Pulse withstand capability of self-healing metalized polypropylene capacitors in power applications

摘要

Experiments performed on the end-edge contacts of polypropylene capacitors to determine whether the thermal effect is the main cause of their degradation are described. Current pulses with different wave-shapes but with the same value of the Joule integral were applied to the contacts, and the degradation levels were ascertained by measuring the tan delta variation, since degradation of the contacts results in an increase of the equivalent series resistance of the capacitor. The results obtained show only a partial dependence of the degradation level on thermal stress, revealing a contribution from the electrical and mechanical stresses.