The dielectric strength retention of film coated magnet wire after repeated surge voltage stress

Over the last few years, the surge test has become a very common useful tool for analyzing the quality of electrical equipment. Test stands are commercially available for installation on production lines whereby units such as stators can be quickly examined for electrical properties turn to turn, phase to phase, or coil to ground. Usually, the unit under test is compared to a "standard" by applying relatively high voltage surges with fast rise times at frequencies of approximately 120 cycles per second with the voltage patterns superimposed on an ocilloscope. Should there be a deviation, the test operator can determine where and why the patterns are not identical and may take corrective action. Other surge equipment is also available where comparisons are not made but pattern deviations are cause for rejection.