How there is the maintenance of electric motors?
At technical maintenance the personnel on duty constantly watch loading and vibration of electric motors, temperature and availability of lubricant in bearings, lack of abnormal noise and sparking under brushes. The personnel on duty also make external examination and clean the electric motor from dust and pollution.
Periodic surveys of electric motors make according to the schedule established by the chief engineer of the enterprise. Surveys plan that more often than it is heavier than the working condition and what electric motors are more worn-out. Treat severe conditions of work: big duration or high frequency of start-up, high temperature or dust content of the environment. The qualification group of the person examining has to be not lower than III.
The purpose of surveys is determination of technical condition of the electric motor and identification of amount of works which have to be executed at the next repair. Besides, at survey make technical maintenance of bearings, rings, brushes and carry out minor repair without dismantling of the machine.
It is possible to look at structure of works at surveys and technical maintenance of asynchronous electric motors in this article. Before turning on of the electric motor in work it is necessary to be convinced of lack of foreign objects on the mechanism, the electric motor, in operability of contact rings. The handle of the starting rheostat has to be set to position "Start-up", at small engines turn the rotor manually.
After launch of the electric motor vibrations, beats of the belt drive or the connecting coupling with the mechanism watch lack of noise and buzz, heating of the body and bearings. The emergency stop of the electric motor is made at accident, at emergence of smoke or the flame from the engine or the puskoreguliruyushchy equipment, at breakdown of the given mechanism, at strong vibration, at excessive heating of the engine with noticeable decrease in rotating speed.
At excess of oil it is sprayed, foams and sucked in in the machine. Getting on windings, oil reduces characteristics of isolation that can lead to its breakdown. The lack of oil leads to weak lubricant of the bearing and its overheating. Oil in necessary quantity is added at least in 10 days of operation of the bearing. Not later than in 300 h work oil in the reservoir is completely replaced. For this purpose the fulfilled oil is merged, the reservoir is washed out kerosene, blown compressed air and repeatedly washed out, but not kerosene, but the oil intended for filling. Then fill the reservoir with oil to norm. Oil level owing to its considerable viscosity is established not at once. Therefore oil replenishment to norm is made in the small portions.
Rolling bearings grease, as a rule, with jellied structures. The volume of the camera of the rolling bearing has to be filled on 1/2 with higher frequencies of rotation. If to use lubricant in the quantities exceeding specified bearings overheat, and lubricant flows from the body. At detection in use smaller amounts of lubricant the last are added to norm. Lubricant should be applied the same grade, as contained in the bearing. Depending on operating conditions, jellied lubricant is replaced in 3 - 6 months of work with preliminary washing with mix of B-70 gasoline with pure transformer oil (6 - 8%).
Washing is conducted when turning the shaft of the electric motor until from the body of the bearing the uncontaminated flushing structure does not begin to follow. Replacement of lubricant in electric motors of new series (4A) can be made on the run without washing. In the bearing node the opening for the lubricator (in the upper) and the exhaust outlet for the fulfilled lubricant is for this purpose provided (in the lower part). New lubricant moves for the bearing, passes through it and forces out old lubricant.
The contacting surfaces of rings and brushes have to be clean and have the correct cylindrical form, brushes have to adjoin to rings not less than two thirds of the contact surface. The adverse effect on brush contact is exerted by the coal or metal dust carrying current which is formed at friction of brushes about rings or the collector.
Pollution of the collector are the reason of sparking under brushes. At adverse conditions of work of brush contact sparking happens so strong that causes the deposit.
Daily at technical maintenance delete pollution of contact rings with coal and metal dust, carefully wiping the surface of sliding with pure dry fabric. The deposit and roughnesses polish with glass abrasive paper No. 100/180.
Paper is strengthened on the insulating (wooden) block having working dredging in the ring surface form. The block for convenience of use is supplied with one or two handles.Top