Line failure
In our life, we often encounter faulty wires or cables. In general, power cables are much more practical than ordinary cables. We can illustrate the importance of power cables with examples of common line faults, because faults can be used to know.
Common line faults
Short-circuit fault: there are two-phase short-circuit and three-phase short-circuit, which are mostly caused by hidden dangers left in the manufacturing process.
Ground fault: The breakdown of one or several cores of the power cable to the ground, the insulation resistance of which is lower than 10kΩ is called low-resistance grounding, and higher than 10kΩ is called high-resistance grounding. Mainly due to cable corrosion, lead cracks, dry insulation, joint technology and materials.
Disconnection fault: One or several cores of the cable are completely or incompletely broken. Cables can be disconnected due to mechanical damage, terrain changes, or short circuits.
Mixed faults: More than two of the above-mentioned faults.
Causes and Countermeasures of Power Cable Line Faults
External force damage: During the storage, transportation, laying and operation of the cable, it may be damaged by external force, especially the directly buried cable that has been in operation, which is easily damaged in the ground construction of other projects. Such incidents tend to account for 50% of cable incidents. 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 ground breaking system.
Corrosion of protective layer: The galvanic corrosion of underground stray current or the chemical corrosion of non-neutral soil makes the protective layer fail and lose its protective effect on insulation. The solution is to install drainage equipment in the stray current dense area; when the local soil on the cable line contains chemicals that damage the lead package of the cable, the cable should be installed in a pipe, and neutral soil should be used as a cushion for the cable. and covering, but also coating the cable with asphalt.
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.
The outdoor terminal is soaked in water: due to poor construction, the insulating glue is not fully filled, causing the terminal to be flooded and eventually explode. Therefore, it is necessary to strictly implement the construction process regulations, conscientiously check and accept; strengthen inspection and timely maintenance.
The oil leaks from the terminal head, which destroys the sealing structure, causes the impregnating agent at the end of the cable to dry up, increases the thermal resistance, accelerates the aging of the insulation, and easily absorbs moisture, causing thermal breakdown. When oil leakage is found at the terminal head, inspections should be strengthened, and power outages should be redone in serious cases.