How independently to repair electric motors?
In the course of service of operation of electric motors there comes the moment when further operation is impossible without carrying out repair.
Let's try to describe in this article the most often found breakdowns of bearings which happen in the course of operation of electric motors. It will be a question of engines with power up to 100 kW which can be repaired by own efforts, without involving many people and auxiliary mechanisms.
First of all we make division of units, for example, we will be engaged in the electric motor which works together with the water supply pump, in the system of heating (the network pump). We remove the back casing of the impeller of cooling which fastens three or four screws or bolts depending on electric motor power, we throw off also the impeller. That should be made, - to try to define the following what backlash in bearings, both front, and back. For this purpose it is necessary to raise and lower the engine shaft the sharp movements. At development of bearings the backlash will be felt, and it can be understood at once. It is also necessary "to probe" the backlash and across, i.e. to move backwards-forward. And one more small diagnostics - to turn on the engine and to listen to it without loading and without cooling noise. It would seem why these excess efforts. However in the course of these several steps you precisely define whether it is worth repairing the engine.
Now we start dismantling. There can be several options. It is possible to begin dismantling if disturbs on both sides of nothing you. It is possible just to unroll aside, everything depends on the installation site. There are cases when it is necessary to disconnect also the feeding cable. In that case it is necessary to mark phases in any convenient way. The main thing that at resetting you did not guess whether you connected everything as was.
First of all we remove the semi-coupling the remover intended for these affairs. We look further whether is on the body, more precisely on side covers, traces, drips or even pieces of the flowing lubricant. All this should be removed before dismantling not to bring all this then on stator windings. If all in pure form, we begin to remove covers which fasten bolts, them can be 3, 4, 5 and even more. When bolts are taken, easy percussions by the hammer we throw off covers. On the one hand we tap, and we keep another in the tightness that the cover did not leave back at blow. It is necessary to do it accurately, there are cases when "ears" on the cover break off, and it is already the headache.
Having thrown off covers, we are defined whether it is necessary to pull out the rotor outside or further repair can be made directly on site. Usually at electric motors with power up to 17 kW the rotor can be pulled out aside if from above - it is possible to perform works on site. If after all the rotor of the big electric motor has to be pulled out, then for this purpose it is necessary to put on on both sides the rotor shaft suitable pipes and besides accurately to take the rotor from the stator, without touching the winding.
So, the shaft is taken or remained inside, now we pull together with the remover bearings. Further we delete the flowed-out lubricant from bearings, also the winding of the stator can be filled in. Aviation kerosene will be suitable for these purposes, it dries well. There are cases that it is necessary to wash all winding because of gross contamination with lubricant, in such situation the rotor should be taken surely from the stator. After diligent washing it will be necessary to dry the obmotochka. It is possible to do it by the bulb or the heater, from time to time measuring insulation resistance.
In my practice it was necessary to be engaged in repair of big generators (ship), however, washed with alcohol, but slightly diluted acetone (such cocktail does not go to the use) and drying after washing made up to several days, through periods measuring insulation resistance and writing down indications in the magazine.
In your situation everything should be defined pindividualno. But general "scenario" after all is. The situation when "well turned" the bearing on the shaft, that is landing of the bearing of the proslablen is unpleasant. Here only one exit - to build up the shaft electric welding, with the subsequent groove on the lathe. Shaft to the 309th number of the bearing it is possible опаять tin, it is checked on personal experience. Still I want to focus attention that it is about engines up to 100 kW and on which there are rolling bearings.
During the operation of the electric motor in critical condition when temperature reaches to critical, and thermal protection did not work, the bandage of the winding (coordination) can burst. In that case it is necessary to take all remains of coordination, to make the new bandage and it is obligatory to put the varnish coat that coordination was pasted to windings and did not dangle during the electric motor operating time. It is possible to use furniture or parquet lacquer.
Having performed all listed works, we begin to collect everything upside-down. We get bearings, previously their heating. It is good if for these purposes you have necessary adaptation – the transformer for heating of bearings.
Having put on bearings, first of all we put on the front cover up to the end that the bearing completely came into the slot of the cover. Now we heat the semi-coupling and we get on the place and, splinting the spline, we insert the rotor into place if you took it. Now we put on the second cover (it is possible both symmetrically at once, it is possible at first one, then the second), we tighten bolts, slightly podstukivy the hammer or the kuvaldochka, watching what engine, and in parallel twisting and tightening bolts.
Having tightened bolts of covers, we turn the hand the shaft, we define how it turns. If there is the small distortion, the shaft will have a snack, i.e. to brake. Everything is removed by pulling up of bolts until when the shaft freely rotates. Further it is necessary to fix the engine by bolts and to make trial start-up (having previously again given the power supply). During trial start-up at small engines it is possible to podstuknut slightly shaft end faces with one and on the other hand that the shaft found the place. It will be noticeable aurally.
When everything is leveled, the engine can allow to work without cooling of minutes 10 – 15 and to make the first small running in. It is very well heard what quality you put bearings. Everything is ready – repair is made. If there is the need to paint, then it should be made now while the casing of cooling is not necessary and all parts are readily available. Well, and if paint in good shape, we put and we fix the impeller, the casing of cooling and we make lining of units.
Repair of electric motors, if прослаблен bearing
In holding time and repair of electric motors seldom, but there are cases when the bearing without tightness, is easily put on the shaft or the cover is easily put on the bearing. Let's stop on the example when the bearing прослаблен in the cover. There are widespread ways of elimination of this trouble: drawing the notch the core or the chisel, coppering by means of the welding machine.
But in recent years the way of the opaivaniye of the upper holder of the bearing tin is especially popular. The soldering iron of 200 W is for this purpose used. The bearing heats up the transformer for heating of bearings. Well warmed bearing obluzhivatsya quickly and without problems, at the same time it is necessary to use acid for soldering. If the bearing прослаблен on the shaft, we do the same, but here heating happens only the soldering iron.Top