Experience with Acoustic Emission Monitoring of Stator Winding Delaminations During Thermal Cycling Testing

摘要

This paper describes a novel technique for acoustic emission monitoring of insulation delaminations during thermal cycling (TC) testing on a stator bar. Acoustic signals emitted from insulation delaminations within the stator bar were continuously recorded during TC testing. An increase in measured acoustic signals indicates insulation delaminations within the stator bar under testing. To complement the acoustic detection method, several diagnostic tests, such as dissipation factor tests, partial discharge tests, tap tests and dissections, were performed. These diagnostic test results were compared with the acoustic test results to verify the insulation delamination process at various stages. It is concluded that acoustic monitoring is a useful tool to help establish the extent of insulation delamination during thermal cycling testing, the cycle in which delamination was most pronounced, and when delaminations occurred during the cooling or heating cycle. This technique could help refine the thermal cycling test program by optimising the number of test cycles required and achieving potential cost savings, and avoiding the need to disassemble and reassemble the test setup for the diagnostic tests currently used.