Pre-insertion resistor (PIR) is an important component of circuit breaker. The healthiness of the circuit breaker (CB) depends upon that of PIR contact. With the increasing demand of uninterrupted power supply, failure in major equipment like CB may incur huge loss to the utility. The existing study reveals that mechanical failures are more dominant than other types of failures. Thus, many industries prefer to undertake preventive maintenance of equipment rather than break down maintenance. This paper describes the actual problem detected in PIR contact of North Eastern Regional Transmission System, having a 400 kV, 3000 A, SF6 CB through testing and rectification thereafter. The results obtained from the graph helped in detecting mechanical dis-alignment of the connecting link in the link arm and the tubular contact of the PIR. Furthermore, a model has been developed to show the possible threat that would have occurred, had the problem been not rectified. This paper will help the utilities to emphasize on detecting the problem by undergoing preventive maintenance and thereby saving unprecedented failure of equipment.

预插电阻器（PIR）是断路器的重要元件。断路器 (CB) 的健康状况取决于 PIR 触点的健康状况。随着不间断供电需求的不断增加，CB等主要设备发生故障可能会给公用事业带来巨大损失。现有研究表明，机械故障比其他类型的故障更占主导地位。因此，许多行业更愿意对设备进行预防性维护，而不是故障维护。本文介绍了东北区域输电系统400 kV、3000 A、SF6 CB通过测试和整改发现的PIR接触的实际问题。从图表中获得的结果有助于检测连杆臂中的连杆和 PIR 管状接触的机械错位。此外，已经开发了一个模型来显示如果问题不得到纠正可能发生的威胁。本文将帮助公用事业公司重点通过预防性维护来检测问题，从而避免出现前所未有的设备故障。