Buchholz Relay
A gas-actuated protective relay between transformer tank and conservator detecting internal faults by sensing gas accumulation.
The Buchholz relay is critical protection for oil-immersed transformers, positioned between the main tank and conservator. It detects incipient faults before they become catastrophic.
When internal faults occur—insulation breakdown, overheating, or arcing—oil decomposes and generates gas. Small accumulations trigger alarm; rapid gas flow trips the circuit breaker.
Detects partial discharges, hot spots, loss of oil level. Mandatory for transformers above 1 MVA per IEC/IEEE.
QDTB equips all oil-immersed transformers above 1 MVA with high-quality Buchholz relays as standard protection.
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Related Terms
Oil-Immersed Transformer
A transformer using mineral oil as insulation and cooling medium, most common for outdoor power and distribution.
Partial Discharge (PD)
Localized electrical discharges in small insulation regions not bridging electrodes, indicating defects or aging.
Dissolved Gas Analysis (DGA)
A diagnostic technique analyzing gases dissolved in transformer oil to detect internal faults before they become critical.
More Terms Starting with “B”
BIL (Basic Impulse Level)
The ability of transformer insulation to withstand high-voltage surges from lightning or switching, measured in kV peak.
Bushing
An insulated device allowing a conductor to pass through a grounded barrier while maintaining insulation integrity.
Busbar
A metallic strip conducting electricity within switchgear, transformers, and distribution equipment.
Box-Type Substation (Prefabricated)
A factory-assembled compact substation integrating transformer, HV/LV switchgear, and protection in a weatherproof enclosure.
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Lightning Arrester (Surge Arrester)
A protective device diverting high-voltage surges from lightning and switching to ground, safeguarding transformer insulation.
Network Protector
An automatic switching device on secondary network systems preventing reverse power flow from distributed generation sources.
Relay Protection (Transformer)
Protective relay schemes detecting transformer internal and external faults, initiating circuit breaker tripping to isolate faults.
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