Line Fault Of Power Cable

Common line faults
Short-circuit faults: There are two-phase short circuits and three-phase short circuits, which are mostly caused by hidden dangers left in the manufacturing process.
Grounding fault: When one or more cores of the cable are broken down to the ground, the insulation resistance is lower than 10kΩ, which is called low-resistance grounding, and higher than 10kΩ, which is called high-resistance grounding. It is mainly caused by cable corrosion, lead cracks, insulation dryness, joint technology and materials, etc.
Line break fault: One or more cores of the cable are completely or partially broken. The cable can be broken if it is mechanically damaged, affected by terrain changes, or has a short circuit.
Mixed fault: more than two of the above faults.
Causes and countermeasures of power cable line failures
External force damage: The cable may suffer external force damage during storage, transportation, laying and operation, especially the directly buried cable that has been in operation, which is easily damaged during the ground construction of other projects. This type of accident often accounts for 50% of cable accidents. In order to avoid such accidents, in addition to strengthening the work quality of cable storage, transportation, laying and other links, it is more important to strictly implement the groundbreaking system.
Corrosion of protective layer: Electrochemical corrosion of underground stray current or chemical corrosion of non-neutral soil makes the protective layer ineffective and loses its protective effect on insulation. The solution is to install drainage equipment in areas with dense stray current; when the local soil on the cable line contains chemical substances that damage the cable lead sheath, this section of cable should be installed in a pipe, and neutral soil should be used as the cable lining and cover, and asphalt should be applied to the cable.
Overvoltage and overload operation: Improper selection of cable voltage, sudden high voltage intrusion during operation or long-term overload may damage the insulation strength of the cable and break down the cable. This needs to be solved in time by strengthening inspections and improving operating conditions.
Water immersion in outdoor terminal heads: Due to poor construction, the insulation glue was not filled, causing the terminal heads to be immersed in water and eventually exploded. Therefore, it is necessary to strictly implement the construction process regulations, carefully accept the inspection, strengthen inspections and timely repairs. The terminal head leaks oil, destroys the sealing structure, causes the impregnant at the end of the cable to drain and dry, increases thermal resistance, accelerates aging of insulation, and easily absorbs moisture, causing thermal breakdown. When oil leakage is found at the terminal head, inspection should be strengthened, and in serious cases, power should be cut off and redone.