Some knowledges you may need to know about power cable
March 13, 2021
1. What is the main electrical connection?
Answer: the main electrical connection is the connection mode of main electrical equipment and bus in power plant and substation, including the connection mode of main bus and auxiliary power system according to certain functional requirements
2. What regulations should be followed when selecting the section of power cable?
A: the selection of power cables should follow the following principles:
(1) The rated voltage of the cable shall be greater than or equal to the rated voltage of the power supply system at the installation point;
(2) The continuous allowable current of cable shall be equal to or greater than the maximum continuous current of power supply load;
(3) The cross section of the core should meet the stability requirements of the power supply system in case of short circuit;
(4) Check whether the voltage drop meets the requirements according to the cable length;
(5) The minimum short-circuit current at the end of the line shall enable the protection device to operate reliably.
3. What inspection work should be carried out before cable laying?
Answer: (1) the bracket should be complete and the paint should be complete.
(2) The cable model, voltage and specification meet the design requirements.
(3) The cable insulation is good. When the sealing of oil paper cable is in doubt, it should be judged to be affected with damp; the directly buried cable and small bottom cable should pass the DC withstand voltage test; the oil sample of oil filled cable should pass the test.
(4) The oil pressure of oil filled cable should not be lower than 1.47mpa.
4. Where should the orientation mark of directly buried cable be set?
Answer: at both ends of the cable, at the 50 ~ 100m straight section of the cable, the cable joint is at the bend angle where the direction of the cable changes.
5. What is the function of cable inner sheath?
A: the insulation layer will not contact with water, air or other objects to prevent the insulation from moisture and mechanical damage.
6. What are the main properties of the insulation materials of power cables?
A: it should have the following main functions:
(1) High breakdown strength;
(2) Low dielectric loss;
(3) High insulation resistance;
(4) Excellent discharge resistance;
(5) It has certain softness and mechanical strength;
(6) The insulation performance is stable for a long time.