Disadvantage of Oil Circuit Breakers

1. The decomposed products of dielectric oil are inflammable and explosive. If the oil circuit breaker is unable to break the fault current, the pressure in the tank may rise above safe limit and explosion may occur. This does not happen in SF6, ABCB, and vacuum C.B.
2. The oil absorbs moisture readily. The dielectric strength reduces by carbonization which occur during arcing. The oil needs replacement after a certain breaker operations. It needs regular maintenance.
3. Oil is not a suitable medium for breakers which have to operate repeatedly. Breakers used for furnaces, railways, industrial loads etc., operate frequently. Oil circuit breakers are unsuitable because oil gets deteriorated. 
4. The oil leakage, losses, replacement and purification is often troublesome. Hence oil circuit breakers involve more maintenance.