Cyndi Nyberg
Former EASA Technical Support Specialist
In the April 2007 issue of CURRENTS, we covered surge testing anomalies, speci.cally for AC windings. The surge test can be used for DC windings as well. It can be a useful tool for evaluating armatures and some DC fields.
A note of caution: If a winding does not have a minimum insulation resistance per ANSI/EASA AR100-2006, it is not safe to apply an overpotential test (surge or high potential).
Surge testing shunt .elds may not provide meaningful results if the surge pulse decays too quickly — if it dissipates through only the .rst few hundred turns. To obtain a test voltage high enough to test every turn would require too high a voltage. That high voltage would overstress the ground-wall insulation.
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