1. Different systems are used. DC wires are used in rectified DC transmission systems. AC wires are often used in power frequency (domestic 50Hz) power systems.
2. Compared with the AC wire, the power loss in the transmission process of the DC wire is smaller. The power loss of the DC wire is mainly the DC resistance loss of the conductor. The insulation loss part is small.The AC resistance of low-voltage AC cables is slightly larger than the DC resistance. High-voltage cables are obvious. Mainly because of proximity effect and skin effect. The loss of insulation resistance accounts for a large proportion. Mainly the impedance created by capacitance and inductance.
3. High transmission efficiency and small line loss.
4. It is convenient to adjust the current and change the direction of power transmission.
5. Although the price of converter equipment is higher than that of transformers, the cost of using cable lines is much lower than that of AC cables. The DC cable has positive and negative poles, and the structure is simple.The AC cable is a three-phase four-wire or five-wire system. Insulation safety requirements are high, and the structure is more complex. Cables cost more than three times as much as DC cables.
6. The DC wire is safe to use.
1）the inherent characteristics of DC transmission, it is difficult to generate induced current and leakage current. There will be no electric field interference to other cables laid with the same cable.
2）The single-core laying cable will not affect the transmission performance of the cable due to the hysteresis loss of the steel structure bridge.
3）It has higher current interception capability and over-interruption protection capability than DC wires of the same structure.
4）The direct and alternating electric fields of the same voltage are applied to the insulation, and the direct electric field is much safer than the alternating electric field.
7. The installation and maintenance of the DC wires are simple and the cost is low.