Electrical Breakdown Voltage

Method Transformer Insulating Oil Tester
Standards ASTM D 1816, ASTM D 877, IEC 60156

What is it used for?

The oil used in a transformer, irrespective of whether it is mineral or silicone. It has the primary functions of insulating the electrical components within the transformer and dissipating the heat generated during operation.  If the oil begins to lose it’s ability to insulate effectively, transformer failure will follow.


How does it work?

A portion of the oil is poured into a bath with two electrodes separated at a predetermined interval depending on the exact method being applied.  Current is applied until a spark is observed between the two oil-immersed electrodes at the point where the oil becomes an ineffective insulator.


What do the results tell us?

The voltage at which the oil loses it’s ability to insulate effectively.  The breakdown voltage should typically be significantly more than twice the rating of the transformer from which the oil sample was taken.


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