MOTOR SURGE COMPARISON TESTING BASIC INFORMATION AND TUTORIALS

What is Motor surge comparison testing? How is it done?

Motor surge comparison testing addresses the problem of insufficient test voltage to find the weak insulation between turns by utilizing a high-voltage pulse. Two identical high-voltage pulses are introduced into two windings of a motor.

The propagation of the pulse through one winding is compared to the propagation of the identical pulse through the winding next to it.

An oscilloscope (usually built into the surge tester) is used to look at the traces and to compare them. The patterns should be identical (or very nearly so) and can appear as one trace (two superimposed traces) if both windings are good.

A turn-to-turn failure (or a failure to ground) is indicated by two distinctly different traces appearing on the oscilloscope.

Motor surge comparison testing has been used by motor winding shops for many years. There are now portable models that are available for field testing.

Motor surge comparison testing has proven to be a valuable tool in detecting the early stages of a winding failure, both from the standpoint of preventing an unexpected failure during operation and preventing a catastrophic failure of the motor so it can be repaired instead of needing to be replaced.