Common faults of wire and cable lines cause mechanical damage, insulation damage, insulation dampness, insulation deterioration, over-voltage, cable overheating faults. When the above faults occur in the line, the power supply of the fault cable should be cut off, to find the fault point, to the fault.
The direct cause of the cable failure is the breakdown of insulation. Mainly include:
1.Overload operation: long-term overload operation will increase the temperature of the cable and make the insulation aging, which will lead to the breakdown of insulation and reduce the construction quality.
2. Electrical interview: the construction of the cable head fails to meet the requirements, the cable head seals badly, moisture intruded into the cable interior, the cable insulation performance declined, no protective measures were taken when laying the cable, the protective layer was damaged, and the insulation declined.This problem is particularly obvious in all aluminum cables.
3. Civil engineering aspects: poor drainage in working well pipe trench, cable soaked in water for a long time, damaging insulation strength; The working well is too small, the bending radius of the cable is not enough, and the cable is damaged by extruding force for a long time. Mainly in the municipal construction of mechanical barbaric construction, cut and cut the cable.
4. Corrosion: The protective layer suffers chemical corrosion or cable corrosion for a long time, resulting in the failure of the protective layer and the decline of insulation.
5. The cable itself or the cable head accessories are of poor quality, the cable head seals are poor, the insulation glue dissolves and cracks, and the resonant phenomenon of the station is that the phase-to-phase capacitance of the line and the capacitance to the ground and the excitation inductance of the voltage distributor form a resonant circuit, so as to excite the ferroresonance.