What is Buchholz relay and where it is used?

What is a Buchholz relay? Buchholz relay is a safety device which is generally used in large oil immersed transformers (rated more than 500 kVA). It is a type of oil and gas actuated protection relay.

What is working principle of Buchholz relay?

Buchholz Relay Working Principle It is mechanically actuated. Whenever there will be a minor internal fault in the transformer such as an insulation fault between turns, break down of core of the transformer, core heating, the insulating transformer oil will be decomposed in different hydrocarbon gases, CO2 and CO.

For what type of fault Buchholz relay is used?

Buchholz relay is used for the protection of transformers from the faults occurring inside the transformer. Short circuit faults such as inter-turn faults, incipient winding faults and core faults may occur due to the impulse breakdown of the insulating oil or simply the transformer oil.

Which relay is used for transformer protection?

The protection of a transformer against the overloads is performed by a dedicated protection usually called thermal overload relay. This type of protection simulates the temperature of the transformer’s windings.

What is PRV in transformer?

Therefore, to release the excess pressure of transformer tank pressure relief device or PRD of transformer is installed for oil filled transformer to protect the transformer under severe fault condition. A Pressure Relief device (PRD of Transformer) is also called Pressure Relief Valve(PRV).

Why mercury is used in Buchholz relay?

Gas produced by abnormal conditions in the transformer, collects in the Buchholz relay which lowers the oil level so that the top float gradually comes down and ultimately operates the mercury switch when it reaches a certain level. This switch is usually connected to external alarm circuit.

Why is silica gel used in transformer?

The main function of silica gel is to control the amount of moisture available within a breather transformer. They are used to prevent any extra moisture from entering the transformer which may bring forth many unnecessary damaging effects to the transformer.

Which oil is used in transformer?

mineral oil
Transformer oil is most often based on mineral oil, but alternative formulations with different engineering or environmental properties are growing in popularity.

Where is Buchholz relay located?

Construction. Buchholz relay can be used in the transformers having the conservators only. It is placed in the pipe connecting the conservator and the transformer tank. It consists of an oil filled chamber.

What is OTI and WTI in transformer?

They are commonly referred to in the industry as Oil Temperature Indicators (OTI) and Winding Temperature Indicators (WTI). Electrical utilities often utilize oil and winding temperature indicators to provide alarm and control signals that are used to activate cooling control systems on a transformer.

What is PRV and PRD?

A Pressure Relief device (PRD of Transformer) is also called Pressure Relief Valve(PRV). A (PRV) is a type of valve used to release stored gas in various equipment in order to maintain an optimal pressure level. PRV opens gradually as pressure builds up in order to release the necessary amount of pressure.