GB/T 18890.3-2015Power cables with cross-linked polyethylene insulation and their accessories for rated voltage of 220 kV (Um=252 kV) - Part 3: Accessories (English PDF)

4.1 Rated voltage and conductor operating temperature

The rated voltage, maximum operating temperature and short-circuit temperature of the accessories during normal operation are consistent with the provisions for cables in

Chapter 4 of GB/T 18890.2-2015.

4.2 Environmental conditions (for outdoor termination)

4.2.1 Standard reference atmospheric pressure conditions

The standard reference atmospheric pressure conditions are:

-- temperature, t 0 = 20 °C;

-- pressure, p0 = 101.3 kPa;

-- absolute humidity, h0 = 11 g/m

3

.

The test voltages specified in this Part are all values under standard reference atmospheric pressure conditions.

4.2.2 Normal service conditions

The test voltages specified in this Part are applicable to equipment operating under the following service conditions.

a) The maximum ambient air temperature does not exceed 40 °C;

b) The altitude of the installation site does not exceed 1 000 m.

4.2.3 Temperature correction of test voltage value

For equipment where the ambient air temperature is higher than 40 °C, the test voltage of the external insulation in the dry state shall be the test voltage value specified in this

Part multiplied by the temperature correction factor KT. The temperature correction factor is calculated as formular (1):

Where:

T – ambient air temperature, in degrees Celsius (°C).

4.2.4 Altitude correction of test voltage value

The dielectric strength of the external insulation of outdoor termination used at altitudes above 1 000 m but not exceeding 4 000 m shall be corrected for altitude. The correction method is shown in Appendix B of GB 311.1-2012. For outdoor termination installed and used at an altitude higher than 1 000 m but not exceeding 4 000 m, when tested at an altitude not higher than 1 000 m, the test voltage shall be the test voltage specified in this Part multiplied by the altitude correction factor Ka [calculated as shown in

Formula (2)], and the insulation level of the external insulation of the outdoor termination shall be increased accordingly.

Where:

H – the altitude of the outdoor termination installation location, in meters (m).

4.2.5 Pollution environment

The external insulation environment classification, pollution type and site pollution severity (SPS) grade shall comply with GB/T 26218.1-2010.

4.2.6 Special environmental conditions

Equipment designed for use in special environmental conditions, such as earthquakes, hurricanes, icing and other abnormal conditions, may require certain specific tests. See

GB/T 21429-2008, GB/T 23752-2009 and GB/T 4109-2008. This Part does not provide for these tests.

4.3 Pressure on gas-immersed termination for GIS

The design pressure (relative pressure) of the SF6 gas surrounding the external insulation of the gas-immersed termination for GIS is 0.75 MPa at 20 °C, and the minimum functional pressure shall not exceed 0.25 MPa (relative pressure). The rated inflation pressure of GIS shall not be lower than its minimum functional pressure.

When the GIS enclosure to which the cables are connected is evacuated as part of the

SF6 filling process, the cable terminals shall withstand vacuum conditions (see IEC

62271-209:2007).

4.4 Termination installation angle

The termination shall generally be installed vertically. If the angle between the axis of the terminal and the vertical line exceeds 30°, the bending resistance load specified in

GB/T 4109-2008 shall be met. This requirement does not apply to gas-immersed termination for GIS and transformer termination.

4.5 System category

The system categories for which the accessories included in this Part are applicable are consistent with the requirements of 4.1 of GB/T 18890.2-2015.

5.1 Code

5.1.1 Series code

Cables with cross-linked polyethylene insulation ········································· YJ

5.1.2 Accessories code

(Outdoor) termination with porcelain insulator ··········································· ZW (Outdoor) termination with composite insulator ······································· ZWF

Gas-immersed termination for GIS ························································ ZG

Oil-immersed (transformer) termination ·················································· ZY

Straight joint ··················································································· JT

Sectionalizing joint ············································································· JJ

5.1.3 Internal insulation code

5.1.3.1 Termination internal insulation characteristics

Liquid-filled insulation ········································································ Y

Dry insulation ··················································································· G

Sulfur hexafluoride (SF6) gas-filled insulation ············································· Q

5.1.3.2 Joint internal insulation characteristics

The specifications of accessories shall be compatible with the cross-section of the matching cable conductor.

The specifications of gas-immersed termination for GIS and oil-immersed (transformer) termination shall be compatible with the rated voltage and rated current of their supporting equipment.

5.4 Product representation method

Products are indicated by model, specifications (rated voltage, number of phases, applicable cable cross-section) and standard number.

Example 1: Liquid-filled insulated termination with porcelain insulator for power cables with cross-linked polyethylene insulation, of nominal conductor cross-sectional area 1 000 mm

2 , rated voltage 127/220 kV, external insulation pollution severity c, is expressed as: YJZWY2 127/220 1×1000 GB/T 18890.3-2015.

Example 2: Dry insulated gas-immersed termination for GIS for power cables with cross-linked polyethylene insulation, of nominal conductor cross-sectional area 630 mm

2 , rated voltage 127/220 kV, is expressed as: YJZGG 127/220 1×630 GB/T 18890.3-

2015.

Example 3: One piece pre-molded sectionalizing joint for power cables with cross- linked polyethylene insulation, of nominal conductor cross-sectional area 1 600 mm

2 , rated voltage 127/220 kV, with insulated copper shell protection box, is expressed as:

YJJJI2 127/220 1×1600 GB/T 18890.3-2015.

6.1 Conductor connection fittings

Conductor connecting rods shall be made of copper materials that comply with GB/T

4423-2007.

Conductor connecting tubes shall be made of copper materials that comply with GB/T

1527-2006. The copper content of the crimped conductor connecting tube shall not be less than 99.90% and it shall be annealed.

The termination terminals shall be made of copper or copper alloy with good conductivity, and their dimensions shall comply with IEC/TR 62271-301:2009 or user requirements.

The surface of the conductor connection fittings shall be smooth and clean, and free of damage, burrs, concave-convex marks or other defects that affect electrical contact and mechanical strength. The contact surface and connection holes of the cast terminals shall not have defects such as air holes, sandish holes and slag inclusions.

The specifications of the connection fittings shall not be smaller than the cross-section of the cable conductor. The mechanical strength of the connection fittings shall meet the requirements of installation and operation conditions.

When required, conductor connecting rods and conductor connecting tubes may be subjected to the tests specified in 8.4.2 to demonstrate that their performance meets the requirements.

6.2 Structural fittings

Accessory structural fittings (metal shell, flange, sleeve, surrounding bracket, etc.) shall be made of non-magnetic metal materials.

The mating surface of the spring compression device shall be smooth and free of protrusions, and shall fit tightly with the rubber stress cone to provide the specified design pressure within the design life.

All sealing fittings shall have good assembly sealing and fit, and shall not have defects that may cause subsequent leakage, such as scratches, dents, etc. The sealing performance shall comply with the test requirements specified in 8.4.1.

6.3 Sealing ring and semi-conductive rubber belt

The sealing rings used for accessories shall be compatible with the surrounding media and be able to maintain their functionality for a long time under rated load.

The semi-conductive rubber belt used for shielding shall be cross-linked. Its properties are shown in Appendix A.

6.4 Rubber stress cones and prefabricated rubber insulation parts

For the properties of insulating materials and semi-conductive materials used in rubber stress cones and prefabricated rubber insulating parts, refer to GB/T 20779.2-2007 (not applicable to the artificial weathering and tracking resistance tests).

Rubber stress cones and prefabricated rubber insulation parts shall be free of bubbles, burnt materials and other harmful impurities, and the inner and outer surfaces shall be smooth without scars, cracks and protrusions. The interface between insulation and semi-conductivity shall be well bonded, without cracks or peeling, and there shall be no harmful impurities in the semi-conductive shield.

The dimensions of the rubber insulation shall be compatible with the outer diameter of the cable's main insulation.

6.5 Epoxy prefabricated parts and epoxy casings

For the properties of cured epoxy resin, refer to Appendix B.

22381-2008. Other matching dimensions may also be used when the termination manufacturer and the GIS switch manufacturer agree.

The supplier boundaries between terminal manufacturers and GIS switch manufacturers can be found in Figures 2 and 4 of IEC 62271-209:2007 or Tables A.1 and A.3 of GB/T

22381-2008.

Gas-immersed termination for GIS shall adopt a structure that prevents SF 6 gas from entering the terminal and the cable.

6.12 Accessory products

Accessory products and their main components shall comply with the requirements of

Chapters 7 and 8.

7.1 Product marking

Each cable accessory product shipped out of the factory shall have a clear durability marking, the content of which is as follows:

a) Name of manufacturer;

b) Model and specifications;

c) Rated voltage, kV;

d) Production date and serial number.

7.2 Marking of parts

Parts such as joint protection boxes and prefabricated rubber insulation parts shall be marked with the manufacturer's name, model and specifications in an appropriate manner.

8.1 General

The tests are divided into routine test (code-named R), sample test (code-named S), type test (code-named T), additional test (code-named A) and pre-qualification test (code-named PQ).

The test conditions shall comply with the requirements of Chapter 8 of GB/T 18890.1-

2015.

8.2 Routine test of accessory parts

Routine test of prefabricated rubber insulation parts for accessories shall include the following items:

a) Sealing test of sealing fittings;

b) Partial discharge test of prefabricated rubber insulation parts (see 9.2 of GB/T

18890.1-2015);

c) Voltage test of prefabricated rubber insulation parts (see 9.3 of GB/T 18890.1-

2015).

Prefabricated rubber insulation parts include stress cones or integrally prefabricated composite stress control insulation parts.

The sealing test of sealing fittings may be carried out using one of the methods specified in 8.4.1.1 or 8.4.1.2 according to the applicable conditions. Other tests shall be carried out in accordance with Chapter 9 of GB/T 18890.1-2015 and meet the requirements.

Note: With the consent of the manufacturer and the buyer, the sealing test of the sealing fittings may be carried out using a leak detector or other methods.

8.3 Sample test of accessories

The sample test of accessories shall be carried out in accordance with Chapter 11 of

GB/T 18890.1-2015 and meet the requirements.

8.4 Type test of accessories

The type tests and requirements of accessories shall comply with Chapter 12 and

Chapter 15 of GB/T 18890.1-2015. In addition, the following tests shall be carried out:

a) Sealing test after terminal assembly (see 8.4.1);

b) Thermomechanical performance test of conductor crimps and mechanical connectors, if required by the buyer (see 8.4.2);

c) Additional test: outdoor termination rain power frequency voltage test, if required by the buyer (see 8.4.3).

The accessories under test shall be assembled in accordance with the installation instructions provided by the manufacturer and using the specified grade and quantity of materials (including lubricants) provided by the manufacturer. See Appendix D for general installation instructions.

The dimensions of the connection enclosure used in the electrical type test of gas- immersed termination for GIS shall comply with Figure 3 or Figure 5 of IEC 62271-

209:2007. The size of the connection enclosure used in the electrical type test of the