Bucholz Relay Operation

The Bucholz relay is a protective device installed between the main tank and the conservator tank of oil-immersed transformers.

• Fault Detection: It primarily detects internal faults, such as winding or core faults, within the transformer.
• Oil Decomposition: These faults cause overheating, leading to the decomposition of the transformer oil.
• Gas Generation: Oil decomposition produces gases (like hydrogen).
• Pressure Build-up: The generated gases accumulate in the top of the transformer tank and conservator pipe, increasing the internal gas pressure.
• Relay Activation: The Bucholz relay contains floats. A significant build-up of gas causes the oil level to drop, lowering the floats and activating a mechanism.
• Operation Trigger: This mechanism operates alarm contacts or trip contacts, which can either sound an alarm or disconnect the transformer from the power supply.

The core principle of its operation relies on sensing the change in gas pressure caused by faults.