What Is a High Voltage Cable?

High voltage cable is a kind of power cable, which refers to the power cable used for transmission between 1kv-1000kv, and is mostly used for power transmission and distribution.

High voltage cable

NA-YJV, NB-YJV, XLPE insulated PVC sheathed A (B) fire-resistant power cables can be laid in rooms, tunnels and pipes that require fire resistance.

NA-YJV22, NB-YJV22, XLPE insulated steel tape armored PVC sheath A (B) fire-resistant power cables are suitable for laying in the ground when fire resistance is required, not suitable for laying in pipelines.

NA-VV, NB-VV, PVC insulated and PVC sheathed A (B) fire-resistant power cables can be laid in rooms, tunnels and pipes that require fire resistance.

NA-VV22, NB-VV22, PVC insulated steel tape armored PVC sheath A (B) fire-resistant power cables are suitable for laying in the ground when fire resistance is required, not suitable for laying in pipelines.

WDNA-YJY23, WDNB-YJY23, XLPE insulated steel tape armored polyolefin sheath A (B) halogen-free low-smoke fire-resistant power cable is suitable for laying in the ground when halogen-free low-smoke and fire resistance is required, not suitable Lay inside the pipeline.

ZA-YJV, ZA-YJLV, ZB-YJV, ZB-YJLV, ZC-YJV, ZC-YJLV, XLPE insulated PVC sheath A (B, C) flame-retardant power cables can be laid in the resistance Burning required indoors, tunnels and pipes.

ZA-YJV22, ZA-YJLV22, ZB-YJV22, ZB-YJLV22, ZC-YJV22, ZC-YJLV22, XLPE insulated steel tape armored PVC sheath A (B, C) flame-retardant power cables are suitable It is not suitable for laying in the pipeline if it is buried in the ground when flame retardance is required.

ZA-VV, ZA-VLV, ZB-VV, ZB-VLV, ZC-VV, ZC-VLV, PVC insulated and PVC sheathed A (B, C) flame retardant power cables can be laid on the flame retardant Required indoors, tunnels and pipes.

ZA-VV22, ZA-VLV22, ZB-VV22, ZB-VLV22, ZC-VV22, ZC-VLV22, PVC insulated steel tape armored PVC sheath A (B, C) flame-retardant power cables are suitable for It is buried in the ground when flame retardance is required, and it is not suitable for laying in the pipeline.

WDZA-YJY, WDZA-YJLY, WDZB-YJY, WDZB-YJLY, WDZC-YJY, WDZC-YJLY, XLPE insulated polyolefin sheath A (B, C) flame retardant power cable can be laid on the flame retardant And halogen-free low-smoke indoors, tunnels and pipes are required.

WDZA-YJY23, WDZA-YJLY23, WDZB-YJY23, WDZB-YJLY23, WDZC-YJY23, WDZC-YJLY23,

XLPE insulated steel tape armored polyolefin sheath A (B, C) flame retardant power cables are suitable for laying in the ground when flame retardant and halogen-free and low smoke are required, and are not suitable for laying in pipes.

VV, VLV, copper (aluminum) core PVC insulated and PVC sheathed power cables are laid in indoors, tunnels and pipes or outdoor brackets, without bearing pressure and mechanical external forces

VY, VLY, copper (aluminum) core PVC insulated polyethylene sheathed power cable

VV22, VLV22, copper (aluminum) core PVC insulated steel tape armored PVC sheathed power cables are laid indoors, in tunnels, cable trenches and directly buried soil. The cables can withstand pressure and other external forces.

VV23, VLV23, copper (aluminum) core PVC insulated steel tape armored polyethylene sheathed power cable

1.8kV and below are low voltage cables; 3.6KV ~ 35KV are medium voltage cables; 35KV ~ 110KV are high voltage cables; 110 ~ 220KV are extra high voltage cables;

UHV cable is a kind of power cable that has emerged with the continuous development of cable technology. UHV cable is generally used as a hub in large-scale power transmission systems. It belongs to a kind of high-voltage cable with high technical content and is mainly used for long-distance power transmission.

The cable is the bridge between the power supply equipment and the power consumption equipment, and it plays the role of transmitting electrical energy. The application is widely used, so the failures often occur. The following briefly analyzes the causes of common problems of high-voltage cables. The breakdown is divided into the following categories: manufacturers' manufacturing reasons, construction quality reasons, design unit design reasons, and external force damage. Four categories. ^[1]

The manufacturing reasons of manufacturers are divided into three types: cable body reasons, cable connector reasons, and cable grounding system reasons.

Reasons for the manufacture of the cable body

Generally, problems that easily occur during the production of cables include eccentric insulation, uneven thickness of the insulation shield, impurities in the insulation, protrusions inside and outside the shield, uneven cross-linking, moisture in the cable, and poor sealing of the cable's metal sheath. Serious failures may occur during the completion test or shortly after commissioning, and most of them exist in the form of defects in the cable system, causing serious hidden dangers to the long-term safe operation of the cable.

Cable joint manufacturing reasons

High-voltage cable connectors used to be wound-wrap, die-cast, and molded types, which required a large amount of on-site production work, and due to the constraints of on-site conditions and manufacturing processes, air gaps inevitably existed between the layers of the insulating tape. And impurities, so prone to problems. The types commonly used in China are assembled and prefabricated.

Cable joints are divided into cable terminal joints and cable intermediate joints. No matter what kind of joints, cable joint faults generally occur at the cable insulation shield break, because this is the place where electrical stress is concentrated, and the cable joint failure is stressful due to manufacturing reasons. Cone body manufacturing defects, insulation filler problems, sealing ring oil leakage and other reasons.

Cable grounding system

The cable grounding system includes a cable grounding box, a cable grounding protection box (with a protective layer protector), a cable cross-connect box, and a protective layer protector. Generally, the problems that easily occur are mainly due to the poor sealing of the box and the ingress of water to cause multiple points to ground, which causes the induced current of the metal sheath to be too large. In addition, the parameters of the sheath protector are unreasonable or the quality is not stable. Zinc oxide crystals are also unstable and easily cause damage to the sheath protector.

There are many examples of high-voltage cable system failures due to construction quality. The main reasons are as follows: First, the site conditions are relatively poor. The cables and connectors have high environmental and process requirements when they are manufactured in the factory. The temperature, humidity, and dust at the construction site are high. Are not easy to control. The second is that small slip marks will inevitably be left on the insulation surface during the construction of the cable. Semi-conductive particles and sand particles on the abrasive cloth may also be embedded in the insulation. In addition, the insulation will be sucked into the insulation during the construction of the connector. Moisture, these leave hidden dangers for long-term safe operation. Third, the installation did not strictly follow the process construction or process regulations and did not consider possible problems. The fourth is the completion and acceptance of the DC withstand voltage test, which causes an anti-electric field in the joint to cause insulation damage. Fifth, it was caused by poor sealing. The intermediate joint must be sealed with a metal copper shell and a PE or PVC insulation and anticorrosive coating. The lead seal must be tight during construction on site, which effectively ensures the waterproof and waterproof performance of the joint.

Cable crushing due to thermal expansion of the cable can cause breakdown. When the load of the cross-linked cable is high, the core temperature rises and the cable expands due to heat. The cable tops on the support facade at the turns in the tunnel. The long-term high-load operation of the cable has a large amount of creep force, which causes the support facade to break the cable outer sheath 2. The metal sheath, which penetrates into the cable insulation layer, leads to cable breakdown.