Common malfunction of cable and wire are mechanical damage, insulation damage, insulation moisture, insulation aging deterioration, over-voltage, cable overheating faults, etc. When the malfunction mentioned above occurs on the cable and wire, the power supply of the faulty cable should be cut off and the faulty point should be found. the malfunction should be inspected and analyzed, and then repaired and tested. The cut-off can be resumed after the malfunction is eliminated. The most direct cause of cable failure is the breakdown of the reduced insulation.
The main causes of cable failure are:
a) Overload operation: A long-term overload operation will increase the cable temperature, insulation aging, resulting in the breakdown of insulation and reducing construction quality;
b) Electrical aspects: Cable head construction process cannot meet the requirements, the sealing of cable head is poor. When moisture intrudes into the cable, the insulation performance of the cable is degraded; the protective measures are not taken when the cable is laid, the protective layer is damaged, and the insulation is reduced;
c) The civil engineering has: If the drainage of the well is poor, the cable will be soaked for a long time and the insulation strength will be damaged. If the work well is too small, the cable bending radius will be not enough, and it will be damaged by the external force for a long time. It’s mainly in the municipal construction of mechanical barbaric construction, digging and cutting cables;
d) Corrosion: The protective layer has been subjected to chemical corrosion or cable corrosion for a long time, resulting in failure of the protective layer, insulation reduction;
e) Cable itself or cable head accessories is with poor quality, cable The cable head has poor sealing performance, the insulating glue dissolves and cracks, and the resonance phenomenon that occurs at the station is that the cable breakage fault causes the cable phase capacitance and the ground capacitance to form a resonant circuit with the distribution transformer excitation inductance, thereby exciting the ferromagnetic resonance.