Bare conductor cores can be divided according to the number of single-core cable cores, two-core, three-core, four cores, five cores, or more, then in engineering applications how to choose the number of cores it, this should be based on a detailed analysis of the appropriate. Roughly divided into the following categories.
1. Such is the bare conductor to say 1kV and below the neutral point directly to ground, the bare conductor cores three-phase circuit selection should meet the following requirements.
1.1 Protection of line and exposed conductive parts of electrical equipment that is connected to the grounding of the case.
1.1.1 The protection line and the neutral line independently when, using the five-core cable, when they meet the provisions of section 3 of this specification, the composition may also be a four-core cable with another line of protection conductors.
1.1.2 Protection and neutral conductor combination should be used in the four-core bare conductor.
1.2 Powered device exposed conductive parts of the ground and the power supply system ground separate case, four-core cable.
2. This category is 1kV and below the neutral point directly to the ground power supply, cable cores' single-phase circuit selection should meet the following requirements.
2.1 Protection of line and exposed conductive parts of electrical equipment that is connected to the grounding of the case.
2.1.1 Protection and neutral conductor same combination should be used in two-core cables.
2.1.2 To protect independent and neutral should adopt three core bare conductor, in this specification to meet the provisions of Article 3 of the case, consisting of the two-core bare conductor can also be used with additional protective wire conductors.
2.2 Powered device exposed conductive parts of the ground and the power supply system ground separate case.
The two-core bare conductor should be used.
2.3 When technical and economically reasonable, operating a current larger loop or underwater laying can be single-core cables.
2.4 DC power supply circuit should adopt the two-core cable; a single-core cable can be used when needed.
Of course, in the application of a specific selection of cores but also according to the rational use of a variety of other circumstances, this is only a basic basis. We want local conditions, as the case may be.