Loss Factor and Non-Linearity of Volt-Ampere Characteristic of Capacitors from Metalized PP Film

Capacitors made of polypropylene film metalized on one or both surfaces are examined for a long time. The loss factor of these capacitors is very low and its changes during the climatic aging are low. Therefore, there are examined new ways how to inspect the changes of quality of these capacitors. One possible way is measurement of non-linearity of Voltage-current characteristic of these capacitors. This parameter is evaluated according to the value of the third harmonics component that occurs on the capacitor when it is supplied with a sinusoidal current. The capacitors from five different manufacturers have been temperature aged for 5,316 hours and values of the loss factor and non-linearity have been measured continuously throughout the aging period. It has been found that for some types of capacitors the courses are similar, whereas for other type differs significantly. The reason is using of different types of PP film and technology of capacitors manufacturing.