Main Components of a Transformer – Operating Principle, Faults, and Phenomena of the Gas Relay

Gas accumulation: Free gas is present in the transformer oil. Response: The gas in the liquid rises and accumulates in the Buchholz relay, compressing the transformer oil. As the liquid level drops, the float also descends. The movement of the float drives a switch element (magnetic contact), thereby triggering an alarm signal. However, the float is not affected, because a certain amount of gas can flow through the pipe into the storage chamber.

Fault: Due to leakage causing loss of transformer oil. Response: As the liquid level drops, the float simultaneously sinks, at which point an alarm signal is issued. As the liquid continues to be lost, the storage chamber, piping, and Buchholz relay are emptied. With further drop in the liquid level, the lower float descends. The movement of the float drives a switch element, thereby disconnecting the transformer power supply.

Fault: Due to a sudden unexpected event, a pressure wave moving toward the storage chamber is generated. Response: The pressure wave impacts the baffle installed in the flowing liquid. If the flow rate of the pressure wave exceeds the operating sensitivity of the baffle, the baffle moves in the direction of the pressure wave, thus activating the switch element. As a result, the transformer trips.