The parallel use of cables should pay attention to the problem

For some new expansion projects of industrial and mining and chemical companies, the power cables are supplied in parallel. It is inevitable that in the parallel use of power cables, the current carrying capacity of the two cables must be evenly distributed. Otherwise, the cable will be subject to thermal shock. Wear breakdown.

The two power cables used in parallel are preferably of the same length and length, so that when the cable is powered on, the parameters of the two power cables are basically close to each other, and the ampacity distribution is basically uniform. There will be no single cable overload. A large area of ​​heat burned out in advance. Second, the parallel operation of the cable, the distance between each other should be considered appropriate amplification, so that when a cable fails, it will not affect the next parallel use of the cable burned at the same time, which to a certain extent, reducing the power of the company's economic losses . Thirdly, the power cables running in parallel should be checked regularly to ensure that the cables and the switches are in good contact with each other because the cables used in parallel are mostly above 35mm2, and the conductor resistance is every kilometer. Below zero ohm, the magnitude of the resistance is about 10-1. If the nose of the cable is not in good contact with the switch, it is easy to cause the contact resistance of one or more phases of a cable at the switch to be too large, resulting in two cables carrying current. Inconsistent distribution, the current cable customers consider the economy and the design of the power grid. The selection of cable model specifications does not leave too much ampacity. When the contact resistance at the line nose is too large, the first one is to continuously use the place where the heat is generated. Burnout and blowout, in turn, result in a shift in the current carrying capacity of the two cables, causing one of the cables to overheat and burn.

Another case worth mentioning is that when the multi-core armored power cable is used in parallel in the AC power grid, it is necessary to separately take out the phase A, phase B, and phase C of each cable separately from the switches A, B, and B. C Three-phase connection, it is forbidden to short-circuit all the cores of a cable and then connect one phase of the switch. Because this kind of cable is equal to the single-phase operation in the electrification, the single-phase alternating current will produce the eddy current in the steel strip to cause the cable to cause the thermal burning accident.