The transformer tank filled with cooling liquid is a container subject to internal pressure and then has to be provided with one or more safety valves suitably calibrated for the maximum allowed pressure, so that overpressure caused by internal faults can be instantaneously relieved through the valves, thus avoiding greater damages such as the deformation or even the burst of the tank and the spraying of hot oil with subsequent fire risks. It is necessary to protect the transformer tank with a suitable equipment capable of almost instantaneously discharging overpressure already at the development, before the structure integrity is damaged and the safety valves has just this function.
The safety valves consist schematically of:
1. A valve base comprising the valve opening venting area with its specially profiled gasket and a seat
for an O-ring gasket on the flanged end towards the transformers tank;
2. A valve cap pressed against the profiled gasket by calibrated helical spring,
thus making the valve completely tight up to the rated pressure;
3. A splash diverter to avoid damages caused by hot oil sprinkles (on request);
4. A single or a double electrical contact (on request).