Common faults in cable lines are mechanical damage, ins […]
Common faults in cable lines are mechanical damage, insulation damage, insulation moisture, insulation aging and deterioration, overvoltage, cable overheating faults, etc. When the above-mentioned fault occurs on the line, the power supply of the faulty cable should be cut off, the fault point is found, the fault is checked and analyzed, and then repaired and tested. After the fault is removed, the power supply can be restored after the fault is eliminated.
The most direct cause of cable failure is insulation breakdown and breakdown.
a. Over-load operation. Long-term over-load operation will increase the temperature of the cable and aging the insulation, which will break down the insulation and reduce the construction quality.
b. Electrical aspects: the construction technique of the cable head does not meet the requirements, the cable head has poor sealing, moisture penetrates into the cable, and the cable insulation performance decreases; when the cable is laid, protective measures are not taken, the protective layer is damaged, and the insulation is reduced.
c. In civil engineering, the drainage of the gutter pipe trench is not smooth, the cable is immersed in water for a long time, and the insulation strength is damaged; the well is too small, the cable bending radius is not enough, and it is damaged by the external force for a long time. It is mainly the brutal construction of machinery in municipal construction. Digging cut the cable.
d. Corrosion. The protective layer has been exposed to chemical corrosion or cable corrosion for a long time, resulting in the failure of the protective layer and the reduction of insulation.
e. Poor quality of the cable itself or cable head accessories, poor sealing of the cable head, dissolving and cracking of the insulating glue, causing the resonance phenomenon of the station to be a line break fault, causing the line interphase capacitance and the ground capacitance to resonate with the distribution transformer excitation inductance Loop, thereby exciting ferromagnetic resonance.