits are prohibited from working on slinging loads and on lifting mechanisms. electric motor overhaul

Unloading and moving electric motors manually by two workers is allowed with a weight of not more than 80 kg. When loading and unloading electric motors manually from vehicles, reliable flooring should be used. When moving electric motors on a horizontal plane, special carts must be used; in the case of manual movement, a wide board, wooden shield or frame is placed under the electric motor and it is moved along the rollers from sections of steel pipes.

Installation of electric motors on the bases is carried out, as a rule, with the help of cranes. In the absence of cranes, electric motors can be installed on the ground using hand winches, as well as hoists, blocks and other devices located above the installation site of the electric motor, with a preliminary check of the possibility of loading these floors with the weight of the lifted electric motor.

Alignment of electric motors with a technological machine should be carried out with the circuit breaker, knife switch and fuses removed on the supply line with a poster prohibiting the switch being turned on; the ends of the wires or cables supplying the electric motor must be reliably short-circuited and grounded. The rotation of the rotor of the electric motor and the technological machine must be coordinated with the workers working on the technological machine.

Checking the air gaps, changing the grease in the bearings, adjusting and adjusting the brushes for an electric motor with a phase rotor, and checking the insulation resistance of the windings should also be carried out with the switch disconnected, the fuses on the supply line removed, with a prohibition poster hanging on the switch.

Manual disassembly and assembly of electric motors by two workers is allowed with the weight of the rotors and side covers not exceeding 80 kg, with precautionary measures. Details of dismantled electric motors (rotors, covers) must be placed on reliable wooden pads to prevent them from falling.

Removal of connecting halves, pulleys, gears and bearings by blows of hammers and sledgehammers is prohibited; special pullers must be used for this purpose.

When washing bearings with kerosene and gasoline, as well as when varnishing the windings, smoking and making fire near the place of work are unacceptable.

During the drying of the electric motor with current, its case must be grounded, and the power supply must be made in accordance with the rules and safety requirements. Before testing the electric motor idle and under load after installation, it is necessary to: remove debris and foreign objects, check the presence and reliability of grounding, warn and remove workers from the process machine, put a guard on the coupling or belt drive.

Changing the direction of rotation of the electric motor (replacing the supply ends), as well as troubleshooting, both in the electrical and mechanical parts of the unit, must be carried out without fail with the knife switch turned off, the fusible links removed, and a prohibition poster posted.

When mounting electric motors, special attention must be paid to the good condition of the tool and not to allow the use of a tool that has defects. Hammers and sledgehammers must have handles of the proper length, made of dried hard wood (dogwood, birch or beech). Pine, spruce, aspen and similar types of wood are not allowed to be used as tool handles.

Wooden handles of tools, hammers, sledgehammers, files, screwdrivers must be smoothly processed (not have knots, chips, cracks) and securely fixed in the tool.

Wrenches must be applied exactly to the size of the nuts or bolt heads. The use of wrenches is recommended. Chisels are allowed for use with a length of at least 150 mm, their backs must not be knocked down.

CONCLUSION

In the course work, the features of the main electromechanical equipment of the workshop were indicated. The levels and structure of the power consumption of the shop were determined, separate stages of operational work were considered, the actual annual fund of the engine was calculated, an engine shutdown schedule was drawn up, a process map for the engine overhaul was drawn up, the time for engine overhaul, the number of crew were calculated, and safety issues were considered. Used various reference books and Internet resources.

Having calculated the overhaul, the cost of which is 12 thousand, having learned the market value of the new equipment, equal to 46 thousand, I believe that the overhaul for this electric motor can be considered appropriate, since its cost will not exceed 30% of the cost of new equipment.

LIST OF USED LITERATURE

1 Konyukhova E.A. Power supply of objects / E.A. Konyukhov. - Mastery, 2002. - 71 p., 92 p.

2 Lipkin B.Yu. Power supply of industrial enterprises and installations / B.Yu. Lipkin. - Higher School, 1990. - 105 p.

3 Shekhovtsov V.P. Calculation and design of power supply schemes / V.P. Shekhovtsov. - FORUM - INFRA - M, 2005 - 69 p.

4 Yashur A.I. System of maintenance and repair of power equipment / A.I. FMD. - 53 s, 76 s, 126 s.

5 Bolsham Yu.G. Reference book on the design of electrical networks and electrical equipment / Edition Yu.G. Bolsham and others - M .: Energy, 1981. - 37 p.

6 Fedorov A.A. Handbook of power engineering volume II / A.A. Fedorov. - State Energy Publishing House Moscow-Leningrad, 1963. - 47 p.

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Determination of suitability of windings

Typical winding damages are insulation damage and electrical circuit integrity failure. The condition of the insulation is judged by such indicators as the insulation resistance, the results of the insulation test with increased voltage, the deviations of the DC resistance values of individual windings (phases, poles, etc.) from each other, from previously measured values \u200b\u200bor from factory data, as well as by the absence of signs of interturn short circuits in individual parts of the winding. In addition, the assessment takes into account the total duration of the electric motor without rewinding and its operating conditions.

Determination of the degree of wear of the insulation of the windings is carried out on the basis of various measurements, tests and assessment of the external state of the insulation. In some cases, the insulation of the winding in appearance and according to the test results has satisfactory results, and the motor, after repair, is put into operation without its repair. However, after working for a short time, the machine fails due to insulation breakdown. Therefore, the assessment of the degree of wear of the machine insulation is a crucial moment in determining the suitability of the windings.

A sign of thermal aging of the insulation is its lack of elasticity, brittleness, tendency to cracking and fracture under rather weak mechanical stresses. The greatest aging is observed in places of increased heating, remote from the outer surfaces of the insulation. In this regard, to study the thermal wear of the winding insulation, it is necessary to open it locally to the full depth. For the study, select areas of a small area located in the areas of the greatest aging of the insulation, but available for reliable restoration of the insulation after opening. To ensure the reliability of the results of the study, there should be several places for opening the insulation.

At the opening, the insulation is examined in layers, repeatedly bending the removed sections and examining their surface through a magnifying glass. If necessary, compare identical samples of old and new insulation from the same material. If the insulation during such tests breaks, peels and multiple cracks form on it, then it must be replaced in whole or in part.

The signs of unreliable insulation are also the penetration of oil contaminants into the thickness of the insulation and the loose fitting of the winding in the groove, in which vibration movements of the conductors or sides of the sections (coils) are possible.

To determine the malfunction of the windings, special devices are used. So, to detect turn short circuits and breaks in the windings of machines, to check the correct connection of the windings according to the scheme, to mark the output ends of the phase windings of electrical machines, the EL-1 electronic apparatus is used. It allows you to quickly and accurately detect a malfunction during the manufacture of windings, as well as after laying them in the grooves; the sensitivity of the device allows you to detect the presence of one short-circuited turn for every 2000 turns.

If only a small part of the windings has malfunctions and damages, then a partial repair is prescribed. However, in this case, it must be possible to remove the defective parts of the winding without damaging the healthy sections or coils. Otherwise, a major overhaul with a complete replacement of the winding is more appropriate.

Repair of stator windings

Repair of stator windings is carried out in cases of insulation friction, short circuit between wires of different phases and between turns of one phase, short circuit of the winding to the housing, as well as breaks or poor contacts in soldered joints of windings or sections. The scope of repair depends on the general condition of the stator and the nature of the fault. After determining the stator malfunction, a partial repair is performed with the replacement of individual winding coils or a complete rewind is carried out.

In the stators of asynchronous motors with a power of up to 5 kW of a single series, single-layer random windings are used. The advantages of these windings are that the wires of one coil are laid in each half-closed slot, the laying of the coils in the slots is a simple operation, and the fill factor of the slot with wires is very high. In the stators of electrical machines with a power of 5-100 kW, two-layer loose windings are used with a half-closed groove shape. For asynchronous motors with power above 100 kW, the windings are made with coils of rectangular wire. The stators of machines for voltages above 660 V windings are wound with rectangular wires.

Rice. 103. Hinged template for winding coils:
1 - clamping nut; 2 - fixing bar; 3 - hinge bar.

The methods of manufacturing and laying in the grooves of the stators are different for windings of round or rectangular wires. Coils of round wire are wound on special templates. Manual winding of coils requires a lot of time and labor. More often, mechanized winding of coils is used on machines with special hinged templates (Fig. 103), with which coils of various sizes can be wound. The same templates allow you to wind all coils in series, designed for one coil group or for the entire phase.

The windings are made of wires of the PELBO brand (wire enameled with oil varnish and covered with one layer of cotton threads), PEL (wire enameled with oil-based varnish), PBD (wire insulated with two layers of cotton threads), PELLO (wire, insulated with oil varnish and one layer of lavsan threads).

Having wound the coil groups, they are tied up with tape and proceed to laying in the grooves. To isolate the windings from the housing in the grooves, groove sleeves are used, which are a single-layer or multi-layer U-shaped bracket made of a material selected depending on the insulation class. So, for insulation class A, electric cardboard and varnished cloth are used, for heat-resistant winding - flexible micanite or glass micanite.

Production of insulation and laying soft loose winding of an asynchronous electric motor

The block diagram of the algorithm and the flow chart for the repair of the bulk winding of an asynchronous motor is shown below.

Winding technology:

Cut a set of strips of insulating material according to the dimensions of the winding data. Bend the cuff on the cut strips on both sides. Make a set of groove sleeves.

Clean the stator slots from dust and dirt. Insert the groove insulation to its full length in all grooves.

Cut a set of strips of insulating material and prepare the gaskets to size. Prepare a set of gaskets for the frontal parts of the windings.

Insert two plates into the groove to protect the wire insulation from damage when laying them. Insert a coil group into the stator bore; straighten the wires with your hands and put them into the grooves Remove the plate from the groove Distribute the wires evenly in the groove with a fiber rod. Insert an interlayer insulating gasket into the groove. Set the coil on the bottom of the groove with a hammer (hatchet) With a two-layer winding, place the second coil in the groove.

Use ready-made wedges made of plastic materials (PTEF films, etc.) or make wooden ones. Cut wooden blanks to the size of the winding data. Determine their relative humidity and dry to a relative humidity of 8%. Soak wooden wedges in drying oil and dry.

Insert the wedge into the groove and jam with a hammer.
Cut off the ends of the wedges protruding from the ends of the stator with needle-nose pliers, leaving 5-7 mm ends on each side. Cut off the protruding parts of the insulating gaskets.

Insert insulating spacers in the ends of the windings between adjacent coils of two groups of different phases laid side by side.
Bend the frontal parts of the winding coils by 15-18 ° with hammer blows towards the outer diameter of the stator. Follow the smooth bending of the coil wires at the points of their exit from the groove.

The procedure for manufacturing insulation and laying winding wires may be different. For example, the manufacture of slot sleeves, interlayer gaskets, the manufacture of wooden wedges can be carried out before laying the windings, and then the work order remains according to this scheme.

In winding manufacturing technology, some generalizations are made in detail.

Rice. 104. Laying and insulation of a two-layer stator winding of asynchronous motors:
slot (a) and frontal parts of the winding (b):
1 - wedge; 2, 5 - electric cardboard; 3 - fiberglass; 4 - cotton tape; 6 - cotton stocking.

Coils of a two-layer winding are placed (Fig. 104) in the grooves of the core in groups as they were wound on a template. Coils are stacked in the following sequence. The wires are distributed in one layer and put those sides of the coils that are adjacent to the groove. The other sides of the coils are inserted after the lower sides of the coils of all slots covered by the winding pitch are inserted. The following coils are laid simultaneously with the lower and upper sides with a gasket in the grooves between the upper and lower sides of the coils of insulating pads made of electrical cardboard, bent in the form of a bracket. Between the frontal parts of the windings, insulating gaskets made of varnished cloth or sheets of cardboard with pieces of varnished cloth glued to them are laid.

Rice. 105. Device for driving wedges into grooves

After laying the winding in the grooves, the edges of the groove sleeves are bent and wooden or textolite wedges are driven into the grooves. To protect the wedges 1 from breakage and protect the frontal part of the winding, a device (Fig. 105) is used, consisting of a bent sheet steel of the clip 2, into which a steel rod 3 is freely inserted, having the shape and size of a wedge. The wedge is inserted with one end into the groove, the other into the holder and driven by hammer blows on the steel rod. The length of the wedge should be 10 - 20 mm longer than the length of the core and 2 - 3 mm less than the length of the sleeve; wedge thickness - not less than 2 mm. The wedges are boiled in drying oil at a temperature of 120-140 C for 3-4 hours.

After the coils are laid in the grooves and the windings are wedged, the circuit is assembled, starting with the serial connection of the coils into coil groups. For the beginning of the phases, the conclusions of the coil groups coming out of the grooves located near the input shield of the electric motor are taken. The conclusions of each phase are connected, having previously stripped the ends of the wires.

Having assembled the winding circuit, they check the dielectric strength of the insulation between the phases and on the case. The absence of turn short circuits in the winding is determined using the EL-1 apparatus.

Replacing a coil with damaged insulation

The replacement of a coil with damaged insulation begins with the removal of the insulation of the inter-coil connections and bandages, which attach the front parts of the coils to the bandage rings, then the spacers between the front parts are removed, the coil connections are unsoldered and the slot wedges are knocked out. The coils are heated by direct current to a temperature of 80 - 90 °C. The upper sides of the coils are raised with the help of wooden wedges, carefully bending them inside the stator and tying them to the frontal parts of the stacked coils with a keeper tape. After that, the coil with damaged insulation is removed from the grooves. The old insulation is removed and replaced with a new one.

If, as a result of turn short circuits, the wires of the coil are burned out, it is replaced with a new one wound from the same wire. When repairing windings from rigid coils, it is possible to save winding wires of rectangular cross section for restoration.

The technology of winding rigid coils is much more complicated than random winding coils. The wire is wound on a flat template, the grooved parts of the coils are stretched to an equal distance between the grooves. Coils have considerable elasticity, therefore, to obtain accurate dimensions, their grooved parts are pressed, and the frontal parts are straightened. The pressing process consists in heating coils lubricated with bakelite or glyptal varnish under pressure. When heated, the binders soften and fill the pores of the insulating materials, and after cooling, they harden and hold the wires of the coils together.

Before laying in the grooves, the coils are straightened with the help of devices. The finished coils are placed in grooves, heated to a temperature of 75 - 90 ° C and upset with light hammer blows on a wooden sedimentary plank. The frontal parts of the coils are also straightened. The lower sides of the frontal parts are tied to the bandage rings with a cord. Gaskets are clogged between the frontal parts. The prepared coils are lowered into the grooves, the grooves are wedged and the inter-coil connections are connected by soldering.

Repair of rotor windings

In asynchronous motors, the following types of windings are used: "squirrel cages" with rods filled with aluminum or welded from copper rods, coil and rod. The most widespread are "squirrel cages" filled with aluminum. The winding consists of rods and closing rings on which fan wings are molded.

To remove the damaged “cell”, melt it or dissolve aluminum in a 50% solution of caustic soda for 2–3 hours. A new “cell” is poured with molten aluminum at a temperature of 750–780 °C. The rotor is preheated to 400-500 °C to avoid premature solidification of aluminum. If the rotor is weakly pressed before pouring, then during pouring aluminum can penetrate between the iron sheets and close them, increasing the losses in the rotor from eddy currents. Too strong pressing of iron is also unacceptable, since breaks of newly poured rods may occur.

Repair of "squirrel cages" from copper rods is most often carried out using old rods. After sawing the connections of the “cage” rods on one side of the rotor, the ring is removed, and then the same operation is performed on the other side of the rotor. Mark the position of the ring relative to the grooves so that the ends of the rods and the old grooves coincide during assembly. The rods are knocked out by carefully hitting the aluminum tamps with a hammer and straightened.

The rods should enter the grooves with a light hammer blow on the textolite lining. It is recommended to simultaneously insert all the rods into the grooves and knock out the diametrically opposite rods. The rods are soldered in turn, preheating the ring to a temperature at which the copper-phosphorus solder easily melts when brought to the junction. When soldering, they monitor the filling of the gaps between the ring and the rod.

In asynchronous motors with a phase rotor, the methods for manufacturing and repairing rotor windings are not much different from the methods for manufacturing and repairing stator windings. The repair begins with the removal of the winding circuit, the locations of the beginning and ends of the phases on the rotor and the location of the connections between the coil groups are fixed. In addition, sketch or record the number and location of bandages, the diameter of the bandage wire and the number of locks; number and location of balancing weights; insulation material, the number of layers on the rods, gaskets in the groove, in the frontal parts, etc. Changing the connection diagram during the repair process can lead to rotor imbalance. A slight imbalance while maintaining the circuit after repair is eliminated by balancing weights that are attached to the winding holders of the rotor winding.

After establishing the causes and nature of the malfunction, the issue of partial or complete rewinding of the rotor is decided. The bandage wire is unwound onto a drum. After removing the bandages, the solderings in the heads are unsoldered and the connecting clamps are removed. The frontal parts of the rods of the upper layer are bent from the side of the contact rings and these rods are taken out of the groove. Clean the rods from the old insulation and straighten them. The grooves of the rotor core and the winding holder are cleaned of insulation residues. Straightened rods are isolated, impregnated with varnish and dried. The ends of the rods are tinned with POS-ZO solder. The groove insulation is replaced with a new one, laying the boxes and gaskets on the bottom of the grooves with a uniform projection from the grooves on both sides of the core. After the completion of the preparatory work, they begin to assemble the rotor windings.

Rice. 106. Laying the coil of the rotor winding:
a - coil; b - an open groove of the rotor with a laid winding.

In a single series A of asynchronous motors with a power of up to 100 kW with a phase rotor, loop two-layer rotor windings from multi-turn coils are used (Fig. 106, a).

When repairing, the windings are put into open grooves (Fig. 106, b). The previously removed rods of the rotor windings are also used. The old insulation is removed from them and new insulation is applied. In this case, the assembly of the winding consists of laying the rods in the grooves of the rotor, bending the frontal part of the rods, and connecting the rods of the upper and lower rows by soldering or welding.

After laying all the rods or finished windings, temporary bandages are applied to the rods, they are tested for the absence of a short circuit to the case; the rotor is dried at a temperature of 80-100 °C in an oven or oven. After drying, the winding insulation is tested, the rods are connected, the wedges are driven into the grooves and the windings are bandaged.

Often in repair practice, bandages are made of fiberglass and baked together with the winding. The cross section of the fiberglass bandage is increased by a factor of 2 to 3 in relation to the section of the wire bandage. The fastening of the end coil of fiberglass with the underlying layer occurs during the drying of the winding during sintering of the thermosetting varnish with which the fiberglass is impregnated. With this design of the bandage, such elements as locks, brackets and under bandage insulations disappear. Devices and machines for winding fiberglass bandages use the same as for winding wire.

Repair of anchor windings

Faults in the windings of the armatures of DC machines can be in the form of a connection between the winding and the housing, interturn short circuits, wire breaks, and soldering of the ends of the winding from the collector plates.

To repair the winding, the armature is cleaned of dirt and oil, the bandages are removed, the connections to the collector are unsoldered and the old winding is removed. To facilitate the removal of the winding from the grooves, the armature is heated at a temperature of 80 - 90 ° C for 1 hour. To lift the upper sections of the coils, a polished wedge is driven into the groove between the coils, and to lift the lower sides of the coils - between the coil and the bottom of the groove. The grooves are cleaned and covered with insulating varnish.

In the armatures of machines with a power of up to 15 kW with a semi-closed groove shape, bulk windings are used, and for machines of higher power with an open groove shape, coil windings are used. Coils are made of round or rectangular wire. The most widely used template anchor windings are made of insulated wires or copper tires insulated with varnished cloth or mica tape.

Sections of the template winding are wound on a universal template in the form of a boat and then stretched, since it must lie in two grooves located around the circumference of the armature. After giving the final shape, the coil is insulated with several layers of tape, impregnated twice in insulating varnishes, dried and tinned the ends of the wires for subsequent soldering in the collector plates.

An insulated coil is inserted into the grooves of the armature core. They are fixed in them with special wedges and the wires are attached to the collector plates by soldering with POS-30 solder. Wedges are pressed from heat-resistant plastic materials - isoflex-2, trivolterm, PTEF films (polyethylene terephthalate).

The connection of the ends of the winding by soldering is carried out very carefully, since poor-quality soldering will lead to a local increase in resistance and an increase in the heating of the connection during operation of the machine. The quality of the soldering is checked by inspecting the soldering point and measuring the contact resistance, which should be the same between all pairs of collector plates. Then the operating current is passed through the armature winding for 30 minutes. In the absence of defects in the joints, there should be no increased local heating.

All work on the dismantling of bandages, the application of bandages made of wire or glass tape on the anchors of DC machines is carried out in the same manner as when repairing the windings of phase rotors of asynchronous machines.

Repair of pole coils

Pole coils are called excitation windings, which are divided by purpose into coils of the main and additional poles of DC machines. The main parallel excitation coils consist of many turns of thin wire, while the series excitation coils have a small number of turns of heavy gauge wire wound from bare copper bars laid flat or edgewise.

After determining the faulty coil, it is replaced by assembling the coil at the poles. New pole coils are wound on special machines using frames or templates. Pole coils are made by winding insulated wire directly onto an insulated pole, previously cleaned and coated with glyptal varnish. A varnished cloth is glued to the pole and wrapped with several layers of micafolium impregnated with asbestos varnish. After winding, each layer of micafolium is ironed with a hot iron and wiped with a clean cloth. A layer of varnished cloth is glued onto the last layer of micafolium. Having insulated the pole, they put on the lower insulating washer, wind the coil, put on the upper insulating washer and wedge the coil on the pole with wooden wedges.

Coils of additional poles are repaired, restoring the insulation of the turns. The coil is cleaned of old insulation, put on a special mandrel. The insulating material is asbestos paper 0.3 mm thick, cut in the form of frames according to the size of the turns. The number of spacers must be equal to the number of turns. On both sides they are covered with a thin layer of bakelite or glyptal varnish. The turns of the coil are moved apart on the mandrel and spacers are inserted between them. Then the coil is pulled together with a cotton tape and pressed. The coil is pressed on a metal mandrel, on which an insulating washer is put on, then the coil is installed, covered with a second washer and the coil is compressed. Heating by means of a welding transformer up to 120 C, the coil is additionally compressed. Cool it in the pressed position to 25 - 30 °C. After removal from the mandrel, the coil is cooled, coated with air-drying varnish and kept at a temperature of 20–25 °C for 10–12 hours.

Rice. 107. Options for insulation of pole cores and pole coils:
1, 2, 4 - getinaks; 3 - cotton tape; 5 - electric cardboard; 6 - textolite.

The outer surface of the coil is insulated (Fig. 107) alternately with asbestos and micanite tapes, fixed with taffeta tape, which is then varnished. The coil is mounted on an additional pole and wedged with wooden wedges.

Drying, impregnation and testing of windings

Manufactured windings of stators, rotors and armatures are dried in special ovens and drying chambers at a temperature of 105-120 °C. By drying, moisture is removed from hygroscopic insulating materials (electrocardboard, cotton tapes), which prevents deep penetration of impregnating varnishes into the pores of insulating parts during impregnation of the winding.

Drying is carried out in infrared rays of special electric lamps, or using hot air in drying chambers. After drying, the windings are impregnated with varnishes BT-987, BT-95, BT-99, GF-95 in special impregnating baths. The premises are equipped with supply and exhaust ventilation. Impregnation is carried out in a bath filled with varnish and equipped with heating for better penetration of the varnish into the insulation of the wire winding.

Over time, the varnish in the bath becomes more viscous and thicker, due to the volatilization of varnish solvents. As a result, their ability to penetrate into the insulation of the winding wires is greatly reduced, especially in cases where the winding wires are tightly packed into the grooves of the cores. Therefore, when impregnating the windings, the density and viscosity of the impregnating varnish in the bath are constantly checked and solvents are periodically added. The windings are impregnated up to three times, depending on their operating conditions.

Rice. 108. Device for impregnation of stators:
1 - tank; 2 - pipe; 3 - branch pipe; 4 - stator; 5 - cover; 6 - cylinder; 7 - rotary traverse; 8 - column.

To save varnish, which is consumed due to sticking to the walls of the stator frame, another method is used to impregnate the winding using a special device (Fig. 108). Ready for impregnation, the stator with winding 4 is installed on the lid of a special tank 1 with varnish, having previously closed the stator terminal box with a plug. A seal is laid between the end of the stator and the tank cover. In the center of the cover there is a pipe 2, the lower end of which is located below the level of varnish in the tank.

To impregnate the stator winding, compressed air is supplied to the tank through pipe 3 with a pressure of 0.45 - 0.5 MPa, with which the varnish level rises to fill the entire winding, but below the upper edge of the stator frame. At the end of the impregnation, turn off the air supply and hold the stator for about 40 minutes (to drain the remaining varnish into the tank), remove the plug from the terminal box. After that, the stator is sent to the drying chamber.

The same device is also used to impregnate the stator windings under pressure. The need for this arises in cases where the wires are very tightly packed in the stator grooves and during normal impregnation (without varnish pressure), the varnish does not penetrate into all the pores of the insulation of the turns. The pressure impregnation process is as follows. Stator 4 is installed in the same way as in the first case, but is closed from above by cover 5. Compressed air is supplied to tank 1 and cylinder b, which presses cover 5 to the end of the stator frame through the installed seal gasket. Rotary traverse 7, mounted on column 8, and the screw connection of the cover with the cylinder make it possible to use this device for impregnating stator windings of various heights.

The impregnating varnish is supplied to the tank from a container located in another, non-flammable room. Lacquer and solvents are toxic and flammable and, in accordance with labor protection rules, work with them should be carried out in goggles, gloves, rubber apron in rooms equipped with supply and exhaust ventilation.

After impregnation, the windings of the machines are dried in special chambers. The air supplied to the chamber by forced circulation is heated by electric heaters, gas or steam heaters. During the drying of the windings, the temperature in the drying chamber and the temperature of the air leaving the chamber are continuously monitored. At the beginning of the drying of the windings, the temperature in the chamber is slightly lower (100-110 °C). At this temperature, solvents are removed from the insulation of the windings and the second drying period begins - baking of the varnish film. At this time, the drying temperature of the windings is increased to 140 ° C for 5-6 hours (for insulation class L). If after several hours of drying the insulation resistance of the windings remains insufficient, then the heating is turned off and the windings are allowed to cool to a temperature 10-15 ° C higher than the ambient temperature, after which the heating is turned on again and the drying process continues.

The processes of impregnation and drying of windings at power repair enterprises are combined and, as a rule, mechanized.

In the process of manufacturing and repairing the windings of machines, the necessary tests of the insulation of the coils are carried out. The test voltage should be such that during the tests defective sections of the insulation are revealed and the insulation of good windings is not damaged. So, for coils with a voltage of 400 V, the test voltage of a coil not dismantled from the grooves for 1 min should be 1600 V, and after connecting the circuit during partial repair of the winding - 1300 V.

The insulation resistance of the windings of electric motors with voltage up to 500 V after impregnation and drying must be at least 3 MΩ for the stator windings and 2 MΩ for the rotor windings after full rewinding and 1 MΩ and 0.5 MΩ, respectively, after partial rewinding. These winding insulation resistance values are recommended based on the practice of repair and operation of repaired electrical machines.

Current repairs are carried out to ensure and restore the efficiency of the electric motor. It consists in the replacement or restoration of individual parts. Carried out at the installation site of the machine or in the workshop.

The frequency of current repairs of electric motors is determined by the PPR system. It depends on the location of the engine, the type of machine or machine in which it is used, as well as the duration of work per day. Electric motors are subject to current repairs mainly once every 24 months.
During the current repair, the following operations are performed: cleaning, dismantling, disassembly and fault finding of the electric motor, replacement of bearings, repair of terminals, terminal box, damaged sections of the winding end parts, assembly of the electric motor, painting, idling and under load testing. For DC machines and electric motors with a phase rotor, the brush-collector mechanism is additionally repaired.

Table 1 Possible malfunctions of electric motors and their causes

Malfunction	The reasons
Electric motor does not start	Break in the mains or in the stator windings
The electric motor does not turn over at start-up, hums, heats up	There is no voltage in one of the phases, a phase is cut off, the electric motor is overloaded, the rotor rods are broken
Reduced speed and hum	Bearing wear, bearing shield misalignment, shaft bending
The electric motor stops when the load increases	Reduced mains voltage, incorrect connection of the windings, breakage of one of the stator phases, interturn short circuit, motor overload, breakage of the rotor winding (for a motor with a phase rotor)
The motor makes a lot of noise when starting	Fan shroud is bent or foreign objects have fallen into it
The electric motor overheats during operation, the connection of the windings is correct, the noise is uniform	Mains voltage too high or too low, motor overloaded, ambient temperature too high, fan defective or clogged, motor surface clogged
Running engine stopped	Power outage, prolonged voltage drop, mechanism jamming
Reduced resistance of the stator (rotor) winding	Dirty or damp winding
Excessive heating of motor bearings	Alignment is broken, bearings are faulty
Increased overheating of the stator winding	Phase failure, high or low supply voltage, machine overloaded, interturn short circuit, short circuit between winding phases
When the motor is turned on, protection is activated	The stator windings are connected incorrectly, the windings are shorted to the housing or to each other

Current repairs are carried out in a certain technological sequence. Before starting the repair, it is necessary to review the documentation, determine the operating time of the motor bearings, and establish the presence of unrepaired defects. A foreman is appointed to carry out the work, the necessary tools, materials, devices, in particular, lifting mechanisms, are prepared.

Before starting dismantling, the electric motor is disconnected from the network, measures are taken to prevent accidental voltage supply. The machine to be repaired is cleaned of dust and dirt with brushes, blown with compressed air from the compressor. Unscrew the screws securing the terminal box cover, remove the cover and disconnect the cable (wires) supplying power to the motor. The cable is removed, observing the required bending radius so as not to damage it. Bolts and other small parts are placed in a box that is included in the tool kit.

When dismantling the electric motor, it is necessary to make marks with a core to fix the position of the coupling halves relative to each other, and also to note which hole in the coupling half the pin enters. The pads under the paws should be tied and marked so that after repair each group of pads should be installed in its place, this will facilitate the centering of the electric machine. Covers, flanges and other details should also be marked. Failure to follow this rule may result in the need for re-disassembly.

Remove the electric motor from the foundation or workplace by the eyebolts. A shaft or endshield must not be used for this purpose. Lifting devices are used for removal.

Disassembly of the electric motor is carried out in compliance with certain rules. It begins with the removal of the coupling half from the shaft. In this case, manual and hydraulic pullers are used. Then the fan casing and the fan itself are removed, the bearing shield fastening bolts are unscrewed, the rear bearing shield is removed with light hammer blows on the extension made of wood, copper, aluminum, the rotor is removed from the stator, the front bearing shield is removed, the bearings are dismantled.

After disassembly, the parts are cleaned with compressed air using a hair brush for the windings and a metal brush for the casing, end shields, and frame. Dried dirt is removed with a wooden spatula. Do not use a screwdriver, knife or other sharp objects. Detection of an electric motor involves an assessment of its technical condition and the identification of faulty components and parts.

In case of fault detection of the mechanical part, the following is checked: the condition of the fasteners, the absence of cracks in the housing and covers, the wear of the bearing seats and the condition of the bearings themselves. In DC machines, a serious node that is subject to comprehensive consideration is the brush-collector mechanism.

Here, damage to the brush holder, cracks and chips on the brushes, wear of the brushes, scratches and dents on the surface of the collector, and the protrusion of micanite gaskets between the plates are observed. Most of the malfunctions of the brush-collector mechanism are eliminated during current repairs. In case of serious damage to this mechanism, the machine is sent for overhaul.

Malfunctions of the electrical part are hidden from the human eye, it is more difficult to detect them, special equipment is needed. The number of damages to the stator winding is limited by the following defects: open circuit, short circuit of individual circuits between themselves or on the housing, coil short circuits.

A break in the winding and a short circuit to the case can be detected using a megohmmeter. Turn circuits are determined using the EL-15 apparatus. A break in the rods of a squirrel-cage rotor is found on a special installation. Malfunctions eliminated during current repairs (damage to the frontal parts, breakage or burning of the lead ends) can be determined with a megohmmeter or visually, in some cases an EL-15 device is required. During fault detection, the insulation resistance is measured to determine the need for drying.

Directly current repair of the electric motor is as follows. When the thread is broken, a new one is cut (for further operation, a thread with no more than two cut threads is allowed), the bolts are replaced, the cover is welded. Damaged winding leads are covered with several layers of insulating tape or replaced if their insulation along the entire length has cracks, delaminations or mechanical damage.

In case of violation of the frontal parts of the stator winding, air-drying varnish is applied to the defective area. Bearings are replaced with new ones if there are cracks, chips, dents, discoloration and other malfunctions. The landing of the bearing on the shaft is usually carried out by pre-heating it to 80 ... 90 ° C in an oil bath.

The installation of bearings is carried out manually using special cartridges and a hammer or mechanized using a pneumohydraulic press. it was possible to replace them with new ones.

The order of assembly of the electric motor depends on its size and design features. For electric motors of sizes 1 - 4, after pressing the bearing, the front end shield is installed, the rotor is inserted into the stator, the rear end shield is put on, the fan and cover are put on and fastened, after that the coupling half is installed. Further, according to the scope of the current repair, idle scrolling, articulation with a working machine and a load test are carried out.

Checking the operation of the electric motor at idle or with an unloaded mechanism is carried out as follows. After checking the operation of protection and signaling, a test run is performed with listening to knocking, noise, vibrations and subsequent shutdown. Then the electric motor is started, the acceleration to the rated speed and the heating of the bearings are checked, the no-load current of all phases is measured.

The no-load current values measured in the individual phases must not differ from each other by more than ±5%. A difference between them of more than 5% indicates a malfunction of the stator or rotor winding, a change in the air gap between the stator and rotor, or a bearing failure. The duration of the check is usually at least 1 hour. The operation of the electric motor under load is carried out when the process equipment is turned on.

Post-repair testing of electric motors in accordance with the current Norms should include two checks - measurement of insulation resistance and operability of protection. For electric motors up to 3 kW, the insulation resistance of the stator winding is measured, and for motors over 3 kW, additionally. In this case, for electric motors with voltage up to 660 V in the cold state, the insulation resistance must be at least 1 MΩ, and at a temperature of 60 ° C - 0.5 MΩ. Measurements are made with a megohmmeter at 1000 V.

Checking the operation of machine protection up to 1000 V with a power system with a grounded neutral is carried out by directly measuring the current of a single-phase short circuit to the case using special instruments or by measuring the impedance of the "phase - zero" loop, followed by determining the current of a single-phase short circuit. The received current is compared with the rated current of the protective device, taking into account the PUE coefficients. It must be greater than the current of the fuse link of the nearest fuse or circuit breaker release.

In the process of performing current repairs, it is recommended to carry out modernization measures to improve the reliability of electric motors of old modifications. The simplest of them is the triple impregnation of the stator winding with varnish with the addition of an inhibitor. The inhibitor, diffusing into the lacquer film and filling it, prevents the penetration of moisture. It is also possible to encapsulate the frontal parts with epoxy resins, but in this case the electric motor may become unrepairable.

Technological map of electric motor repair

Technological map of repair of windings of an asynchronous motor

1.4 Technological map of repair and maintenance of an asynchronous motor with a squirrel-cage rotor

Send your good work in the knowledge base is simple. Use the form below

INTRODUCTION

The relevance of the course work lies in the knowledge of the rules for organizing the maintenance of the electric motor, and makes it possible to carry out the smooth operation of the equipment.

The purpose of the course project is to determine the feasibility of a major overhaul of an asynchronous motor. To do this, you need to solve some problems:

1. GENERAL

1.1 Production and energy characteristics of the aggregate

The pumping station (PS) is designed for land reclamation. On the National Assembly there is a machine room, a repair area, an aggregate, a welding post, service, amenity and auxiliary premises. The National Assembly receives electricity from the power plant via overhead transmission line-35.

The distance from the power plant to its own transformer substation (TS) is 5 km. The TP is located outside the PS at a distance of 10 km.

Consumers of electricity in terms of reliability of power supply belong to categories 1, 2 and 3.

The number of operating schemes - 3. The main consumer is 5 powerful automated pumping units. The frame of the building and the transformer substation is constructed from blocks-sections 6 m long each. Dimensions of the building NS A x B x H = 42 x 30 x7 m.

The layout of the power supply on the territory of the pumping station is shown in drawing 1. In the course project, an aggregate unit is considered.

1.2 The main electromechanical equipment of the aggregate

1.3 Levels and structure of energy consumption of the unit

2.1 Organization of operation of electrical equipment of the aggregate

Proper operation of the equipment includes:

2.2 Types and features of operational work

2.3 Acceptance of equipment

The rest (minor) equipment is accepted by the commission, whose members are well acquainted with the device and operation of the received equipment.

The commissions are responsible for strict and precise compliance with the equipment acceptance rules, including:

For equipment, the installation of which must be carried out or completed only at the place of use, the work must be carried out in accordance with the special instructions for installation, start-up, adjustment and running-in of the product at the place of use.

Installation and dismantling of equipment should be carried out by specialized teams of the enterprise or specialized commissioning organizations.

Acceptance of the installed equipment and its transfer into operation are documented by the act of acceptance and transfer of fixed assets.

In the act of delivery of the installed equipment, it is required to state in detail the procedure for the start-up (testing), regulation, running-in and registration of delivery.

When describing the start-up (testing) during the acceptance of the installed equipment, the following should be indicated:

2.5 Types of repair of electrical equipment

2.6 Maintenance

The norms and typical scope of maintenance work are considered on the example of an asynchronous electric motor 4A200M2U3 37.0 kW. The norm of maintenance of the electric motor is the number of hours allotted for maintenance.

Maintenance for all types of electrical machines in operation includes unscheduled and scheduled maintenance operations.

During maintenance, the following work is carried out:

2.7 Maintenance

One of the sources when carrying out a typical scope of current repairs is a typical nomenclature. A typical range of work during the current repair of an asynchronous electric motor with a squirrel-cage rotor includes all maintenance operations:

2.8 Overhaul

One of the sources when carrying out a typical scope of overhaul work is a typical nomenclature. A typical range of work during the overhaul of an asynchronous electric motor with a squirrel-cage rotor includes all current repair operations and, in addition:

3. ORGANIZATIONAL AND TECHNOLOGICAL PART

3.1 Determining the required overhaul time and the size of the repair team

Electrician for the repair of electrical equipment (ERE):

3.2 Drawing up a list of materials required for engine overhaul

To repair an asynchronous motor with a squirrel-cage rotor 4A200M2U3 37.0 kW, you must have the right amount of materials and spare parts, for this the exact cost for repairing this electric motor is calculated. All data are entered in table 4.

Table 4 - list of necessary materials for repairs

4. SAFETY

4.1 Safety measures during the repair of an asynchronous motor with a squirrel-cage rotor 4A200M2U3 37.0 kW

The cable is attached to the electric motor to the eyelets (lifting rings), into which a steel rod or special figure-eight hooks are passed. Before slinging, it is necessary to check whether the eyelets are securely screwed into the motor housing.

Manual disassembly and assembly of electric motors by two workers is allowed with the weight of the rotors and side covers not exceeding 80 kg, with precautionary measures. Details of dismantled electric motors (rotors, covers) must be placed on reliable wooden pads to prevent them from falling.

Removal of connecting halves, pulleys, gears and bearings by blows of hammers and sledgehammers is prohibited; special pullers must be used for this purpose.

When washing bearings with kerosene and gasoline, as well as when varnishing the windings, smoking and making fire near the place of work are unacceptable.

Changing the direction of rotation of the electric motor (replacing the supply ends), as well as troubleshooting, both in the electrical and mechanical parts of the unit, must be carried out without fail with the knife switch turned off, the fusible links removed, and a prohibition poster posted.

Wooden handles of tools, hammers, sledgehammers, files, screwdrivers must be smoothly processed (not have knots, chips, cracks) and securely fixed in the tool.

Wrenches must be applied exactly to the size of the nuts or bolt heads. The use of wrenches is recommended. Chisels are allowed for use with a length of at least 150 mm, their backs must not be knocked down.

CONCLUSION

Having calculated the overhaul, the cost of which is 12 thousand, having learned the market value of the new equipment, equal to 46 thousand, I believe that the overhaul for this electric motor can be considered appropriate, since its cost will not exceed 30% of the cost of new equipment.

LIST OF USED LITERATURE

1 Konyukhova E.A. Power supply of objects / E.A. Konyukhov. - Mastery, 2002. - 71 p., 92 p.

2 Lipkin B.Yu. Power supply of industrial enterprises and installations / B.Yu. Lipkin. - Higher School, 1990. - 105 p.

3 Shekhovtsov V.P. Calculation and design of power supply schemes / V.P. Shekhovtsov. - FORUM - INFRA - M, 2005 - 69 p.

4 Yashur A.I. System of maintenance and repair of power equipment / A.I. FMD. - 53 s, 76 s, 126 s.

5 Bolsham Yu.G. Reference book on the design of electrical networks and electrical equipment / Edition Yu.G. Bolsham and others - M .: Energy, 1981. - 37 p.

6 Fedorov A.A. Handbook of power engineering volume II / A.A. Fedorov. - State Energy Publishing House Moscow-Leningrad, 1963. - 47 p.

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