Buchholz Relay — Transformer Glossary

A gas-actuated protective relay installed in the pipe between the main tank and conservator of oil-filled transformers. Detects gas accumulation from internal faults.

Backprotection

Buchholz Relay

A gas-actuated protective relay installed in the pipe between the main tank and conservator of oil-filled transformers. Detects gas accumulation from internal faults.

The Buchholz relay provides two stages of protection: (1) Alarm stage — triggered by slow gas accumulation from minor faults (partial discharge, hot spots). The relay collects gas and activates an alarm contact when the gas volume exceeds a threshold. (2) Trip stage — triggered by rapid oil surge caused by severe internal faults (arc, short circuit). The oil displacement activates a trip contact that disconnects the transformer. The collected gas can be analysed to identify the fault type (DGA).

Specify the Right Product

Where this term matters in the ETS portfolio.

transformersContainerized SubstationPlug & play containerized systems, custom skid and container fabrication, and complete mechanical & electrical integration.

transformersPackage Substation TransformersCompact, factory-assembled package substation transformers for utility and industrial distribution networks.

Ready to Specify

Get a Quote Tailored to This Specification

Send us your application context — we'll come back with a sized solution, certified to IEC, IEEE/ANSI or UL, and a delivery slot from our Dubai factory.

Talk to Engineering

DGA (Dissolved Gas Analysis)Diagnostic technique that analyses gases dissolved in transformer oil to detect incipient faults.

Partial Discharge (PD)Localised electrical discharge that does not fully bridge the insulation between conductors. A precursor to insulation failure.