Transformer Buchholz Relay Working

It is a mechanical device that accompanies two numbers of mercury electric switches for sending the electrical command to the relays.

Transformer buchholz relay working. The transformer is filled with hydrocarbon oil for the insulation of. The switches of the contacts stopped and an alarm circuit strengthened. Buchholz relay is a safety device which is generally used in large oil immersed transformers rated more than 500 kva. Buchholz relay diagram working principle.

This means lowering the location of the float and thus rolling the mercury switch. As we proceed further we will learn the construction and working principle of the buchholz relay. The relay was first developed by max buchholz 1875 1956 in 1921. Before learning the operating principle and design features it is necessary to understand why is a buchholz relay used in a transformer they are used to sense the faults occurring in the transformer winding and core such as inter turn faults short circuits earth faults overheating of the core oil leakage etc it senses these faults and interrupts the transformer s input supply so.

Working principle of buchholz relay. It is the gas actuated relay. The float is attached to a hinge in such a way that it can move up and down depending upon the oil level in the buchholz relay container. The buchholz relay protects the transformer from internal faults.

Check the following buchholz relay diagram to understand the working principle and construction. This relay is mainly used in oil immersed transformer for providing protection against all types of internal faults. The upper element consists of a float. Depending on the requirements it is equipped with up to four 2 per float switches or change over switches which can either send a light signal or switch off the transformer.

The buchholz relay is placed between the main tank and the conservator. Buchholz relay relies on the fact that an electrical fault inside the transformer tank is accompanied by the generation of gas and if the fault is high enough it will be accompanied by a surge of oil from the tank to the conservator. Buchholz relay in a transformer is an oil container housing the connecting pipe from the main tank to the conservator tank it has mainly two elements. Sometimes due to oil outflow on the major tank air bubbles may build up in the upper part of the buchholz container which may also source a drop of oil level in it and alarm circuit will strengthen.

Buchholz relay is located in the pipeline connecting the transformer main tank and the conservator. Such type of relay is used in the transformer having the rating higher than 500kva. The classic buchholz relay has to comply with the requirements of the din en 50216 2 standard. It is not used in small transformer because of economic consideration.