The Buchholz relay serves a crucial role in safeguarding oil-filled transformers by detecting and responding to internal faults. Positioned within the transformer’s oil conservator, this protective device is designed to identify the accumulation of gases, notably hydrogen and methane, generated during electrical faults such as internal short circuits and partial discharges. A float within the relay is connected to contacts, and as gas accumulates, the float rises, signaling potential issues.
The relay’s contacts are linked to either an alarm or a trip circuit. In the case of minor faults, an alarm may be triggered, while for more severe faults, the relay initiates a trip signal. This rapid response helps isolate the transformer from the power system, preventing further damage. By offering protection against incipient faults and responding swiftly to gas generation within the transformer, the Buchholz relay plays a crucial role in preventing catastrophic failure. Its ability to detect developing faults and initiate timely actions ensures the safety of the transformer and the overall power system. In essence, the Buchholz relay acts as a critical component within the protective relay system, contributing to the reliability and longevity of transformers in power networks.
See below basic construction and working of Buchholz Relay:
Also see here, what is role of Breather in Transformer.