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Buchholtz Relay: Working Principle, Fault Detection & Transformer Protection

  Buchholtz Relay – A Quick Overview What is a Buchholtz Relay? The Buchholtz relay, also known as a gas relay or sudden pressure relay, is a protective device used in oil filled transformers. It is mounted in the pipeline between the conservator oil tank and the main transformer tank. This relay helps in detecting incipient faults and prevents severe damage by triggering alarms and circuit breaker mechanisms. Working Principle of Buchholtz Relay The relay functions using two distinct detection modes: 1. Slow Gas Accumulation Detection Over time, gas is generated due to insulating oil decomposition caused by slight overloading or minor faults. This gas accumulates at the top of the relay, pushing the oil level down. A float switch is triggered, activating an alarm signal, which may also indicate slow oil leaks. 2. Rapid Gas Accumulation Detection (Arc Faults) If an internal fault occurs, gas production increases rapidly, and oil flows quickly into the conservator. A vane switch, lo...