For maximum life, capacitors usually need to be able to handle the maximum amount of reversal that a system will experience. An AC circuit will experience 100% voltage reversal, while under-damped DC circuits will experience less than 100%. Reversal creates excess electric fields in the dielectric, causes excess heating of both the dielectric and the conductors, and can dramatically shorten the life expectancy of the capacitor. Reversal ratings will often affect the design considerations for the capacitor, from the choice of dielectric materials and voltage ratings to the types of internal connections used. COUNT 5
QSN1 What percentage of voltage reversal does an AC circuit experience? ANS1 100% voltage reversal QSN2 What does voltage reversal create in the dielectric of a capacitor? ANS2 excess electric fields QSN3 What percentage of voltage reversal will an under damped DC circuit experience? ANS3 less than 100% QSN4 What does excess electric field present in the dielectric lead to? ANS4 heating of both the dielectric and the conductors QSN5 When designing a capacitor, what is an important rating to consider? ANS5 Reversal ratings