金属氧化物避雷器缺陷与阻性电流关系的分析探讨

Approach to Correlation of MOA Defaults with Its Resistive Current

用阻性电流基波值来简单判断金属氧化物避雷器缺陷已不能满足实际要求,阐述了金属氧化物避雷器缺陷引起泄漏电流和阻性电流异常常见的四种现象:一内部电阻片与外瓷套之间的局部放电;二内部受潮;三金属氧化物避雷器发生热击穿;四金属氧化物避雷器外套表面的污秽。分析了各种缺陷的特点:一当阻性电流上有脉冲电流尖峰出现时,可作为局部放电的判据;二当阻性电流长期增加,不因时间的增加而减小,说明避雷器内部受潮;三监测金属氧化物避雷器总电流中的有功分量,可以了解其发热功率的变化,只要发热功率与散热功率曲线之间裕度足够,就不会发生热击穿;四如泄漏电流的增加只在一段时间内出现,过一段时间后将消失,说明是污秽引起的,其与内部受潮引起的阻性电流增加是不同的。通过对金属氧化物避雷器缺陷与阻性电流关系的探讨,为金属氧化物避雷器缺陷的判断和解决提供了帮助和指导。

Simple assessment of MOA defaults with basic wave amplitude of resistive current can not more meet practical need. Four phenomena of MOA defaults leading to abnormal leakage current and resistive components are described： 1.Partialdischargebetweenvaris!torsandouterhousing. 2. Moisture ingress. 3. Thermal breakdown. 4. Pollutwd housing surface. The features of above mentioned defaults are as follows： 1. Appearance of pulse peaks on resistive component is the evidence of partial discharge. 2. Permanent increase of resistive current instead of drop with time proves moisture ingress. 3. Monitoring active component of joint current can reveal variation of heating power of MOA, so long as sufficient margin exists between heating power and dissipating power graphics the thermal breakdown wouldn＇t occur. 4. Increase of leakage current is caused by surface pollution if it takes place occasionally which differs from moisture ingress. Study on correlation of MOA defaults with its resistive current provides assistance in determining MOA defaults and their solution.