Research on Low Temperature Stability and Measuring Accuracy of SF6 Gas Density Sensor

SF6 gas density sensor can monitor the density change of the SF6 gas in an electrical power equipment. The stable of SF6 gas density sensor is of great significance for ensuring the security of power grid. According to statistics, the low temperature level of most SF6 gas density sensors installed in the power grid does not exceed -40°C, while the lowest temperature in some parts of China is lower than -50°C. This research investigated the working stability of two types of SF6 sensors in the temperature range from 20°C to -50°C from the aspects of basic function performance and mearing accuracy, and give suggestion for developing SF6 gas density sensor with higher low temperature level.

I. Introduction

SF₆ is a gas type dielectric with strong electronegativity, which has excellent insulation and arc extinguishing capabilities, and is widely used in high-voltage equipment such as switchgear and circuit breakers [1], [2]. The insulation and arc extinguishing ability of SF₆ mainly depends on the density of SF₆ gas (that is, the mass of SF₆ gas in unit volume). When the density of SF₆ gas in the power equipment decreases, the insulation performance of the power equipment decreases significantly, which leads to the failure of the power equipment and seriously affects the Safe and stable operation of the power grid [3]–[5].