Wuqiang Jinheng Trading Co., Ltd.
What is the working principle of a gas relay?
Aug 10,2025
Gas relays (also known as gas gas relays) are the core protection devices for internal faults in oil-immersed transformers. Their working principle mainly achieves hierarchical protection by monitoring the gases produced by the decomposition of transformer oil or abnormal oil flows. The specific mechanism is as follows:
I. Core Logic of the working principle
1. Light gas protection (signal alarm)
Trigger condition : Minor faults inside the transformer (such as local overheating, insulation aging) cause the oil to decompose and produce a small amount of gas.
Action process :
The gas enters the upper gas chamber of the relay through the connecting pipe and accumulates, causing the oil level to drop.
The float cup (or open oil cup) descends with the oil level, driving the magnet closer to the reed contact.
The reed contact is engaged, triggering the light gas signal circuit and sounding an alarm.
2. Heavy gas protection (tripping and power-off)
Trigger condition : severe faults (such as short-circuit arcs) generate a large amount of gas and high-speed oil flow (flow rate up to 0.6-1.5m/s) instantaneously.
Action process :
The oil flow impacts the baffle, overcoming the resistance of the spring and causing the baffle to deflect.
The magnet on the baffle attracts the heavy gas dry spring contact.
Connect the tripping circuit and immediately cut off the power supply of the transformer.
Ii. Design Features and Technical Advantages
Hierarchical response mechanism :
Light gas only alarms to avoid false tripping due to minor faults. The heavy gas circuit breaker trips directly to prevent the fault from expanding.
Seismic resistance and sealing performance :
Seismic design (4-20Hz /4g) prevents vibration misoperation. The sealing structure (with a pressure resistance of 200kPa) ensures long-term stable operation.
Gas-guided path :
The pipeline design optimizes the direction of gas aggregation and oil flow to enhance the detection accuracy.
This working principle design takes into account both sensitivity and reliability, and it is the cornerstone of non-electrical protection for transformers.
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Wuqiang County HengShui City Hebei Provinice China