Corona characteristics of metallized mylar capacitors for power electronics circuits

Metallized Mylar high voltage capacitors made in ratings up to 20 kV with special metallization patterns allow a single winding with two terminations and several series sections. These capacitors can be operated at stresses of about 2500 volts/mil, and energy densities up to 1. 24 j/cu.in. -- a 75% improvement over new resin-impregnated mica paper capacitors and 400% over conventional paper units. They are self-healing against a limited number of breakdowns. A weakness of this construction is it may result in low level dc corona below the dc rating and relatively low corona inception voltage on ac. This paper is concerned with quantitative measurements of corona on dc and ac, and an evaluation of corona's voltage dependence to establish safe levels of operating stress.