The Buchholz Relay and How it Works
Here’s what inside a Buchholz Relay (in upside down position).
A Buchholz relay is an instrument used to detect unusual incident inside a power transformer. Such unusual incidents are;
1. Accumulation of gasses inside the transformer. It could indicate partial discharges or fault inside.
2. Sudden surge of pressure through spontaneous flow of oil to the conservator due to fault inside the transformer. (Buchholz is connected between the oil tank and the conservator)
3. Detects low level of oil.
Buchholz usually have two floats. The first float (the one closer to the cap) detects gas accumulation. Some plant operators use this to trigger an alarm signal only. The second float detects the level of oil and pressure surge through a damper attached to the float. Spontaneous flow of oil and low oil level detection of the second float triggers a trip or total plant shutdown signal mainly due to the possible severity of event that it has detected.
Buchholz Relay was invented by Max Buchholz.
Q: Can you get the gas accumulated in the Buchholz relay for analysis?
A: Yes you could, Buchholz relays usually have a so called “gas relief valve”. You could collect the gas there.
Related Articles:
Where to buy/order a Buchholz relay?
Posted in Transformers and Accessories
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