The difference between overhead lines and power cable lines

Overhead lines: They usually has no insulation, bare metal conductor, set up in the air to insulator string fixed on the tower, the air for the insulation. Key advantages: Low cost The disadvantage is the occupation of land resources (line corridor) more, affecting the city appearance.
Power cable: the use of insulating media will be insulated from the outside world, laying on the ground or underground. The main advantages, laying more convenient, less land occupied, does not affect the city city. The disadvantage is that the cost is too high. In terms of safety, the current line that, due to material and manufacturing processes and other reasons, overhead line safety is better than the power cable, the failure rate is far lower than the power cable. In addition, there is a “pipe insulated bus”, is between the conductor and metal shell filled with SF6 gas (or other) as an insulating medium.