A fault indicator is an electromagnetic induction device that can reflect the presence of a short circuit current passing through and display a fault sign (red card). Install this fault indicator along the distribution line. Once a fault occurs in the line and a short-circuit current flows, the fault indicator will activate and a red fault sign will appear. Then, during the inspection along the line, all fault indicators from the power supply side to the fault point showed a red card, while those after the fault point did not show a red card, indicating that the fault point was between the last red card point and the first non red card point after it. 
Fault indicators usually include current and voltage detection, fault discrimination, fault indicator drive, fault status indication and signal output, and automatic delay reset control.
Fault indicators are generally installed on overhead lines, overhead cables or buried cables, and switchgear busbars. Therefore, they detect voltage by detecting spatial electric field potential gradients, and detect line currents through electromagnetic induction.
Recently, State Grid Ningde Power Supply Company carried out high-precision line fault indicator installation work to assist in the integration of power distribution and operation, and fully ensure the safe and stable operation of the power grid, in response to the high number of overhead lines in its jurisdiction, which are easily affected by thunderstorms, typhoons, and other weather conditions.
It is understood that the installation of line type indicators requires the company's distribution staff to carry tool bags and climb up a 15 meter high pole, using insulated rods to complete the operation on the pole. In order to quickly complete the installation of high-precision line fault indicators and ensure the reliability of the operation of overhead lines in the jurisdiction, the company's staff carried out the installation work in a centralized and continuous manner while ensuring the physical and mental health of the staff.
The newly installed high-precision line fault indicator is powered by solar panels and does not require maintenance by team members. When a fault occurs, it can be accurately located, directly sending messages to the main station and notifying the device owner via SMS, greatly reducing the response time for fault repair and accelerating the speed of fault repair. Next, the company will continue to complete the installation of the remaining high-precision line fault indicators, carry out daily inspections, maintenance, and repair work, and ensure the stable operation of the power grid.