Gas relays also referred to as Buchholz relays play a role in oil filled distribution transformers. These relays are specifically designed to identify and raise an alert when gas or air bubbles are detected in the transformer oil. The presence of gas or air bubbles in the oil can be an indication of a problem within the transformer, such as overheating or a short circuit. Upon detecting a fault the gas relay will trigger a signal to the circuit breaker to disconnect and protect the transformer from harm. This article looks into why gas relays are vital for distribution transformers, how they work and their different types.
Importance of Gas Relays in Distribution Transformers
Distribution transformers are components of the power network as they step down electricity voltage from transmission lines to levels for household and commercial use. These transformers utilize oil as both an insulator and cooling agent. However faults can arise within the transformer leading to gas or air bubble formation in the oil. These bubbles can compromise the insulating properties of the oil resulting in faults and damage to the transformer.
Gas relays are specifically designed to identify the presence of gas or air bubbles, in the transformer oil. In case of a fault the gas relay will signal the circuit breaker to trip. Disconnect the transformer from the power grid preventing any harm to the transformer and ensuring the safety of the power system.
Working Principle of Gas Relays
Gas relays operate based on gas evolution principles. When a fault like overheating or a short circuit occurs in the transformer gas is produced in the oil. This gas moves upward within the transformer and enters the gas relay for detection. The purpose of this relay is to detect any gas or air bubbles in the oil and send a signal to trigger the circuit breaker isolating the transformer from the power system.
Types of Gas Relays
There are two types of gas relays: the Buchholz relay and the oil surge relay.
●Buchholz Relay
The Buchholz relay (DIN EN 50216-2) is the most common type of gas relay used in distribution transformers. It is named after its inventor, the German engineer Max Buchholz, who developed the relay in 1921.
Function:
The Buchholz relay is designed to detect gas accumulation and minor oil movements within the transformer. It’s primarily used for detecting faults such as insulation failures, overheating, or minor leaks that produce gas within the transformer oil.
Location:
It’s installed in the pipe connecting the main transformer tank to the conservator tank.
Working Principle:
When gas is generated due to a fault, it rises and enters the Buchholz relay, displacing oil and causing a float to drop. This activates a switch that sends a signal to trip the circuit breaker, isolating the transformer.
Usage:
Commonly used in distribution transformers and is effective for detecting slow-developing faults.
●Oil Surge Relay
Function:
The oil surge relay is designed to detect sudden changes in oil flow, which can indicate major faults such as large leaks or severe short circuits.
Location:
It is also placed in the pipeline between the transformer tank and the conservator tank, but its focus is on detecting rapid oil movement rather than gas accumulation.
Working Principle:
A sudden surge in oil flow causes a float within the relay to move, triggering a switch that sends a signal to trip the circuit breaker, isolating the transformer.
Usage:
Typically used in larger transformers where the risk of sudden oil movement is greater.
Takeaway
Gas relays play a role in oil filled distribution transformers by sensing and notifying about gas or air bubbles in the transformer oil. These bubbles can indicate issues, like short circuits. Upon detection of a fault the gas relay activates the circuit breaker to isolate the transformer from the power system preventing harm. There are two types of gas relays; Buchholz relay and oil surge relay. The Buchholz relay is commonly used in distribution transformers while larger transformers utilize the oil surge relay.
Post time: Nov-15-2024