Kinds of repair of electric motors

Any electric motor whatever reliable it was has to understand for survey, check and repair from time to time. During the long work in it is mute razyolichny defects can appear. If timely not to eliminate them, then the electric motor will fail abnormally with such damages at which it is necessary to zameyonit the winding completely. In certain cases damages can turn out на­столько big that it will be impossible to recover the electric motor and it should be written off in scrap metal. Than more reliably the electric motor is manufactured, the it is easier than the condition of its work, the supervision and care of it, the less probability of emergence of defects are better in it is mute and the less often it is necessary to repair it.

Схема подсоединения электродвигателя

Scheme of connection of the electric motor.

Absolutely it is impossible to refuse carrying out predupreditelyyony repair of electric motors, however. In any elekyotrodvigatel there are rolling bearings or podshipyonik of sliding. Rated service life of rolling bearings on average does not exceed 8 000 - 10 000that soyostavlyat slightly more than one year of continuous work.

In practice rolling bearings often serve also the bolyyosha of this term. But it is impossible to guarantee high reliability during the extra urgent operation of ball-bearings and roliyokopodshipnik. Therefore if not to replace then to check the bearing which fulfilled gayorantirovanny number of hours it is necessary.

In sliding bearings during the work because of the vyrayobotka the gap between the neck of the shaft and vklayodyshy increases. If the size of this gap exceeds maksiyomalno admissible norms, then vibration of the rotor can increase, and at further operation of the insert the rotor will touch the stator. Large damage of the electric motor in this case is inevitable. Therefore it is necessary to watch gap size in bearings and to timely make refilling of the worked well together inserts.

Схемы подключения однофазного электродвигателя

Schemes of connection of the single-phase electric motor.

Check and the more so replacement of the rolling bearing or one-piece bearing of sliding demand detachment of the electric motor from the given machine or the mechanism, expansion of the electric motor on the base, removals from it of the semi-coupling and face kryyoshka.

For full check of the electric motor after removal of edge covers it is necessary to take out the rotor that at the naliyochiya of devices for dredging of the rotor big is not difficult. Dredging of the rotor is necessary for full check as some defects of the stator and the rotor can be obnayoruzhit only at the taken-out rotor.

Repair of the electric motor with full dismantling nazyyovatsya by major repair. In the volume of major repair, except full dismantling enter: cleaning, survey and check of the stator and the rotor, elimination of the revealed defects (for example rebanding of the circuit part of the winding of the stator, replacement of the weakened wedges, etc.); painting if it is necessary, front parts of the winding and boring of the stator, the rotor; proyomyvka and check of bearings; if it is necessary, the pereyozalivka of bearings of sliding or replacement of podshipyonik of swing; carrying out routine tests.

Except repair of the electric motor with full dismantling, so-called running repair at which lubricant is replaced is made and gaps are measured in podshipyonik of sliding or lubricant is added and separators in rolling bearings look round, cleaning and blowing of the stator and the rotor from dust at the removed back cover proizvoyoditsya, windings and steel in available places are examined.

In what terms do electric motors have to be repaired?

On PTE capital ре­монт with dredging of the rotor of electric motors of the responsible mechanisms working under trying conditions on temperature and impurity of the ambient air дол­жен to be made at least 1 time in 2 years. For the electric motors working in standard conditions, the term of major repair is established depending on local conditions. Frequency of tekuyoshchy and capital repairs is established by the chief engineer

Схема устройства электродвигателя

Scheme of the device of the electric motor.

Responsible it is considered to be such mechanisms which shutdown can cause the stop or sniyozheny loadings of the boiler, turbine or to create threat of damage them.

Dymoyososa, blow and mill fans, fans of primary air, feeder, condensate and tsiryokulyatsionny pumps, the engine generators and the number of druyogy mechanisms are among responsible mechanisms. In certain cases also network pumps are among otvetyostvenny.

The role and value of the specified mechanisms is deystvitelyyono big. For example, shutdown of the smoke exhauster, blow fan or fan of primary air priyovedt, at best, to decrease in loading or the fake stop of the boiler, and in the worst if the blokiyorovka, and to explosion refuses the boiler. Shutdown of the feeder pump at refusal of automatic turning on of the rezervyony pump will lead to the boiler stop, and at the promedyoleniye with the boiler stop - and to its damage because of the upusk of water.

Practically the majority large elektrodvigateyoly, established at power plant, are responsible. The exception is made by electric motors of mills, crushers, compressors and some other. Their shutdown will not cause immediate decrease in the nayogruzka and damage of the boiler and the turbine. However at the vyyokhoda out of operation of these electric motors for the period of their reyomont or replacement by power plants there can be emergency situation, sometimes with decrease in loading.

Division of electric motors into responsible and neyootvetstvenny is justified at the solution of the question of what of them should be provided with self-starting at the time of voltage recovery on own needs to the poyosla of emergency situation and what can be disconnected at the same time to facilitate start-up of responsible dvigayotel. When determining terms of repair it is hardly reasonable to divide averages and large electric motors on responsible and neyootvetstvenny. It is worth to remember that failure of the electric motor with a power of several hundred kilowatts where it was established, will bring extensive damage to production.

Схема клеммной коробки трехфазного электродвигателя

Scheme of the terminal box of the three-phase electric motor.

It is quite obvious that to risk the exit of such electric motor out of operation because of untimely preyodupreditelny repair inadmissibly. Therefore tselesoobrazyono to consider all averages and large electric motors when determining terms between repairs responsible.

Concerning small engines (with power up to 100 kW) it is necessary to adhere to other approach.

The possibility of emergence of removable defects in the winding of the stator and the rotor of these engines on the sravneyoniya with larger engines is much lower. Defects in ball-bearings and roller bearings of these engines, as a rule, develop more slowly, than in large, and they can be obnaruyozhit and eliminated beforehand, without bringing the matter to the exit of the elektroyodvigatel out of operation. At last, if there is the engine povrezhyodeniye, then the cost of its rewind, on the sravneyoniya to the cost of rewind large elektrodvigateyoly, is small.

Therefore for small electric motors at the opredeyoleniye of terms between repairs it is necessary to consider on what they mechanisms are established, on responsible or not.

If they are established on responsible mechanisms, then terms between repairs have to ensure nadezhyony and smooth functioning of these electric motors from repair before repair. Otherwise business can come to an end in serious accident. For example, emergency вы­ход out of operation the small electric motor of the pump of cooling of the generator in the absence of the reserve can lead to decrease in loading or the stop of the generayotor, and the exit of the electric motor of any oil pump - to damage of the large unit on which установ­лен the oil pump.

For small electric motors of irresponsible meyokhanizm it is possible to repair only at the obnayoruzheniye of any defect, or as speak, as required.

Схема управления бесколлекторным электродвигателем

Scheme of control of the beskollektorny electric motor.

So, on PTE frequency of major and tekuyoshchy repair of electric motors, depending on usloyoviya of their work, is established by the chief engineer. What reasons does follow руководствовать­ся by preparation of the decision of the chief engineer?

It is possible to arrive simply. Irrespective of conditions of their work to do to all electric motors major repair once a year. Earlier and arrived. But such decision will be wrong. Too frequent dismantling and assembly of electric motors not only will not increase their reliability, but at insufficiently high quality of the reyomont can result in the return result. At neyoostorozhny dismantling graze by the rotor or the edge cover for the winding and povrezhdeyony it can be allowed. Bearings at neprayovilny tamping of the semi-coupling can be damaged. These damages are not always found, and as a result the elektrodvigayotel fails through short time after repair. Therefore emphasis needs to be placed not on more frequent repair, and on higher quality of its proveyodeniye.

It is worth to remember also the main thing: too frequent ре­монт will lead to unnecessary, unjustified labor and material inputs on repair of electric motors.

However from told it is not necessary to draw the conclusion that in all cases major repair is not necessary once a year. For example, for again mounted elektrodvigayotely, especially mean and large power, it makes sense to make the first major repair че­рез year since the beginning of operation. Wooden wedges in grooves of the stator and laying under them if they are made of insufficiently dry mayoterial, during this time will manage to dry and will begin to vyyopadat. Because of drying and mechanical influences from starting currents and currents of loading krepyoleniye of front parts can weaken. In the year will manage to be shown and will be revealed at the disassembled engine the bolshinyostvo of other defects which could be allowed at production of the electric motor at the plant.

At last, at survey of the disassembled electric motor it will be established, how strongly it became dusty whether overheated, whether oil from bearings gets on the winding as bearings, etc. worked. On reyozultata of survey the decision on the perioyodichnost of further repairs will be made.

The term of performance of the subsequent capital remonyot if the electric motor works normally and there are no zameyochaniye on it, as a rule, will be defined by the soyostoyaniye of its bearings.

Схема управления трехфазным электродвигателем

Scheme of control of the three-phase electric motor.

At sliding bearings gap size between the insert and shaft is decisive. The term of the sluzhyoba of bearings of sliding fluctuates in big preyodela, of one-two years to ten.

To specify in advance in how many years it is necessary to perezayolivat inserts of bearings and to determine by that the term of major repair of electric motors does not predyostavlyatsya by possible.

It is necessary to measure periodically once a year zayozor in bearings of the electric motor and if they are vozyorosl up to the size close to the most admissible, to provide major repair of this electric motor the next year. If the gap increased for the koyorotky interval by big size, then kapitalyyony repair should be executed at the next vozmozhyonost.

Almost major repair of electric motors with sliding bearings in most cases is enough to make 1 time in 3 years or, judging by uspeshyony operating experience at the number of power plants, even more rare. Apparently, for such electric motors tseleyosoobrazno to pass to major repair as required and to make only the first repair че­рез year since the beginning of operation.

When determining frequency of the capital remonyot of electric motors with rolling bearings number of business hours of the electric motor in the year and its rapidity have to be considered.

For high-speed electric motors (1 500 and osoyobenno 3 000 about. / mines) major repair has to proizyovoditsya after 8 000 - 10 000 h work. At the same time reasonablly the bearings which fulfilled at 3 000 about. / min. 8 000 - 10 000to replace on new if in them outer defects are not found even.

Схемы включения асинхронных электродвигателей

Schemes of turning on of asynchronous electric motors.

For electric motors with the speed of 1000 about. / min. and less major repair is admissible to be made 1 time in 3 years. In this case it is possible to leave the bearings which do not have outer defects for the following term.

If in the electric motor during its work there are obnayoruzhena defects as, for example, leak of oil from the podyoshipnik and its hit on the winding, or will happen swamping of ventilating channels dust, dirt that will lead to the increased heating of active steel and the winding, then major repair has to be executed as soon as possible.

Major repair of electric motors it is desirable (but it is not obligatory) to combine with carrying out kapiyotalny repair of the main unit (the boiler, the turbine, the pump) to which these engines belong. In this case repair can be executed in rather long time, without haste and, therefore, with higher quality. Besides, at the same time the number of operations on the conclusion of electric motors in repair decreases, otpayodat need for additional lining of electric motors with the unit.

For the small electric motors (with power up to 100 kW) installed on responsible mechanisms, major repair is enough to make 1 time in 2-3 years. For the electric motors with power up to 100 kW installed on irresponsible units it is quite admissible to make major repair only at detection of any defect (in process of the neobkhodiyomost).

And large elektrodvigateyoly should make running repair of average once a year.

For small electric motors frequency of tekuyoshchy repair is defined on the basis of results of observation of the condition of lubricant in bearings.

Frequency of blowing of electric motors from dust has to be established depending on conditions of their work.

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