A BRIEF INTRODUCTION OF ELECTRIC CABLE

The history of electric cable using is long, but people knows it a little, so I’ll introduce some basic knowledge of electric cable below.

About Electrical Cables
Power cables are cables used to transmit and distribute electric energy. Power cables are commonly used in urban underground power grids, power station outgoing lines, power supply in industrial and mining enterprises and underwater power transmission lines across rivers and seas. In power lines, the proportion of cables is gradually increasing. Power cables are cable products used to transmit and distribute high-power electric energy in the trunk lines of power systems, including 1-500KV and above various voltage levels and various insulated power cables.

Cable Application
The use of power cables has a long history of more than 100 years. In 1879, American inventor t a Edison wrapped jute around a copper rod and put it into an iron pipe, then filled it with asphalt mixture to make a cable. He laid the cable in New York and initiated underground power transmission. The following year, British Calende invented asphalt impregnated paper insulated power cables. In 1889, British s z Ferrand laid a 10kv oil-immersed paper insulated cable between London and Detford. In 1908, Britain completed a 20 kV cable network. Power cables are being used more and more widely. In 1911, Germany laid 60 kV high-voltage cables and began the development of high-voltage cables. In 1913, German M. Hochstadt developed a phase-shielded cable, which improved the distribution of electric field inside the cable and eliminated the tangential stress on the insulating surface, thus becoming a milestone in the development of power cables. In 1952, Sweden laid 380 kV UHV cables in the northern power plant, realizing the application of UHV cables. By the 1980s, 1,100 kV and 1,200 kV UHV power cables had been produced.

Cable Classification
(1) Low-voltage Cable
It is suitable for fixed laying on power transmission and distribution lines with AC 50Hz and rated voltage of 3kv and below for power transmission.
(2) Medium and Low Voltage Cables (Generally 35KV and Below)
PVC insulated cables, polyethylene insulated cables, crosslinked polyethylene insulated cables, etc.
(3) High Voltage Cables (Generally 110KV and Above)
Polyethylene cables and crosslinked polyethylene insulated cables, etc.
(4) UHV Cable (275 ~ 800 kV)
(5) UHV Cables (1000 kV and Above)

Cable Selection Guide
(1) Selection of Wire and Cable Models

When selecting wires and cables, the purpose, laying conditions and safety shall be considered. According to different purposes, power cables, overhead insulated cables and control cables may be selected. According to the different laying conditions, general plastic insulated cables, steel tape armored cables, steel wire armored cables, anti-corrosion cables, etc. can be selected. According to safety requirements, flame-retardant cables, halogen-free flame-retardant cables and fire-resistant cables can be selected.

(2) Selection of Wire and Cable Specifications

When determining the usage specifications (conductor section) of wires and cables, conditions such as heating, voltage loss, economic current density, mechanical strength, etc. shall be considered. According to experience, the low-voltage power line usually selects the section according to the heating condition because of its large load current, and then checks its voltage loss and mechanical strength. Low-voltage lighting line has higher requirements for voltage level, so the section can be selected according to the allowable voltage loss condition before checking the heating condition and mechanical strength. For high-voltage lines, first select the section according to the economic current density, and then check the heating conditions and allowable voltage loss. The mechanical strength of high-voltage overhead lines should also be checked. If users have no experience, they should consult the relevant professional organizations or people.

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