The gassing of liquid dielectrics under electrical stress — Part I

The results of a study of the breakdown of a U.S.P. white mineral oil under electrical stress are presented. The extent of the breakdown was studied by measuring the pressure of gas developed during the application of voltage, starting with a system that was initially evacuated. The apparatus was constructed so that thorough degassing of the oil could be achieved prior to subjecting it to voltage stress. The oil was subjected to an alternating voltage (60 c.p.s.) under a stress of 130 kv/cm.