Relief valve for transformer oil tank - is controlled by spring-loaded float operated swinging arm without need for expansion tank

摘要

The large oil filled transformer without an expansion vessel has a relief valve (7) at the top of the tank. A float (20) on an arm (19) controls it in response to the level of the liquid. This arm (19) is V shaped, with the float on one arm, the end of the other arm being spring loaded, and their junction mounted on a pivot pin (21). The spring loaded end has a spherical block (18) attached to a spindle (10) carrying a valve head (9) one end and a stop plate (14) the other end. Another stop plate (17) rests against the spherical block (18) and the spring (15) is located on the spindle (10) between the two stop plates (14, 17). A slider (11) at the far end of the spindle travels inside a guide (13) suspended on an arm attached to the tank.