Acoustic emission spectrum signatures from capacitors under AC and transient conditions

In order to improve diagnostic∗ testing, the acoustic emission spectrum signatures from model and full-size power capacitors were examined under ac and transient conditions. Acoustic emissions were monitored from the foil and insulation structure, poor electrical contacts and from partial discharge or corona activity. It was found that noise apparently associated with the aluminum foil occurs at a frequency near 27 kHz, and that it is generally best to monitor the acoustic emissions from both contact arcing and partial discharges or corona at a frequency of ∼80 kHz.