Common faults of cable lines include mechanical damage, insulation damage, insulation damp, insulation aging deterioration, overvoltage, cable overheating faults, etc. When the above-mentioned fault occurs in the line, the power supply of the faulty cable should be cut off, the fault point should be found, the fault should be checked and analyzed, and then repair and test should be carried out. The power supply can be restored after the removal of the fault.
The most direct cause of cable failure is breakdown due to insulation degradation.
There are:
a. Overload operation. Long-term overload operation will increase the temperature of the cable and age the insulation, which will lead to breakdown of the insulation and reduce the quality of construction.
b. Electrical aspects include: the cable head construction process fails to meet the requirements, the cable head has poor sealing performance, moisture penetrates into the cable, and the cable insulation performance is reduced; when the cable is laid, protective measures are not taken, the protective layer is damaged, and the insulation is reduced.
c. Civil engineering: poor drainage of pipe trenches in industrial wells, long-term soaking of cables in water, impairing the insulation strength; too small wells, insufficient cable bending radius, and long-term damage by external forces of squeezing. Mainly brutal mechanical construction in municipal construction. Cut and cut the cable.
d. Corrosion. The protective layer suffers from chemical corrosion or cable corrosion for a long time, causing the protective layer to fail and the insulation to decrease.
e. The quality of the cable itself or the cable head accessories is poor, the cable head is poorly sealed, the insulating glue is dissolved, and cracked. The resonance phenomenon in the station is the line disconnection. The line phase capacitance and the ground capacitance and the distribution transformer excitation inductance form resonance Loop to excite the ferromagnetic resonance.
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