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What is the difference between DC cable&AC cable?

January 18, 2022

1. The systems used are different. DC cables are used in rectified DC transmission systems, and AC cables are often used in power frequency (domestic 50Hz) power systems.
2. Compared with the AC cable, the power loss in the transmission process of the DC cable is smaller. The power loss of the DC cable is mainly the DC resistance loss of the conductor, and the insulation loss is small (the size depends on the current fluctuation after rectification); while the AC resistance of the low-voltage AC cable is slightly larger than the DC resistance, and the high-voltage cable is obvious, mainly because Proximity effect and skin effect, the loss of insulation resistance accounts for a large proportion, mainly the impedance generated 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 three-phase four-wire or five-wire system, which requires high insulation safety and complex structure, and the cable cost is more than three times that of the DC cable.
6. DC cables are safe to use
1) Due to the inherent characteristics of DC transmission, it is difficult to generate induced current and leakage current, and it will not cause electric field interference to other cables laid in the same way.
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 cables of the same structure.
4) 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 cable are simple and the cost is low.