HVDC (High Voltage Direct Current) Cable

It can be installed in tunnels or pipelines and can withstand certain pressure. The cable has good longitudinal and radial waterproof performance.

1、 Product execution standards

1. GB/T 11017.1-2014 Cross linked polyethylene insulated power cables and their accessories with rated voltage of 110kV (Um=126kV) - Part 1: Test methods and requirements

2. GB/T 11017.2-2014 Cross linked polyethylene insulated power cables and their accessories with rated voltage of 110kV (Um=126kV) - Part 2: Cables

3. IEC 60840-2011 Test methods and requirements for extruded insulated power cables and their accessories with rated voltage above 30kV (Um=36kV) to 150kV (Um=170kV)

2、 Cable structure

1. Conductor 5, Buffer Barrier Layer

2. Internal shielding 6, metal sheath

3. Insulation 7, outer sheath

4. External shielding

3、 Product Features

1. Usage conditions

Rated voltage: U/U0 (Um)=64/110 (126) kV

Conductor cross-sectional area (mm ²): 240-1600

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

The maximum allowable long-term working temperature for cable conductors is 90 ℃;

Maximum operating temperature of cable during short circuit (up to 5s): 250 ℃

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

2. Structural requirements

1) Conductor

The conductor is made of twisted copper or aluminum wire, with a cross-sectional area of 800mm2 or less using layer by layer compression method. The conductor has good roundness and high compression coefficient. The use of segmented conductors for conductor cross-sections of 1000mm2 and above effectively reduces the skin effect of the conductor and improves the current carrying capacity of the cable. For segmented conductors, our company produces conductors with a maximum cross-section of 3000mm2. Water absorbing and expanding materials can be twisted into the conductor to achieve longitudinal water resistance along the conductor.

2) Insulation

Conductor shielding, insulation, and insulation shielding are extruded simultaneously using VCV tower with three layers. The vertical cross-linking workshop of the company is 129 meters high and is equipped with three vertical cross-linking production lines, which are imported from Maillefer in Finland and TROESTER in Germany. All three production lines are equipped with front and rear preheating systems, which can effectively remove moisture inside the conductors and make insulation heating more uniform. The production line is equipped with German Sikora online deflectors to control insulation eccentricity within the minimum range. The online stress relief system can effectively reduce residual stress inside the insulated wire core, further improving the electrical and mechanical performance of the cable. All three production lines adopt fully dry crosslinking 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 generated under high temperature and high voltage conditions. To accelerate the release of cross-linking by-products, the cross-linked wire core needs to enter the insulation wire core constant temperature drying room for degassing treatment before entering the next production process. Accelerating gas discharge effectively reduces the possibility of accidents during cable laying and operation.

4) Vertical water blocking layer and buffer layer

In order to buffer the thermal expansion of cable insulation during operation and achieve cable waterproofing, there is a buffer water barrier layer between the insulation shield and the metal sleeve. The company uses a semiconductor buffer water barrier tape with excellent expansion buffering performance to wrap around the insulation. The conductivity of the semiconductor water barrier tape is uniform, and there is a margin between the metal sleeve 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 production process of the company's metal sleeves includes two forms: extruded aluminum sleeves and welded aluminum sleeves, which can be produced according to the needs of users. Aluminum sleeves can meet the requirements of cable short-circuit capacity, and have the characteristics of light weight, high strength, easy bending, and excellent waterproof performance. The aluminum sleeve is coated with cable asphalt or hot melt adhesive as a corrosion-resistant layer.

6) Outer sheath

The outer sheath is made of PE or PVC, and materials such as flame retardant, anti termite, low smoke and low halogen flame retardant, low smoke and halogen-free flame retardant can also be provided according to customer requirements. Simultaneously extrude a semiconductive layer on the outer sheath as an electrode for the outer sheath withstand voltage test.

4、 Cable model, name, and installation location

Conductor material code

The second type of copper conductor - (T) omitted; Aluminum Conductor-L

Insulation material code

YJ cross-linked polyethylene insulation

Sheath material code

02 PVC sheath; 03- Polyethylene sheath; Q-lead sleeve; Wrinkled aluminum sleeve LW; Metal plastic composite sleeve-A;

Code for water blocking structure

Longitudinal water blocking structure-Z