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The function of gas operated relay is_____________
To operate during short circuit fault
To operate during inter turn fault
To operate during both (a) and (b)
To operated during internal arcing
To operate during both (a) and (b)
The gas-operated relay, commonly known as a Buchholz relay, is a protective device used in oil-immersed transformers to detect incipient faults. It acts as a safety mechanism that responds to the accumulation of gases or pressure surges generated by internal faults, triggering an alarm or tripping the circuit breaker to prevent major damage.
The gas-operated relay, commonly known as a Buchholz relay, is a protective device used in oil-immersed transformers to detect incipient faults. It acts as a safety mechanism that responds to the accumulation of gases or pressure surges generated by internal faults, triggering an alarm or tripping the circuit breaker to prevent major damage.
VfaultтАЛтИЭdtdGтАЛ тАФ The rate of gas production is proportional to the fault intensity
When an internal fault occurs (like an inter-turn short or local arcing), the insulation decomposes, releasing gases that rise toward the transformer conservator tank. These gases get trapped in the Buchholz relay chamber, displacing the oil and causing the float to descend, which closes the alarm contact. In the event of a severe fault (like a major short circuit), the resulting oil pressure surge operates the lower element (a flapper or vane), which directly trips the circuit breaker.
Buchholz relays are strictly for oil-immersed transformers.
The relay is installed in the pipe connecting the transformer tank and the conservator.
It detects faults like core heating, inter-turn shorts, and arcing before they evolve into catastrophic failures.
It does not respond to external faults.
Detects incipient faults at a very early stage.
Provides reliable protection against internal short circuits.
Applicable only to oil-immersed transformers.
Requires the transformer to have a conservator tank.
Oil-filled power transformers
Large oil-filled distribution transformers
The Buchholz relay is the 'first line of defense' for internal transformer health.
Option D is also a cause for operation, but Option C is more comprehensive as it encompasses various internal fault types (short circuit, inter-turn, and arcing).
C is correct тАФ The gas-operated (Buchholz) relay is designed to detect and respond to various types of internal faults, including short circuits, inter-turn faults, and internal arcing.
Remember that Buchholz relays are mechanical devices that respond to physical movement of oil/gas, distinguishing them from electrical relays like Differential or Overcurrent relays.