The Phenomenon of Low Frequency Dielectric Losses Increasing in Metallized Film Capacitors

Metallized film capacitors have the highest operating electric field (more than 200 kV/mm) compare another capacitor types. Such high operating electric field explains by self-healing ability which related with isolating of breakdown channel. Multiple self-healing acts lead to changing of capacitors parameters: capacitance, dielectric losses and equivalent parallel resistance. These parameters changing during capacitors aging was investigated in a wide frequency range (0.1 Hz – 1 MHz). It was found that as the capacitors aging, dielectric losses increase at low frequency of electric field (less than 10 Hz). This phenomenon of low frequency dielectric losses increasing can be explained by formation of graphite layers between polymer films near breakdown channels.