CB/T3843-2000 Pressure relief valve 

Pressure Reducing Valve is the pressure protection device of transformer. When the transformer fails, the oil will decompose and produce a lot of gas. Because the transformer is basically closed, and the pipe fitting accessories connecting the oil conservator are very thin, only a small connecting pipe can not effectively and quickly reduce the pressure, resulting in a sharp rise in the pressure in the oil tank, which leads to the fracture of the transformer oil tank. The Steam Pressure Reducing Valve will be opened in time to drain some transformer oil and reduce the pressure in the oil tank. When the pressure in the oil tank decreases, the Steam Pressure Reducing Valve will automatically close and keep the oil tank sealed.