Causes of common problems with high voltage cables (1)
A cable is a bridge between a power supply device and a powered device, and functions to transmit electrical energy. Widely used, so faults often occur. The following is a brief analysis of the causes of common problems of YJV high-voltage cables. The classification according to the causes of faults can be roughly divided into the following categories: manufacturer manufacturing reasons, construction quality reasons, design unit design reasons, external forces. Destroy four major categories.
First, manufacturers manufacture reasons
The manufacturing reasons of the manufacturer are divided into three categories: the cause of the cable body, the cause of the cable connector, and the cause of the cable grounding system.
1. Causes of cable body manufacturing
Generally, the problems that are easy to occur in the cable production process are insulation eccentricity, uneven thickness of the insulation shield, impurities in the insulation, protrusions in the inner and outer shields, uneven cross-linking degree, moisture in the cable, poor sealing of the cable metal sheath, etc. It is serious that failure may occur in the completion test or shortly after the operation, and most of them are in the form of defects in the cable system, which poses a serious hidden danger to the long-term safe operation of the cable.
2, cable connector manufacturing reasons
High-voltage cable joints used in the past, such as wrapping, molding, molding, etc., require a lot of work on site, and because of the limitations of the field conditions and the manufacturing process, there will inevitably be air gaps between the layers of the insulation. And impurities, so problems are easy to occur. Types commonly used in the country are assembled and prefabricated.
Cable connectors are divided into cable terminations and cable intermediate connectors. Regardless of the connector type, cable connector failures generally appear at the cable insulation shield breaks. This is because the electrical stress is concentrated. The cause of the cable joint failure is stress due to manufacturing reasons. Cone body manufacturing defects, insulation filler problems, seal oil leakage and other reasons.
3, cable grounding system
The high-voltage cable grounding system includes a cable grounding box, a cable grounding protection box (with a sheath protector), a cable cross-connect box, and a sheath protector. The problem that is generally prone to occur is mainly because the tank is not well sealed and the water is caused to cause multiple points of grounding, causing the metal sheath to induce excessive current. In addition, the parameters of the sheath protector are unreasonable or the quality is not good. The instability of the zinc oxide crystal is also likely to cause damage to the sheath protector.