What are the precautions for using SF6 gas density relays?- SF6在线监测系统_SF6检漏仪_SF6传感器_SF6密度继电器

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What are the precautions for using SF6 gas density relays?

发布时间：2017-02-20 来源：ydlcb 浏览次数：53次

The SF6 gas density relay can accurately measure the SF6 gas density value only when the circuit breaker is out of operation and the temperature inside and outside the circuit breaker reaches the balance. When the circuit breaker is running, if the circuit breaker leaks SF6 gas, due to the effect of temperature rise, more SF6 gas should be leaked than when the circuit breaker exits the operation, so that the electrical contact of the density relay can be closed.

The verification of SF6 circuit breaker density table or density relay is to use the instrument to automatically convert the SF6 gas pressure value at 20 ° C, showing the density value under various temperatures and pressures, and compare it with the various pressures simulated by the instrument to observe the contact situation of the electrical contact, whether it can signal or lock the circuit breaker within the specified value of the low voltage. To judge the SF6 circuit breaker density meter or density relay is good or bad.

In the process of verifying the density table and density relay of SF6 circuit breaker, it was found that the density relay of several circuit breakers was unqualified, but the phenomenon of unqualified density table has not been found. The reason for the unqualified density relay may be that the SF6 standard gas package carries a long thin copper pipe during installation or maintenance. Due to the bending or collision of copper pipes, the pressure in the standard SF6 gas package increases. It may also be due to the damage of the bellows of the density relay, resulting in the leakage of the standard gas packet of the density relay. When the circuit breaker leaks SF6 gas, the C1-L1 and C2-L2 contacts cannot be connected, resulting in the loss of the function of the density relay, which seriously threatens the safe operation of the equipment or even the safety of the system. It is recommended to replace the density relay with a density meter. On the one hand, it can reduce SF6 gas pipelines and joints, that is, reduce the probability of SF6 gas leakage; On the other hand, it can improve the operation reliability of the equipment.

In the actual work on site, when the circuit breaker is charged with SF6 gas, it is often believed that more SF6 gas can prevent the release of gas and blocking signals. Indeed, if the pressure of the gas is higher, the probability of sending gas and blocking signals will be reduced, but the burden on the seal of the circuit breaker will be increased, and the seal of the circuit breaker may be damaged and gas leakage occurs. Therefore, it is not recommended to charge SF6 gas pressure high phenomenon, should be strictly controlled within the standard.

(1) The SF6 gas density relay is similar to the SF6 gas density meter, and the SF6 gas density value can be accurately measured only when the circuit breaker is withdrawn from operation and the temperature inside and outside the circuit breaker is balanced; When the circuit breaker is charged with SF6 gas and when the circuit breaker is put into operation, the density of SF6 gas can not be accurately measured.

(2) No matter how different the structure principle of SF6 air-rest density relays is, they can only compensate for the pressure change caused by the change of ambient temperature, and can not compensate for the pressure change caused by the internal temperature rise of the circuit breaker.

(3) In actual engineering, the pressure unit MPa is used, rather than the unit of density.

(4) When the circuit breaker is put into operation, if the circuit breaker leaks SF6 gas, due to the role of temperature rise, more SF6 gas is turned over than when the circuit breaker exits the operation, in order to make the relevant electrical contacts of the density relay closed.