Gas relay, also known as gas relay, is a component that uses the hot oil flow and hot air flow generated during faults in a transformer to drive the relay to operate, and is a protective component of the transformer; The gas relay is installed in the pipeline between the oil conservator and oil tank of the transformer; If there is a discharge fault inside the oil-filled transformer, the discharge arc causes the transformer oil to decompose, producing various characteristic gases such as methane, acetylene, hydrogen, carbon monoxide, carbon dioxide, ethylene, ethane, etc. The more severe the fault, the larger the amount of gas. These gases, after being generated, rise from the inside of the transformer to the upper conservator and flow through the gas relay; If the amount of gas is low, the gas accumulates in the gas relay, causing the float to drop and the normally open contact of the relay to close, acting as a warning signal for light gas protection; If there is a large amount of gas, oil and gas will quickly rush out through the gas relay, pushing the internal gear lever of the gas relay to close another set of normally open contacts. Heavy gas will directly start the relay protection trip, disconnect the circuit breaker, and cut off the faulty transformer