Arc light sensor is called probe for short, which plays a very important role in the whole arc protection system. The arc light sensor is used to detect the intensity of the arc light, transmit the arc signal to the arc light protection device, and then judge whether to cut off the power supply of the system according to the arc light intensity.

The arc sensor is installed in each compartment of the cabinet, which can realize the protection from simple to complex and selective. As a light sensing element, the arc light sensor detects the sudden increase of light intensity in the event of arc fault, and transmits the analog light signal to the arc light unit or directly to the main control unit. The arc light unit converts the optical signal into electrical signal, and compares, filters, encodes and converts the electro-optic signal. The digital optical signal is transmitted to the arc light expander or the main control unit by the light.

When the arc light sensor is installed in the 35 kV switch cabinet, one arc light sensor shall be installed in the busbar compartment and the busbar side isolating knife switch room respectively. For 10 kV switchgear, only one arc light sensor shall be installed if the bus bar and the isolating knife switch on the bus side are in the same room; if the isolation knife switch on the bus side and the bus side are not in the same room, they shall be installed separately. Not only to ensure sufficient insulation distance, but also to detect the arc in the cabinet.

As the fast protection of 35 kV and 10 kV bus and switch cabinet internal fault, arc light protection is configured according to bus section, that is, each bus section is equipped with one main unit, several expansion units and several arc light sensors. The specific number of expansion units should match the number of arc sensors. Each switch cabinet compartment is equipped with an arc sensor, which can effectively protect the bus short circuit caused by the switch explosion damage caused by feeder branch fault, and can better play the effectiveness of the protection system, and the protection range is wider.

The installation principle of arc probe is to make the bus in the switch cabinet completely under the monitoring of the probe, that is, the monitoring angle of the probe is expanded. Therefore, the probe should be installed at the upper left or right corner facing the bus.