Transformer Breakdown Voltage Test
BDV = Breakdown Voltage
The Breakdown Voltage (BDV) Test is an important test used to assess the dielectric strength of transformer oil.
Transformer oil serves two critical functions:
- Electrical Insulation
- Heat Transfer & Cooling
Over time, transformer oil can become contaminated with moisture, dust, carbon particles, sludge and other impurities, which may reduce its insulating performance.
Why is BDV Testing Performed?
BDV testing helps determine whether the transformer oil has adequate dielectric strength for its intended service or whether filtration, drying, treatment or replacement may be required.
How does the BDV Test Work?
- A clean test vessel is filled with the transformer oil sample.
- Two electrodes are positioned with the specified test gap.
- AC voltage is gradually increased at the prescribed rate.
- Initially, the oil withstands the applied voltage.
- At a certain voltage, electrical breakdown occurs and an arc develops between the electrodes.
- The voltage at which breakdown occurs is recorded as the BDV value.
The test is normally repeated for the required number of breakdowns, and the results are evaluated according to the applicable standard, manufacturer requirements and project specification.
Good Transformer Oil = Better Insulation + Effective Cooling + Improved Transformer Reliability