Main characteristics of overhead cables

High Power Supply Reliability
The use of overhead cables significantly reduces various short-circuit faults (especially flashover faults common in bare overhead conductors), with a failure rate 4-6 times lower than that of bare overhead conductors.

Domestically produced overhead cables underwent trial operation in Shanghai in 1988. The test cable ran along the densely tree-lined Huaihai Road, withstanding the typhoon season and high summer temperatures in Shanghai. It performed well, with a significantly lower power supply failure rate than the original bare overhead conductors. Overhead cables do not produce water treeing during use, and the insulation quality showed no significant decline after many years of operation.

Good Power Supply Safety
The use of overhead cables greatly reduces electric shock accidents. The Shanghai Cable Research Institute conducted a special research project on "Research and Experiment on the Insulation of Overhead Cables and Personal Safety." Tests and calculations showed that even if a hand touches the surface of the live cable insulation, the induced current is less than 0.1mA (10kV) and 0.2mA (35kV), significantly lower than the 50-100mA lethal standard stipulated in the national electrical safety regulations. It is evident that when overhead cables are energized, if a human or other animal accidentally touches the cable insulation, it will not cause harm to humans or animals as long as the cable is not punctured.

Establishment and maintenance are convenient. Overhead cables can be installed on any type of pole or tower, along walls, and even through bushes in special circumstances, directly secured to tree trunks with hardware. Single-circuit installations are possible, as are multiple circuits on the same pole, without requiring a wide "electrical corridor." Installation can be conveniently done on existing overhead lines, utilizing existing crossarms and insulators, or using a complete set of matching hardware and accessories. Special hardware can also be custom-made or manufactured according to site conditions, making construction extremely convenient. Overhead cables do not require specialized inspections and are not prone to short-circuit tripping due to flashovers from tree branches, littering by residents, or accidental collisions with crane booms, thus greatly reducing line maintenance and repair work.

Economic Efficiency

Although overhead cables are more expensive than bare overhead conductors, they are cheaper than ordinary underground cables. Therefore, while the initial investment for overhead cables is slightly higher, the operating costs, considering other factors, are significantly lower than those for bare overhead conductors. For example, using overhead cables reduces the size of the transmission corridor, and multiple lines can even share a single tower, reducing land acquisition costs. There is also no need to cut down or prune trees along the lines, saving on felling and pruning costs. Most importantly, it reduces line faults and the resulting direct and indirect losses. Therefore, its overall cost is clearly lower, more economical, and more reasonable.