Correct selection and application of the number of power cable cores 1. When a neutral point of 1 kV or less is directly earthed, the number of cable cores in the three-phase circuit should meet the following requirements:
1.1 The condition of the exposed conductive ground of the protection line and the powered device is:
(1) When the same conductor is used for the protection line and the neutral line, a four-core cable should be used.
(2) When the protection line and the neutral line are independent, it is preferable to use a five-core cable; when the provisions of Article 5.1.16 of this specification are satisfied, a four-core cable and another protection line conductor may also be used.
1.2 The four-core cable should be used when the ground of the exposed conductive part of the powered device and the power system ground are independent of each other.
2. When the neutral point of 1kV or below is directly earthed, the number of single-phase circuit cable cores should meet the following requirements:
2.1 The condition of the exposed conductive ground of the protection line and the powered device is:
(1) When the same conductor is used for the protection line and the neutral line, a two-core cable should be used.
(2) When the protection line and the neutral line are independent, three-core cables should be used; in the case of satisfying the provisions of Article 5.1.16 of this code, two-core cables and other protection line conductors can also be used.
2.2 Two-core cable should be used when the ground of the exposed conductive parts of the powered device and the grounding of the power supply system are independent of each other.
3. When the circuit with large operating current or underwater laying is used, single-core cables can be used when the technical and economical conditions are reasonable.
4. Except for the stipulations of Articles 1, 2 and 3 of this code, the three-core cable should be used for the AC power supply circuit.
5, DC power supply circuit, should adopt two-core cable; when necessary, single-core cable can be used.
1.1 The condition of the exposed conductive ground of the protection line and the powered device is:
(1) When the same conductor is used for the protection line and the neutral line, a four-core cable should be used.
(2) When the protection line and the neutral line are independent, it is preferable to use a five-core cable; when the provisions of Article 5.1.16 of this specification are satisfied, a four-core cable and another protection line conductor may also be used.
1.2 The four-core cable should be used when the ground of the exposed conductive part of the powered device and the power system ground are independent of each other.
2. When the neutral point of 1kV or below is directly earthed, the number of single-phase circuit cable cores should meet the following requirements:
2.1 The condition of the exposed conductive ground of the protection line and the powered device is:
(1) When the same conductor is used for the protection line and the neutral line, a two-core cable should be used.
(2) When the protection line and the neutral line are independent, three-core cables should be used; in the case of satisfying the provisions of Article 5.1.16 of this code, two-core cables and other protection line conductors can also be used.
2.2 Two-core cable should be used when the ground of the exposed conductive parts of the powered device and the grounding of the power supply system are independent of each other.
3. When the circuit with large operating current or underwater laying is used, single-core cables can be used when the technical and economical conditions are reasonable.
4. Except for the stipulations of Articles 1, 2 and 3 of this code, the three-core cable should be used for the AC power supply circuit.
5, DC power supply circuit, should adopt two-core cable; when necessary, single-core cable can be used.
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