1. Load monitoring
The monitoring of the cable load can master the change of cable line load, control the cable line in principle but not load, analyze the running state of the cable line. Because overload is harmful to the cable, the load of the cable should be measured and monitored frequently. Measurement of cable line load can be made with a clipper ammeter to keep the cable line operating under the specified allowable continuous load.
In order to prevent premature aging of cable insulation, line voltage should not be too high, generally should not exceed 15% of the cable rated voltage.
2. Temperature monitoring
The operation of the cable line will be affected by the environmental conditions and heat dissipation conditions, and in the early stage of the cable line fault will be accompanied by local temperature rise phenomenon, so it is necessary to conduct temperature monitoring of the cable line.
The purpose of measuring the temperature of cable line sheath, cable joint and other parts with various instruments is to prevent the cable insulation from exceeding the maximum allowable temperature and shorten the cable life and prevent cable accidents in advance.
The measurement of cable temperature should be carried out in summer or when the cable load is at its maximum. The cable should be arranged in the densest place or the place with the worst heat dissipation condition and the line segment affected by the external heat source. When measuring the temperature of the buried cable, the soil temperature should be measured. The distance between the installation point of the thermocouple thermometer measuring soil temperature and the cable shall be no less than 3m.
The newly put in service cable cold head should be tracked and checked by infrared temperature tester, and personnel should be arranged to tighten the conductive connection part during power failure maintenance. Because the connection of the cable cold head relies on the mechanical force such as double-head screws to press the conductive contact surface, the working load current and fault short-circuit current all rely on the pressure contact surface for energy transmission, and the thermal expansion and contraction and electromagnetic vibration may cause poor contact.