This part of the scope GB 20840 is applicable to electrical measuring instruments or relay protection devices. Newly manufactured electromagnetic voltage transformers with frequencies ranging from 15 Hz to 100 Hz. Note 301: This section does not include the supplementary technical requirements for three-phase voltage transformers, but the relevant parts of Chapter 4-10 Technical Requirements also apply to three-phase voltage transformers, and some clauses (such as 3.1.303, 5.5.301, 5.301.1, 5.301.2, 6, 13.301, and Table 303) already include a small amount of content related to them. All voltage transformers are suitable for measurement purposes. But certain types of voltage transformers are also suitable for protection purposes. Voltage transformers for both measurement and protection purposes shall comply with the requirements of all clauses in this section. The following normative references are essential for the application of this document. For dated references, only the dated version applies to this document. The latest version (including all modification orders) of any referenced document without specifying the date applies to this document. Chapter 2 of GB 20840.1-2010 and the following additions apply. GB/T 156 Standard Voltages (GB/T 156-2007, IEC 600382002, IEC Standard Voltages, MOD) GB 311.1 Insulation Coordination, Part I: Definitions, Principles, and Rules (GB 311.1-2012, IEC 60071-1:2006. MOD) GB/T 2900.15 Electrotechnical Terminology, Transformers, Transformers, Voltage Regulators, and Reactors (GB/T 2900.151997, IEC 60050 (421): 199o, IEC 60050 (321): 1986, NEQ) GB/T5585.1 Copper for Electrical Purposes Aluminum and its alloy busbars Part 1: Copper and copper alloy busbars GB/T 7252 Guidelines for the analysis and judgment of dissolved gases in transformer oil (GB/T 7252-2001, IEC 605991999, NEQ) GB/T 7595 Quality of transformer oil in operation GB 20840,1-2010 Transformer Part 1: General technical requirements (IEC 61869-1; 2007, MOD) GB/T 22071.2 Transformer testing guidelines Part 2: Electromagnetic voltage transformer 3 Terms and definitions
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