四、conclusion
1、When the switch trips and the power is not run, the insulation resistance of the motor should be checked with a multimeter to confirm that there is no problem before running the power again;
2、Whether the power failure motor is burnt out
（1）Check the three-phase coil of the motor first with Multimeter. the three-phase coil should balanced. The resistance tolerance does not exceed 0.2 ohms in principle.
（2）If the coil resistance is balanced, check the ground insulation ,in principle, the ground insulation resistance is not less than 5 megohms.
3、After the above steps are completed, if there is no problem, power on again, check the three-phase current of the motor, and find out the abnormalities in time;
==== Every time the line trip fault must have a reason, it depends on whether it can be found in time; timely elimination can better ensure the normal operation of the equipment;
Post time: May-22-2020