Pressure Relief Valve is a safety device used on oil filled transformer. Electrical faults may increase the temperature tremendously and disintegrate the oil into hydro carbon gases thus increasing the internal pressures beyond their safe limits. Pressure Relief Valves operate at this instance and gives opening for passage of oil and manage to relieve the pressure by releasing considerable amount of it. If the Relief valve is equipped with switches then additionally it gives an alarm and trips the total electrical system.
Base body is of aluminium pressure die casted and heavily powder coated. Diaphragm pressed from Stainless Steel sheet covers the base body and rests on a gasket rubber ring. Set of springs provide the necessary resistance towards rising of Diaphragm and lets it rise only on a set pressure. These springs remain in position with provision of a cap dome over it which is bolted with the base body. A limit switch is housed over the body with a trigger projecting. When the pressure in Tank increases on a certain set pressure the diaphragm lifts from its seat. This pushes the trigger which ultimately strikes the roller of limit switch which rises above and so the flap of indication.
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