The reason of high voltage cable faults

The reason of high voltage cable faults：

According to causes of fault:manufacturing reasons, quality of construction, design reasons, external damage.

1.manufacturing reasons

1.) Cable ontology：

Generally，problems happening in the cable manufacturing process are insulation eccentricity, uneven thickness of the insulating shield, insulating impurities, both inside and outside the shield protuberance, the degree of crosslinking is uneven, cable damp,and poor sealing cable metal sheath.

2.) Cable connector：

High voltage cable connector used wrapping, molded and Molding type etc, needing big workload of field fabrication, and because of restrictions of site conditions and the production process, inevitably there will be an air gap and impurities between the insulation tape layer, so prone to problems. The reason due to manufacturing faults cause the cable connector body have stress cone manufacturing defects, insulation fillers problem, seals oil spills and other reasons.

3.) Cable grounding system:

Ground systems include cable grounding cable boxes, cable grounding protection box (with a protective layer of protection), cable crossover interconnection boxes, protective layer of protection, and other parts. Generally prone to problems mainly because of poor box sealed lead to multi-point ground water, causing the metal sheath induced current is too large. Another parameter selection sheath protector unreasonable or poor quality zinc oxide crystals can easily lead to instability protective sheath damage.

2.Construction quality reason

First, the relatively poor field conditions, cables and connectors in the factory manufacturing environment and process requirements are high, and the construction site of temperature, humidity, dust is not well controlled.

Second, the construction process in the cable insulating surface will inevitably leave a small slip marks, abrasive grains and semi-conductive particles may also be embedded on the insulation, the additional joint construction process due to exposure to air insulation, the insulation will also suction water, which gave the long-term safe operation of the stay hidden.

Third, when the installation is not in strict accordance with the provisions of the construction process or process does not take into account the problems that may arise.

Fourth, the completion and acceptance of the use of DC voltage test result leads to the formation of the joint anti-electric insulation damage. Fifth, due to mismanagement led to seal the deal.

3.Design reason:

Cable because the cable thermal expansion caused by crushing cause breakdown. XLPE cable load is high, core temperature, thermal expansion of the cable, the cable bend in the tunnel at the top of the bracket facade, long-term high-load operation cable squirm with great force, causing the stent facade crush the cable sheath metal sheath, squeeze the cable insulation cause cable breakdown.

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