开关柜内部发生局部放电时，放电产生的电磁波大部分被开关设备的金属外壳所屏蔽，小部分通过金属箱体的接缝处，同时产生一个瞬态对地电压。通过利用测试探头测试金属箱体外表面瞬间电位变化即可反映开关柜内部局部放电程度。

When the partial discharge occurs inside the switchgear, most of the electromagnetic waves generated by the discharge are shielded by the metal housing of the switchgear, while a small part generates a transient earth voltage through the joint of the metal box. The partial discharge in the switchgear can be reflected by measuring the change of the instantaneous potential of the metal box on the surface of the metal box by using the test probe.

通过在开关柜表面布置多个测试探头，并在周围辅以若干个干扰信号采集探头，同步开展连续监测，根据时延原理，即可实现对开关柜内部局部放电源的定位。

By arranging multiple test probes on the surface of the switchgear and adding several interfering signals around the switchgear to collect probes, synchronously carry out continuous monitoring, according to the principle of time delay, the location of partial discharge power inside the switchgear can be realized.