高压电能表中电容分压器稳定性试验分析

Stability test analysis on capacitive voltage dividers in high-voltage watt-hour meter

针对挂网运行中的高压电能表中电容分压器长期稳定性较差的问题,提出一种多级串联结构的干式电容分压器,并对其分压电容进行7 000h加速电压老化试验、温度试验和取能试验。试验结果表明,分压电容容量随电压老化时间不断衰减,且衰减分散性较大,试验初期衰减较快、后期趋缓,衰减特性可用高斯函数进行拟合,因此可通过电压加速老化和筛选分散性较小分压电容的方式提高电容分压器的长期稳定性;温度系数对电容分压器的影响较小,在计量精度允许范围内;取能电容分压器有稳定的功率输出,能够满足高压电能表中高电位电子线路的功耗要求。文章试验结论为高压电能表的稳定、可靠运行提供了技术支撑。

To solve the poor stability of capacitive voltage dividers inside the high-voltage watt-hour meter, this paper presents a kind of dry-type capacitive voltage divider with a multi-level series structure. The 7 000 hours voltage ac- celerated aging test, temperature test and power source test were taken for this kind of capacitive voltage divider. The test results demonstrate that the capacitance of voltage-dividing capacitors is attenuating with aging test time, and the dispersion of the attenuation is large. The capacitance attenuates fast at the beginning of test, afterwards gradually slows down, and the capacitance attenuation data can be fitted by a Gaussian function. Thus it is possible to improve the long-term stability of capacitive voltage dividers by either voltage accelerating aging for a certain time or screening capacitors with small dispersion. In addition, the temperature coefficient is too small to affect the accuracy of a CVD, which is within the allowable range of metering accuracy; and capacitive voltage divider for power source is able to provide stable output power which can meet the power consumption requirement of electronic circuits floated at high potential inside the high-voltage watt-hour meter. The test results provide technical support for the stable and reliable operation of high-voltage watt-hour meter.