宁波轨道交通1号线低压柜故障分析

针对宁波轨道交通1号线变电所低压全所失电及低压柜部分抽屉被烧毁情况,从设备的继电保护设置及开关柜装配两方面进行分析:低压柜进线及母联继电保护的设置可以对各种形式的金属性短路进行有效保护;低压柜进线继电保护整定值与配电变压器35 kV馈线开关及低压馈线开关有很好的选择性配合;故障是由于低压开关触头与铜排接触不良产生电弧短路造成的。在分析的基础上提出解决方案:对低压开关触头与铜排连接的一次插件及断路器脱扣性能进行检查;增加母线间隔离板以提高开关柜的防电弧等级;适当减少继电保护动作时间;增加弧光保护;增加35 kV开关后备保护动作,闭锁低压备自投启动的闭锁条件等。

Malfunction of Low-voltage Switchgear of Ningbo Rail Transit Line 1

This paper explored the reasons behind the total loss of power of the low-voltage substation and burning of some switchgear drawers in terms of setting of relay protection and assembling of the switchgear.The result showed that the low-voltage relay protection setting can effectively protect all kinds of metallic short circuits;the circuit breaker of low-voltage incoming and bus tie can match with 35kV transformer feeder and low-voltage feeder;the malfunction is caused by the arc short circuit due to loose contact between the switch contact and the copper bus.On this basis,the paper proposed some solution schemes:checking the switch contact and circuit breaker tripping performance;enhancing the grade of switchgear arc protection by adding division plate between buses;reducing relay tripping time properly;adding arc protection;adding the condition of 35kV backup protection interlock low voltage BZT start program.