Break Down Voltage(BDV)

BDV is Breakdown voltage value of insulating oil of the transformer. It refers to the dielectric strength of transformer oil. Transformer oil act as an insulating medium and also as a coolant that dissipates heat of the transformer.

Now after a long-term operation transformer oil loses its properties slightly and a dip in dielectric strength is observed due to impurities or moisture in the oil.

We have BDV tester kits to test the Breakdown Voltage of the transformer oil.

BDV test kit

Oil collected from the main tank is filled in the chamber and is placed inside the tester kit. The two electrodes you see are seperated by 2.5mm. Now high voltage at a rate of 2KV/s is applied between the electrodes and observes the voltage applied when sparks occur between the electrodes. The test is repeated minimum three times and the values are recorded.

It gives the value of voltage at which the oil loses its dielectric property.

A BDV rating around 30KV is considered good. If lower values are recorded do not energize the transformer and the oil is recommended for filtration.