Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
Buccholz relay gives warning of
Internal fault
External fault
Both of above
None of above
Internal fault
The Buchholz relay is a gas-actuated protective device installed in oil-immersed transformers to detect incipient internal faults. It operates by detecting the accumulation of gases produced due to insulation breakdown or arcing within the transformer tank before the fault escalates into a major catastrophe.
The Buchholz relay is a gas-actuated protective device installed in oil-immersed transformers to detect incipient internal faults. It operates by detecting the accumulation of gases produced due to insulation breakdown or arcing within the transformer tank before the fault escalates into a major catastrophe.
VgasтАЛтИЭI2t тАФ Indicates that gas production is proportional to the energy of the internal arc.
During minor internal faults, arcing decomposes the transformer oil, releasing gases that rise toward the conservator. These gases get trapped in the upper float chamber of the Buchholz relay, causing the float to move and trigger an alarm contact. The relay does not trip the circuit breaker immediately for minor faults, but provides a warning for maintenance intervention.
Buchholz relay is used only for oil-immersed transformers having a conservator tank.
It is a gas-actuated relay, not an electrical relay.
The alarm circuit is connected to the upper float, while the tripping circuit is connected to the lower float.
It cannot detect external faults as it is located in the pipe between the transformer tank and the conservator.
Detects incipient faults at a very early stage.
Provides a clear distinction between minor (warning) and severe (trip) faults.
Applicable only to oil-immersed transformers.
Cannot detect faults in the tank where no gas is produced.
Large oil-immersed power transformers.
Distribution transformers with conservator tanks.
Option B (External fault) is incorrect because the relay is placed between the main tank and the conservator; external faults do not cause gas formation inside the tank.
Gas formation is usually due to localized heating, partial discharge, or insulation failure.
A is correct тАФ The Buchholz relay is specifically designed to provide an alarm/warning upon the accumulation of gas caused by incipient internal faults within an oil-immersed transformer.
Always remember that Buchholz relays are never used in dry-type transformers, as they rely on the decomposition of insulating oil to detect faults.