How do shock-proof motor suppliers judge the quality of a three-phase motor?

How to judge the quality of a three-phase motor? First of all, we measure the voltage of the motor, which can be measured when the motor is running or at rest. In order to be intuitive, we will introduce how to measure the voltage when the motor is running. Turn the multimeter to the voltage gear, and the gear is higher than 380V. Red test lead voltage jack, black test lead common terminal jack. Measure whether the three line voltages are all 380V.
Current measurement: Clamp multimeter, if you don't know the motor current, select the maximum gear of the current file, the clamp meter is very convenient to measure the current, just clip the wire. When measuring, three wires must be measured, so how to use the shaker to measure the insulation degree of the motor?
Before use, the shaker should be placed in a position away from the magnetic field, and placed on a horizontal surface, and should not be tilted too much.
Fix the measuring wire of the shaker to the two binding posts of the shaker, and the two measuring wires are opposite to each other, and then tighten the screws.
Clamp one measurement wire around the motor winding and the other measurement wire around the motor housing.
At this time, start to rotate the handle of the shaker, about 120 revolutions per minute, and read it after the number of shakes is not disturbed.
It is necessary to measure each pair of windings of the motor according to this method. If one group does not meet the standard, the motor cannot be used.