GB/T 1094.7-2024Power transformers - Part 7: Loading guide for mineral-oil-immersed power transformers (English PDF)

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1: Structure and drafting rules for standardization documents" Drafting.

This document is Part 7 of GB/T 1094 "Power Transformers". GB/T 1094 has published the following parts.

--- Part 1: General;

--- Part 2: Temperature rise of liquid immersed transformers;

--- Part 3: Insulation levels, insulation tests and external insulation air gaps;

--- Part 4: Guidelines for lightning impulse and switching impulse tests on power transformers and reactors;

--- Part 5: Ability to withstand short circuit;

--- Part 6: Reactors;

--- Part 7: Guidelines for loading of oil-immersed power transformers;

--- Part 10: Determination of sound levels;

--- Part 101: Application Guidelines for Sound Level Determination;

--- Part 11: Dry-type transformers;

--- Part 12: Guidelines for loading of dry-type power transformers;

--- Part 14: Liquid immersed power transformers using high temperature insulating materials;

--- Part 15: Gas-filled power transformers;

--- Part 16: Transformers for wind power generation;

--- Part 18: Frequency response measurement;

--- Part 23: DC bias suppression device.

This document replaces GB/T 1094.7-2008 "Power transformers Part 7: Loading guidelines for oil-immersed power transformers" and Compared with GB/T 1094.7-2008, in addition to structural adjustments and editorial changes, the main technical changes are as follows.

--- Added some new research results on insulation life (see Chapter 6);

--- Added the recommended maximum core temperature (see Chapter 7);

--- Increased the number of fiber optic sensors recommended for use in temperature rise tests (see Chapter 8);

--- The thermal model has been modified and rewritten in a generally applicable mathematical form (see Chapter 8, Chapter 8 of the 2008 edition).

This document is modified to adopt IEC 60076-7:2018 "Power transformers Part 7: Guidelines for loading of oil-immersed power transformers".

This document has made the following structural adjustments compared to IEC 60076-7:2018.

Adjust Annex H, Annex E and Annex G of IEC 60076-7:2018 to Annex E, Annex G and Annex H respectively.

The technical differences between this document and IEC 60076-7:2018 and their reasons are as follows.

--- The normative references GB/T 1094.2 and GB/T 1094.14 replace IEC 60076-2 and IEC 60076-14 respectively, to apply According to the technical conditions of our country;

--- Added normative references to GB/T 2900.95 (see Chapter 3);

--- Deleted the last paragraph of 5.5."For sealed transformers without pressure relief devices, the problem of excessive pressure should be considered to avoid the fuel tank is not allowed to deform permanently when the load exceeds the nameplate rating, in order to meet the actual situation in my country.

The following editorial changes were made to this document.

---The content of Chapter 1 has been adjusted;

--- Adjust "Note 1" in 3.4, 3.5, 3.11, 3.13, 3.14, 3.15 and 3.16 to "Note";

--- In Chapter 4, an introductory phrase is added, and "WOP" is changed to "WCO", "ppm" is changed to "mg/L", and the arrangement of symbols and abbreviations is adjusted.

The column order was adjusted;

--- Change IEC 60076-1:2011 in Note 5.2 to GB/T 1094.1-2013;

---Change "ppm" in paragraph 5 of 6.2 to "uL/L", "200%" in paragraph 6 to "200", and "ppm" in the title of Figure 3 Change to "uL/L";

--- Correct the paragraph in Table 1 of 6.3 to a note;

--- Correct "150mWb/phase or less" in c) of 8.1.3 to "<=150mWb/phase";

--- Correct Table 5 in the note of 8.2.1 to Table 4;

---Change EA (kJ/mol) in the third row of Table A.1 to EA (J/mol), 128 to 128000, 89 to 89000, 86 to 86000, 82 changed to 82000; Deleted the fifth paragraph of A.2 "The same method can also be used to improve the IEEE on aging the content of "Equation for the speed coefficient FAA and the equivalent aging coefficient FEQA"; Correct the paragraphs in Table A.3 and Table A.4 to Notes; Change Table A.4 Correct 10.07 to 10.1; Correct "E" in formula (A.3) to "EA";

--- The text structure of Appendix C and Appendix E (Appendix G in this document) has been adjusted;

--- Correct 8.2.3 in paragraph 1 of F.1 to 8.2.2;

--- In Appendix G (Appendix H in this document), the "x-axis --- loss, in kW" and "y-axis --- loss, in kW" in the symbol description of Figure G.1 are replaced by the time in hours is corrected to "x-axis --- time in hours (h)" and "y-axis --- loss in kilowatts" (kW)"; Correct the first sentence of 3) in G.4."After recording the thermal resistance measurement value at rated current" to "70% of rated current" After the thermal resistance measurement value of the flow is recorded";

--- Correct "time (y axis)" in the symbol description of Figures I.1 and I.2 to "abscissa axis --- time";

---Correct "thetao(t=1)=76.5°C" and "thetah(t=1)=111°C" in Appendix K to "thetao(t=31)=76.5°C" respectively.

and "thetah(t=31)=111°C", "deltathetahi1=4.95K" was corrected to "deltathetahi2=4.95K", and Table K.1 and Table K.2 were adjusted.

structure;

---The references were adjusted.

Introduction

The purpose of formulating the power transformer standard is to establish a set of optimal evaluation criteria for power transformers, and to provide a reference for the selection of raw materials for power transformers.

GB/T 1094 series of standards aims to provide guidance on the matters needing attention in selection, design, production, inspection, selection, operation and maintenance.

The 16-part series of regulations will be used to formulate principles and rules for the design, manufacture, testing, operation and maintenance of power transformers.

constitute.

--- Part 1: General. The purpose is to establish the principles that need to be followed for the design, manufacture and production testing of various types of power transformers.

General principles and relevant rules.

--- Part 2: Temperature rise of liquid immersed transformers. The purpose is to establish the temperature rise of various types of liquid immersed power transformers technical requirements and test methods.

--- Part 3: Insulation level, insulation test and external insulation air gap. The purpose is to establish the requirements for various types of liquid immersed power transformers.

Technical requirements and insulation test methods for insulation levels, insulation tests and external insulation air gaps of devices.

--- Part 4: Guidelines for lightning impulse and switching impulse tests on power transformers and reactors. The purpose is to establish Technical requirements and test methods for lightning impulse tests and switching impulse tests on power transformers and reactors.

--- Part 5: Short-circuit withstand capability. The purpose is to establish the short-circuit withstand capability applicable to various types of power transformers.

Technical requirements and test methods.

--- Part 6: Reactors. The purpose is to establish technical requirements and test requirements applicable to various types of reactors.

--- Part 7: Loading guidelines for oil-immersed power transformers. The purpose is to evaluate the performance of various mineral oil-immersed power transformers from the perspective of operating temperature and thermal aging.

Provide guidance on the loading conditions of immersion-type power transformers.

--- Part 10: Sound level measurement. The purpose is to establish technical specifications for sound level measurement for various types of power transformers and reactors.

Technical requirements and test methods.

--- Part 101: Guidelines for the application of sound level measurement. The purpose is to provide guidance on the application of sound level measurement for various types of power transformers and reactors.

Provide guidance on this.

--- Part 11: Dry-type transformers. The purpose is to establish technical requirements and test requirements applicable to various types of dry-type power transformers.

--- Part 12: Guidelines for loads on dry-type power transformers. The purpose is to provide guidance on the load operation of various types of dry-type power transformers.

For guidance.

--- Part 14: Liquid immersed power transformers using high temperature insulation materials. The purpose is to establish the applicable Technical requirements and test requirements for liquid immersed power transformers of materials.

--- Part 15: Gas-filled power transformers. The purpose is to establish technical requirements and test methods applicable to various types of gas-filled power transformers.

Test requirements.

--- Part 16: Transformers for wind power generation. The purpose is to establish technical requirements and test methods applicable to various types of wind power transformers.

Test requirements.

--- Part 18: Frequency response measurement. The purpose is to establish technical requirements for frequency response of various types of power transformers.

Summation test method.

--- Part 23: DC bias suppression devices. The purpose is to establish technical requirements and test methods applicable to various types of DC bias suppression devices.

Test requirements.

GB/T 1094 defines the technical contents of various types of power transformers and reactors through 16 parts, and gives specific technical specifications.

Technical requirements, test items, test procedures, test methods and operation instructions, etc. By establishing clear scope, terminology, technical requirements for various products and test requirements, so that personnel engaged in related product design, production, testing, use, operation and maintenance can more clearly and accurately to lay a foundation for the design and manufacture of high-quality products, better promote trade, exchanges and technical cooperation, and provide a solid foundation for my country's power grid to ensure the normal operation of the system.

This document provides guidelines for the specification and loading of power transformers from the perspective of operating temperature and thermal aging.

The system provides guidance for designers in selecting appropriate ratings and loading conditions for new equipment.

Power transformers Part 7.

Guidelines for loading of oil immersed power transformers

1 Scope

This document describes the effects of operating a transformer at different ambient temperatures and load conditions on its lifetime.

This document applies to mineral oil immersed power transformers.

Note. The user should consult the manufacturer for the special load capacity of the electric furnace transformer.

2 Normative references

The contents of the following documents constitute essential clauses of this document through normative references in this document.

For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies to this document.

GB/T 1094.2 Power transformers Part 2: Temperature rise of liquid immersed transformers (GB/T 1094.2-2013, IEC 60076-2.

2011,MOD)

GB/T 1094.14 Power transformers Part 14: Liquid-immersed power transformers using high temperature insulating materials (GB/T 1094.14-2022,IEC 60076-14:2013,MOD) GB/T 2900.95 Electrical terminology transformers, voltage regulators and reactors (GB/T 2900.95-2015, IEC 60050-421.

1990,NEQ)

3 Terms and definitions

The terms and definitions defined in GB/T 2900.95 and the following apply to this document.

Small power transformersmalpowertransformer Power transformers, regardless of rating, without attached (removable) radiators, coolers or radiator pipes (including corrugated oil tanks).

Power transformers with a maximum three-phase rated capacity of 100MVA and a maximum single-phase rated capacity of 33.3MVA.

Power transformers with a three-phase maximum rated capacity greater than 100MVA and a single-phase maximum rated capacity greater than 33.3MVA.

Cyclic loading

A load that varies periodically (the duration of the cycle is usually 24 hours) is considered based on the accumulated aging within one cycle.

Note. Cyclic loads can be either normal loads or long-term emergency loads.

Normal cyclic loading During part of a load cycle, the ambient temperature is high or a load greater than the rated load current is applied, but from the relative thermal