当变压器内部发生故障，油箱内部压力急剧增加，引起气体继电器跳闸动作，若变压器的温度继续升高，探测器达到动作温度，其感温元件熔断，触头接通，电磁机构动作，把快速排油阀打开，开始排出高温油层。延时0～20秒后，开启阀把氮气瓶打开，氮气通过减压阀、开启阀、注氮管路进入油箱底部，迫使油箱内部变压器油循环，使油箱下部较低温度的油和顶层高温油混合，消除热油层，并使表层油温度降到闪点之下，油箱内部火焰自动熄灭。关闭阀的作用是在排油时自动关闭，防止储油柜中的油浇到初燃的火上，加剧火势。
When a fault occurs inside the transformer, the internal pressure of the tank increases sharply, which causes the tripping action of the gas relay. If the temperature of the transformer continues to rise, the detector reaches the operating temperature, the temperature sensor of the transformer is fused, the contacts are connected, and the electromagnetic mechanism acts to open the quick oil discharge valve and start discharging the high-temperature oil layer. After a delay of 0-20 seconds, the opening valve opens the nitrogen cylinder. Nitrogen enters the bottom of the tank through pressure reducing valve, opening valve and nitrogen injection pipeline, which forces the transformer oil in the tank to circulate, mixes the lower temperature oil in the tank with the top high temperature oil, eliminates the hot oil layer, lowers the surface oil temperature below the flash point, and extinguishes the flame in the tank automatically. The function of the shut-off valve is to shut down automatically when oil is discharged, so as to prevent the oil in the oil tank from pouring on the initial fire and aggravating the fire.