The machine should be stopped and isolated from all supplies before any maintenance work is done. The frequency of maintenance required depends to a large extent upon the site conditions.
Clean the winding of motors against affected due to surrounding atmosphere condition.
Air passage for ventilation blown out regularly to avoid interference with cooling system.
Renew switch-gear & fuse worn-out contacts i.e. starter
Do properly maintenance of cooling system.
Check the insulation resistance & polarization Index (P.I) if it is not satisfactory than machine should cleaned & drying test is conducted to improve the insulation resistance
Check continuity of earth conductor if found open correct it.
Tight all the connections in terminal box & starting unit.
Check the condition of foundation and found any defect rectify it.
Checking of base plate fixing on foundation.
Brushes
Replace worn out brushes of similar grade.
Adjust the brush pressure properly.
Free movement of brushes in the respective box must be ensuring.
Check that the brushes are sitting properly on the slip ring & tension is uniform.
Care should be taken that brushes should be vibrating in holders when motor is running.
Replace if brushes are worn out within 3 mm of their supports arm.
Brushes should be checked after every 100 hours running.
Slip-ring
Replace slip-rings if it is uneven wear.
Clean the slip-ring dust.
Tight the connections from winding to Slip lings.
Bearing
Replace worn-out bearings by equipment bearings of similar type.
Clean & recharge the bearings after every 3000 hours of running.
Use sand paper to clean the contacts between brushes & Slip-ring by manually rotating armature and finally clean with dry cloth in the direction of rotation only.
Do not use different grade of grease.
Add lubricating oil, if necessary in case of lubricating motors.
In case of indirect drive, check the belt tension & if found excess ,it should be reduced.
Make alignment proper.
Air gap
The air gap should be periodically checked with a feeler gauge to ensure against a wornbearing that might permit the rotor to rub against the stator core. Even slight rubbing of the rotor against the stator will generate enough heat to destroy the coil insulation. This check is needed particularly for sleeve-bearing motors.
Preventive maintenance schedule of Induction Motor
Inspect plant under working condition and also when it as rest.
It includes visual inspection, cleaning, minor repairs such as replacement of small parts and adjustment of equipment.
Routine maintenance includes all work required in cleaning of electrical equipment from dust & dirt.
Periodic visual inspection of various equipments to locate initial condition leading to breakdown.
Up keep of equipment and plant & repair defects at their initial stage.
Cleaning of the fitting, tank cover, bushing of power transformers.
Cleaning the fixed & moving contacts of starters and replacement of burnt contacts.
Routine maintenances of electric motors involve washing and lubrication of bearing, checking of control equipment and replacement of carbon brushes.
Checking of stationary parts.
Checking of movable parts.
Checking of safety measures.
Checking of protective device
Checking of working condition of equipment or machinery.
Checking of surrounding in which the machinery or equipment has to work i.e. atmospheric condition.
Daily maintenance
Dust & dirt is the principle cause of electrical breakdown. So as possible machine should be kept clean & dry both internally & externally.
Ensure that supply voltage & frequency is within tolerance band specified in the catalog of machine.
The insulation temperature and body temperature must be recorded frequently. It should be within permissible limits so that machine can run smoothly.
Ensure that all terminals are clean & tight.
Check the security of all fixing bolts, coupling grounds etc.
Check the accessories like starter, relays & control equipments.
Checking of cooling arrangements
Air passage for ventilation blown out regularly to avoid interference with cooling system.
To check the motor earthing connection.
In case of indirect drive, check the belt tension & condition.
To check the vibrators, checking whether motor is operating smoothly.
Weekly Maintenance
After completing activities during daily schedule following activity are necessary
during weekly schedule.
Examine contacts of starting equipment.
Air gap between stator and rotor be checked in case of sleeve bearing motor.
Alignment should be thoroughly checked.
Monthly Maintenance
Overhaul controllers.
Renew lubricating oil
Clean winding by vacuum pump
Check the winding for their proper insulation.
Check the bearing condition.
Half Yearly Maintenance
Cleaning of windings of motors against affected due to surrounding atmosphere condition.
Varnishing and Baking is carried out if found necessary.
Check grease in ball and roller bearings.
Check Slip-rings against unusual wearing.
Drain all oil, wash bearings with kerosene.
Flush with fresh oil and refill with fresh and clean lubricating oil.
Yearly Maintenance
Over-haual the motors.
Check bearing against worn-out.
Check the bearing & brushes against worn-out.
Check the condition of foundation.
Check the insulation resistance.
Check the earth resistance.
Hello.This article was extremely remarkable, particularly because I was investigating for thoughts on this subject last Sunday.
Pingback: Rheostatic Braking of D. C. Series Motor