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GB/T 11026.7: Evolution and historical versions
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Electrical insulating materials - Thermal endurance properties - Part 7: Determination of relative temperature index(RTI)of an insulating material
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GB/T 11026.7-2025
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| GB/T 11026.7-2014 | English | 334 |
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Electrical insulating materials -- Thermal endurance properties -- Part 7: Determination of relative thermal endurance index (RTE) of insulating material
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GB/T 11026.7-2014
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Standard similar to GB/T 11026.7-2025 GB/T 11026.3 GB/T 11026.8 GB/T 11026.10
Basic data | Standard ID | GB/T 11026.7-2025 (GB/T11026.7-2025) | | Description (Translated English) | Electrical insulating materials - Thermal endurance properties - Part 7: Determination of relative temperature index(RTI)of an insulating material | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | K15 | | Classification of International Standard | 19.020; 29.020; 29.035.01 | | Word Count Estimation | 26,267 | | Date of Issue | 2025-10-05 | | Date of Implementation | 2026-05-01 | | Older Standard (superseded by this standard) | GB/T 11026.7-2014 | | Issuing agency(ies) | State Administration for Market Regulation and Standardization Administration of China |
GB/T 11026.7-2025: Electrical insulating materials - Thermal endurance properties - Part 7: Determination of relative temperature index(RTI)of an insulating material ---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
ICS 19.020;29.020;29.035.01
CCSK15
National Standards of the People's Republic of China
Replaces GB/T 11026.7-2014
Heat resistance of electrical insulation materials, Part 7.
Determine the relative temperature index (RTI) of insulating materials.
insulating material, MOD]
Released on October 5, 2025; to be implemented on May 1, 2026.
State Administration for Market Regulation
The State Administration for Standardization issued a statement.
Table of contents
Preface III
Introduction V
1.Scope 1
2 Normative References 1
3.Terms, Definitions, and Symbols 1
3.1 Terms and Definitions 1
3.2 Symbol 2
4.Purpose of RTI determination 3
5.Experimental Procedure 4
5.1 Selection of Benchmark EIM 4
5.2 Selection of Aging Degree Diagnostic Tests 4
5.3 Aging Process 4
6.Calculation Procedure
6.1 Heat Resistance Data – Calculation of Intermediate Parameters
6.2 Calculate RTI 6
6.3 Mathematical Statistics Experiment 6
7 Results and Reports
7.1 Results of the Mathematical Statistics Experiment 7
7.2 Results 8
7.3 Report 8
8.Material testing through short-term thermal aging.
9.Insulation Classification 8.
Appendix A (Informative) Repeatability of Relevant Time Periods 9
A.1 General Rules 9
A.2 F-test for linearity 9
A.3 Standard error of the difference between the two means 9
A.4 t-test for the difference between two means 9
A.5 Data Combinations 10
Appendix B (Informative) Thermal Classification 11
Appendix C (Informative) Computer Program 13
C.1 General Provisions 13
C.2 Data file structure used by the program 15
C.3 Perform RTI calculation 15
C.4 Output Files and Graphics 15
Appendix D (Informative) Selection of Baseline EIM 17
D.1 General Rule 17
D.2 Specify the baseline EIM 17
D.3 Reporting Item 17 of the Benchmark EIM
Reference 18
Figure 1.Heat resistance diagram 5
Figure 2.Unacceptable heat resistance (Figure 5)
Figure C.1 Shortcut properties dialog box for program startup 14
Figure C.2 Heat resistance diagram 15
Figure C.3 Example 16 of heat resistance data processing
Table 1.Input parameters for calculating RTI (Retrieval of Integrity) (6)
Table B.1 Heat Resistance Ratings of Insulation Materials 11
Table B.2 F function, p=0.05 11
Table B.3 F function, p=0.005 12
Table B.4 t function 12
Foreword
This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1.Structure and Drafting Rules of Standardization Documents".
Drafting.
This document is Part 7 of GB/T 11026 "Heat Resistance of Electrical Insulation Materials". GB/T 11026 has already published the following parts.
---Part 1.Aging Procedures and Evaluation of Test Results;
---Part 2.Selection of Test Judgment Criteria;
---Part 3.Procedures for calculating heat resistance characteristic parameters;
---Part 4.Aging Oven - Single Chamber Oven;
---Part 5.Precision ovens with aging temperatures up to 300℃;
---Part 6.Aging Ovens - Multi-chamber Ovens;
---Part 7.Determining the Relative Temperature Index (RTI) of Insulating Materials;
---Part 8.Determining the heat resistance index (TI and RTI) of insulating materials using the fixed time limit method;
---Part 9.Guidelines for calculating heat resistance using simplified procedures;
---Part 10.Guidelines for accelerating the determination of the relative heat resistance index (RTEA) based on activation energy calculations using analytical testing methods.
This document replaces GB/T 11026.7-2014 "Heat Resistance of Electrical Insulation Materials - Part 7.Determination of Relative Heat Resistance of Insulation Materials".
Compared with GB/T 11026.7-2014, the main technical changes in the "Real-Time Expansion (RTE) Index" are as follows, except for structural adjustments and editorial changes.
a) The term "Relative Heat Resistance Index (RTE)" has been changed to "Relative Temperature Index (RTI)" (see full text,.2014 edition).
b) Added "When thermal stress is the primary aging factor, the calculation procedure in this document is applicable to determining the heat resistance, etc., of electrical insulation systems."
Level (see Chapter 1);
c) The term "validation test" has been changed to "inspection test" (see Chapter 1,.2014 edition);
d) The term "estimated heat resistance index" has been changed to "estimated temperature index" (see 3.1.2,.2014 version 3.1.2);
e) The term "relevant time" has been changed to "relevant time of RTI" (see 3.1.6,.2014 version 3.1.6);
f) The term “relative heat resistance index” has been changed to “relative temperature index” (see 3.1.10,.2014 edition of 3.1.10).
This document is modified to adopt IEC 60216-5.2022 "Electrical insulating materials - Heat resistance - Part 5.Determination of relative temperature of insulating materials".
The Index (RTI).
The technical differences between this document and IEC 60216-5.2022, and the reasons therefor, are as follows.
a) IEC 60216-1.2013 (see 5.3) has been replaced with the normatively referenced GB/T 11026.1 to improve operability;
b) Modify "shall comply with the requirements of IEC 60216-1.2013, 5.3.2, 5.4 and 5.5" to "shall comply with GB/T 11026.1".
The requirements (see 5.3) are to increase operability;
c) IEC 60216-2.2005 (see Chapter 1) has been replaced with the normatively referenced GB/T 11026.2 to increase operability.
The following editorial changes have been made to this document.
---In accordance with the GB/T 11026 series standard numbering, the original English name has been changed to "Electrical Insulation Materials Heat Resistance Part 7.Determination"
"Relative Temperature Index (RTI) of Insulation Materials";
---Replace IEC 60216-3 and IEC 60216-6 in the non-software examples of Informative Appendix C with GB/T 11026.3 and GB/T 11026.3 respectively.
GB/T 11026.8.
Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents.
This document was proposed by the China Electrical Equipment Industry Association.
This document is under the jurisdiction of the National Technical Committee on Standardization of Electrical Insulation Materials and Insulation Systems (SAC/TC301).
This document was drafted by. Zhejiang Rongtai Technology Enterprise Co., Ltd., Suzhou Taihu Electrical New Materials Co., Ltd., and Jiangsu Yuming New Materials.
Materials Co., Ltd., Beijing Institute of Electrical Engineering and Economics of Machinery Industry, Dongfang Electric Corporation Dongfang Electric Machinery Co., Ltd., Shanghai Electric Power Station Equipment
Limited Liability Companies. Shanghai Generator Factory, Wuxi Jiangnan Cable Co., Ltd., Zhejiang Bofei Electric Co., Ltd., Zhejiang Rongtai Electrical Equipment Co., Ltd.
Limited Liability Company, Jiangsu Shangshang Cable Group Co., Ltd., Shanghai Rebos Electric Co., Ltd., Guangdong Huijin Technology Co., Ltd., Anhui Yuan
Optoelectronics Co., Ltd., China Three Gorges Corporation, State Grid Shandong Electric Power Research Institute, Shenzhen Wolong Electric Power
Technology Co., Ltd., Guangzhou Power Supply Bureau Electric Power Research Institute of Guangdong Power Grid Co., Ltd., Jiangsu Wofeng New Materials Co., Ltd., Shanghai Electric Power
Equipment Testing Institute Co., Ltd., Jiangsu CRRC Electric Co., Ltd., Harbin Electric Power Equipment Co., Ltd., Hohai University.
The main drafters of this document are. Liu Yali, Ge Fan, Chen Hao, Shen Bin, Jing Fengxi, Su Ying, Zheng Gang, Yang Shuai, Zhang Yue, Liu Xiangsong, Gao Tianlei, and Wen Chenghan.
Han Xiao, Hu Daoxiong, Zhou Chao, Guan Zhaojie, Song Haoyong, Li Hua, Zhu Yongming, Liu Beijun, Yang Ming, Zhao Yuxin, Li Zhen, Jiang Tao, Gu Chaoliang, Cheng Jiatian
Wang Jian and Ding Kun.
This document was first published in.2014, and this is its first revision.
Introduction
GB/T 11026 aims to establish test procedures, test judgment criteria, aging ovens, and relative standards for the heat resistance of electrical insulation materials.
Procedures for evaluating heat resistance index, etc.
GB/T 11026 consists of the following 10 parts.
---Part 1.Aging Procedures and Evaluation of Test Results. The aim is to establish aging procedures for evaluating the heat resistance of insulating materials and to improve...
How to evaluate the results of aging tests.
---Part 2.Selection of Test Judgment Criteria. The purpose is to propose criteria for judging the endpoint of thermal aging tests on insulating materials.
---Part 3.Procedures for calculating heat resistance characteristic parameters. The purpose is to establish the method for obtaining heat resistance characteristic parameters using GB/T 11026.1 and GB/T 11026.2.
The experimental data were used to derive a calculation program for the heat resistance characteristic parameters.
---Part 4.Aging Oven - Single-chamber oven. The purpose is to specify that the temperature used for heat resistance aging tests should be 20°C higher than ambient temperature.
A single-chamber oven that operates over the entire or a portion of the temperature range of 500℃.
---Part 5.Precision ovens with aging temperatures up to 300°C. The purpose is to specify the temperature relative to ambient temperature used in heat resistance aging tests.
A precision oven that operates within the entire or part of the temperature range of 20℃ to 500℃.
---Part 6.Aging Oven - Multi-chamber Oven. The purpose is to specify that the temperature used for heat resistance aging tests should be 20°C higher than ambient temperature.
A multi-chamber oven that operates within or in part of a temperature range of 500℃.
---Part 7.Determination of the Relative Temperature Index (RTI) of Insulation Materials. The aim is to establish the use of GB/T 11026.1 and...
The test and calculation procedures for deriving the relative temperature index from the test data obtained in GB/T 11026.2.
---Part 8.Determining the Heat Resistance Index (TI and RTI) of Insulating Materials Using the Fixed Time Limit Method. The aim is to establish the use of fixed time limits...
The experimental and calculation procedures for deriving the heat resistance index were developed.
---Part 9.Guidelines for Calculating Heat Resistance Using Simplified Procedures. The aim is to establish simplified procedures for obtaining the heat resistance properties of insulating materials.
---Part 10.Guidelines for accelerating the determination of the relative heat resistance index (RTEA) based on activation energy calculations using analytical experimental methods. Objective
The goal is to establish a thermal degradation activation energy obtained through thermal analysis and a lifetime point obtained through conventional thermal aging tests, and to evaluate the insulation performance.
The procedure for determining the relative heat resistance index of insulating materials.
Heat resistance of electrical insulation materials, Part 7.
Determine the relative temperature index (RTI) of insulating materials.
1 Scope
This document establishes the criteria for deriving the relative temperature index of materials from test data obtained according to GB/T 11026.1 and GB/T 11026.2.
The test and calculation procedures are as follows. These calculation procedures supplement the calculation procedures in GB/T 11026.3.
This document also provides guidelines for evaluating thermal aging at a single fixed time and temperature without extrapolation.
In principle, test data can be obtained through destructive testing, non-destructive testing, and inspection testing. Destructive testing is typically used to obtain data.
According to this, because all samples may have stopped at some point after the median time and before the endpoint time, therefore, from a non-destructive perspective...
Data obtained from failure tests or inspection tests may be incomplete (see GB/T 11026.1).
This document provides guidance for the preliminary classification of the heat resistance level of insulating materials based on their thermal aging properties.
Although the heat resistance rating of electrical insulation materials is not directly related to the heat resistance rating of electrical insulation systems, the heat resistance of electrical insulation systems...
The grading system follows the same concepts presented in this section. When thermal stress is the primary aging factor, the calculation procedures in this document are suitable for determining...
Heat resistance rating of electrical insulation systems.
2 Normative references
The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included.
For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies.
This document.
GB/T 11026.1 Electrical insulating materials – Heat resistance – Part 1.Aging procedures and evaluation of test results (GB/T 11026.1-
2016, IEC 60216-1.2013, IDT)
GB/T 11026.2 Electrical insulating materials—Heat resistance—Part 2.Selection of test criteria (GB/T 11026.2-
2012, IEC 60216-2.2005, IDT)
GB/T 11026.3-2025 Electrical insulating materials – Heat resistance – Part 3.Procedure for calculating characteristic parameters of heat resistance
(IEC 60216-3.2021, MOD)
Note. There are no technical differences between the content referenced in GB/T 11026.3-2025 and the content referenced in IEC 60216-3.2021.
3.Terms, Definitions and Symbols
3.1 Terms and Definitions
The following terms and definitions apply to this document.
The URLs for the terminology databases maintained by ISO and IEC for standardization are as follows.
3.1.1
Materials with low electrical conductivity are used to isolate conductive components at different potentials or to isolate these components from the surrounding environment.
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