Full name of VV cable PVC insulated PVC sheathed power cable (copper core)
YJLV cable full name XLPE insulated PVC sheathed aluminum core power cable
VLV cable full name PVC insulated PVC sheathed aluminum core power cable
Due to the excellent conductivity of copper conductor, more and more projects use copper core power cable as the main road of power supply system, while aluminum core power cable is less used, especially in the higher voltage power system, more copper core cables are selected.
structure
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High voltage cable
The components of high-voltage cable from inside to outside include: conductor, insulation, inner sheath, filler (armor) and outer insulation.Of course, the armored high-voltage cable is mainly used for burial, which can resist the high-strength compression on the ground and prevent other external force damage.
Model and purpose
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NA-YJV，NB-YJV，XLPE insulated PVC sheathed Class A (B) fire-resistant power cables can be laid indoors, in tunnels and in pipes with fire resistance requirements.
NA-YJV22，NB-YJV22，Cross linked polyethylene insulated steel tape armored PVC sheathed Class A (B) fire-resistant power cable is suitable for buried laying when fire-resistant requirements exist, not suitable for laying in pipes.
NA-VV，NB-VV，PVC insulated PVC sheathed Class A (B) fire-resistant power cables can be laid indoors, in tunnels and in pipes with fire resistance requirements.
NA-VV22，NB-VV22，PVC insulated steel tape armored PVC sheathed Class A (B) fire-resistant power cable is suitable for buried laying when fire-resistant requirements exist, not suitable for laying in pipes.
WDNA-YJY23，WDNB-YJY23，Cross linked polyethyleneInsulating steel tape armored polyolefin sheath Class A (B) halogen-free low smokeFire resistant power cableIt is suitable for buried laying when halogen-free low smoke and fire resistance are required, not suitable for laying in pipelines.
ZA-YJV，ZA-YJLV，ZB-YJV，ZB-YJLV，ZC-YJV，ZC-YJLV，Cross linked polyethyleneinsulationpolyvinyl chlorideSheathed Class A (B, C) flame-retardant power cables can be laid indoors, in tunnels and in pipes with flame retardant requirements.
ZA-YJV22，ZA-YJLV22，ZB-YJV22，ZB-YJLV22，ZC-YJV22，ZC-YJLV22，Cross linked polyethylene insulated steel tape armored PVC sheathed Class A (B, C) flame-retardant power cables are suitable for buried laying when flame-retardant requirements exist, not for laying in pipelines.
ZA-VV，ZA-VLV，ZB-VV，ZB-VLV，ZC-VV，ZC-VLV，PVC insulated PVC sheathed Class A (B, C) flame-retardant power cables can be laid indoors, in tunnels and in pipes with flame retardant requirements.
ZA-VV22，ZA-VLV22，ZB-VV22，ZB-VLV22，ZC-VV22，ZC-VLV22，PVC insulated steel tape armored PVC sheathed Class A (B, C) flame-retardant power cables are suitable for buried laying when required for flame-retardant, not suitable for laying in pipes.
WDZA-YJY，WDZA-YJLY，WDZB-YJY，WDZB-YJLY，WDZC-YJY，WDZC-YJLY，Cross linked polyethyleneInsulated polyolefin sheathed Class A (B, C) flame-retardant power cables can be laid indoors, in tunnels and in pipelines that have requirements for flame-retardant, halogen-free and low smoke.
Cross linked polyethyleneInsulated steel tape armored polyolefin sheathed Class A (B, C) flame-retardant power cables are suitable for buried laying when flame retardant and halogen-free low smoke are required, not suitable for laying in pipelines.
VV、VLV，Copper (aluminum) corepolyvinyl chlorideInsulated PVC sheathed power cables are laid indoors, in tunnels and pipelines or on outdoor brackets without bearing pressure and mechanical external forces
VY、VLY ，Copper (aluminum) core PVC insulated polyethylene sheathed power cable
VV22、VLV22 ，Copper (aluminum) corepolyvinyl chlorideInsulated steel tape armored PVC sheathed power cable is laid indoors, in tunnels, cable trenches and directly buried soil, and the cable can withstand pressure and other external forces
This product is suitable for power supply, transmission and distribution with AC rated voltage of 35KV and below. The maximum long-term working temperature of cable conductor is 90 degrees. In case of short circuit (the maximum time is not more than 5S), the maximum temperature of cable conductor is not more than 250 degrees.
UHV cable
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1.8kV and below are low-voltage cables;3.6KV~35KV are medium voltage cables;35KV~110KV are high-voltage cables;110~220KV are UHV cables;
UHV cable is a kind of power cable with the continuous development of cable technology. As the backbone link in large transmission systems, UHV cable is a kind of high-voltage cable with high technical content, which is mainly used for long-distance power transmission.
Cause of fault
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High voltage cable
Cable is the bridge between power supply equipment and electrical equipment, which plays the role of transmitting electric energy.It is widely used, so faults often occur. The following is a brief analysis of the causes of common problems of high-voltage cables. According to the causes of faults, they can be roughly divided into the following four categories: manufacturer's manufacturing reasons, construction quality reasons, design unit's design reasons, and external force damage.[1]
Manufacturer's manufacturing reason
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The manufacturer's manufacturing reasons can be divided into three categories according to the location of occurrence: cable body reasons, cable joint reasons, and cable grounding system reasons.
Reason for cable body manufacturing
In general, the problems that are easy to occur in the cable production process include eccentric insulation, uneven thickness of insulation shield, impurities in the insulation, protrusions of internal and external shields, uneven degree of cross-linking, cable moisture, poor sealing of cable metal sheath, etc. Some serious cases may occur in the completion test or shortly after commissioning, and most of them exist in the form of defects in the cable system,It will cause serious hidden dangers for long-term safe operation of cables.
High voltage cable connectorIn the past, there was a large amount of work to be done on site with winding, mold casting, molding and other types. Due to the limitation of site conditions and production process, there will inevitably be air gaps and impurities between the layers of insulating tape, so problems are prone to occur.Assembly type and prefabricated type are widely used in China.
Cable connectorIt is divided into cable terminal joint and cable intermediate joint. No matter what joint form, cable joint failure generally occurs at the cable insulation shield fracture, because this is the part where electrical stress is concentrated. The causes of cable joint failure due to manufacturing reasons include manufacturing defects of the stress cone body, insulation filler problems, sealing ring oil leakage and other reasons.
Cable grounding system
The cable grounding system includesCable grounding box, cable grounding protection box (with sheath protector), cable cross connection box, sheath protector and other parts.Generally, the problem that is easy to occur is mainly due to poor sealing of the box body and water ingress, which leads to multi-point grounding and excessive induced current of the metal sheath.In addition, unreasonable selection of sheath protector parameters or unstable zinc oxide crystals with poor quality are also likely to cause sheath protector damage.
Construction quality reasons
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There are many cases of HV cable system failure caused by construction quality, and the main reasons are as follows: First, the site conditions are relatively poor, the environment and process requirements for cable and connector manufacturing in the factory are very high, and the temperature, humidity and dust at the construction site are not well controlled.Second, it is inevitable that small slip marks will be left on the insulation surface during cable construction. Semi conductive particles and sand particles on the sand cloth may also be embedded in the insulation. In addition, due to the insulation being exposed to the air during joint construction, moisture will also be sucked into the insulation, which will leave hidden dangers for long-term safe operation.Third, the installation did not strictly follow the process construction or the process regulations did not take into account the possible problems.Fourth, completion acceptanceDC withstand voltage testThis will cause the formation of counter electric field in the joint and lead to insulation damage.The fifth is due to poor sealing treatment.The intermediate joint must adopt the sealing structure of metal copper shell plus PE or PVC insulation anti-corrosion layer to ensure the density of lead seal in the field construction, so as to effectively ensure the sealing and waterproof performance of the joint.
Design reasons
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The cable is crushed due to thermal expansion, resulting in breakdown.When the load of the cross-linked cable is high, the core temperature rises, and the cable is heated and expanded. At the corner of the tunnel, the cable top is on the elevation of the support. Long term heavy load operation has a great creeping force of the cable, which causes the elevation of the support to crush the outer sheath and metal sheath of the cable, and squeeze into the cable insulation layer, causing cable breakdown.
