The first feature of product quality is the appearance quality of the product. Regardless of the product or semi-finished product, the appearance quality must be paid attention to in the production, and strict control and inspection shall be carried out on it. The sheath is the appearance of the cable. Its appearance requirements are smooth and round, uniform gloss, not eccentric (not exceeding the specified deviation), no mechanical damage, flattening, no visible debris, air bubbles, sand holes, obvious particles, and bamboo Nodal shape, twist shape, etc. In addition to meeting the above quality requirements, the thickness of the sheath also has a certain impact on the quality of the cable.
The thickness of the sheath is lower than the standard requirement, of course it is unqualified, but the thickness exceeds the standard requirement, it is also unqualified.
For example: the cable model is ZR-KVVP 4*1.5mm2, and the measured thickness of the sheath has an average thickness of 1.6mm. For this model, the thickness should be 1.2mm according to the GB9330-88 standard. The reasons for the unqualified judgment are as follows:
(1) Reduce the service life. After the cable is laid, it will be energized for a long time, which will generate heat energy. The allowable working temperature of the conductor is 70¡æ. The long-term use temperature of polyvinyl chloride should not exceed 65¡æ. If in summer, the working temperature will rise, and these temperatures will pass outside. When the sheath is emitted, the thickness of the sheath increases, and the heat energy is difficult to dissipate, which will affect the service life of the cable. Due to the heat of PVC, the insulation layer will undergo a series of physical and chemical changes, which will lose its original excellent performance. , Resulting in a significant decrease in insulation performance, and even a short circuit, affecting the normal operation of the unit.
(2) Material performance defects. The performance of the material is not reflected by the thickness. According to the requirements of the GB8815-2002 standard, one of its indicators does not meet the standard, and the flame-retardant PVC material has an oxygen index lower than 30.
(3) There is a problem with the cable structure. If the conductor, insulation layer, and braid density are controlled in accordance with the standard requirements, and appropriate filling materials are selected to make them round, how can the sheath be so thick?
(4) Increase the difficulty of cable laying. Nowadays, cable laying is mainly based on bridges or pipes. Now many companies are implementing tight cable requirements and small outer diameters. There can be gaps during the laying process and heat can be dissipated to ensure that the outer sheath of the cable is not damaged. Otherwise, give the construction unit And cable laying brings certain difficulties.
The thickness of the sheath is lower than the standard requirement, of course it is unqualified, but the thickness exceeds the standard requirement, it is also unqualified.
For example: the cable model is ZR-KVVP 4*1.5mm2, and the measured thickness of the sheath has an average thickness of 1.6mm. For this model, the thickness should be 1.2mm according to the GB9330-88 standard. The reasons for the unqualified judgment are as follows:
(1) Reduce the service life. After the cable is laid, it will be energized for a long time, which will generate heat energy. The allowable working temperature of the conductor is 70¡æ. The long-term use temperature of polyvinyl chloride should not exceed 65¡æ. If in summer, the working temperature will rise, and these temperatures will pass outside. When the sheath is emitted, the thickness of the sheath increases, and the heat energy is difficult to dissipate, which will affect the service life of the cable. Due to the heat of PVC, the insulation layer will undergo a series of physical and chemical changes, which will lose its original excellent performance. , Resulting in a significant decrease in insulation performance, and even a short circuit, affecting the normal operation of the unit.
(2) Material performance defects. The performance of the material is not reflected by the thickness. According to the requirements of the GB8815-2002 standard, one of its indicators does not meet the standard, and the flame-retardant PVC material has an oxygen index lower than 30.
(3) There is a problem with the cable structure. If the conductor, insulation layer, and braid density are controlled in accordance with the standard requirements, and appropriate filling materials are selected to make them round, how can the sheath be so thick?
(4) Increase the difficulty of cable laying. Nowadays, cable laying is mainly based on bridges or pipes. Now many companies are implementing tight cable requirements and small outer diameters. There can be gaps during the laying process and heat can be dissipated to ensure that the outer sheath of the cable is not damaged. Otherwise, give the construction unit And cable laying brings certain difficulties.
