The protective Oil Surge Relay (OSR) is used to protect the malfunction developed inside the On Load Tap Changer (OLTC). It is installed in the pipe between OLTC head and oil conservator.
Any malfunction builds pressure which leads to increased oil flow. This protective relay triggers the tripping circuit when the oil flow exceed the specified limits, thus making the transformer to be turned off and contain the damager to the OLTC and Transformer.
OSR is fitted with special Reed switch which assures rust free contacts even after decades after installation thereby is alert for operation. This OSR is designed and tested for very intensive seismic levels.
The protective relay serves for signalling a fault in the diverter switch / selector switch oil compartment and is to limit the damage to the on-load tap changer in case of a failure.It is, therefore, part of our delivery as a standard with all OLTC supplies.
OSR is a part of the OLTC and its properties are subject to IEC 60214.