Relations between sheath thickness and quality of the cable

As we all know, the product quality, advantages and disadvantages, the first characteristic is reflected from the appearance of the product quality, no matter the product or semi-finished products, must paid attention to the appearance and the quality in production, implemente strict control and inspection. Sheath is the appearance of the Flex cable, the requirement is smooth and rounded appearance, uniform luster, unbiased core shall not exceed the stipulated deviation, no mechanical damage, flattening, perception of visible without sundry, bubble, sand holes, clear grain, bamboo, twist, etc.Sheathed in addition to meet the quality requirements, quality of cable sheath thickness also has certain influence.

Sheath thickness less than standard requirement, of course is not qualified, but the thickness is beyond standard request, it also is not qualified. For example: cable type for ZR - KVVP 4 * 1.5 was, by the measured average thickness of sheath thickness of 1.6mm, this model as reference to GB9330-88 standard request, the thickness should be 1.2mm. For the unqualified reason has the following points:
(1) Reduce the service life. When Cable laying after a long time electricity, electricity will generate heat, conductor allowed working temperature is 70 ℃, polyvinyl chloride (PVC) long-term use of temperature should not exceed 65 ℃, if in the summer, the temperature will rise, the temperature will be through the outer sheath, and sheath thickness increase, the heat is difficult to send out, then it will affect the service life of the cable, because of PVC under the action of heat, has brought a series of physical and chemical changes in the insulating layer, lost the original fine performance, cause the insulation performance significantly lower, even a short circuit, affecting the normal operation of the unit.
(2) The material performance defects. Material performance is not reflected by thickness, according to the GB8815-2002 standard requirements, one of the indicators is not up to standard and flame retardant PVC material, its oxygen index is less than 30.
(3) The control cable structure exist problems. If conductor, insulation, weave density, according to the standard control, selecting the appropriate filling material make it round, how can such sheath packed so thick?
(4) Increase the difficulty of cable laying. Now give priority to with bridge or wear tube cable laying, many companies are now in a cable tight, small diameter, has space during the installation process, send out heat, guarantee the cable outer sheath is not damaged, otherwise, bring some difficulties in the construction unit and cable laying.
To sum up, the thickness of sheath shall be in accordance with the standard controls, it can not only save resources, reduce material consumption, increase profits for the enterprise, but also can ensure the quality of cable, create a high quality and low price products.