By sion932 
Combined instrument transformers play a crucial role in power systems, serving as core components for electrical measurement and protection. GB 17201-2007, the national standard of the People’s Republic of China titled “Combined Instrument Transformers”, establishes comprehensive technical requirements and test criteria for such devices. This standard, which replaced the previous GB 17201-1997, was issued on July 2, 2007, and officially implemented on July 1, 2008, before being superseded on June 1, 2016. Nevertheless, its technical framework and regulatory principles remain of great reference value in the field of power equipment manufacturing and testing.
GB 17201-2007 is modified from IEC 60044-3:2002 “Instrument Transformers – Part 3: Combined Transformers” (MOD), aligning with international technical standards while incorporating adjustments tailored to China’s power system characteristics. The standard is classified under the CCS category K41 (Electrical Engineering – Power Transmission and Distribution Equipment – Transformers) and ICS category 29.180 (Electrical Engineering – Transformers, Reactors, Inductors), ensuring its compatibility with both national and international industry classification systems. It should be noted that Chapter 1, Chapter 2, Chapter 3, Chapter 4, and Clause 7.4 of this standard are recommendatory, while all other provisions are mandatory, highlighting the rigorous regulatory requirements for key technical indicators of combined instrument transformers.
The scope of application of GB 17201-2007 covers newly manufactured combined instrument transformers used for electrical measuring instruments and electrical protection devices, with a frequency range of 15Hz to 100Hz. The standard clearly specifies that in addition to the requirements and tests stipulated herein, the relevant provisions of GB 1207-2006 (Voltage Transformers) and GB 1208-2006 (Current Transformers) are also mandatory for combined instrument transformers. For combined transformers equipped with capacitive voltage transformers, the requirements and tests specified in GB/T 4703 are additionally applicable, forming a complete technical specification system covering different types of combined instrument transformers.
The technical content of GB 17201-2007 is structured systematically, encompassing multiple core modules such as scope, normative references, terms and definitions, normal and special service conditions, rated values, design requirements, tests, marking, and supplementary requirements for combined instrument transformers for measurement and protection. In terms of rated values, the standard not only puts forward general requirements but also classifies temperature rise limits into this chapter, clarifying the thermal performance indicators of the equipment during operation. The newly added Chapter 6 “Design Requirements” focuses on general design principles and transmission overvoltage control, addressing potential safety hazards in the design stage. Chapter 7 “Tests” classifies tests into type tests, routine tests, and special tests, with detailed provisions on the test scope, methods, and acceptance criteria for each type.
Regarding type tests, GB 17201-2007 specifies key items such as temperature rise tests and impulse tests on primary windings, which are crucial for verifying the long-term reliability and insulation performance of combined instrument transformers under rated operating conditions. Routine tests include power frequency withstand voltage tests on primary windings, measurement of capacitance and dielectric loss factor, ensuring that each product meets basic quality requirements before leaving the factory. Special tests focus on the measurement of transmission overvoltage, aiming to assess the device’s performance under abnormal voltage conditions. Additionally, the standard adds the item of “Radio Interference Voltage (RIV) Measurement” to the type tests, enhancing the electromagnetic compatibility requirements of the equipment.
A notable feature of GB 17201-2007 is the addition of Chapter 12 “Supplementary Requirements for Combined Instrument Transformers for Measurement and Protection”, which separately addresses the mutual influence between current transformers and voltage transformers. This chapter specifies the type test and routine test methods for errors of such combined transformers, emphasizing the impact of current-carrying conductor magnetic fields on voltage transformer errors and the impact of applied voltage on current transformer errors. The standard also includes informative appendices, such as the comparison of chapter and clause numbers with IEC 60044-3:2002, technical differences and their reasons, and detailed analysis of mutual influence, providing technical support for the understanding and application of the standard.
In terms of marking, GB 17201-2007 stipulates strict requirements for nameplate marking and terminal marking. Nameplates must clearly indicate key information such as the standard number, product model, rated parameters, and manufacturer’s information, while terminal marking must comply with uniform specifications to ensure correct installation and use. These provisions contribute to the standardized management of combined instrument transformers throughout their life cycle, from production to operation and maintenance.
GB 17201-2007 was proposed by the China Electrical Equipment Industrial Association, standardized by the National Technical Committee for Transformers and Instrument Transformers (SAC/TC 222), and drafted by multiple authoritative institutions including Shenyang Transformer Research Institute, Legend Electric (Shenyang) Co., Ltd., and Wuhan High Voltage Research Institute. The joint development of these institutions ensures the scientificity, authority, and practicality of the standard. During its implementation period, it effectively regulated the production and application of combined instrument transformers in China, improving the safety, reliability, and measurement accuracy of power systems.
In conclusion, GB 17201-2007, as an important national standard for combined instrument transformers, integrates international advanced experience with domestic practical needs, establishing a comprehensive and rigorous technical specification system. Although it has been superseded, its technical concepts and regulatory framework still provide valuable guidance for the research, development, manufacturing, and testing of combined instrument transformers. For professionals in the power industry, a thorough understanding of this standard is essential for ensuring the stable and efficient operation of power systems.