ORO(L3F) Oil Dielectric Loss Tester I. Product i ntroduction In the preventive test of electrical equipment insulation, a periodic measurement for the parameter of insulation oil was required. The insulation oil dielectric loss factor and DC resistivity measurement is one of the main methods in a series of preventive tests. Bridge method mostly used for a long time, but this method is complex to operate, also the measurement accuracy will influence by many factors, and that