COMPARISON OF LOW-FREQUENCY AND HIGH-FREQUENCY PARTIAL DISCHARGE MEASUREMENTS ON ROTATING MACHINE STATOR WINDINGS

摘要

Partial discharge (PD) testing has long been used for quality control purposes and also for determining the in-service aging of electrical insulation in rotating machines, transformers, power cables, and switchgear. Partial discharges are small sparks that occur within the insulation system in poorly made equipment and when insulation deteriorates due to aging. Since each discharge causes a flow of charge for a very short period of time, it can be measured by detecting the resulting current pulses. The frequency spectrum of each pulse spans from dc to a few hundred MHz. This article discusses PD testing of stator windings in medium-voltage motors and generators. It additionally examines why different frequency ranges are used for measurement, and especially, what published standards say about the frequency ranges.