Analysis of the Relationship Between Insulation Resistance Testing and Voltage withstand Testing

In the motor manufacturing and use of the process, may be involved in electrical performance testing, a fan of insulation resistance and withstand voltage test is not very clear about the contents of the test, today we have a simple exchange with you.

I.Insulation Resistance and its Detection

Insulation resistance is a measure of motor insulation safety performance of an index, different voltage levels, different environments, different motor requirements are not the same. Insulation resistance is not a fixed value, the dielectric in a certain electric field has a certain insulation resistance with the change of electric field, insulation resistance value will also change. This is what we usually require, different voltage levels of motors can not be used in the same specifications of the fundamental reasons for testing equipment.

For any kind of insulating medium, the higher the temperature and the higher the humidity, the lower the insulation resistance. For any electrical products including motors, the higher the insulation resistance, the better, of course, to meet the requirements is the basic premise.

For motor products with different voltage levels, the minimum limit of insulation resistance R=rated voltage U/(1000+rated power P/100) is calculated. It should be emphasized here that the insulation resistance detection should be carried out after the completion of the thermal state or thermal test of the motor. According to the performance characteristics of insulation resistance, the insulation resistance in hot state is lower than that in cold state.

II.Voltage Withstand Test

For motor products, in the electrician semi-finished products and factory test link should be on the motor winding phase to phase (only for three-phase motors), to ground and turn-to-turn insulation voltage withstand test, voltage withstand test in principle should be carried out in the motor after the completion of the thermal test. For the performance test, some customers will always be uneasy and asked to carry out voltage withstand, it should be emphasized that the test on the insulation of the motor has a different degree of destructive, and therefore do not recommend repeating the test, if necessary, should be carried out to reduce the voltage test.

The turn-to-turn withstand voltage test of the motor winding is to detect the insulation between turns of the same phase winding.

Whether there is a substitution relationship between insulation resistance testing and voltage withstand test

In the motor test process, we not only insulation resistance test, but also voltage withstand test, many people are more confused about this, since both are insulation performance test, is not repeated? Is it possible to replace or choose one of them? The answer is of course no, we can understand this.

1.Insulation resistance is the motor winding and its associated parts of the insulation structure in line with the check, is a comprehensive insulation safety performance parameters of the motor; and withstand voltage test is through the application of a certain voltage on the motor insulation fault checking means, that is, to find the motor insulation faults or weak links.

2.When the insulation resistance test complies, the voltage withstand test may not necessarily be qualified, and similarly, when the voltage withstand is qualified, the insulation resistance test may not necessarily comply. However, for serious insulation faults, they can be detected during the insulation resistance test.

3.Another question is, insulation resistance test and withstand voltage test whether there is a certain order requirements? The answer is yes, in the withstand voltage test should be carried out before the insulation resistance test, the test is consistent with the voltage test can be carried out, in order to prevent because of the withstand voltage test damage to the insulation properties of the motor winding.