EN
上一条： 
沪公网安备31011802003762
-
-
Tel:13585763546 -
扫码咨询
-
-
TOP
韦弗斯新闻动态
最新动态
SF6安全保障专家
专注于SF6气体检测的专业化
Why does sulfur hexafluoride equipment use density relays instead of pressure gauges?
发布时间：2019-12-19
来源：ydlcb 浏览次数：42次
1, why not use pressure gauge?
According to ideal gas (equation of state of state) pv=nRT, it can be seen that pressure p is a linear relationship of temperature. As shown in the figure below, when the gas temperature in the sulfur hexafluoride equipment changes, the value of the pressure gauge changes along with it, and it cannot be prepared to show the state of the equipment.
2, density relay structure
As shown in the figure below, the structure of the compensation chip type sulfur hexafluoride density relay
The SF6 gas density meter shown is mainly composed of Bourdon tube, gear mechanism, pointer, metal belt and other parts. The hollow elastic Bourdon tube is connected with the circuit breaker, and its internal space is communicated with the SF6 gas in the circuit breaker. The elastic Bourdon tube end is hinged with a metal belt that plays a temperature compensation role, and the metal belt is hinged with the gear mechanism and the pointer mechanism.
3, density relay temperature compensation principle
The SF6 gas density relay is actually a pressure relay with temperature compensation, and its density value is expressed by the corresponding pressure value of 20 ° C. When the temperature changes, the elastic Bourdon tube and metal band change at the same time, so that the pointer displays unchanged.
In the case of constant volume, any pressure change due to temperature change alone can be compensated by the corresponding change of Bourdon tube and metal sheet at the same time, so as not to cause the deflection of the pointer and ensure the correctness of the pressure indication value. As shown in the following picture.
The response of the pressure element to any pressure change that is not caused by a temperature change is translated into the gas density relay pointer action and reflected on the dial, and the pressure value beyond the minimum or maximum pressure allowed by the system can be monitored. Air leakage as shown below.
4, the State grid new 18 anti-measures on the density relay requirements
The density relay shall be installed at the same operating ambient temperature as the monitored air chamber
Explanation: If the operating environment temperature is different, the compensation temperature of Bourdon tube and metal strip is inconsistent, resulting in inaccurate values.