Film Capacitors in the High Voltage - Temperature Humidity Bias (HV-THB) Test

Abstract:
The humidity performance of six different film capacitor types from three different manufacturers was investigated. All samples have a nominal voltage of 1600 V and a rated capacitance of 68 nF. They were exposed to 85 °C and 85 % relative humidity. These groups were tested with a constant voltage of 1600 V for 2300 h. Additionally, selected groups were tested at 80 % of the nominal voltage, which is 1280 V. A second test was carried out under a dynamic voltage stress at a switching frequency of 80 Hz and with a peak voltage of 1600 V and 1280 V, respectively. Compared to the constant voltage test, these conditions result in a much faster degradation of the capacitors. All samples were electrically characterised by capacitance and series resistance at intermediate measurements. Both parameters were used for condition monitoring.