Diagnosis method for high voltage coils based on electrical and tap tone characteristics

A new diagnosis method for high voltage coils has been developed. In this method, two diagnosis techniques are involved. One is an evaluation method for breakdown voltage based on nondestructive electric characteristics and the other is a delamination detection technique using a neural pattern recognition system for tap tone signals of the insulation layer. The evaluated breakdown voltage value is corrected by a rectifying factor determined from the delamination form of the insulation layer.