Amendment 2 - Winding wires - Test methods - Part 1: General
1Key Takeaways
This part of IEC 60851 specifies general instructions for testing methods of winding wires. It also provides definitions of terms used in IEC 60851 (all parts). Appendix A provides an overview of the contents of IEC 60851-2 to IEC 60851-6.
2Expert Interpretation
This article provides an in-depth analysis of the IEC 60851-1:2021 international standard, "Test methods for winding wires - Part 1: General principles," covering the standard's scope, definitions of key terms, test environment requirements, test management principles, and a comparative analysis of the series of standards, offering professional implementation guidance for winding wire manufacturers and electrical equipment users.
IEC 60851-1:2021 Standard Framework and Positioning Analysis
IEC 60851-1:2021 "Test Methods for Winding Wires - Part 1: General Principles", as the third edition standard published by the International Electrotechnical Commission (IEC), forms the basic framework of the series of standards for testing methods for winding wires. This standard was officially released in June 2021, replacing the second edition published in 1996 and its subsequent revisions (Amendment 1:2003 and Amendment 2:2009). Developed by IEC Technical Committee 55 (Winding Wires), this standard is the first part of the IEC 60851 series of standards, providing unified terminology definitions, test environment requirements, and overall management principles for subsequent specific test method standards (IEC 60851-2 to IEC 60851-6).
In the electrical insulation materials standard system, the IEC 60851 series, together with the IEC 60317 series (specifications for certain types of winding wire) and the IEC 60264 series (winding wire packaging), constitute a complete winding wire standard system. This three-in-one structure ensures standardization throughout the entire process, from material properties and testing methods to packaging and transportation, providing a unified technical language and quality benchmark for the global electrical equipment manufacturing industry.
Standard Core Technology Changes and Evolution
Compared to the previous version, IEC 60851-1:2021 has undergone four important technical revisions. These changes reflect the latest developments in winding wire testing technology and changes in industry practice requirements:
| Revision Items | Changes in 2021 Version | Technical Significance | Impact on Testing Practice |
|---|---|---|---|
| Updated Normative References | Comprehensive update of IEC 60851 series standards referenced in Chapter 2 to ensure consistency of references | Maintaining the integrity and timeliness of the standard system | Test laboratories must update all referenced standard versions simultaneously |
| Revision of Test Atmospheric Conditions | Clarifies that the test ambient temperature is 15°C-40°C and the relative humidity is 25%-75% | Unifies global test benchmark conditions to reduce test result deviations caused by environmental factors | Laboratories must establish a strict environmental monitoring system |
| Test Frequency and Management Instructions | Adds instructions on the frequency and management of periodic compliance tests | Clarifies the boundary between standards and certification management, enhancing the operability of standards | Both suppliers and buyers must specify test frequency requirements in the contract |
| Updated Appendix A Content | Updated the IEC 60851 series test content list to reflect the latest test methods | Provides users with a complete test method navigation | Facilitating quick location of required test method standards for users |
These technical changes reflect the progressive improvement principle of IEC standard development, maintaining technical continuity while adapting to new testing requirements. In particular, the explanation regarding test management clarifies that IEC standards only specify product requirements and do not involve certification management or supplier-customer agreements. This clarification is crucial for avoiding misuse of the standard.
Analysis of Core Terminology Definitions
IEC 60851-1:2021 establishes a complete terminology system for winding wire testing in Chapter 3. These definitions are the foundation for understanding subsequent test method standards. The following is a professional interpretation of key terms:
Winding wire: Defined as "a conductor used to wind a coil to provide a magnetic field." This definition clarifies the functional characteristics of winding wire, distinguishing it from ordinary conductors.
In practical applications, winding wires need to meet specific electrical, mechanical, and thermal performance requirements to ensure the reliable operation of electromagnetic equipment (such as motors, transformers, and inductors). Enamelled wire: Defined as "a conductor with a coated and cured resin insulation layer." This is the most common type of winding wire, with its insulation layer formed through a coating and curing process. Depending on the insulation material, enamelled wire can be divided into various types, such as polyester, polyurethane, and polyimide, each corresponding to different temperature ratings and application scenarios. Grade: Defined as "the range of increases in conductor size due to insulation." This concept is crucial for the spatial design of winding wires. For example, in compact motor designs, selecting the appropriate grade of enamelled wire can maximize slot fill factor while ensuring insulation performance. Zero-defect wire: Defined as "a winding wire that does not exhibit electrical discontinuities when tested under specific conditions." This concept is mainly used in fields with extremely high reliability requirements, such as aerospace and medical equipment. Zero-defect wire testing typically requires 100% inspection using specialized equipment such as an online high-voltage tester. Other important terms include: **bonding layer**, **bunched wire**, **class** (referring to thermal properties expressed by temperature index and thermal shock temperature), and **crack**. These terms collectively constitute a precise language system describing the structure and performance of the winding wire.General Requirements and Implementation Points for Test Methods
Section 3.2 of the standard specifies the general requirements for test methods, which are the basis for ensuring the comparability and accuracy of test results:
1. Atmospheric Condition Control: All tests shall be conducted in an environment with a temperature of 15°C–40°C and a relative humidity of 25%–75%.
This broad scope considers the actual conditions of different climate regions worldwide, but requires that the specimens be pretreated under these conditions for a sufficient time to reach a stable state before testing. In practice, it is recommended that laboratories maintain the environment at standard conditions of 23°C ± 2°C and 50% ± 5% RH to improve the consistency of test results.2. Specimen Preparation Specifications: The standard clearly requires that tension or unnecessary bending of the conductors be avoided when removing specimens from the packaging. Sufficient length of conductor should be discarded before each test to ensure that damaged portions are not included in the specimen. This provision is crucial for ensuring the representativeness of the test samples, especially for testing long winding wires.
3. Standard Priority: When there is inconsistency between the IEC 60317 specification and this standard, the specification takes precedence. This principle reflects the relationship between product specifications and test method specifications, ensuring the authority of specific product requirements.
4. Periodic Compliance Testing: Tests marked with an asterisk (*) in Appendix A are periodic compliance tests, the frequency of which is determined through negotiation with the end user. This flexible arrangement balances quality control costs with risk control requirements. 5. Test Number Correspondence: Test numbers in the IEC 60851 series correspond to clause numbers in the IEC 60317 series. This numbering system facilitates users in quickly locating relevant requirements across different standards.
Comparison of IEC 60851 Series Test Method Framework
Appendix A provides an overview of the contents of IEC 60851-2 to IEC 60851-6. These five parts address different performance dimensions of winding wires:
| Standard Section | Core Test Content | Applicable Winding Wire Types | Key Test Items | Examples of Test Equipment | |||||
|---|---|---|---|---|---|---|---|---|---|
| IEC 60851-2 Dimensional Measurement | Conductor Dimensions, Roundness, Insulation Addition Dimensions, Overall Dimensions, etc. | Round Wire, Flat Wire, Bundled Wire | Test 4: Dimensional Measurement | Micrometer, Projector, Laser Diameter Gauge | Solvent resistance, refrigerant resistance, solderability, hydrolysis resistance, etc. | Enameled wire, bundled wire | Tests 12, 16, 17, 20 | Solvent immersion apparatus, Solder bath, Aging test chamber | |
| IEC 60851-5 Electrical performance | Resistance, breakdown voltage, insulation continuity, dielectric loss factor, etc. | Various winding wires | Tests 5, 13, 14, 19, 23 | High voltage tester, Continuity tester, | IEC 60851-6 | Thermal Properties Thermal Shock, Thermal Cutting, Temperature Index, Mass Loss, etc. | Enameled Wire, Sheathed Wire | Tests 9, 10, 15, 21, 22 | Thermal Aging Chamber, Thermal Cutting Device, Thermogravimetric Analyzer | |
This framework covers all key dimensions of winding wire performance evaluation. Each part includes detailed test principles, equipment requirements, sample preparation, test procedures, and result evaluation methods. The unified system of test numbers (e.g., Test 4 corresponds to dimensional measurement, Test 13 corresponds to breakdown voltage testing) provides clear navigation for users.
Technical Challenges and Solutions for Standard Implementation
Case Study: Testing Practice of Flat Copper Wire for New Energy Vehicle Drive Motors
With the rapid development of the new energy vehicle industry, the performance requirements for winding wires in drive motors are increasing. Taking enameled flat copper wire for 800V high-voltage platform motors as an example, its testing implementation faces the following challenges:
1. **Partial Discharge Initiation Voltage Test**: The breakdown voltage test (Test 13) in IEC 60851-5 mainly evaluates the short-term withstand voltage capability of insulation, but for high-voltage motors, it is also necessary to evaluate the partial discharge characteristics. The solution is to refer to the IEC 60270 standard "Partial Discharge Measurement" and add partial discharge initiation voltage (PDIV) and extinction voltage (PDEV) tests to the winding wire test.
2. **Adaptability to High-Speed Automatic Winding**: Modern motor production uses high-speed automatic winding machines, which places higher demands on the mechanical performance of the winding wires.
In addition to the standard flexibility test (Test 8) in IEC 60851-3, dynamic test methods that simulate the actual winding process need to be developed, such as using a high-speed winding test machine to assess insulation damage to conductors at high speeds. 3. Thermal Cycling Durability Assessment: Motors undergo frequent temperature cycles in actual operation. The thermal shock test (Test 9) in the standard mainly assesses the short-term thermal stability of insulation, but is insufficient to assess performance degradation under long-term thermal cycling. It is recommended to supplement with thermal cycling tests to simulate the repeated changes in temperature from low to high temperatures and assess the aging behavior of the insulation. These practices show that although the IEC 60851 series provides a comprehensive framework of test methods, for specific application scenarios, it may be necessary to supplement or adjust the test methods. The standard itself allows for this flexibility, provided that the supplier and the user agree.Test Laboratory Capability Building Guidelines
To effectively implement IEC 60851-1:2021 and related standards, test laboratories need to establish a comprehensive capability system:
1. Environmental Control Capability: Establish a temperature and humidity controlled laboratory that meets the standard requirements, equipped with a continuous monitoring and recording system. For precision tests (such as dielectric loss factor measurement), it is recommended to control the environment within a narrower range (e.g., 23°C±1°C, 50%±3%RH).
2. Equipment Calibration and Validation: All test equipment must be calibrated regularly according to international standards (such as ISO/IEC 17025). The calibration of critical equipment such as high-voltage testers should be traceable to national metrological standards to ensure the accuracy and traceability of test results.
3. Personnel Qualification Requirements: Test operators should receive professional training and understand the principles and requirements of the standard.
It is recommended to establish a personnel competency assessment system and conduct regular competency verification to ensure the consistency and reliability of testing operations. 4. Documentation of Test Procedures: Based on the IEC 60851 series standards, develop detailed test operation instructions, including requirements for the entire process such as sample preparation, equipment operation, data recording, result calculation, and uncertainty assessment. 5. Quality Control System: Establish internal quality control procedures, including regular verification using standard samples, participation in inter-laboratory comparisons, and implementation of statistical analysis of test data, to ensure the continuous provision of reliable test results. Standard Development Trends and Future Prospects: Based on the general principles of IEC standard development and the development trends of winding wire technology, the possible future development directions of the IEC 60851 series standards can be predicted as follows: 1. High-Frequency Application Test Methods: As power electronics technology develops towards higher frequencies, the performance evaluation of winding wires at high frequencies becomes increasingly important. Future standards may add new test methods such as high-frequency loss testing and skin effect assessment. 2. Environmentally Friendly Material Assessment: Facing global environmental requirements, the testing needs for new environmentally friendly winding wires, such as bio-based insulation materials and halogen-free flame-retardant materials, will increase. Standards may need to supplement assessment methods for the special properties of these materials. 3. Digital Testing Technology: The application of digital technologies such as artificial intelligence and machine vision in testing will drive innovation in testing methods. For example, automatic detection of insulation defects based on image recognition and performance prediction based on big data analysis. 4. Extreme Environment Adaptability: Extreme environment applications such as aerospace and deep-sea exploration place special requirements on the performance of winding wires. Standards may need to supplement testing methods for extreme environments such as low temperature, high vacuum, and strong radiation. 5. Life Cycle Assessment: Expanding from simple product performance testing to full life cycle assessment, including environmental impact assessments of raw material acquisition, production processes, usage stages, and end-of-life recycling. IEC 60851-1:2021, as the foundational standard for winding wire testing methods, typically has a stability period of 5-10 years. During this period, the technical committee will maintain the standard through technical errata and revisions. Users should regularly check the standard status information on the IEC website (webstore.iec.ch) to ensure they are using the latest version. Implementation Recommendations and Best Practices Based on an in-depth analysis of IEC 60851-1:2021, the following implementation recommendations are made for winding wire manufacturers, users, and testing laboratories: 1. Systematic Standard Application: Apply the IEC 60851 series of standards as a complete testing method system, avoiding the isolated use of individual testing methods. It is recommended to establish a standard application matrix, clearly defining the test items and requirements corresponding to different product types. 2. **Supplier-Demand Collaboration:** Fully utilize the flexibility provided by standards; both suppliers and demanders should reach a clear agreement on testing frequency, acceptance criteria, etc. For special application needs, mutually agreed-upon testing methods can be supplemented to the standards. **3. Test Data Management:** Establish an electronic test data management system to achieve long-term storage, rapid retrieval, and statistical analysis of test results. Utilize Statistical Process Control (SPC) technology to monitor product quality trends. **4. Continuous Improvement of Technical Capabilities:** Regularly participate in IEC technical committee activities, industry seminars, and technical training to keep abreast of the latest developments in standards and technologies. Encourage technical personnel to participate in the standard-setting process and contribute practical experience. **5. Integration of International Standards and Localization:** While adhering to international standards, consider local regulations and market requirements. For example, some regions may have additional environmental or safety certification requirements, which need to be considered in the testing plan. By systematically implementing IEC 60851-1:2021 and its series of standards, a unified quality language can be established across all links of the winding wire industry chain, improving product reliability, reducing technical risks, and ultimately promoting the healthy development of the entire electrical equipment industry.