一起有载分接开关故障引起乙炔超标的案例分析

Analysis on Over-standard of Ethyne Caused by Fault of On-load Tap Changer

针对一起变压器油乙炔超标的案例,对变压器进行故障分析。先通过改良三比值法定性变压器有低能放电现象,再通过直流电阻测试等常规试验将排查范围缩小至分接抽头引线处,然后根据局部放电试验结果推断9号分接开关静触头与处于地电位的分接选择器接触不良,最后解体检查明确变压器故障部位为9号分接开关静触头。指出在故障诊断中,宜采用手动调节方式对所有分接位置进行直流电阻测试,以全面考察不同极性选择开关下各分接位置的连接状况。对有载分接开关的选型和设计提出纵向尺寸不宜过大、连接引线的长度应留有一定裕度的建议。

Taking one case of over-standard of ethyne in transformer oil as an example,this paper analyzes the fault of transformer.It firstly characterizes the transformer as low energy discharge by using improved three ratio method and by using routine tests such as direct current（DC） resistance test to narrow fault investigation scope to the lead of shunting tap.According to partial discharge（PD） test result,it deduces bad contact of static contact of No.9 tap changer with tap selector in ground potential,and finally determines fault position of the transformer is at the static contact of No.9 tap changer by strip inspection.This paper points out it is ought to adopt manual adjustment way to conduct DC resistance tests on all tap positions in order to investigate connection status of each tap position under different polar selective switches.It also suggests for type selection and design on the on-load tap changer that longitudinal dimension of the on-load tap changer should not be too large and there should be a certain margins for connecting leads.