Chuck Yung
EASA Senior Technical Support Specialist
Concerns about partial discharge (PD) used to be limited to repairers and users of machines rated over 7 kV. PD is a common consideration for machines rated 11 kV and higher. This article will describe PD, explain how to detect it, and offer repair solutions.
What is partial discharge?
Air, like Nomex®, Mylar®, mica and Dacron®, is an insulator. Like any insulation, it will break down electrically if subject to too high an impressed voltage. Air is capable of withstanding approximately 75 volts/mil (3000 volts/mm), as compared to modern insulating materials rated many times higher. (See Table 1.)
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