What document establishes the frequency of repairs of electric motors? Maintenance, current repair of engines

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Types of electric motor repairs

Any electric motor, no matter how reliable it may be, must be disassembled from time to time for inspection, testing and repair. With prolonged use, various defects may appear in it. If they are not eliminated in a timely manner, the electric motor will fail unexpectedly with such damage that the winding will have to be completely replaced. In some cases, the damage may be so extensive that it will be impossible to restore the electric motor and it will have to be scrapped. The more reliable an electric motor is made, the easier its operating conditions are, the better the supervision and care for it, the less likely it is that defects will appear in it and the less often it will have to be repaired.

However, it is impossible to completely abandon preventive repairs of electric motors. Any electric motor has rolling or plain bearings. The estimated service life of rolling bearings on average does not exceed 8,000 - 10,000 h., which amounts to just over one year of continuous work.

In practice, rolling bearings often last longer than this. But it is impossible to guarantee high reliability during long-term operation of ball bearings and roller bearings. Therefore, if not replaced, then at least check the bearing, which has worked for the guaranteed number of hours.

In sliding bearings, during operation, due to wear, the gap between the shaft journal and the liner increases. If the value of this gap exceeds the maximum permissible by standards, then vibration of the rotor may increase, and with further operation of the liner, the rotor will touch the stator. In this case, major damage to the electric motor is inevitable. Therefore, it is necessary to monitor the size of the gap in the bearings and promptly refill worn-out bearings.

Checking and, especially, replacing a rolling bearing or one-piece sliding bearing requires disconnecting the electric motor from the driven machine or mechanism, deploying the electric motor on the foundation, and removing the coupling half and end covers from it.

To fully check the electric motor, after removing the end covers, all that remains is to remove the rotor, which is not difficult if you have tools for removing the rotor. Removing the rotor for a complete inspection is necessary, since some defects in the stator and rotor can only be detected when the rotor is removed.

Repairing an electric motor with complete disassembly is called a major overhaul. The scope of a major overhaul, in addition to complete disassembly, includes: cleaning, inspection and testing of the stator and rotor, elimination of identified defects (for example, rebanding the circuit part of the stator winding, replacing weakened wedges, etc.); painting, if necessary, the frontal parts of the winding and boring of the stator and rotor; washing and checking bearings; if necessary, refill the plain bearings or replace the rolling bearings; carrying out preventive tests.

In addition to repairing the electric motor with complete disassembly, so-called current repairs are carried out, during which the lubricant is replaced and the gaps in the plain bearings are measured or grease is added and the separators in the rolling bearings are inspected, the stator and rotor are cleaned and blown from dust with the back cover removed, and the windings are inspected and steel in accessible places.

When should electric motors be repaired?

According to the PTE, major repairs with removal of the rotor of electric motors of critical mechanisms operating in difficult conditions of temperature and ambient air pollution must be carried out at least once every 2 years. For electric motors operating under normal conditions, the overhaul period is set depending on local conditions. The frequency of current and major repairs is established by the chief engineer

Responsible mechanisms include smoke exhausters, blower and mill fans, primary air fans, feed, condensate and circulation pumps, engine generators and a number of other mechanisms. In some cases, network pumps are also responsible.

The role and significance of these mechanisms is really great. For example, turning off the smoke exhauster, blower fan or primary air fan will, at best, lead to a decrease in load or a complete stop of the boiler, and at worst, if the blocking fails, it will lead to an explosion in the boiler. Disabling the feed pump if the automatic activation of the backup pump fails will lead to the boiler stopping, and if there is a delay in stopping the boiler, it will be damaged due to loss of water.

Almost the majority of large electric motors installed in a power plant are critical. The exception is the electric motors of mills, crushers, compressors and some others. Disabling them will not cause immediate load reduction or damage to the boiler and turbine. However, if these electric motors fail during their repair or replacement, an emergency situation may arise at the power plant, sometimes with a decrease in load.

The division of electric motors into critical and non-critical ones is justified when deciding which of them should be provided with self-starting at the moment of restoration of voltage for their own needs after an emergency, and which can be turned off in order to facilitate the start of critical motors. When determining repair periods, it is hardly advisable to divide medium and large electric motors into responsible and non-responsible. We should not forget that the failure of an electric motor with a power of several hundred kilowatts, wherever it is installed, will cause great damage to production.

It is quite obvious that it is unacceptable to risk the failure of such an electric motor due to untimely preventative repairs. Therefore, it is advisable to consider all medium and large electric motors responsible when determining the time between repairs.

For small engines (power up to 100 kW) a different approach should be taken.

The possibility of reparable defects in the stator and rotor windings of these motors is much lower compared to larger motors. Defects in the ball and roller bearings of these motors tend to develop more slowly than in larger ones, and they can be detected and eliminated early, without causing the motor to fail. Finally, if damage to the motor does occur, the cost of rewinding it is small compared to the cost of rewinding large electric motors.

Therefore, for small electric motors, when determining the time between repairs, one should take into account what mechanisms they are installed on, whether they are responsible or not.

If they are installed on critical mechanisms, then the timing between repairs should ensure reliable and uninterrupted operation of these electric motors from repair to repair. Otherwise, the matter may end in a serious accident. For example, an emergency failure of a small electric motor of a generator cooling pump in the absence of a reserve can lead to a decrease in load or shutdown of the generator, and the failure of an electric motor of any oil pump can lead to damage to a large unit on which the oil pump is installed.

For small electric motors of non-essential mechanisms, repairs can be made only when any defect is detected, or, as they say, as needed.

So, according to the PTE, the frequency of major and current repairs of electric motors, depending on their operating conditions, is established by the chief engineer. What considerations should be used when preparing the chief engineer's decision?

You can do it simply. All electric motors, regardless of their operating conditions, must undergo major repairs once a year. This is how they used to do it. But such a decision would be wrong. Too frequent disassembly and reassembly of electric motors will not only not increase their reliability, but if the quality of repair is not high enough, it can lead to the opposite result. During careless disassembly, the rotor or end cover may touch the winding and damage it. Bearings may be damaged if the coupling half is not packed correctly. These damages are not always detected, and as a result the electric motor fails within a short time after repair. Therefore, the emphasis should be placed not on more frequent repairs, but on a higher quality of its implementation.

We should not forget the main thing: too frequent repairs will lead to unnecessary, unjustified labor and material costs for repairing electric motors.

However, from the above one should not conclude that in all cases major repairs once a year are not necessary. For example, for newly installed electric motors, especially of medium and large power, it makes sense to carry out the first major overhaul a year after the start of operation. Wooden wedges in the stator grooves and gaskets under them, if they are made of insufficiently dry material, will have time to dry out during this time and begin to fall out. Due to drying and mechanical stress from starting currents and load currents, the fastenings of the frontal parts may become loose. Within a year, most of the other defects that could have occurred during the manufacture of the electric motor at the factory will have time to appear and will be identified when the engine is disassembled.

Finally, when inspecting the disassembled electric motor, it will be determined how dusty it is, whether it has overheated, whether oil from the bearings is leaking onto the windings, how the bearings worked, etc. Based on the results of the inspection, a decision will be made on the frequency of further repairs.

The timing of subsequent major repairs, if the electric motor is operating normally and there are no comments on it, will, as a rule, be determined by the condition of its bearings.

With plain bearings, the size of the gap between the bearing and the shaft is decisive. The service life of sliding bearings varies widely, from one or two years to ten.

It is not possible to indicate in advance how many years later the bearing shells will have to be refilled, and thereby determine the period for major overhaul of electric motors.

It is necessary to periodically measure the gaps in the bearings of the electric motor once a year and, if they have increased to a value close to the maximum permissible, provide for a major overhaul of this electric motor for the next year. If the gap has increased by a large amount in a short period of time, then a major repair should be carried out at the earliest opportunity.

In most cases, it is enough to carry out major overhauls of electric motors with plain bearings once every 3 years or, judging by the successful operating experience at a number of power plants, even less often. Apparently, for such electric motors it is advisable to switch to overhauls as needed and only carry out the first repairs a year after the start of operation.

When determining the frequency of overhaul of electric motors with rolling bearings, the number of operating hours of the electric motor per year and its speed must be taken into account.

For high-speed electric motors (1,500 and especially 3,000 rpm) major repairs should be carried out after 8,000 - 10,000 h. work. In this case, it is advisable to use bearings that have worked at 3,000 rpm 8 000- 10 000h., replace with new ones even if no external defects are found in them.

For electric motors with speed 1000 rpm and less major repairs can be carried out once every 3 years. In this case, bearings that do not have external defects can be left for the next period.

If defects are found in the electric motor during its operation, such as oil leakage from the bearing and getting onto the winding, or the ventilation ducts become clogged with dust and dirt, which will lead to increased heating of the active steel and winding, then major repairs must be carried out at first opportunity.

It is advisable (but not necessary) to combine a major overhaul of electric motors with a major overhaul of the main unit (boiler, turbine, pump) to which these motors belong. In this case, repairs can be completed in a sufficiently long time, without haste and, therefore, with better quality. In addition, this reduces the number of operations to remove electric motors for repair, and eliminates the need for additional alignment of electric motors with the unit.

For small electric motors (power up to 100 kW), installed on critical mechanisms, it is enough to carry out major repairs once every 2-3 years. For electric motors up to 100 kW, installed on non-critical units, it is quite acceptable to carry out major repairs only if any defect is detected (as necessary).

Routine repairs of medium and large electric motors should be carried out once a year.

For small electric motors, the frequency of maintenance is determined based on the results of monitoring the condition of the lubrication in the bearings.

The frequency of blowing dust off electric motors should be set depending on their operating conditions.

Electric Motor Maintenance

During maintenance, specialists monitor the load and vibration of electric motors, the temperature and presence of grease in the bearings, the absence of abnormal noise and sparking under the brushes. Specialists also perform an external inspection and clean the electric motor of dust and contaminants. Periodic inspections of electric motors are carried out according to the schedule established by the chief engineer of the enterprise. The more severe the working conditions and the more worn out the electric motors, the more often inspections are scheduled.

Severe working conditions include:

Long duration or high frequency of starts, high temperature or dusty environment.

The purpose of the inspections is to determine the technical condition of the electric motor and identify the scope of work that must be performed during the next repair. In addition, during inspection, maintenance of bearings, rings, brushes is carried out and minor repairs are performed without disassembling the machine. The scope of work during inspection and maintenance of asynchronous electric motors is given in the table.

Scope of work and sequence of their implementation during maintenance

Before turning on the electric motor, you should make sure that there are no foreign objects on the mechanism, the electric motor, that the slip rings are in good condition, the starting rheostat handle should be set to the “Start” position; for small engines, turn the rotor manually. After starting the electric motor, monitor the absence of noise and hum, heating of the housing and bearings, vibration, runout of the belt drive or coupling with the mechanism. An emergency stop of the electric motor is carried out in the event of an accident, if smoke or flame appears from the engine or ballasts, if the driven mechanism breaks down, if there is strong vibration, if the engine is overheated with a noticeable decrease in rotation speed.

If there is excess oil, it splashes, foams and is sucked into the machine. When oil gets on the windings, it reduces the insulation characteristics, which can lead to its breakdown. Lack of oil leads to poor lubrication of the bearing and its overheating.

Oil is added in the required quantity at least after 10 days of bearing operation. No later than after 300 hours of operation, the oil in the reservoir is completely replaced. To do this, the used oil is drained, the tank is washed with kerosene, blown with compressed air and washed again, but not with kerosene, but with the oil intended for filling. Then fill the reservoir with oil to normal. Due to its significant viscosity, the oil level is not immediately established. Therefore, oil is added to the required level in small portions.

Rolling bearings are lubricated, as a rule, with consistent (non-liquid) compounds. The volume of the rolling bearing chamber should be filled to 1/2 at higher speeds. If you use grease in quantities exceeding those specified, the bearings overheat and the grease leaks out of the housing. If smaller quantities of lubricant are detected during operation, the latter is added to the required level. The grease should be the same grade as that contained in the bearing. Depending on the operating conditions, the grease is replaced after 3-6 months. work with pre-washing with a mixture of B-70 gasoline and clean transformer oil (6-8%). Flushing is carried out by turning the motor shaft until uncontaminated flushing fluid begins to flow out of the bearing housing. Lubrication in electric motors of the new series (4A) can be changed on the fly without flushing. For this purpose, the bearing assembly has a hole for a grease fitting (in the upper part) and an outlet for used lubricant (in the lower part). New grease is fed behind the bearing, passes through it and displaces the old grease. The contact surfaces of the rings and brushes must be clean and properly cylindrical, and the brushes must be in contact with the rings with at least two-thirds of the contact surface.

The brush contact is adversely affected by conductive coal or metal dust, which is formed when the brushes rub against the rings or commutator. Contamination in the commutator causes sparking under the brushes. Under unfavorable operating conditions of the brush contact, the sparking can be so strong that it causes carbon deposits.

During maintenance, remove contamination of the contact rings with carbon and metal dust by carefully wiping the sliding surface with a clean, dry cloth. Carbon deposits and irregularities are polished with glass abrasive paper. No. 000/180. The paper is fixed on an insulating (wooden) block that has a working recess in the shape of the surface of the ring. For ease of use, the block is equipped with one or two handles.

In accordance with the Technical Operation Rules, the system of scheduled preventive maintenance of electrical equipment (PPRM) provides for two types of repairs: current and major.

Maintenance

It is carried out at intervals (established by the chief power engineer) for all electric motors in operation. The typical scope of work during routine repairs includes the following types of work: external inspection of the electric motor, washing and replacing grease in bearings and, if necessary, replacing rolling bearings, checking and repairing fans and cleaning ventilation devices and ducts, cleaning and blowing with compressed air windings, slip rings, collectors, brush apparatus, checking the state of fastening of the front windings, restoring the varnish coating of these windings, grinding slip rings and commutators, adjusting the brush apparatus, wiping and replacing brushes, increasing the cost of collectors, checking and tightening all threaded fasteners, checking protective grounding, carrying out preventive tests .

Major renovation

Carry out in the conditions of an electrical repair shop (ERS) or a specialized repair enterprise (SRP). The scope of major repairs includes work provided for by current repairs. It also includes the following types of work: complete disassembly of the electric motor, checking all components and parts and their defect detection, repair of frames and bearing shields, rotor and stator magnetic cores, shafts, fans, rotors, collectors, elimination of local insulation defects in windings and connections, carrying out post-repair tests.

The frequency of major overhauls of electric motors is not established by the Technical Operation Rules. It is determined by the person responsible for the electrical equipment of the enterprise based on estimates of the total operating time of electric motors and local operating conditions.

After transportation, the following additional work is carried out for installation of electric motors on foundations: alignment of the position of the electric motor, alignment and alignment of the new electric motor and the unit, fastening, grouting of the foundations. Partial replacement of windings is advisable in case of damage to several single-layer coils or core windings (partial replacement of double-layer stator windings is not advisable, since this damages the insulation of serviceable coils).

Wires removed from damaged electric motors during repairs are reused. In this case, it is necessary to restore the electrical and mechanical parameters of the windings to their original values. To clean wires of old insulation, annealing is used in furnaces, and mechanical separation of insulation residues from the wire is done by drawing through wooden or textolite cleats. After straightening, the wires are wrapped with new insulation on machines.

When repairing stator windings made from rigid coils, rectangular copper wires are reused. The insulation is restored by wrapping it with overlapping tape, overlapping it by ½ the width of the insulating tape. Replacement of collectors is carried out only in case of significant damage (five or more collector plates) with breakdown and burnout of insulation.

In addition, the collectors must be replaced entirely if the height reserve of the collector plates does not ensure their natural wear without reducing this size below the permissible limit in the time before the next major overhaul.

The rationale for the need for periodic maintenance of blood pressure is given. An approximate list of works on AD maintenance is proposed

Asynchronous electric motors They are distinguished by very high reliability, high uninterrupted operation (subject to the permissible switching time).

However, this does not mean that “asynchronous” are eternal. Therefore, it is recommended that each enterprise draw up a maintenance schedule for asynchronous motors. The list of work during maintenance of asynchronous motors may be as follows:

1. External inspection and assessment of the condition of the mechanical part

Maintenance of an asynchronous electric motor should begin with its detailed external inspection. First of all, the presence of obvious faults is determined. The motor housing should be cleaned of dirt and dust using a steel brush. It should not be chipped or damaged. Due to vibrations and dynamic loads, as well as unevenness and defects of the installation site, it often happens that one of the installation “legs” breaks off. Such an engine is rejected and not allowed for further operation.

It is imperative to check the presence of the terminal box cover, as well as the cover covering the rotor terminals for motors with a wound rotor. These lids must close tightly, without gaps. Their crushing and damage are not allowed.

Each asynchronous electric motor must have a nameplate on its body - a plate with information about the nominal parameters. It is necessary to monitor the readability of all inscriptions on the nameplate and, if necessary, restore them so as not to have “unidentified” electric motors on the farm.

When performing maintenance, the engine must be disconnected from the transmission: remove the drive belt, chain or coupling half. After this, you should turn the shaft manually. It should rotate with force due only to the inertia of the rotor; there should be no extraneous sounds, grinding or crunching.

The casing that hides the engine impeller (if closed) should be opened. The impeller should not wobble or have any play in any direction; the locking screw should be tightened.

The motor shaft should not move in the radial and axial directions, and the sprocket or pulley on the shaft should be securely fastened and not loose. All bolted connections must be tight and threads must not be stripped. Defective parts and fasteners must be replaced.

Next, you need to open the bearing caps. The condition of bearings and bearing seats is determined visually. Cracks, chips of bearing rings, and incorrect position relative to the shaft (misalignment) are excluded. Before closing, the bearing assembly is filled with lubricant (oil or special grease). It is generally recommended to check the presence and condition of lubricant in bearing units on a daily basis.

2. External inspection and assessment of the condition of the electrical part

To assess the condition of the stator leads and the rotor current collector, the engine covers are opened. The insulation of the stator terminals must be intact, without cracks or damage, otherwise the insulation must be restored using electrical tape and tape. The terminal block, if present, must not be melted or damaged - otherwise it must be replaced.

The tips of the stator leads may be oxidized or have carbon deposits on the surface - this is a sign of poor electrical contact. If such defects are present, the tips should be stripped down to metal and the windings should be reconnected according to the required pattern. The cavity of the motor terminal box should be carefully cleaned of dust and dirt.

The residual value of the current-collecting rotor brushes of motors with a wound rotor must be at least 4 mm. Their contact surface must be smooth and fit tightly to the slip ring. Chips and cracks on the brushes are excluded. Defective brushes must be replaced. Before installation, they are ground to the surface of the slip ring using glass paper.

The slip rings should be cleaned of dust and dirt using a rag soaked in kerosene. Scuffing and damage to slip rings are not allowed. The cause of such defects may be the extreme wear of the brushes that was not noticed in time.

Finally, it is necessary to check the condition of the grounding conductor of the electric motor. Its cores must be intact, without damage, and the bolted connections of the tips must be securely tightened.

3. Measurements and tests

At this stage, using a megger, the insulation resistance of the stator windings is checked, and for motors with a wound rotor, the rotor windings as well. The electrical resistance of the stator windings is checked relative to the motor housing, and the resistance of the rotor windings is checked relative to the working shaft. At operating temperature, winding insulation resistance of 0.5 megohms or more is considered normal. In practice, the insulation resistance of serviceable electric motors amounts to tens of megohms.

Next, you need to measure the resistance of the stator windings to direct current. The phase-by-phase resistances must be the same, this indirectly indicates the absence of interturn short circuits. For this measurement, it is better to use not a multimeter, but a device with a higher accuracy class, since the resistance of the DC windings is measured in fractions of Ohms.

After making the above measurements, the engine is connected to the network, its covers are closed. The engine starts at idle speed. The absence of vibrations and beating of the working shaft is checked, the no-load currents are measured in phases and correlated with each other. The presence/absence of heating of the engine housing is checked by hand for at least 15 minutes of operation.

Some temperature rise is normal, and its permissible degree is determined by the insulation resistance class. But, for example, an increase in the housing temperature to 100°C clearly indicates some problems in the operation of the electric motor.

Only after this is the engine connected to the transmission of the working mechanism and put into operation under load. Maintenance can be considered completed.

4. General notes

The main goal of maintenance is prevention and timely detection of faults. If the detected defects are not large and serious, a decision is made to eliminate them on site during maintenance. To carry out major and important repairs, engines are delivered to a specially equipped electrical workshop.

It is not only asynchronous electric motors that require systematic maintenance. But it is precisely in their relation that this necessity is often neglected.

However, the lack of timely maintenance is fraught with serious damage and malfunctions for the engine, the elimination of which can take a lot of time and effort. Mechanical damage to the stator iron may occur, the motor winding may become completely unusable, and even a fire may occur in the box or in the working cavity of the motor.

The list of works during maintenance, in agreement with the chief engineer or chief power engineer of the enterprise, does not have to be exactly the same as proposed in this article. Working conditions are of decisive importance: ambient humidity, temperature, dustiness of the room and, finally, work intensity. The same factors should be taken into account when determining the frequency of maintenance of asynchronous motors.

Non-profit Partnership “Innovations in the Electric Power Industry”

ELECTRIC MOTORS WITH VOLTAGE OVER 1000 V WITH A POWER OF 100 KW OR MORE
General technical conditions for major repairs
Norms and requirements

Date of introduction - 2010-01-11

Moscow
2010

Preface

The goals and principles of standardization in the Russian Federation are established by the Federal Law of December 27, 2002 “On Technical Regulation”, and the rules for the development and application of organization standards are GOST R 1.4-2004 “Standardization in the Russian Federation. Organization standards. General provisions".

This standard establishes technical requirements for the repair of electric motors with voltages over 1000 V and a power of 100 kW or more and requirements for the quality of repaired electric motors.

The standard was developed in accordance with the requirements for the standards of electric power industry organizations “Technical conditions for major repairs of power plant equipment. Standards and requirements” established in section 7 of STO “Thermal and hydraulic power plants. Methodology for assessing the quality of repairs of power equipment.”

The use of this standard, together with other standards of RAO UES of Russia and NP INVEL, will ensure compliance with the mandatory requirements established in the technical regulations for the safety of power plants and networks.

Standard information

1. DEVELOPED by the Closed Joint Stock Company "Central Design Bureau for the Modernization and Repair of Energy Equipment of Power Plants" (ZAO "TsKB Energoremont")

2 INTRODUCED by the Commission for Technical Regulation of NP "INVEL"

3. APPROVED AND ENTERED INTO EFFECT by Order of NP "INVEL" dated December 18, 2009 No.

4. INTRODUCED FOR THE FIRST TIME

STANDARD OF THE ORGANIZATION NP "INVEL"

Electric motors with voltage over 1000 V and power from 100 kW or more

General technical conditions for major repairs

Norms and requirements

Date of introduction - 2010-01-11

1 area of ​​use

This organization standard:

It is a regulatory document establishing technical requirements for the repair of asynchronous and synchronous electric motors with voltages over 1000 V and a power of 100 kW or more, as well as for the repair of stators and rotors of the above electric motors, aimed at ensuring the industrial safety of thermal power plants, environmental safety, increasing operational reliability and quality of repair;

Establishes technical requirements, scope and methods of defect detection, repair methods, control and testing methods for components and electric motors with voltages over 1000 V and power from 100 kW or more in general during the repair process and after repair;

Establishes volumes, test methods and comparisons of quality indicators of repaired electric motors with voltages over 1000 V and power from 100 kW or more with their standard and pre-repair values;

Applies to the overhaul of asynchronous and synchronous electric motors with a voltage of over 1000 V and a power of 100 kW or more (hereinafter referred to as electric motors) of thermal power plants;

Intended for use by generating companies operating thermal power plants, repair and other organizations performing repair maintenance of power plant equipment.

The organization's standard does not apply to DC electric motors and special designs (explosion-proof, waterproof, gas-proof, moisture-resistant, frost-resistant, chemical-resistant).

2 Normative references

This standard uses normative references to the following standards and other normative documents:

Federal Law of the Russian Federation of December 27, 2002 No. 184-FZ “On Technical Regulation”

3.2 Symbols and abbreviations

NTD - regulatory and technical documentation;

OTU - general technical conditions;

TU - technical conditions.

4 General provisions

4.1 Preparation of electric motors for repair, removal for repair, performance of repair work and acceptance from repair must be carried out in accordance with the standards and requirements of STO 70238424.27.100.017-2009.

Requirements for repair personnel and manufacturer's guarantees for repair work are established in STO 17330282.27.100.006-2008.

4.2 Compliance with the requirements of this standard determines the assessment of the quality of repaired electric motors. The procedure for assessing the quality of repair of electric motors is established in accordance with the standard for organizing service stations, approved by Order of RAO UES of Russia OJSC No. 275 dated April 23, 2007.

4.3 The requirements of this standard, except for capital ones, can be used for medium and current repairs of electric motors. The following features of their application are taken into account:

Requirements for components and electric motors as a whole during average or current repairs are applied in accordance with the nomenclature performed and the scope of repair work;

Requirements for the scope and methods of testing and comparison of quality indicators of a repaired electric motor with their standard and pre-repair values ​​during an average repair are applied in full;

Requirements for the scope and methods of testing and comparison of quality indicators of a repaired electric motor with their standard and pre-repair values ​​during routine repairs are applied to the extent determined by the technical manager of the power plant and sufficient to establish the operability of the electric motor.

4.4 If the requirements of this standard diverge from the requirements of other technical documentation issued before the approval of this standard, it is necessary to be guided by the requirements of this standard.

When the manufacturer makes changes to the design documentation for electric motors and when issuing regulatory documents from state supervisory authorities, which will entail changes in the requirements for repaired components and for electric motors as a whole, one should be guided by the newly established requirements of the above documents before making appropriate changes to this standard .

4.5 The requirements of this standard apply to major repairs of an electric motor during the full service life established in the normative and technical documentation for the supply of electric motors or in other regulatory documents. When extending the service life of electric motors in accordance with the established procedure beyond the full service life, the requirements of this standard are applied during the permitted period of operation, taking into account the requirements and conclusions contained in the documents for extending the service life.

5 General technical information

5.1 Electric motors are designed for continuous operation as a drive for station pumps (feed, circulation, condensate, chemical, fire, etc.) of various capacities and pressures, mills for grinding fuels, draft machines (fans and smoke exhausters for various purposes), etc. P.

5.2 Electric motors consist of:

Beds;

Stator;

Rotor;

Windings and insulation;

Brush-contact apparatus (for electric motors with a wound rotor);

Rolling bearings;

Sliding bearings and thrust bearings;

Air coolers (oil coolers) built into the stator;

Terminal boxes;

Fan on the rotor shaft.

5.3 Design characteristics, operating parameters and purpose of electric motors must comply with the technical specifications and delivery certificates of the manufacturer.

5.4 The standard was developed on the basis of the design documentation of manufacturing plants and takes into account the requirements of GOST 9630, GOST 17494, GOST 20459 and GOST R 51757.

6 General technical requirements

6.1 Requirements for metrological support for repair of electric motors:

Measuring instruments used for measurement control and testing must not have errors exceeding those established by GOST 8.051, taking into account the requirements of GOST 8.050;

Measuring instruments used in measurement control and testing must be verified in accordance with the established procedure and are suitable for use;

Non-standardized measuring instruments must be certified;

It is allowed to replace measuring instruments provided for in this standard, if this does not increase the measurement error and the safety requirements for performing work are met;

It is allowed to use additional auxiliary control means that expand the capabilities of technical inspection, measurement control and non-destructive testing, not provided for in this standard, if their use increases the efficiency of technical control;

Equipment, devices and tools for processing and assembly must provide accuracy that complies with the tolerances given in the design documentation.

6.2 When performing major repairs of an electric motor, methods, scope and means of technical control are used to determine the compliance of parts, assembly units and the electric motor as a whole with the requirements of paragraphs of this standard.

6.3 Visual inspection without the use of additional control means is carried out according to the following points: ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; , ; ; ; ; ; ; .

6.4 Measurement control is carried out using measuring instruments in accordance with the table.

Table 1

The place and method of marking must comply with the requirements of the design documentation.

When disassembling the electric motor, it is not allowed to apply marks to the seating, sealing and mating surfaces.

6.7 Methods of disassembly (assembly), cleaning, tools used and conditions for temporary storage of components must prevent their damage.

6.9 When disassembling (assembling) components, measures must be taken to temporarily secure the released parts to prevent them from falling or moving.

Electric motor assembly units, bearing parts, rotor shafts and other unpainted surfaces must be cleaned of oil, external contaminants and oxides to the second degree according to GOST 9.402 before defect detection. The internal surfaces of switchboards, fans and other unpainted components and components must be cleaned until the paint coating is completely exposed, and if it is damaged - to the third degree according to GOST 9.402.

The places for connecting the grounding wire on the electric motor must be cleaned of paint and varnish.

Contact surfaces of conductive parts must be protected with cable paper in accordance with GOST 645;

The surfaces of the rotor shaft and the labyrinth grooves on it are wrapped in waxed paper in accordance with GOST 9569 or sheet rubber in accordance with GOST 7338;

The rotor contact rings must be wrapped in electrical insulating cardboard in accordance with GOST 2850;

When working with an open flame within the frontal parts of the stator and rotor windings, the winding insulation must be protected from damage by wet asbestos cardboard in accordance with GOST 2850 and (or) asbestos cloth in accordance with GOST 6102;

When removing bearings from the rotor shaft, the shaft journals must be protected with asbestos cloth in accordance with GOST 6102.

It is allowed not to remove the rolling bearings from the electric motor rotor to check the fits, if no loose fits or bearing defects are found in the assembly.

6.14 Insulation of electric motor windings must be made on the basis of thermosetting electrical insulating materials of heat resistance class not lower than B according to GOST 8865.

Insulation type - according to the design documentation for a specific electric motor.

Nicks, scuffs, breaks, chipping and thread breaks, corrosion pits of the working part of the thread with a depth of more than half the height of the thread profile on more than two threads;

A one-sided gap of more than 1.7% of the turnkey size between the supporting surface of the bolt head (nut) and the surface of the parts after installing the bolt (nut) before touching the part;

Damage to bolt heads (nuts) and splines in screws, preventing screwing with the required force.

6.20 Threaded connections must be cleaned of dirt, calibrated and lubricated with grease in accordance with GOST 1033.

Taper pins must be replaced if the plane of the pin's largest diameter extends below the plane of the part by more than 10% of its thickness.

Cylindrical and conical pins must be replaced if there are burrs, nicks, corrosion pits on their working surface in an area exceeding 20% ​​of the mating area and (or) the threaded part has damage specified in.

Before use, electrodes must be calcined in an oven according to the calcination regime recommended for electrodes of this brand.

Signs of a violation are: discoloration of the outer coating area, leakage of solder, increased fragility of the insulation in comparison with other compounds.

table 2

9.17 If it is impossible to carry out any tests during delivery for repair and acceptance from repair, the scope and methods of testing, as well as the conditions for their conduct, are established by the customer together with the repair contractor, depending on the type, purpose of the electric motor, and testing capabilities.

10 Safety requirements

10.1 Special devices for lifting and transportation (eye bolts, lugs, holes) on repaired components and parts of the electric motor must fully comply with the requirements of the design documentation.

10.2 When performing repairs on electric motors (components), the safety requirements, including fire safety, established in GOST 12.2.007.0 must be observed.

10.4 Vibration safety criteria - according to GOST 12.1.012.

11 Conformity assessment

11.1 Conformity assessment is carried out in accordance with STO 17230282.27.010.002-2008.

11.2 Assessment of compliance with technical requirements, scope and methods of defect detection, repair methods, control and testing methods for components and electric motors as a whole with the standards and requirements of this standard is carried out in the form of control during the repair process and upon acceptance into operation.

11.3 During the repair process, monitoring of compliance with the requirements of this standard for components and electric motors as a whole is carried out during repair work, performing technological repair operations and unit-by-unit tests.

When accepting repaired electric motors into operation, the results of acceptance tests, work during the period of controlled operation, quality indicators, established quality assessments of repaired electric motors and repair work performed are monitored.

11.4 The results of the conformity assessment are characterized by assessments of the quality of the repaired electric motors and the repair work performed.

11.5 Monitoring compliance with the norms and requirements of this standard is carried out by bodies (departments, divisions, services) determined by the generating company.

11.6 Monitoring compliance with the norms and requirements of this standard is carried out according to the rules and in the manner established by the generating company.

Bibliography

Yu.B. Trofimov

Performers

Chief Specialist

Yu.P. Kosinov