Insulating liquids breakdown voltage determination: Test method efficiency
The 50-60 Hz breakdown voltage of insulating liquids is not an intrinsic property of the dielectric but strongly depends on the presence of contaminants, such as particles and suspended water. Both IEC and ASTM give tests procedures finalized to determine the 50-60 Hz breakdown voltages. This test is adopted as acceptance on new deliveries, testing of treated liquids prior to or during filling into electrical equipment, and monitoring and maintaining oil-filled apparatus in service. Following the IEC Standards, this test has to be performed following the IEC 60156, Ed.