Here we discuss procedure for AC motor checking
- Check body of motor, is there any physical damage of not ?
- check mouting and alignment
- check bearing of motor , is it moving freely or not ?
- Push and pull down shaft of motor and check movement of shaft
- Check resistance of each lead (R,Y,B) with respect ground . it should be in mega ohm (R and ground, Y and ground, B and ground )
Thumb rules for insulation resistance
- 2 megaohms or less Bad
- 2-5 megaohms Critical
- 5-10 megaohms Abnormal
- 10-50 megaohms Good
- 50-100 megaohms Very Good
- 100 megaohms or more Excellent
6. check all connection it should be properly tight. 7. check resistance of all tree winding and it should be balance 8. Resistance between earth and motor frame should be less than 0.5 ohms 9. 230 v per line and 415 between l1 and l2, l2 and l3, l3 and l1. 10. check continuity of winding from phase to phase. if windong is ok, contunuity must come. 11. Check Amps of motor in running condition with clamp meter and compare it with name plate of motor.