In order to guard against the possibility of a sudden high pressure caused by a breakdown or a short circuit in the transformer winding. a diaphragm relief device is used.
This device consists of a large opening to the atmosphere covered by thin non metallic diagram
The diaphragm burst if the pressure beside the tank becomes excessiveThe relief device must be above the level of oil in the conservation in order to prevent an overflow of oil in case the device operates.
