The basic structure and purpose of power cables in Zhongtong Cable Group

The innermost part of the power cable of Zhongtong Cable Group is the core (conductor), which is surrounded by phase insulation and fillers, and then by three-phase insulation. The outer layer of the insulation is a lead sheath, and the outer layer of the lead sheath is a protective layer such as steel armor and polyvinyl chloride sheath. The structure of YJQOZ220/1 × 800 cross-linked cable from inside to outside is as follows: conductor, semiconducting tape, conductor shielding, insulation, insulation shielding, longitudinal water blocking layer, lead sheath, asphalt, PVC tape, PVC sheath, and semiconducting coating.

1. Minimum allowable bending radius of cable

The minimum bending radius of a cable is related to its diameter, and the allowable bending radius is expressed as a multiple of the cable diameter: 15 times for three core oil immersed insulated cables and 25 times for single core cables; Oil immersed paper insulated lead sheathed cables with an outer diameter of 40mm or more are 30 times, while those with an outer diameter of 40mm or less are 25 times; Rubber and plastic insulated cables are 10 times

2. What are the levels of cables classified by voltage level

According to the customary classification at home and abroad, cables are divided into low-voltage cables, medium voltage cables, high-voltage cables, and ultra-high voltage cables, that is, low-voltage cables with a voltage of 35kV or below; 35kV and above -69kV are medium voltage cables; 110-220kV is a high-voltage cable; A voltage greater than 220kV is called an ultra-high voltage cable.

3. The role of cable shielding layer and grounding wire

The shielding layer is divided into two parts: internal shielding and external shielding. They are all designed to ensure good contact between the cable conductor and the insulation layer, as well as between the cable insulation layer and the inner protective layer, and to eliminate the increase in surface electric field strength caused by the roughness of the conductor surface and inner protective layer surface. Generally, metalized paper tape or semiconductor paper tape is applied on the surface of the conductor.

The installation of grounding wires on cables is mainly to protect against insulation breakdown faults or large fault currents passing through the core. The induced voltage of the metal sheath may cause insulation breakdown, arc, and burn through of the metal sheath.

4. What is the basic structure and function of the cable outer protective layer of Zhongtong Cable Group's power cables

The outer protective layer of a cable generally consists of three parts: an inner lining layer, an armor layer, and an outer coating layer.

The inner lining layer is located between the armor layer and the inner protective layer, and its function is to prevent the inner protective layer from being corroded and to prevent the inner protective layer from being damaged by the armor layer when the cable is bent.

The function of the armor layer outside the inner lining layer is to reduce the impact of mechanical forces on the cable, so that the mechanical forces acting on the cable are borne by the armor layer.

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

So, the function of the outer protective layer of the cable is to protect the inner protective layer from external influences and mechanical damage.