How much min BDV of oil in transformer is required when charged it first time in 11kv 66kv and 132 kv of transformer?

The minimum Breakdown Voltage (BDV) of transformer oil required typically varies based on the voltage level of the transformer. For 11 kV Transformers, a minimum BDV of around 30 kV is usually acceptable. For 66 kV transformers, a BDV of approximately 50 kV is often required, while for 132 kV transformers, it should be at least 60 kV or higher. Ensuring adequate BDV is crucial for the insulation performance and reliability of the transformer.