Service characteristics and operating conditions of insulated overhead cables: 1. Service characteristics and operating conditions of insulated overhead cables 2. The crosslinking polyethylene insulation overhead cable core maximum working temperature of
Sheath thickness below the standard requirements of course is unqualified, but the thickness exceeds the standard requirements, but also unqualified. For example: cable model ZR-KVVP 4 * 2.5mm2, measured thickness of the sheath thickness of 1.6mm, this model as reference to GB9330-88 standard requirements, the thickness should be 1.2mm. The reasons for their failure are the following:
(1) to reduce the service life. After the cable laying, will be a long time power, power will produce heat, the conductor allows the working temperature of 70 ℃, PVC long-term use temperature should not exceed 65 ℃, if in summer, the working temperature will rise, these temperatures will be outside The thickness of the sheath is increased and the heat energy is difficult to be distributed. It will affect the service life of the cable.
(2) material performance defects. Material performance is not reflected by the thickness, in accordance with GB8815-2002 standard requirements,
That one of its indicators is not up to standard, flame retardant PVC material, then its oxygen index is less than 30.
(3) cable structure problems. If the conductor, insulation, weaving density, in accordance with the standard requirements of control, select the appropriate filler to make it round.