GB/T 311.11-2025Insulation co-ordination - Part 11: Definitions, principles and rules for HVDC system (English PDF)
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Issued by
State Administration for Market Regulation, China National Standardization Administration
Level / Type
National · Recommended
Issue date
June 30, 2025
Implementation date
January 1, 2026
Scope
GB/T 311.11-2025 (Insulation co-ordination - Part 11: Definitions, principles and rules for HVDC system) is available as an English-translated PDF.
GB/T 311.11-2025 — This document specifies the insulation requirements associated with line-commutated converters (LCCs) and voltage source converters (VSCs) in high voltage direct current (HVDC) systems.
The principle of coordination procedure is applicable to HVDC systems with nominal voltage above 1.5kV. Its main principles are also applicable to other special structures of LCC.
The capacitor-commutated converter (CCC) and the controlled series-compensated converter (CSCC) are commonly used converters.
This document specifies the principles for the procedure for determining the specified withstand voltage, creepage distances and minimum air clearance distances for equipment and devices in a system; The typical DC voltage, specified withstand voltage and corresponding minimum air gap distance are given.
This document applies to the connection between the AC busbar (including AC harmonic filter, converter transformer, circuit breaker) and the DC line side of the converter station.
The insulation coordination of equipment. The impact of lines and cables on the insulation coordination of converter station equipment is also included. This document is only applicable to HVDC systems in power systems and is not applicable to industrial converter equipment.
The principles and rules given are only for this document does not address requirements for personal safety.
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Document preview — GB/T 311.11-2025
National Standard of the People's Republic of China
- ICS
- 29.080
- Classification
- K 40
Issued by: State Administration for Market Regulation, China National Standardization Administration
Contents
- Preface
- Introduction
- 1 Scope
- 2 Normative references
- 3 Terms and Definitions
- 4 Symbols and abbreviations
- 4.1 Overview
- 4.2 Symbols
- 4.3 Abbreviations
- 5 Insulation coordination principles
- 5.1 Overview
- 5.2 Main Differences between AC and DC Systems
- 5.3 Insulation coordination procedure
- 5.4 Differences in Withstand Voltage Selection Between AC and DC Systems
- 6 Insulation Coordination Design Procedure
- 6.1 Overview
- 6.2 Characteristics of lightning arresters
- 6.3 Insulation properties
- 6.4 Determination of representative overvoltage (Urp)
- 6.5 Determination of coordinated withstand voltage (Ucw)
- 6.6 Determination of Required Withstand Voltage (Urw)
- 6.7 Determination of specified withstand voltage (Uw)
- 7 Requirements for withstand voltage test
- 8 Creepage distance
- 8.1 General Principles
- 8.2 Creepage distance reference voltage
- 9 Air gap distance
- Appendix A (Informative) Structure diagram of a typical HVDC converter station
- Appendix B (Informative) Air Gap Distance Calculation Example
- B.1 General instructions
- B.2 Calculation of minimum air gap distance under switching impulse voltage
- B.3 Calculation of minimum air clearance distance under lightning impulse voltage
- Appendix C (Normative) Insulation levels and corresponding air clearance distances of typical high-voltage DC equipment
- C.1 General instructions
- C.2 Specified impulse withstand voltage series value
- C.3 Operational shock insulation level and minimum air gap distance
- C.4 Lightning impulse insulation level and minimum air clearance distance
- C.5 Recommended DC withstand voltage
- Reference
- Figure 1 Flowchart for determining the insulation level of HVDC equipment
- Figure A.1 Typical lightning arrester layout diagram for a single-pole LCC converter station using a series structure of dual 12-pulse converter units.
- Figure A.2 Schematic diagram of typical arrester arrangement for one pole in a bipolar VSC converter station 15
- Figure A.3 Typical lightning arrester arrangement in a symmetrical single-pole VSC converter station
- Table 1 Comparison of insulation coordination procedures between AC and DC systems
- Table 2 Overvoltage classification and waveform, standard voltage waveform and standard withstand voltage test
- Table 3 Required ratio of impulse withstand voltage to impulse protection level
- Table A.1 Graphic symbols
- Table C.1 Insulation level of high voltage DC equipment
- Table C.2 specifies the relationship between the switching impulse withstand voltage and the minimum relative air gap distance
- Table C.3 specifies the relationship between lightning impulse withstand voltage and minimum relative air gap distance
Foreword
This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1: Structure and drafting rules for standardization documents" Drafting.
This document is Part 11 of GB/T 311 "Insulation Coordination". GB/T 311 has been published in the following parts.
--- Part 1: Definitions, principles and rules;
--- Part 2: Guidelines for use;
--- Part 3: Insulation coordination procedures for HVDC converter stations;
--- Part 4: Calculation guide for network insulation coordination and simulation;
--- Part 11: Definitions, principles and rules for insulation coordination of high voltage DC systems;
--- Part 14: Insulation coordination of AC/DC filters for high voltage DC systems.
This document is modified to adopt IEC 60071-11:2022 "Insulation coordination - Part 11: Definitions and principles of insulation coordination for high-voltage direct current systems" and Rules.
This document has the following structural adjustments compared to IEC 60071-11:2022.
a) Chapter 3 corresponds to Chapter 3 of IEC 60071-11:2022, where 3.5 to 3.8 correspond to 3.4 to 3.6 of IEC 60071-11:2022.
3.7; 3.9~3.10 correspond to 3.7.1~3.7.2 of IEC 60071-11:2022; 3.10.1~3.10.4 correspond to IEC 60071-11.
2022 3.7.2.1~3.7.2.4; 3.12 corresponds to 3.8 of IEC 60071-11:2022; 3.13~3.15 correspond to IEC 60071-11.
3.9~3.11 of IEC 60071-11:2022; 3.16 corresponds to 3.12 of IEC 60071-11:2022; 3.17~3.19 corresponds to IEC 60071-11:2022 3.14~3.16;3.20~3.23 of IEC 60071-11:2022 correspond to 3.18~3.21 of IEC 60071-11:2022.IEC 60071-11:2022 has been deleted.
2022 3.3, 3.7.2.5, 3.8.1, 3.8.2, 3.8.3, 3.11.1, 3.11.2, 3.11.3, 3.13, 3.17.Added 3.3~3.4, 3.11.
b) Chapter 4 corresponds to Chapter 4 of IEC 60071-11:2022, where 4.2 to 4.3 correspond to 4.3 to 4.4, and IEC 60071-11:2022 is deleted.
4.2 of 2022.
c) Chapter 8 corresponds to Chapter 8 of IEC 60071-11:2022, where 8.1 to 8.2 correspond to 8.1 to 8.2, and IEC 60071-11:2022 is deleted.
August 3rd to August 5th, 2022.
d) Appendix D of IEC 60071-11:2022 has been deleted.
This document has many technical differences compared to IEC 60071-11:2022.
These technical differences and their reasons are as follows.
a) The voltage range description has been added to the scope, "applicable to HVDC systems with a nominal voltage of 1.5kV or above".
The following DC projects are common, but are relatively rare internationally except in China. The purpose of clarifying the voltage range is to adapt to the actual needs of Chinese projects.
At the same time, it is also consistent with the description of voltage range in GB/T 311.1.
b) Regarding normative references, this document has made adjustments to technical differences to adapt to my country's technical conditions. The specific adjustments are as follows.
- The normative reference GB/T 311.1 replaces IEC 60071-1:2019.There is no consistency between the two documents.
relation;
- The normative reference GB/T 311.2 replaces IEC 60071-2:2018.There is no consistency between the two documents.
relation;
- The normative reference GB/T 11032-2020 replaces IEC 60099-4:2014, and the consistency between the two documents to modify;
- The normative reference GB/T 16927.1 replaces IEC 60060-1, and there is no consistency correspondence between the two documents;
- The normative reference GB/T 26218 (all parts) replaces IEC/T S60815-1.2008 and IEC/T S60815-2.
2008, IEC/T S60815-3.2008, there is no consistency correspondence between the two documents;
- Newly added references to GB/T 2900.19-2022 and GB/T 22389.
c) The relevant terms have been modified to better comply with the basic standard requirements of insulation coordination and adapt to the content of this document. The specific adjustments are as follows.
- Added the terms "grid-commutated converter", "voltage source converter", and "standard voltage waveform for testing" (see 3.3, 3.4, 3.11);
- The terms "maximum DC voltage", "combined overvoltage", "representative slow-front overvoltage", and "representative fast-front overvoltage" have been deleted.
"Representative steep wave front overvoltage", "Switching impulse withstand voltage", "Lightning impulse withstand voltage", "Steep wave front impulse withstand voltage" "Equivalent continuous operating voltage of lightning arresters" "Equipment directly protected" (see 3.3, 3.7.2.5, 3.8.1, 3.8.2, 3.8.3, 3.11.1, 3.11.2, 3.11.3, 3.13, 3.17);
- Adjust the terms "switching impulse protection level", "lightning impulse protection level" and "steep wavefront impulse protection level" (see IEC 60071-11.
2022), merged into. "Operational (or lightning/steep wavefront) impulse protection level" (see 3.20).
d) Add "from the aspects of safe operation and technical and economic rationality" to the definition of "insulation coordination" (see 3.1), the definition of insulation coordination in GB/T 311.1 remains consistent.
e) The definition of "fast-front overvoltage" (see 3.10.2) has been modified to comply with the description requirements of the national standard.
f) 4.2 "Subscript" in IEC 60071-11:2022 has been deleted (see 4.2 of IEC 60071-11:2022).
These subscripts.
g) Modified Figure 1 in Chapter 5 "Insulation Coordination Principles" (see 5.4).
Compared with GB/T 311.1, Figure 1 was modified to be consistent with GB/T 311.1 and to clarify the process.
h) Table 2 in 6.4 corresponds to Table 1 in IEC 60071-11:2022.The steep wavefront impulse voltage waveform and parameters are added to Table 2 and Add temporary DC overvoltage waveform in the "Temporary" column (see Table 2). For DC equipment, temporary DC overvoltage and steep wave pre-surge Overvoltage exists in actual working conditions, and steep wavefront impact is an important assessment item.
i) Added the recommended method for altitude correction factor and the recommended value of safety factor (see 6.6). For insulation coordination, these two factors are it is necessary, so add this content.
j) In "Creep distance", the provisions concerning creepage distance of indoor and outdoor insulation and creepage distance of AC insulators are deleted (see Section 8 this document only provides selection principles, and 8.1 has clearly referred to GB/T 26218 (all parts), so this part is deleted.
content.
k) Modify the title of Appendix C to "Insulation levels and corresponding air clearance distances of typical high-voltage DC equipment" and optimize the wording.
l) Modified the content of C.1.To better suit the use of this document, the content of this section has been simplified.
m) Add "1600" to the impulse withstand voltage series values specified in C.2 of Appendix C to meet the needs of Chinese projects.
n) Modify the title of C.2 to "Specify series values of impulse withstand voltage" to correspond with the main text.
o) Delete "Recommended" in the titles of C.3 and C.4.Appendix C is a normative appendix.
p) Added ±10kV, ±20kV, ±50kV, ±100kV/±120kV/±125kV, ±160kV, ±660kV, ±1100kV DC system nominal voltage insulation level (see Table C.1) and related air gap distance calculation data According to my country's DC projects, the corresponding insulation level and related air gap distance data are added and improved.
q) Modify the title of C.5.3 to "Standard rated short-duration power-frequency withstand voltage series values" to refer to the description of AC insulation coordination.
The following editorial changes have been made to this document.
a) Incorporate the corrigendum of IEC 60071-11:2022/COR1.2023, and the outer margins of the clauses involved are marked with vertical Double lines (||) are marked;
b) The symbols and descriptions of f, T1, T2, Tp, and Tt are added to 4.2 Symbols;
c) Delete the informative Appendix D in IEC 60071-11:2022.
Introduction
GB/T 311 "Insulation Coordination" aims to establish the principles and guidelines for high-voltage AC and high-voltage DC insulation coordination.
There are obvious differences between AC insulation coordination and DC insulation coordination, and it needs to be divided into two aspects. AC insulation coordination and DC insulation coordination, which are planned to be composed of the following parts.
--- Part 1: Definitions, principles and rules. The purpose is to establish the definitions, principles and rules of insulation coordination and to provide insulation coordination for AC systems.
Cooperate to provide guidance.
--- Part 2: User Guide. The purpose is to provide user guidance for the correct implementation of Part 1.
--- Part 3: Insulation coordination procedures for HVDC converter stations. The purpose is to provide guidance on insulation coordination for HVDC converter stations.
--- Part 4: Calculation guide for insulation coordination of power grids and its simulation. The purpose is to determine the guidelines for digital calculation of insulation coordination.
--- Part 11: Definitions, principles and rules for insulation coordination of high voltage DC systems. The purpose is to establish the insulation coordination of DC systems.
Defines, principles and rules and provides guidance for insulation coordination in HVDC systems.
--- Part 12: High-voltage DC converter station (LCC) insulation coordination application guide. The purpose is to use LCC as the converter of high-voltage DC converter station Provide guidance for insulation coordination of DC converter stations.
--- Part 13: High-voltage DC converter station (VSC) insulation coordination application guide. The purpose is to use VSC as the converter of high-voltage Provide guidance for insulation coordination of DC converter stations.
--- Part 14: Insulation coordination of AC/DC filters in high voltage DC systems. The purpose is to determine the insulation coordination of AC and DC filters in high voltage DC systems.
Insulation coordination of current filters.
--- Part 15: Insulation coordination of DC transmission lines. The purpose is to determine the insulation coordination of DC transmission lines and grounding electrode lines.
This document is part 11 of GB/T 311 "Insulation coordination".
In the difference. my country's DC engineering construction and operation experience is increasingly rich, and it is urgent to unify the DC system insulation coordination standards.
Provide guiding technical documents for construction.
Insulation coordination - Part 11: High voltage direct current systems Definition, principles and rules of insulation coordination
1 Scope
This document specifies the insulation requirements associated with line-commutated converters (LCCs) and voltage source converters (VSCs) in high voltage direct current (HVDC) systems.
The principle of coordination procedure is applicable to HVDC systems with nominal voltage above 1.5kV. Its main principles are also applicable to other special structures of LCC.
The capacitor-commutated converter (CCC) and the controlled series-compensated converter (CSCC) are commonly used converters.
This document specifies the principles for the procedure for determining the specified withstand voltage, creepage distances and minimum air clearance distances for equipment and devices in a system;
The typical DC voltage, specified withstand voltage and corresponding minimum air gap distance are given.
This document applies to the connection between the AC busbar (including AC harmonic filter, converter transformer, circuit breaker) and the DC line side of the converter station.
The insulation coordination of equipment. The impact of lines and cables on the insulation coordination of converter station equipment is also included.
This document is only applicable to HVDC systems in power systems and is not applicable to industrial converter equipment. The principles and rules given are only for this document does not address requirements for personal safety.
2 Normative references
The contents of the following documents constitute the essential clauses of this document through normative references in this document.
For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies to this document.
GB/T 311.1 Insulation coordination Part 1: Definitions, principles and rules (GB/T 311.1-2012, IEC 60071-1:2006, MOD) GB/T 311.2 Insulation coordination Part 2: Guidelines for use (GB/T 311.2-2013, IEC 60071-2:1996, MOD) GB/T 2900.19-2022 Electrical terminology - High voltage test techniques and insulation coordination GB/T 11032-2020 AC gapless metal oxide surge arresters (IEC 60099-4:2014, MOD) GB/T 16927.1 High voltage test technology Part 1: General definitions and test requirements (GB/T 16927.1-2011, IEC 60060-1:2010, MOD) GB/T 22389 High Voltage Direct Current Converter Station Ungapped Metal Oxide Arresters (GB/T 22389-2023, IEC 60099-9.
2014, MOD)
GB/T 26218 (all parts) Selection and sizing of high-voltage insulators for use under polluted conditions Note. GB/T 26218.1-2010 Selection and sizing of high-voltage insulators for use under polluted conditions Part 1: Definitions, information and general principles (IEC/T S60815-1.2008,MOD) GB/T 26218.2-2010 Selection and sizing of high-voltage insulators for use under polluted conditions Part 2: Porcelain and glass insulators for AC systems Edge (IEC/T S60815-2.2008, MOD) GB/T 26218.3-2011 Selection and sizing of high-voltage insulators for use under polluted conditions Part 3: Composite insulators for AC systems (IEC/T S60815-3.2008,MOD) GB/T 26218.4-2019 Selection and sizing of high-voltage insulators for use under polluted conditions Part 4: Insulators for DC systems
3 Terms and Definitions
The terms and definitions defined in GB/T 2900.19-2022, GB/T 11032-2020 and the following apply to this document.
......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 31 pages — is available in the English PDF.
Referenced standards
Normative references
- GB/T 2900.19-2022Electrotechnical terminology - High-voltage test technique and insulation co-ordination
- GB/T 11032-2020Metal-oxide surge arresters without gaps for a. c. systems
- GB/T 16927.1High-voltage test techniques -- Part 1: General definitions and test requirements
- GB/T 16927.1-2011High-voltage test techniques -- Part 1: General definitions and test requirements
- GB/T 22389Metal-oxide surge arresters without gaps for HVDC converter stations
- GB/T 22389-2023Metal-oxide surge arresters without gaps for HVDC converter stations
GB/T 311.1 · GB/T 311.1-2012 · IEC 60071 · GB/T 311.2 · GB/T 311.2-2013 · IEC 60099 · IEC 60060 · GB/T 26218 · GB/T 26218.1-2010 · GB/T 26218.2-2010
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Related Standards
GB/T 11032-2020 — Metal-oxide surge arresters without gaps for a. c. systems
GB/T 16927.1-2011 — High-voltage test techniques -- Part 1: General definitions and test requirements
GB/T 22389-2023 — Metal-oxide surge arresters without gaps for HVDC converter stations
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