BDV- BREAK DOWN VALUE- DI-ELECTRIC STRENGTH :
Break Down Voltage (BDV) is a characteristic of an insulator that defines the maximum voltage difference that can be applied across the material before the insulator collapses and conducts. Thus Break Down Voltage of insulating oil is the minimum voltage at which insulating property of oil breaks down and causes a portion of the oil to become electrically conductive. BDV is performed to determine the suitability of transformer oil to withstand electric stress. The measurement of BDV, serves to indicate the presence of conductive contaminants and water (moisture) in used and unused transformer oil. The electric strength of insulating oil is expressed in KV.