What principles should be followed in selecting power cables?（2）

What are the rated voltage levels of power cables, and how to determine them according to different places?
1. The rated voltage levels of power cables are mainly divided into the following categories:
1-1. Low-voltage cables: suitable for fixed laying on AC 50Hz, rated voltage 3kV, and below transmission and distribution lines for transmitting electric energy.
1-2. Medium and low voltage cables: generally refer to cables of 35kV and below, including polyvinyl chloride insulated cables, polyethylene insulated cables, and cross-linked polyethylene insulated cables.
1-3. High-voltage cables: generally 110kV and above, using polyethylene cables and cross-linked polyethylene insulated cables.
1-4. Ultra-high voltage cables: voltage levels between 275 and 800 kV.
1-5. UHV cables: voltage levels of 1000 kV and above.
2. When determining the rated voltage level of cables according to different places, the following factors need to be considered:
2-1. System nominal voltage: the rated voltage of the cable must be greater than or equal to the rated voltage of the network in which it operates. For example, if the nominal voltage of the system is 220/380V, the rated voltage of the cable should meet this requirement.
2-2. Maximum operating voltage: The maximum operating voltage of the cable shall not exceed 15% of its rated voltage.
2-3. Technical requirements: When selecting a cable model, the development of the cable industry and technical policies of various countries should be taken into account while meeting the technical requirements of the cable laying occasion.