Some points to pay attention to when using power cables in parallel
2020-09-08 09:34:18
In some industrial, mining, and chemical enterprises' new expansion and renovation projects, power cables are supplied in parallel. It is inevitable that when using power cables in parallel
In some newly expanded technical renovation projects of industrial, mining and chemical enterprises, power cables are supplied in parallel. It is inevitable that when the power cables are used in parallel, two power cables must be used. The carrying capacity of the cable must be evenly distributed, otherwise it will cause thermal breakdown failure of the cable.
Two power cables are first used in parallel. The cable models, specifications and lengths are the same. In this way, when the cables are energized and running, the various parameters of the two power cables are basically close, and the current carrying capacity is basically adjusted. Evenly, no single cable will be overloaded and large-area heating failure will occur in advance.
Secondly, the distance between cables running in parallel should be considered to be appropriately enlarged, so that when a cable fails, it will not affect the total distance between the left and right cables running in parallel. Timely waste, which to a certain extent reduces the enterprise's power economic damage.
Third, for power cables running in parallel, it is necessary to regularly check the contact and docking conditions between the two-end wire noses of the cable and the opening and closing contacts to ensure that the cables and the opening and closing are well connected. Because most of the cables used in parallel are above 35mm2, the conductor resistance per kilometer is below zero ohms, and the magnitude of the resistance is around 10-1. If the cable nose does not contact the opening and closing well, it is easy to cause a cable to be attached to the opening and closing. The contact resistance of one phase or several phases is too large, causing the current carrying capacity of the two cables to be unevenly distributed.
There is another situation worth mentioning, that is, when multi-core armored power cables are used in parallel in a switching power grid, the A-phase, B-phase, and Phase C is taken out separately and connected separately and in parallel with the three phases A, B and C of the switch. It is strictly prohibited to short-circuit all the cores of a cable and then connect them to one phase of the switch. Because the cable is running in a single-phase power supply, the single-phase variable current will generate eddy currents in the steel belt, causing the cable to burn out.
Two power cables are first used in parallel. The cable models, specifications and lengths are the same. In this way, when the cables are energized and running, the various parameters of the two power cables are basically close, and the current carrying capacity is basically adjusted. Evenly, no single cable will be overloaded and large-area heating failure will occur in advance.
Secondly, the distance between cables running in parallel should be considered to be appropriately enlarged, so that when a cable fails, it will not affect the total distance between the left and right cables running in parallel. Timely waste, which to a certain extent reduces the enterprise's power economic damage.
Third, for power cables running in parallel, it is necessary to regularly check the contact and docking conditions between the two-end wire noses of the cable and the opening and closing contacts to ensure that the cables and the opening and closing are well connected. Because most of the cables used in parallel are above 35mm2, the conductor resistance per kilometer is below zero ohms, and the magnitude of the resistance is around 10-1. If the cable nose does not contact the opening and closing well, it is easy to cause a cable to be attached to the opening and closing. The contact resistance of one phase or several phases is too large, causing the current carrying capacity of the two cables to be unevenly distributed.
There is another situation worth mentioning, that is, when multi-core armored power cables are used in parallel in a switching power grid, the A-phase, B-phase, and Phase C is taken out separately and connected separately and in parallel with the three phases A, B and C of the switch. It is strictly prohibited to short-circuit all the cores of a cable and then connect them to one phase of the switch. Because the cable is running in a single-phase power supply, the single-phase variable current will generate eddy currents in the steel belt, causing the cable to burn out.