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What are the characteristics of low-voltage power cables?
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What are the characteristics of low-voltage power cables?
With the development of the economy and the large consumption of energy, the demand for cables will increase. At the same time, power cables are widely used in buildings because of their good durability, such as power cables and thermal power generation. cables, industrial cables and data transmission cables. Then you need to choose a cable with good quality and can guarantee its good quality. Let's talk about the performance characteristics of low-voltage insulated power cables.
一、Structural form of low-voltage power cables:
It consists of three parts: core, insulating layer and protective layer. The wire core is used to conduct current, and is generally formed by twisting multiple strands of copper wire or multiple strands of aluminum wire. There are several types of low-voltage cables, such as single-core, double-core, three-core, and four-core. Two-core cables are used for single-phase lines, three-core and four-core cables are used for three-phase three-wire lines and three-phase four-wire lines respectively, and single-core cables can be used for single-phase or three-phase lines as required. Commonly used low-voltage cables have core cross-sectional areas of 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240 mm, etc.
二、Features of low voltage insulated power cables:
Rated voltage: rated voltage 0.6/1KV, AC system voltage does not exceed 1.2KV
Working temperature: The long-term allowable working temperature of the cable conductor is 90°C. When short-circuited, the temperature of the cable conductor is 250°C, and the duration does not exceed 5s.
Ambient temperature: The ambient temperature for cable operation is -10°C.
Laying temperature: When installing and laying, the temperature should not be lower than 0°C.
Bending radius: Recommended Small bending: the bending radius of single-core cables does not exceed 20D, and the bending radius of multi-core cables does not exceed 15D
Unarmored cable The bending radius of the cable does not exceed 15D, and that of the armored cable does not exceed 12D
Small bend radius near connection box and terminal cables (but bends should be carefully controlled, such as using formed conduits): no more than 12D for unarmoured cables, and no more than 10D for armored cables
Laying drop: Laying is not restricted by horizontal drop.
Low-voltage power cables, common models are:
W—PVC insulated PVC sheathed (copper core) power cable; YJV-XLPE insulated PVC sheathed (copper core) power cable. If it is an (aluminum core) conductor, add L in the middle, that is, VLV and YJLV; for flame-retardant cables, add ZR in front, that is, ZR-W, ZR-YJV.
三、Laying method of low-voltage power cables:
The commonly used laying methods of low-voltage cables include direct buried laying, cable trench laying, tunnel laying and wall laying. In addition, the low-voltage cable is composed of a core, an insulating layer and a protective layer. They are mainly used to connect the cables from the distribution cabinet to the equipment side. Compared with high-voltage cables, low-voltage cables have more abundant technical structures and uses. They are both carriers for conducting electric energy and have a wide range of applications.
Cable routing:
四、Select the cable routing considering the following criteria:
(1) Avoid the cables from being subjected to mechanical external force, overheating, corrosion and other hazards;
(2) The cable laying path should be as short as possible;
(3) It is convenient for construction and maintenance;
(4) Avoid places where construction is required in planning;
(5) Try not to cross with other pipelines.