Main features of overhead cables

1. High power supply reliability

The use of overhead cables can greatly reduce all kinds of short circuit faults (especially flashover faults common in overhead bare wires), and the failure rate is 4-6 times lower than that of overhead bare wires.[2]

Domestic overhead cables were put into trial operation in Shanghai in 1988. The test of overhead cables was conducted along the dense forest avenue of huaihai road. It passed the test of typhoon season and high temperature in summer in Shanghai area and ran well.Aerial cable will not produce water tree in use. After years of operation, the insulation quality of the cable does not decrease significantly.

2. Good power supply safety

The use of overhead cables greatly reduces the number of electric shock casualties [3].Shanghai cable research institute has set up a special subject, "overhead cable insulation on personal safety research and test".The test and calculation show that: namely, when touching the insulation surface of live cable with hands, the induced current is less than 0.1mA(10kV) and 0.2mA(35kV), which is much lower than the standard of 50-100ma death stipulated by the national electrical safety regulations.It can be seen that when the overhead cable is energized, when the human body or other animals accidentally touch the cable insulation surface, as long as the cable is not broken down, it will not cause harm to human and animal.

3. Easy erection and maintenance

Overhead cables can be set up on any kind of pole tower, along the wall, or, in special cases, through the trees, directly fixed to the poles with metal.It can be set up in a single circuit or multiple circuits on the same pole without requiring a wide "electrical corridor".In the installation can be erected on the original overhead line, the use of the original cross arm and porcelain bottles, but also can use a full set of supporting hardware and accessories.Can also be based on the actual situation of the site, please manufacturers special or homemade some special hardware, so the construction is very convenient.Overhead cables also do not need to carry out special inspection inspection, and will not be because of branches flashover and residents littering debris, or crane boom collision and so on and the formation of short circuit trip accident, which greatly reduces the maintenance and maintenance of the line.

4. Reasonable economy

Although overhead cables are more expensive than bare overhead wires, they are cheaper than regular underground cables.Therefore, although the one-time investment of overhead cable is slightly higher, combined with other factors, its operating cost will be significantly lower than that of overhead bare wire.If the overhead cable is used to narrow the corridor of the line, or even more than one tower is Shared by the line, the cost of land acquisition and occupation is reduced. In operation, there is no need to cut or trim offline trees, which saves the cost of cutting and trimming. The most important thing is to reduce the direct or indirect losses caused by line faults.Therefore, its comprehensive cost is obviously lower, more economical and more reasonable.