Patent ID: 8351169

Claim:
A system for preventing, protecting On Load Tap Changer (OLTC) from fire and/or transformer from explosion in advance before decomposition of combustible coolant fluid ( 11 )/dielectric oil, said system comprising: a. current sensing electrical relay ( 26 ) for determining difference of input current and output current and providing input to control unit if ratio of the input current to the output current exceeds predetermined limit, and/or one more detector to detect fire from OLTC chamber, b. one or more circuit breakers ( 24 , 28 ) for isolating the electrical transformer from incoming source, c. one or more oil surge relay for sensing excessive oil surge in OLTC chamber ( 33 ), d. one or more Buchholz relays ( 18 ) for sensing excessive oil surge in transformer tank ( 14 ) and/or at least one Rapid Pressure Rise Relay (RPRR) ( 31 ) for detecting rate of change of pressure in the transformer tank, and/or at least one Pressure Relief Valve (PRV) ( 32 ) for detecting pressure in the transformer tank ( 14 ), and e. one or more control unit ( 1 ) for receiving inputs from the aforementioned parameters thereby optionally generating control signal to energize one or more lifting magnet ( 5 ) for draining of the combustible coolant fluid ( 11 ) through the drain valve and subsequently provide signal for injecting inert gas from the bottom of the electrical transformer tank and/or to top of OLTC chamber ( 33 ) through a nitrogen flow control valve for stirring the combustible coolant fluid ( 11 ).