Electrical Property Test and Research of Insulated Operating Rods with Metal Joint for Live Working

Abstract

Sectional structure with metal joint is commonly found in an insulated operating rod for live working in an extra- or ultra-high voltage power transmission line but the metal joint is inclined to discharge because uneven distribution of electric fields around the metal joint. In this paper, power frequency discharge tests are made on operating rods with metal joint and insulated joint, including even boost and discharge test and 300s power frequency voltage withstand test and test results are analyzed and studied. Results show: operating rods with two types of joints in the even boost test have basically the same discharge voltage values; the operating rod with insulated joint has significantly higher discharge voltage value than that with metal joint in the 300s voltage withstand test; the metal joint causes local electric field concentration and internode capacitance effect, leading to uneven electric field point position distribution of the insulated operating rod and reduced electrical property. However, the electrical property of the operating rod may be enhanced by mounting a grading ring at the end of the operating rod or coating functional coating outside the operating rod.