QWhat tests and inspections should be carried out on power cables before laying?ABefore laying, check whether the type, specification and length of the cable meet the requirements and whether there is external force damage. Low-voltage cables use a 1000V megohmmeter to remotely measure the insulation resistance, and the resistance is generally not less than 10MΩ. High-voltage cables use a 2500V megger to measure the resistance. Generally not less than 400MΩ.
QWhat are the factors that determine the long-term allowable current carrying capacity of the cable?A(1) The long-term allowable working temperature of the cable;
(2) The heat dissipation performance of the cable itself;
(3) The condition of the cable installation and the heat dissipation conditions of the surrounding environment.
QAccording to the difference of insulation and protective layer, what are the main types of commonly used low-voltage power cables?A(1)Oil-impregnated paper insulated lead-clad (or aluminum-clad) power cable;
(2)Non-drip oil-impregnated paper insulated power cable
(3)PVC insulated and sheathed power cable;
(4)Cross-linked PVC insulated and PE sheathed power cable;
(5)Cross-linked PVC insulated and sheathed power cable;
(6) Rubber insulated power cables.
QWhat’s the application of stranded or solid conductor Cu/PVC cable?AFor copper core, suitable for the fixed laying of power devices of 450/750V and below, widely used in electromechanical engineering. For aluminum core, due to its light weight, is usually used for overhead lines, especially long-distance transmission lines.
QWhat is the function of the cable inner sheath?AKeep the insulating layer in contact with water, air or other objects to prevent moisture and the insulating layer from mechanical and physical damage.
QWhat is the function of the cable outer sheath?AProtect the inner sheath from mechanical damage and chemical corrosion, and enhance mechanical strength.