Skip to product information
1 of 12

PayPal, credit cards. Download editable-PDF and invoice in 1 second!

GB/T 12706.3-2020 English PDF (GBT12706.3-2020)

GB/T 12706.3-2020 English PDF (GBT12706.3-2020)

Regular price $585.00 USD
Regular price Sale price $585.00 USD
Sale Sold out
Shipping calculated at checkout.
Delivery: 3 seconds. Download true-PDF + Invoice.
Get QUOTATION in 1-minute: Click GB/T 12706.3-2020
Historical versions: GB/T 12706.3-2020
Preview True-PDF (Reload/Scroll if blank)

GB/T 12706.3-2020: Power cables with extruded insulation and their accessories for rated voltages from 1 kV (Um=1.2 kV) up to 35 kV (Um=40.5 kV) -- Part 3: Cables for rated voltages of 35 kV (Um=40.5 kV)
GB/T 12706.3-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.060.20
K 13
Replacing GB/T 12706.3-2008
Power cables with extruded insulation and their accessories
for rated voltages from 1 kV (Um = 1.2 kV) up to 35 kV (Um
= 40.5 kV) - Part 3: Cables for rated voltages of 35 kV (Um =
40.5 kV)
ISSUED ON: MARCH 31, 2020
IMPLEMENTED ON: OCTOBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 4
1 Scope ... 7
2 Normative references ... 7
3 Terms and definitions ... 10
4 Voltage designation and materials ... 11
5 Conductors ... 14
6 Insulation ... 14
7 Shield ... 15
8 Core, lining and filling of three-core cable ... 16
9 Metal layer of single-core or three-core cable ... 17
10 Metal shield ... 17
11 Concentric conductor ... 18
12 Lead sheath of the metal sheath ... 19
13 Metal armor ... 19
14 Outer sheath ... 22
15 Test conditions ... 24
16 Routine test ... 24
17 Sample test ... 26
18 Electrical type test ... 33
19 Non-electrical type test ... 37
20 Electrical tests after installation ... 50
21 Supplementary terms for cable products ... 51
Appendix A (Normative) Assumed calculation method for determining sheath
dimensions ... 52
Appendix B (Normative) Numerical rounding ... 58
Appendix C (Normative) HEPR insulation hardness measurement ... 60
Appendix D (Normative) Measurement method of semi-conducting shield resistivity
... 63
Appendix E (Normative) Water permeability test ... 66
Appendix F (Normative) Tests on cable assemblies with longitudinal metal foil
composite sheaths ... 68
Appendix G (Normative) Supplementary terms for cable products ... 71
Power cables with extruded insulation and their accessories
for rated voltages from 1 kV (Um = 1.2 kV) up to 35 kV (Um
= 40.5 kV) - Part 3: Cables for rated voltages of 35 kV (Um =
40.5 kV)
1 Scope
This Part of GB/T 12706 specifies the structure, dimensions and test requirements for
power cables with extruded insulation for a rated voltage of 35 kV fixedly mounted in
distribution networks or industrial installations.
This Part applies to cables of longitudinal water-blocking structure and their testing.
This Part does not apply to cables with special installation and operation conditions,
such as overhead cables, as well as cables used in the mining industry, in nuclear power
plants (in and near containments), and underwater or on ships.
2 Normative references
The following referenced documents are indispensable for the application of this
document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
GB/T 156, Standard voltages
GB/T 2951.11-2008, Common test methods for insulating and sheathing materials
of electric and optical cables - Part 11: Methods for general application -
Measurement of thickness and overall dimensions
GB/T 2951.12-2008, Common test methods for insulating and sheathing materials
of electric and optical cables - Part 12: Methods for general application - Thermal
ageing methods
GB/T 2951.13-2008, Common test methods for insulating and sheathing materials
of electric and optical cables - Part 13: Methods for general application -
Measurement for determining the density - Water absorption tests - Shrinkage test
GB/T 2951.14-2008, Common test methods for insulating and sheathing materials
of electric and optical cables - Part 14: Methods for general application - Test at low
temperature
IEC 60229:2007, Electric cables - Tests on extruded oversheaths with a special
protective function
IEC 61034-2, Measurement of smoke density of cables burning under defined
conditions - Part 2: Test procedure and requirements
ISO 48, Rubber, vulcanized or thermoplastic - Determination of hardness (hardness
between 10 IRHD and 100 IRHD)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 Terms related to size values
3.1.1
nominal value
A specified quantity value, which is often used in the table.
Note: In this Part, quantity values derived from nominal values are usually verified by
measurement taking into account specified tolerances.
3.1.2
approximate value
A value that is neither guaranteed nor checked.
Note: The approximate value may be used for calculations of other dimensional values.
3.1.3
median value
When several values obtained from the test are arranged in increasing (or decreasing)
order, if the number of values is an odd number, it is the middle value; if the number of
values is an even number, it is the average of the two middle values.
3.2 Terms related to testing
3.2.1
routine tests
Tests carried out by the manufacturer on all manufactured lengths of finished cables to
verify whether all cables comply with specified requirements.
3.2.2
sample tests
Tests carried out by the manufacturer at specified frequencies on finished cable samples
or on certain components taken from the finished cable to check whether the cable
complies with specified requirements.
3.2.3
type tests
Tests carried out on normal commercial principles before supply of a type of cable
covered by this Part to demonstrate that the cable has satisfactory performance under
the intended conditions of use.
Note: The characteristic of this test is that unless changes in the cable material or design
or manufacturing process may change the characteristics of the cable, there is
no need to redo the test after it has been done.
3.2.4
electrical tests after installation
Tests conducted after installation to prove that the installed cables and accessories are
intact.
4 Voltage designation and materials
4.1 Rated voltage
The rated voltage U0/U(Um) of the cables in this Part is marked as 21/35 (40.5) kV and
26/35 (40.5) kV.
In the voltage designation U0/U(Um) of the cable:
-- U0 is the rated power frequency voltage between the conductor for which the cable
is designed and earth or the metal shield;
-- U is the rated power frequency voltage between the conductors for which the cable
is designed;
-- Um is the maximum value of the “maximum system voltage” that the equipment
can use (see GB/T 156).
The rated voltage of a cable for a given application shall be appropriate for the operating
conditions of the system in which the cable is used. To facilitate cable selection, systems
are divided into the following three categories:
If the phase-separated metal shielded cable core of a cable has another overall metal
layer of the same metal material (see Chapter 9), the cable core shall be covered with a
lining on the outside. The lining and filling shall comply with 8.2. Semi-conducting
materials can also be used for the lining and filling.
When the metal materials used for the phase-separated and overall metal layers are
different, extruded isolation sleeves of any material complying with the provisions in
14.2 shall be used to separate them. For lead-sheathed cables, the isolation between the
lead sheath and the phase-separated cladding metal layer may use a lining that complies
with 8.2.
If the cable does not have an overall metal layer (see Chapter 9), the lining may be
omitted as long as the cable shape remains round.
9 Metal layer of sing...
View full details