In order to clarify the function of SF6 relay, it is necessary to understand what SF6 gas density relay is. SF6 gas density relay is an important component used to monitor the change of SF6 gas density in SF6 switch body in operation. Its performance directly affects the operation of SF6 switch. Due to the infrequent operation of the long-running SF6 gas density relay, after a period of time, the phenomenon of inflexibility and poor contact will appear. In a serious case, the temperature compensation performance of the density relay will deteriorate, which will lead to misoperation of the density relay and affect the system.
Based on the above situation, maintenance personnel need to use SF6 relay to calibrate the density relay in operation, so as to ensure its normal performance and not affect the operation. LANSO SF6 gas density relay calibrator has the characteristics of automatic calibration, high degree of integration, good sealing performance, no waste of SF6 gas in the calibration process, simple operation, easy to use. It can print test results at any time, and has been used in many substations on-site calibration.
1. Signal and locking function of SF6 relay
It is a SF6 gas package sealed on the outside of the corrugated pipes and connected with the SF6 gas in the circuit breaker. Through the lever with the shaft as the support point, it is compared with the standard gas package sealed on the outside of the corrugated pipes to drive the electric contact action of the micro switch to realize the signal and locking function.
2. SF6 relay can maintain balance
When the circuit breaker exits from operation, and the temperature of SF6 gas in the circuit breaker at the rated density or pressure is equal to the ambient temperature, the state of SF6 gas outside the corrugated pipes is the same as that of the standard SF6 package outside the corrugated pipes. The lever with the shaft as the support point is maintained in a certain equilibrium position, so that the electric contact of the micro switch is in the open position. With the change of ambient temperature, the pressure of SF6 gas on both sides changes simultaneously. Therefore, the lever acting on the shaft as the support point remains in a certain equilibrium position, and the electric contact of the micro switch remains in the open position.
3. Electrical contact closure function of SF6 relay
When the circuit breaker exits from operation, and the temperature of SF6 gas in the circuit breaker is equal to the ambient temperature, if the circuit breaker leaks SF6 gas, the pressure of SF6 gas outside the corrugated pipes will decrease, the pressure of the standard SF6 gas pack outside the corrugated pipes remains unchanged, the lever is out of balance, and the two ends of the result will rotate counterclockwise to reach the new equilibrium position. When the air leakage reaches a certain extent, it will make the electric contacts with different functions of the micro electric contacts close respectively, send out different instructions or signals, and realize their different functions.
When SF6 relay is put into operation, the standard SF6 gas packet is still under the ambient temperature. As the electrical power consumed when the load current passes through the loop resistance is converted into heat energy, the SF6 gas in the circuit breaker is heated up and pressure increment is generated, namely: The pressure of SF6 gas outside the corrugated pipes will increase, which will push the lever to rotate clockwise around the axis, so that the electric contact of the micro switch will not close. In this case, if the circuit breaker leaks SF6 gas, the pressure of SF6 gas outside the corrugated pipes will decrease. However, due to the effect of temperature rise, it is necessary to leak more SF6 gas than when the circuit breaker is out of operation, in order to make the micro switch electrical contact closed.
