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The innermost part of the power cable is the core (conductor). The outer core of the core is phase insulation and filler. The outside is the three-phase package insulation. The outer package is the lead package. The outer layer of the lead package is the protective layer such as steel and concrete. PVC sheath. For example, the structure of YJQOZ220/1×800 cross-linked cable is from conductor to conductor, semi-conductive tape, conductor shield, insulation, insulation shield, longitudinal water-blocking layer, lead sleeve, asphalt, PVC belt, PVC sheath and Semi-conductive coating.

 

1. Allowable value of minimum bending radius of cable

 

The minimum bending radius of the cable is related to its diameter. The allowable value of the bending radius is expressed by a factor not less than the diameter of the cable: 15 times for the three-core oil-immersed insulated cable and 25 times for the single-core; the oil-impregnated paper-insulated lead-clad cable is 40 mm outside. The above is 30 times, the following is 25 times; rubber and plastic insulated cables are 10 times

 

2, according to the voltage level, what are the grades of the cable

 

According to the habits of domestic and foreign habits, the cables are divided into low-voltage cables, medium-voltage cables, high-voltage cables and ultra-high-voltage cables, that is, low-voltage cables with voltages of 35kV and below; medium-voltage cables of 35kV to 69kV; and high-voltage cables of 110-220kV; More than 220kV is called ultra high voltage cable.

 

3. The role of cable shielding layer and grounding wire

 

The shielding layer is divided into two parts: inner shielding and outer shielding. They are all designed to make the cable conductor and the insulation layer, the cable insulation layer and the inner sheath have good contact, and to eliminate the increase of the surface electric field strength caused by the surface of the conductor surface and the inner sheath layer being unsmooth, generally on the surface of the conductor. Metalized tape or semiconductor tape.

The cable is installed with a grounding wire, mainly to protect the cable from the insulation breakdown or the large fault current in the core. The induced voltage of the metal sheath may cause the insulation to break down, causing an arc and causing the metal sheath to burn through.

 

4. The basic structure of the power cable What is the structure and function of the outer sheath of the cable?

 

The outer sheath of the cable generally consists of an inner liner layer, an armor layer and an outer layer.

 

The inner liner is located between the armor layer and the inner sheath to prevent corrosion of the inner sheath and prevent the inner sheath from being damaged by the armor layer when the cable is bent.

 

The armor layer is outside the inner liner and its function is to reduce the influence of mechanical force on the cable, so that the mechanical force acting on the cable is absorbed by the armor layer.

 

The outer layer is outside the armor layer and its function is to prevent the armor layer from being eroded.

 

Therefore, the role of the outer sheath of the cable is to protect the inner sheath from external influences and mechanical damage.