1. The role of SF6 relay
SF6 relay is mainly responsible for real-time detection of SF6 gas density changes in SF6 circuit breakers and SF6 combined electrical appliances, and monitoring the sealing condition of SF6 electrical appliances, which is an indispensable part of SF6 circuit breakers and SF6 combined electrical appliances.
The SF6 gas in SF6 appliances is sealed in the circuit breaker, which is equivalent to being sealed in a container with a fixed volume. According to the gas density formula, the pressure of SF6 gas at a specified temperature can be equivalent to the SF6 gas density. Therefore, density relays usually use the gas pressure when the ambient temperature is 20°C as the standard value of SF6 density. However, the SF6 relay is used to monitor the normal pressure of the gas in the SF6 appliance in real time, and its pressure value will be changed by the change of the ambient temperature, but its density value is unchanged when the SF6 gas does not leak.
2. SF6 relay temperature compensation principle
Generally, a density relay filled with SF6 judges whether it meets the safety standard by the density of SF6 gas, and it is known that the density of SF6 gas is reflected by measuring the pressure of the gas. In order to make the pressure of the SF6 gas in the density relay change due to any circumstances, and the final result is only the standard pressure value at 20°C, the SF6 relay must be temperature compensated.
The temperature compensation function of the SF6 relay is mainly realized by the balancing action of the lever. The pressure in the standard SF6 gas bag at one end of the lever is equal to the rated pressure specified by the SF6 appliance at 20°C, and the ambient temperature is the same as the outside.
When the ambient temperature rises, the gas in the SF6 appliance connected to the bellows is affected and the pressure increases, the lever will be driven by the pressure to move upward. However, the standard SF6 air bag is also affected by the same external temperature change. The pressure increases and moves upward, and both are affected by the same effect. In this way, the lever maintains a balance and achieves the effect of temperature compensation.
