500kV cross-linked polyethylene insulated power cable

500kV cross-linked polyethylene insulated power cable

The 220kV cross-linked polyethylene insulated power cable     produced by Shandong Yanggu Cable Group is suitable for 110k V high-voltage and ultra-high-voltage transmission and distribution lines. It can be laid in tunnels or pipelines and can withstand a certain amount of pressure. The cable has good longitudinal and radial waterproof properties.

1. Product execution standards

1. GB/T  22078.1-20 08 Cross-linked polyethylene insulated power cables and accessories with rated voltage 500kV (Um=550kV) Part 1: Test methods and requirements

2. GB/T  22078.2-20 08 Cross-linked polyethylene insulated power cables and accessories with rated voltage 500kV (Um=550kV) Part  2 : Cables

3. IEC  62067-2011 Test methods and requirements for power cables with rated voltages above 150kV (Um=170 kV) to 500kV (Um=550kV) extruded insulation and accessories

2. Cable structure

1. Conductor             5. Buffering water blocking layer

2. Inner shield           6. Metal sheath

3. Insulation             7. Outer sheath

4. External shielding

3. Product characteristics

1. Conditions of use

Rated voltage: U/U 0 ( U m ) =290/500 (550) kV

Conductor cross-sectional area ( mm²): 800-2500

Temperature 24 hours before laying PVC sheathed cable : ≥0℃;

 The maximum allowable long-term operating temperature of cable conductors: 90°C;

 Maximum operating temperature of the cable during short circuit (maximum 5s): 250℃

 Minimum allowable bending radius of cable: 20D. Note: D is the actual outer diameter of the cable.

2. Structural requirements

1)  Conductor

    The conductor is made of twisted copper wire or aluminum wire. The conductor cross-section is 800mm2 and is pressed layer by layer. The conductor has good roundness and high compression coefficient. Split conductors are used for conductor cross-sections of 1000mm2 and above, which effectively reduces the skin effect of the conductor and increases the carrying capacity of the cable. For split conductors, our company produces conductors with a maximum cross-section of 3000mm2. Water-absorbing swelling material can be twisted into the conductor to achieve longitudinal water blocking along the conductor.

2)  Insulation

    Conductor shielding, insulation, and insulation shielding are made of three layers of VCV vertical towers extruded simultaneously. The company's vertical cross-linking workshop is 129m high. It is equipped with three vertical cross-linking production lines. The three production lines were imported from Maillefer of Finland and TROESTER of Germany. All three production lines are equipped with front and rear preheating systems, which can effectively remove moisture in conductors and make insulation heating more uniform. The production lines are all equipped with German Sikora online deflection meters to control insulation eccentricity within the minimum range. The online stress relief system can effectively reduce the residual stress inside the insulated core and further improve the electrical and mechanical properties of the cable. All three production lines adopt fully dry cross-linking and cooling methods.

3)  Insulation degassing

    Due to the thick insulation thickness of high-voltage and ultra-high-voltage cross-linked polyethylene insulated power cables, cross-linking by-products will be produced under cross-linking conditions of high temperature and high pressure. In order to speed up the release of cross-linking by-products, the cross-linked wire core must be placed before entering the next production process. Enter the insulated wire core constant temperature drying room for degassing treatment. Accelerating gas discharge effectively reduces the possibility of accidents during cable laying and operation.

4)  Longitudinal water blocking layer and buffer layer

    In order to buffer the thermal expansion of the cable insulation during operation and achieve waterproofing of the cable, there is a buffering and water-blocking layer between the insulation shield and the metal sheath. The company uses semi-conductive buffering and water-blocking tape with excellent expansion buffering performance to wrap around the insulation. The conductivity of the resistive water tape is uniform, and there is a margin between the metal sheath and the buffer layer that can absorb the expansion of the cable core under cyclic load and short-circuit temperature rise.

5)  Wrinkled aluminum sleeve

The company's metal sleeve production processes include extruded aluminum sleeves and welded aluminum sleeves, which can be produced according to user needs. The aluminum sleeve can meet the cable short-circuit capacity requirements, is light in weight, strong in strength, easy to bend, and has excellent waterproof performance. There is cable asphalt or hot melt adhesive on the outside of the aluminum sleeve as an anti-corrosion layer.

6)  Outer sheath

The outer sheath is PE or PVC, and flame retardant, termite-proof, low-smoke low-halogen flame-retardant, low-smoke halogen-free flame retardant and other materials can also be provided according to customer requirements. A semi-conductive layer is extruded on the outer sheath at the same time to serve as an electrode for the outer sheath voltage test.

4. Cable model, name, laying occasion

Product feature code    YJ- cross-linked polyethylene insulated cable

Material code

Type 2 copper conductor - (T) omitted

02- Polyvinyl chloride sheath; 03-Polyethylene sheath ;  Q-Lead sheath; Wrinkled aluminum sheath-LW;

Water blocking structure code

Longitudinal water blocking structure -Z