Oil filled transformer has circuit interrupter disposed within the transformer housing and utilizes a bridging contact movable between an open position spaced from a pair of stationary contacts, and a closed position engaging the stationary contacts, to complete a series circuit through the transformer to a low voltage terminal located on the transformer housing.
A bimetal actuating means which is disposed in series in the circuit through the transformer is connected so that when current flow there through exceeds an overload trip value, the bimetal actuating means moves the latch to an unlatched position, permitting the circuit interrupter to trip open. The bimetal is responsive to the temperature of the surrounding oil and deflects when the oil is heated for any reason. The oil in contact with the winding and core rises as it absorbs the heat.
In terms of phase, the oil filled distribution transformers market can be bifurcated into single phase and three phase. Three phase oil filled distribution transformers are used more for industrial and commercial purposes. The three phase segment held major share of the oil filled distribution transformers market in 2017. This trend is likely to continue throughout the forecast period owing to the expansion in industries around the world. Single phase oil filled distribution transformers are primarily used for residential purposes.