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HV testing for hairpin coils typically used for automotive applications

16/04/2020

Thumb schleich du dt

High-voltage AC with dU/dt analysis. What does dU/dt mean? This technology enables the rapid detection of very small discharge currents – even if full discharge has not yet occurred.

This technology is ideal for laboratory tests on winding goods such as hairpins. The winding wires are often subjected to extreme mechanical stress for shaping. This could cause cracks in the insulating lacquer. To test the quality we supply high-voltage test equipment with the possibility of testing in a ball or water bath. The high-voltage test is usually carried out with continuously increasing test voltage until the desired maximum test voltage is reached. As soon as the first signs of insulation weakness appear, this is detected by the test device and the high voltage is switched off. The dU/dt evaluation is ideally suited for this purpose.

The oscillogram shows the moment when the voltage curve is no longer sinusoidal. This is caused by an insulation weakness in the test object. The dU/dt evaluation detects this and switches off the high voltage.

Please see this video: https://youtu.be/S-nyLlhF6ro

By the way, this type of testing in a ball bath with very small metal balls and even better in a water bath is also used on insulating gloves or on power tools insulated with plastic such as VDE screwdrivers. We supply not only the high-voltage test device, but also the entire test equipment including the water bath or ball bath as well as the necessary test cover for inevitable contact protection.

Suitable testers: GLP1 and GLP2 Basic