We all know about the Buchholz relay. Buccholz relay work as the protector of the transformer. Today we will discuss on Buchholz relay and what is the function of a Buchholz Relay.
What is the function of a Buchholz Relay
What is The Buchholz Relay?
Buccholz relay is a protective device that is used for transformers drowned in oil (more than 500 kVA power rating). It is a kind of oil and gas actuated protective relay. It is used for internal protection of transformers like insulation problems, insulation failure of turns, etc.
Work Principle of Buchholz Relay/What is The Function of a Buchholz Relay?
- Buchholz relay gets activated when it can detect any problem inside the transformer. For example, insulation failure of winding turns, excessively heated core, overload, or short circuit.
- This excess heat creates gas by separating transformer insulating oil.
- The gas flow is dependent on the level of fault. More the level of fault, more the level of gas flow.
- Gas bubbles go upwards to the conservator.
Structure of Buchholz Relay
- There is a chamber full of oil in the Buchholz relay.
- There are two floats. One is in the upper part and the other one is on the lower part.
- The upper float has a mercury switch. The switch is connected to an alarm circuit. And the lower float is connected with the trip breaker.
How Buchholz Relay Shows Its Work?
- When there is any fault inside the transformer, the fault current produces heat.
- Produced heat cause oiliness/crack and makes gas bubbles.
- These bubbles go upwards and get stored in the Buchholz relay.
- Gas collected by the Buccholz relay displaces oil inside the relay and this displacement is equal to the amount of collected gas by the relay.
- The contact of mercury switch connected with upper float gets closed for the displacement of oil. And the switch is connected to an alarm circuit.
- So, when any fault arises the alarm gets activated.
- The amount of collected gas indicates the level of fault.
- For a small fault, the gas amount is not enough for moving the lower float. That’s why their float is not affected during small faults.
- Big faults like the line-to-earth produce excessive heat and gas. Big faults like the line-to-earth short circuit produce excessive heat and gas.
- This gas flows to the upper and lower part.
- Its speed is enough to move the lower float.
- The lower float will isolate the transformer from the supply line with the help of a connected breaker.
Advantages of Buccholz Relay
- Buccholz relay indicates internal faults by producing heat and helps to avoid big faults.
- Transformers fault level can be determined easily.
- If any big fault occurs, buccholz relay disconnects the transformer from supply line.
This is all about what is the function of a Buchholz relay, if you have any questions, please leave a comment.
You can also read: What is Cogging in Induction Motor?
