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GB/T 31489.4-2020 (GBT31489.4-2020)

GB/T 31489.4-2020_English: PDF (GBT 31489.4-2020, GBT31489.4-2020)
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GB/T 31489.4-2020English350 Add to Cart 0--9 seconds. Auto-delivery D. C. extruded cables systems for power transmission at a rated voltage up to and including 500 kV--Part 4: Accessories for D. C. cables Valid GB/T 31489.4-2020

BASIC DATA
Standard ID GB/T 31489.4-2020 (GB/T31489.4-2020)
Description (Translated English) D. C. extruded cables systems for power transmission at a rated voltage up to and including 500 kV--Part 4: Accessories for D. C. cables
Sector / Industry National Standard (Recommended)
Classification of Chinese Standard K13
Classification of International Standard 29.060.20
Word Count Estimation 19,161
Date of Issue 2020-12-14
Date of Implementation 2021-07-01
Quoted Standard GB/T 311.1-2012; GB/T 1527; GB/T 2900.10-2013; GB/T 2951.21-2008; GB/T 3048.8; GB/T 3048.12; GB/T 3048.13; GB/T 3048.14; GB/T 4423; GB/T 4909.3; GB/T 8287.1; GB/T 11017.1-2014; GB/T 12464; GB/T 16927.1; GB/T 20878; GB/T 21429; GB/T 23752; GB/T 26218.1
Drafting Organization Shanghai National Cable Testing Center Co., Ltd.
Administrative Organization National Wire and Cable Standardization Technical Committee
Regulation (derived from) National Standard Announcement No. 28 of 2020
Proposing organization China Electrical Equipment Industry Association
Issuing agency(ies) State Administration for Market Regulation, National Standardization Administration
Summary This standard specifies the use characteristics, product naming, technical requirements, accessory markings, accessory tests, acceptance rules, packaging, transportation and storage of cross-linked polyethylene insulated power cable accessories for DC transmission with a rated voltage of 500 kV and below. This standard applies to the terminals and joints of XLPE insulated DC land cables and DC submarine cables for DC transmission with a rated voltage of 500 kV and below.

Standards related to: GB/T 31489.4-2020

GB/T 31489.4-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.060.20
K 13
D.C. Extruded Cables Systems for Power Transmission at a
Rated Voltage up to and Including 500 kV - Part 4:
Accessories for D.C. Cables
ISSUED ON: DECEMBER 14, 2020
IMPLEMENTED ON: JULY 1, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Terms, Definitions and Symbols ... 6
4 Service Characteristics ... 7
5 Product Naming ... 8
6 Technical Requirements ... 10
7 Marking of Accessories ... 15
8 Tests of Accessories ... 15
9 Acceptance Inspection Rules ... 19
10 Packaging, transportation and Storage ... 20
Appendix A (informative) Properties of Silicone Oil ... 21
Appendix B (normative) Test Requirements and Methods ... 22
Bibliography ... 24
D.C. Extruded Cables Systems for Power Transmission at a
Rated Voltage up to and Including 500 kV - Part 4:
Accessories for D.C. Cables
1 Scope
This Part of GB/T 31489 specifies the service characteristics, product naming, technical
requirements, accessories marking, accessories test, acceptance inspection rules, packaging,
transportation and storage of XLPE insulated power cable accessories for power transmission
at a rated voltage up to and including 500 kV.
This Part is applicable to the terminations and joints of XLPE insulated DC land cables and DC
submarine cables for power transmission at a rated voltage up to and including 500 kV.
2 Normative References
The following documents are indispensable to the application of this document. In terms of
references with a specified date, only versions with a specified date are applicable to this
document. In terms of references without a specified date, the latest version (including all the
modifications) is applicable to this document.
GB/T 311.1-2012 Insulation Co-ordination - Part 1: Definitions, Principles and Rules
GB/T 1527 Drawn Tube of Copper and Copper Alloys
GB/T 2900.10-2013 Electrotechnical Terminology - Electric Cables
GB/T 2951.21-2008 Common Test Methods for Insulating and Sheathing Materials of Electric
and Optical Cables - Part 21: Methods Specific to Elastomeric Compounds - Ozone Resistance,
Hot Set and Mineral Oil Immersion Tests
GB/T 3048.8 Test Methods for Electrical Properties of Electric Cables and Wires - Part 8: AC
Voltage Test
GB/T 3048.12 Test Methods for Electrical Properties of Electric Cables and Wires - Part 12:
Partial Discharge Test
GB/T 3048.13 Test Methods for Electrical Properties of Electric Cables and Wires - Part 13:
Impulse Voltage Test
GB/T 3048.14 Test Methods for Electrical Properties of Electric Cables and Wires - Part 14:
DC Voltage Test
GB/T 4423 Copper and Copper Alloy Cold-drawn Rod and Bar
GB/T 4909.3 Test Methods for Bare Wires - Part 3: Tensile Test
GB/T 8287.1 Indoor and Outdoor Post Insulators for Systems with Nominal Voltage greater
than 1,000 V - Part 1: Test on Insulators of Ceramic Material or Glass
GB/T 11017.1-2014 Power Cables with Cross-linked Polyethylene Insulation and Their
Accessories for Rated Voltage of 110 kV (Um = 126 kV) - Part 1: Test Methods and
Requirements
GB/T 12464 Wooden Boxes
GB/T 16927.1 High-voltage Test Techniques - Part 1: General Definitions and Test
Requirements
GB/T 20878 Stainless and Heat-resisting Steels - Designation and Chemical Composition
GB/T 21429 Composite Insulators - Hollow Insulators for Use in Outdoor and Indoor Electrical
Equipment - Definitions, Test Methods, Acceptance Criteria and Design Recommendations
GB/T 23752 Hollow Pressurized and Unpressurized Ceramic and Glass Insulators for Use in
Electrical Equipment with Rated Voltages greater than 1,000 V
GB/T 26218.1 Selection and Dimensioning of High-voltage Insulators Intended for Use in
Polluted Conditions - Part 1: Definitions, Information and General Principles
GB/T 31489.1-2015 D.C. Extruded Cable Systems for Power Transmission at a Rated Voltage
up to and Including 500 kV - Part 1: Test Methods and Requirements
GB/T 31489.2-2020 D.C. Extruded Cable Systems for Power Transmission at a Rated Voltage
up to and Including 500 kV - Part 2: D.C. Land Cables
GB/T 31489.3-2020 D.C. Extruded Cable Systems for Power Transmission at a Rated Voltage
up to and Including 500 kV - Part 3: D.C. Submarine Cables
YD/T 814.3 Closure for Optical Fiber Cables - Part 3: Closure for Shallow Water Submarine
Optical Fiber Cables
YD/T 814.5 Closure for Optical Fiber Cables - Part 5: Closure for Deep Water Submarine
Optical Fiber Cables
IEC 60840:2020 Power Cables with Extruded Insulation and Their Accessories for Rated
Voltages above 30 kV (Um = 36 kV) up to 150 kV (Um = 170 kV) - Test Methods and
Requirements
IEC 62067:2011 Power Cables with Extruded Insulation and Their Accessories for Rated
Voltages above 150 kV (Um = 170 kV) up to 500 kV (Um = 550 kV) - Test Methods and
The following symbols are applicable to this document.
U0: the rated DC voltage between the conductor and the shield for which the cable system is
designed.
UP2,S: when the operating impulse voltage has the same polarity as the actual DC voltage, 1.15
times the maximum absolute peak value of the operating impulse voltage that the cable system
may withstand.
UP2,O: when the operating impulse voltage is opposite in polarity to the actual DC voltage, 1.15
times the maximum absolute peak value of the operating impulse voltage that the cable system
may withstand.
UP1: when the lightning impulse voltage is opposite in polarity to the actual DC voltage, 1.15
times the maximum absolute peak value of the lightning impulse voltage that the cable system
may withstand.
4 Service Characteristics
4.1 Rated Voltage and Operating Temperature
The land cable accessories shall comply with the stipulations of Chapter 4 in GB/T 31489.2-
2020; the submarine cable accessories shall comply with the stipulations of Chapter 4 in GB/T
31489.3-2020.
4.2 Environmental Conditions (applicable to outdoor termination)
4.2.1 Temperature and altitude
4.2.1.1 Normal operating conditions
The normal operating conditions are as follows:
a) The maximum air temperature of the surrounding environment does not exceed 40 C;
b) The altitude of the installation site does not exceed 1,000 m.
4.2.1.2 Temperature correction of test voltage value
For equipment where the air temperature of the surrounding environment is higher than 40 C,
the test voltage of the outer insulation in a dry state shall be multiplied by the temperature
correction factor Kt, as shown in Formula (1).
Where,
Kt---the temperature correction factor;
The conductor connecting rod shall be made of copper material conforming to GB/T 4423, and
shall be annealed.
The conductor connecting pipe shall be made of copper material conforming to GB/T 1527.
The copper content of the crimp-type conductor connecting pipe shall not be lower than 99.90%,
and shall be annealed.
The connecting terminals shall be made of copper or copper alloy with good electrical
conductivity. See IEC/TR 62271-301 or user requirements for the dimensions.
NOTE: aluminum connection fittings are under consideration.
The surface of the conductor connecting rod and the conductor connecting pipe shall be smooth
and clean, and there shall be no damages, burrs, concave-convex marks and other defects
affecting electrical contact and mechanical strength. For cast-molded terminals, the contact
surface and connection holes shall not have defects like air holes, sand holes and slag inclusions,
etc.
The specifications of the conductor connecting rod and the conductor connecting pipe shall be
not smaller than the cross-sectional area of the cable conductor. The mechanical strength of the
conductor connecting rod and the conductor connecting pipe shall satisfy the requirements of
installation and operating conditions.
When required, the conductor connecting rod and conductor connecting pipe may be tested as
specified in 8.2.4.7, so as to demonstrate that their performance satisfies the requirements.
6.2 Structural Fittings
The structural fittings of the accessories include metal shells, flanges, bushings and surrounding
brackets, etc., and should be made of non-magnetic metal materials.
The matching surface of the spring pressing device shall be smooth and free of protrusions, and
shall be closely matched with the rubber stress cone, so as to provide the specified pressure
within the design life.
All sealing fittings shall have good assembly tightness and fitness, and there shall be no defects
that may cause leakage after assembly, such as: scratches and dents, etc.
6.3 Sealing Rings
The sealing rings for the accessories shall be compatible with the surrounding insulating
medium, and can be used for a long time under a rated load.
6.4 Rubber Stress Cones and Prefabricated Rubber Insulation Pieces
The properties of the insulating materials and semi-conductive materials used for the rubber
stress cones and prefabricated rubber insulation pieces shall satisfy the requirements of use.
The rubber stress cones and prefabricated rubber insulation pieces shall be free of air bubbles,
burns and other detrimental impurities; the inner and outer surfaces shall be smooth, and
without scars, cracks or protrusions. The interface between the insulation and the semi-
conductive shield shall be well bonded, and without cracks or peeling; there shall be no
detrimental impurities in the semi-conductive shield.
The dimensions and specifications of the prefabricated rubber insulation pieces shall be adapted
to the outer diameter of the main insulation of the cable.
The electrical conductivity characteristics of the insulating materials used for the prefabricated
rubber insulation pieces and the main insulating materials of the cables shall match.
6.5 Epoxy Prefabricated Pieces and Epoxy Bushings
The epoxy prefabricated pieces and epoxy bushings shall be free of detrimental impurities and
pores; the inner and outer surfaces shall be smooth and free of defects. The insulator and the
embedded metal parts shall be well bonded, and without cracks, deformations or other abnormal
phenomena.
When applicable, the insulators used for the disconnection of metal sheath of sectionalizing
joints shall be able to withstand the DC voltage test and lightning impulse voltage test in
Appendix H of IEC 60840:2020 or Appendix G of IEC 62067:2011.
6.6 Porcelain Bushings and Composite Bushings
Porcelain bushings and composite bushings shall be selected in accordance with the creepage
distance of the outer insulation of the termination. The creepage distance of the outer insulation
shall satisfy the user’s requirements. Porcelain bushings shall comply with the requirements of
GB/T 23752. Composite bushings shall comply with the requirements of GB/T 21429.
6.7 Post Insulators
Post insulators shall comply with the requirements of GB/T 8287.1.
6.8 Liquid Insulating Fillers
Liquid insulating fillers shall be compatible with the insulating materials and structural
materials that they are in contact with.
For ethylene-propylene rubber stress cones, vacuum-degassed silicone oil should be adopted as
the liquid insulating filler. See Appendix A for the properties of the silicone oil.
If the stress cone is made of silicone rubber, then, a suitable liquid insulating filler shall be
adopted.
6.9 Waterproof Pouring Agents
The pouring agents shall have good waterproof and sealing performance, and no harmful effect
accordance with 8.2.2.1; for molded submarine cable repair joints, the routine test cannot be
carried out, instead, sampling test shall be carried out in accordance with 8.2.3, so as to control
the quality level of the repair joints.
8.2.3 Sampling test
The sampling test of submarine cable factory joints shall be carried out in accordance with the
stipulations of 9.2 in GB/T 31489.1-2015. See the test requirements and methods in Table B.1.
The sampling test of repair joints and terminations shall be carried out in accordance with the
stipulations of 9.3 in GB/T 31489.1-2015.
The sampling test of field molded joints shall be carried out in accordance with the stipulations
of 9.4 in GB/T 31489.1-2015.
8.2.4 Type test
8.2.4.1 Overview
The accessories shall be subject to the type test as part of the cable system. The test requirements
and methods are shown in Table B.2.
The factory joints, together with the submarine cable specimens, shall be subject to the coiling
test and tension bending test specified in 6.4.3.2 in GB/T 31489.1-2015, then, the electrical type
test in accordance with the stipulations of 6.4.4 ~ 6.4.6 in GB/T 31489.1-2015.
The other types of joints and terminations shall be subject to the electrical type test in
accordance with the stipulations of 6.4.4 ~ 6.4.6 in GB/T 31489.1-2015.
The type test and requirements of the accessories shall comply with the stipulations of Chapter
6 in GB/T 31489.1-2015. In addition, the following items shall also be tested:
a) Sealing test after assembly of accessories (see 8.2.4.2);
b) Tensile test of conductor joints of factory joints (see 8.2.4.3);
c) Insulation micropores, impurities and semi-conductive shielding layer, and insulating
layer interface micropores and protrusion test of factory joints (see 8.2.4.4);
d) DC voltage test for outdoor terminations exposed to rain (if applicable, see 8.2.4.5);
e) The outer protective layer test for joints (if applicable, see 8.2.4.6);
f) Thermomechanical properties test of conductor crimps and mechanical connections,
when required (see 8.2.4.7).
8.2.4.2 Sealing test after assembly of accessories
8.2.4.2.1 Installation of specimens
The termination specimen shall be assembled in accordance with the installation requirements
in actual application, and the assembled specimens may not contain insulating pieces.
The test device shall seal the two ends of the specimens of sealing fittings, porcelain bushings,
composite bushings or epoxy bushings.
In accordance with the applicable situation, one of the methods specified in 8.2.4.2.2 or
8.2.4.2.3 can be selected for the test.
The accessories or bushings subject to external pressure shall be tested in accordance with the
method specified in 8.2.4.2.3.
8.2.4.2.2 Pressure leakage test
One of the following methods can be adopted to carry out the test:
---Method 1: at ambient temperature, apply an air pressure with a gauge pressure of (250
 10) kPa to the specimen and maintain it for 1 h. The test product subject to the air
pressure shall have explosion-proof safety measures. Carry out either water immersion
test or soap liquid applying test on the sealing surface to observe whether there is gas
escape.
---Method 2: apply the same water pressure and maintain it for 1 h. On the sealing surface,
apply chalk powder and observe for signs of water seepage.
During the test, there shall be no signs of air leakage or water seepage.
8.2.4.2.3 Vacuum leakage test
At ambient temperature, vacuumize the specimen, until the residual pressure A is 10 kPa of air
pressure, then, close the vacuum valve between the specimen and the vacuum pump and
maintain for 1 h. Afterwards, measure the pressure value B of the specimen, and calculate the
vacuum pressure leak gain (B  A). At the end of the test, the vacuum pressure leak gain (B 
A) shall not exceed 10 kPa.
8.2.4.3 Tensile test of conductor joints of factory joints
The conductor joint tensile test of factory joints shall be carried out in accordance with the
stipulations of GB/T 4909.3. The test results shall comply with the requirements of 9.2.6 in
GB/T 31489.1-2015.
8.2.4.4 Insulation micropores, impurities and semi-conductive shielding layer, and
insulating layer interface micropores and protrusion test of factory joints
The factory joints shall be subject to the insulation micropores, impurities and semi-conductive
shielding layer, and insulating layer interface micropores and protrusion test in accordance with
the stipulations of Appendix H in GB/T 11017.1-2014. The test results shall comply with the
requirements of 6.3.4 in GB/T 31489.1-2015.
8.2.4.5 DC voltage test for outdoor terminations exposed to rain
When required by the user, the DC voltage test for outdoor terminations exposed to rain shall
be carried out. The outdoor terminations shall be exposed to rain, and a DC voltage of 1.85U0
shall be applied for 1 min. The rain condition shall comply with the stipulations of GB/T
16927.1, and the specimens shall not manifest any break down or flashover.
8.2.4.6 Outer protective layer test for joints
The outer protective layer test for joints shall be carried out in accordance with the stipulations
of 6.3.10 in GB/T 31489.1-2015.
8.2.4.7 Recommended tests for conductor primps and mechanical connections
The conductor primps and mechanical connections shall be subject to electrical thermal cycle
tests and mechanical tests. The test methods and requirements are under consideration.
8.2.5 Type test for systems composed by accessories and cables
The type test for the cable systems including accessories shall be carried out in accordance with
the stipulations of Chapter 6 in GB/T 31489.1-2015.
8.2.6 Pre-qualification test for systems composed by accessories and cables
The accessories shall form a system with the corresponding cables. The pre-qualification test
items shall comply with the stipulations of Chapter 7 in GB/T 31489.1-2015. See the test
requirements and methods in Table B.2.
9 Acceptance Inspection Rules
The manufacturer shall carry out the development test, routine test, sampling test, type test and
(or) pre-qualification test in accordance with the test methods specified in Chapter 8. The
frequency and requirements of the sampling test shall comply with the stipulations of 9.2, 9.3
and 9.4 in GB/T 31489.1-2015. For the same accessory structure, if the rated voltage in 4.1 is
adjusted, then, all electrical tests shall be carried out on the basis of the adjusted higher voltage,
and the test report obtained is also valid for the lower rated voltage before the adjustment. For
accessories with a voltage level below 100 kV, with the agreement of both the supply-side and
the demand-side, corresponding tests may also be carried out with reference to this Part.
The type test and pre-qualification test shall be carried out by an independent testing institution
or the manufacturer in accordance with the requirements of Chapter 8, and shall comply with
the requirements.
The product shall pass the inspection by the quality inspection department of the manufacturer
before exiting the factory. Upon request of the purchaser, the manufacturer shall provide the
relevant test reports of the product.
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