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GB/T 16935.1-2023 English PDF (GBT16935.1-2023)

GB/T 16935.1-2023 English PDF (GBT16935.1-2023)

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GB/T 16935.1-2023: Insulation coordination for equipment within low-voltage supply systems - Part 1: Principles, requirements and tests

GB/T 16935.1-2023
ICS 29.080.30
CCS K 30
GB/T 16935.1-2023 / IEC 60664-1:2020
Replacing GB/T 16935.1-2008
Insulation coordination for equipment within low-voltage
supply systems - Part 1: Principles, requirements and tests
(IEC 60664-1:2020, IDT)
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 4
Introduction ... 6
1 Scope ... 7
2 Normative references ... 8
3 Terms, definitions and abbreviated terms ... 8
3.1 Terms and definitions ... 8
3.2 Abbreviated terms ... 18
4 Basic technical characteristics for insulation coordination ... 18
4.1 General requirements ... 18
4.2 Voltages ... 19
4.3 Overvoltage categories... 22
4.4 Frequency ... 24
4.5 Pollution ... 24
4.6 Insulating material ... 25
4.7 Environmental aspects ... 28
4.8 Duration of voltage stress ... 30
4.9 Electrical field distribution ... 30
5 Design for insulation coordination ... 30
5.1 General requirements ... 30
5.2 Dimensioning of clearances ... 31
5.3 Dimensioning of creepage distances ... 35
5.4 Requirements for design of solid insulation ... 40
6 Tests and measurements ... 43
6.1 General requirements ... 43
6.2 Verification of clearances ... 43
6.3 Verification of creepage distances ... 47
6.4 Verification of solid insulation ... 47
6.5 Performing dielectric tests on complete equipment ... 54
6.6 Other tests ... 56
6.7 Measurement of the attenuation of the transient overvoltages... 57
6.8 Measurement of clearances and creepage distances ... 57
Annex A (Informative) Basic data on withstand characteristics of clearances ... 64 Annex B (Informative) Nominal voltages of mains supply for different modes of overvoltage control ... 69
Annex C (Normative) Partial discharge test methods ... 71
C.1 Test circuits ... 71
C.2 Test parameters ... 73
C.3 Requirements for measuring instruments ... 73
C.4 Calibration ... 75
Annex D (Informative) Additional information on partial discharge test methods ... 78 D.1 Measurement of partial discharge (PD), PD inception and extinction voltage ... 78 D.2 Description of PD test circuits (Figure D.1) ... 78
D.3 Precautions for reduction of noise ... 79
D.4 Application of multiplying factors for test voltages ... 80
Annex E (Informative) Comparison of creepage distances specified in Table F.5 and clearances in Table A.1 ... 82
Annex F (Normative) Tables ... 83
Annex G (Informative) Determination of clearance distances according to 5.2 ... 92 Annex H (Informative) Determination of creepage distances according to 5.3 ... 94 Bibliography ... 96
This document was drafted in accordance with the rules provided in GB/T 1.1-2020 Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents.
This document is Part 1 of GB/T 16935, Insulation coordination for equipment within low-voltage supply systems. The following parts have been issued for GB/T 16935: -- Part 1: Principles, requirements and tests;
-- Part 2-1: Application guide - Explanation of the application of the GB/T 16935 series, dimensioning example and dielectric testing;
-- Part 2 -2: Interface considerations - Application guide;
-- Part 3: Use of coating, potting or moulding for protection against pollution; -- Part 4: Consideration of high-frequency voltage stress;
-- Part 5: Comprehensive method for determining clearances and creepage distances equal to or less than 2 mm.
This document replaces GB/T 16935.1-2008, Insulation coordination for equipment within low-voltage systems - Part 1: Principles requirements and tests. Compared with GB/T 16935.1-2008, except for structural adjustment and editorial changes, the main technical changes are as follows:
-- CHANGE the scope (see Clause 1; Clause 1 of the 2008 edition);
-- ADD terms such as “low-voltage supply system”, “mains supply” and “steady- state working voltage” (see 3.1.1, 3.1.2, 3.1.8, etc.), CHANGE terms such as “working overvoltage”, “flashover” and “electrical breakdown” (see 3.1.7, 3.1.46, 3.1.44, etc.; 3.7.2, 3.20.2, 3.20, etc. of the 2008 edition), and DELETE terms such as “switching overvoltage”, “lightning overvoltage” and “functional overvoltage” (see 3.7.3, 3.7.4, 3.7.5, etc. of the 2008 edition);
-- ADD 1500 V DC to tables in Annex B and Annex F;
-- CHANGE the correction factor at an altitude of 1 000 m from 0.844 to 0.884 (see Table F.10; Table F.8 of the 2008 edition).
This document is identical to IEC 60664-1:2020, Insulation coordination for equipment within low-voltage supply systems - Part 1: Principles, requirements and tests. The following minimal editorial changes are made to this document:
Insulation coordination for equipment within low-voltage
supply systems - Part 1: Principles, requirements and tests
1 Scope
This document deals with insulation coordination for equipment having a rated voltage up to AC 1 000 V or DC 1 500 V connected to low-voltage supply systems. This document applies to frequencies up to 30 kHz.
Note 1: Requirements for insulation coordination for equipment within low-voltage supply systems with rated frequencies above 30 kHz are given in IEC 60664- 4.
Note 2: Higher voltages can exist in internal circuits of the equipment. This document applies to equipment for use up to 2 000 m above sea level and provides guidance for use at higher altitudes (See
This document provides requirements for technical committees to determine clearances, creepage distances and criteria for solid insulation. It includes methods of electrical testing with respect to insulation coordination.
The minimum clearances specified in this document do not apply where ionized gases are present. Special requirements for such situations can be specified at the discretion of the relevant technical committee.
This document does not deal with distances:
-- through liquid insulation;
-- through gases other than air;
-- through compressed air.
This basic safety publication focusing on safety essential requirements is primarily intended for use by technical committees in the preparation of standards in accordance with the principles laid down in IEC Guide 104 and ISO/IEC Guide 51.
One of the responsibilities of a technical committee is, wherever applicable, to make use of basic safety publications in the preparation of its publications. For the equipment likely to generate an overvoltage that is higher than the transients expected to come into the equipment, for example due to switching devices, the required impulse voltage shall take into account the transient generated in the equipment. The value of these transient overvoltages generated internally in the equipment shall be used without considering the preferred list in Attenuation of transient overvoltage levels
Equipment or parts of equipment may be used under conditions where the transients are reduced. Various technology of component exists such as surge protective device (SPD), transformer, capacitance, resistance, and can have different behaviour regarding the transient overvoltage attenuation. These various technologies shall be verified and the method of propagation measurement shall be defined based on their relevant product standard.
Attention is drawn to the fact that a surge protective device within the installation or within equipment may have to dissipate more energy than a surge protective device at the origin of the installation having a higher protection level (clamping voltage). This applies particularly to the surge protective device with the lowest protection level (clamping voltage).
In case attenuation of the transient is expected, the transient overvoltage across the insulation may be measured by applying the required impulse test to the equipment and measuring the actual remaining transient over the insulation, see 6.7. The measured value may be used as the expected transient overvoltage. While performing the test, the equipment is energized at rated voltage and transients of both polarities should be considered.
4.2.3 Temporary overvoltages
Due to faults on the mains supply, temporary overvoltages between lines and earth/neutral of several seconds will be generated and shall be considered when applying the concept of insulation coordination.
Insulation coordination with regard to temporary overvoltages is based on the temporary overvoltage specified in IEC 60364-4-44:2007, Clause 442. The values of temporary overvoltage in low-voltage equipment due to an earth fault in the high- voltage system are given in
4.2.4 Recurring peak voltage
Due to the intended operation modes of specific products, internally generated voltages may also include recurring peaks superimposed to the working voltage. These recurring peaks voltages should be considered when applying the concept of insulation coordination.

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