GB/T 20840.10-2025Instrument transformers - Part 10: Additional requirements for low-power passive current 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 10 of GB/T 20840 "Transformers". GB/T 20840 has published the following parts.

--- Part 1: General technical requirements;

--- Part 2: Supplementary technical requirements for current transformers;

--- Part 3: Supplementary technical requirements for electromagnetic voltage transformers;

--- Part 4: Supplementary technical requirements for combined transformers;

--- Part 5: Supplementary technical requirements for capacitor voltage transformers;

--- Part 6: Supplementary general technical requirements for low power transformers;

--- Part 7: Electronic voltage transformer;

--- Part 8: Electronic current transformer;

--- Part 9: Digital interface for transformers;

--- Part 10: Supplementary technical requirements for low power passive current transformers;

--- Part 11: Supplementary technical requirements for low power passive voltage transformers;

--- Part 14: Supplementary technical requirements for DC current transformers;

--- Part 15: Supplementary technical requirements for DC voltage transformers;

--- Part 99: Terminology;

--- Part 100: Application Guidelines for Current Transformers for Power System Protection;

--- Part 102: Ferroresistance in substations with electromagnetic voltage transformers;

--- Part 103: Application of transformers in power quality measurements.

This document is modified to adopt IEC 61869-10:2017 "Transformers - Part 10: Supplementary technical requirements for low power passive current transformers" beg".

Compared with IEC 61869-10:2017, this document has many structural adjustments. Comparison table of structural changes between the two documents See Appendix 10A.

This document has many technical differences compared with IEC 61869-10:2017.

A list of these technical differences and their reasons is given in Appendix 10B.

The following editorial changes were made to this document.

--- The order of symbols has been adjusted (see 3.7);

--- Change "phitdr is 0" to "the phase shift (phitdr) caused by the rated delay time is 0" (see 5.6.1001);

--- The header format of Table 1001 and Table 1002 has been adjusted (see 5.6.1003.3 and 5.6.1004.4);

--- Change the title of Table 1002 from "Error Limits" to "Protection Passive LPCT Ratio Difference and Phase Error Limits", Composite the error symbols "epsilonc, epsiloncorI" are corrected to "epsilonc, epsilonccorI" (see 5.6.1004.4);

--- Added "Note. Derivative type LPCT preferably uses 150mV" (see 5.1004);

---Change "Example 2.5P31000A of passive LPCT for protection, Example 3.0.2/5P31000A of multi-purpose passive LPCT" to Change to "Example 2.5P31500A of passive LPCT for protection, Example 3.0.2(5P 31500A)" (see 6.13.1005);

--- Added the introductory sentence of Table 1003."Table 1003 gives the pin assignment of passive LPCT using RJ45 type connector" (see 6.602.1);

--- Correct (I2th × 1s) to (I2th × tth) and add "where tth is the specified duration of the rated short-time thermal current (Ith)" (see 7.2.1001);

--- The format of Table 1004 was adjusted, and the definition item number corresponding to CFI was corrected from "3.4.1003" to "3.4.1001";

--- Adjust the text content in the upper part of Figure 10A.1 of IEC 61869-10:2017 to the title of the sub-figure, and correct "LPPC" to "LPCT";

---Correct "1%" and "0.1%" in the titles of Figures 10A.3 and 10A.4 of IEC 61869-10:2017 to "1" and "0.1%" respectively "0.1", and the curve position was corrected;

--- The format of Table 10A.2 of IEC 61869-10:2017 was adjusted and some data were corrected;

--- Correct the symbol "RB" for high impedance load in Figure 10B.1 of IEC 61869-10:2017 to "Rb";

--- The winding symbol in Figure 10C.1 and the inductance symbol in Figure 10C.2 of IEC 61869-10:2017 have been adjusted;

--- Replace the "low power passive current transformer" that appears repeatedly in the text with the abbreviation "passive LPCT";

---The formulas in the whole text are numbered;

--- Replaced IEC 61869-8 with the informative reference GB/T 20840.8 (see Chapter 1, Table 1003);

--- Replaced IEC 61869-6:2016 with the informative reference GB/T 20840.6-2017 (see 5.6.1001, 5.6.1003.3,

--- Replaced IEC 61869-2 with the informative reference GB/T 20840.2 (see Note to Table 1002);

--- Replaced IEC 61869-7 with the informative reference GB/T 20840.7 (see Table 1003);

--- Replaced IEC 60028 with the informative reference GB/T 5585.1 (see 7.2.1001);

--- Replaced IEC 60121 with the informative reference GB/T 3954 (see 7.2.1001).

Introduction

The purpose of formulating the transformer standard is to establish a set of optimal evaluation criteria for the transformer, and to provide a reference for the selection of raw materials, design, production and GB/T 20840 aims to specify the precautions applicable to transformers.

The principles and relevant rules to be followed in design, manufacturing, testing, operation and maintenance are planned to consist of 17 parts.

--- Part 1: General technical requirements. The purpose is to establish the requirements for the design, manufacture and production testing of various types of transformers.

General technical requirements to be followed.

--- Part 2: Supplementary technical requirements for current transformers. The purpose is to establish supplementary technical requirements applicable to various types of current transformers.

Require.

--- Part 3: Supplementary technical requirements for electromagnetic voltage transformers. The purpose is to establish the requirements applicable to various types of electromagnetic voltage transformers.

Supplementary technical requirements.

--- Part 4: Supplementary technical requirements for combined transformers. The purpose is to establish supplementary technical requirements applicable to various types of combined transformers.

Require.

--- Part 5: Supplementary technical requirements for capacitor voltage transformers. The purpose is to establish the requirements applicable to various types of capacitor voltage transformers.

Supplementary technical requirements.

--- Part 6: Supplementary general technical requirements for low power transformers. The purpose is to establish supplementary general technical requirements applicable to various types of low power transformers.

Fill in the general technical requirements.

--- Part 7: Electronic voltage transformers. The purpose is to establish supplementary technical requirements applicable to various types of electronic voltage transformers.

--- Part 8: Electronic current transformers. The purpose is to establish supplementary technical requirements applicable to various types of electronic current transformers.

--- Part 9: Digital interfaces for transformers. The purpose is to establish technical requirements for digital interfaces applicable to various types of electronic transformers.

--- Part 10: Supplementary technical requirements for low power passive current transformers. The purpose is to establish Supplementary technical requirements for current transformers.

--- Part 11: Supplementary technical requirements for low power passive voltage transformers. The purpose is to establish Supplementary technical requirements for voltage transformers.

--- Part 14: Supplementary technical requirements for DC current transformers. The purpose is to establish supplementary technical requirements applicable to various types of DC current transformers.

Fill in the technical requirements.

--- Part 15: Supplementary technical requirements for DC voltage transformers. The purpose is to establish the requirements applicable to various types of DC voltage transformers.

Supplementary technical requirements.

--- Part 99: Terminology. The purpose is to establish terms and definitions applicable to various types of transformers.

--- Part 100: Guidelines for the application of current transformers for power system protection. The purpose is to Provide guidance on the application of protection.

--- Part 102: Ferroresistance in substations with electromagnetic voltage transformers.

Provide guidance on the generation and suppression of ferromagnetic resonance in substations with voltage transformers.

--- Part 103: Application of transformers in power quality measurement. The purpose is to describe the application of various types of transformers in power quality measurement.

Provide guidance on use.

GB/T 20840 defines the technical specifications of various types of transformer products through 17 parts, and gives specific technical requirements, test items, by establishing clear scope, terminology, technical requirements and test requirements for various products So that people engaged in product design, production, testing and use can operate more clearly and accurately, thus providing it lays the foundation for manufacturing high-quality products, better promotes trade, exchanges and technical cooperation, and provides guarantee for the normal operation of my country's power grid.

This document is consistent with GB/T 20840.1-2010 "Mutual Inductors Part 1: General Technical Requirements" and GB/T 20840.6-2017 "Mutual Inductors this document complies with GB/T 20840.1-2010 and the writing structure of GB/T 20840.6-2017 is to supplement and modify the corresponding clauses.

When the provisions of GB/T 20840.6-2017 are not mentioned in this document, they shall also apply to this document as long as it is reasonable.

When the document indicates "supplement", "modification" or "replacement", it means the relevant part of GB/T 20840.1-2010 or GB/T 20840.6-2017.

The terms are adapted accordingly in this document.

For the chapters, clauses, figures, tables, notes and appendices added on the basis of GB/T 20840.1-2010 and GB/T 20840.6-2017, this the documents are numbered in the following format.

--- The numbering of chapters, articles, figures, tables and notes starts from 1001;

---Appendices are numbered 10A, 10B, etc.

Low power passive current transformer (passive LPCT) is based on passive technology, does not contain any active electronic components, and the output is the same as the primary current.

A signal proportional to the primary current is used, such as an iron core coil with an integrated shunt resistor as a current-to-voltage converter (primary converter), or an output proportional to the primary current.

A signal proportional to the derivative of the current, such as an air-core coil (Rogowski coil). This document does not include air-core coils with active integrators.

According to the general block diagram given in Figure 601 of GB/T 20840.6-2017, the low-power passive current transformer does not use an active primary converter (i.e., does not use any active electronic components), so no primary power supply is required. In addition, no secondary converter or secondary power supply.

Figure 1001 shows a general block diagram of a low power passive current transformer.

The components required for low power passive current transformers are determined by the technology used. The transmission cable or a the secondary converter is not essential for low power passive current transformers. The derivative type LPCT solution uses only the air core coil as the primary transformer.

The transmission cable is used as the transmission system. When using this technology, the primary converter is not considered. The proportional LPCT solution will the iron core coil is used as a primary sensor, the load resistor is directly connected to the coil output as a primary converter, and the transmission cable is used as a transmission system.

Figure 1001 General block diagram of a single-phase low-power passive current transformer

Instrument transformers Part 10: Low power passive current transformers Supplementary technical requirements for transformers

1 Scope

This document specifies the terms and definitions, ratings, design, and Supplementary technical requirements for design and structure, testing and consultation, bidding and ordering instructions, etc.

This document is applicable to the rated frequency of 15Hz~100Hz, used for measuring and protecting electrical measuring instruments or relay protection devices.

And a multi-purpose newly manufactured analog output passive LPCT with both measurement and protection functions.

This document does not apply to electronic current transformers with digital outputs or using any type of active electronic component technology.

NOTE 1.5.6.1003 gives the accuracy requirements necessary for passive LPCTs used in gas measuring instruments.

NOTE 2.5.6.1004 gives the accuracy requirements necessary for passive LPCTs used in relay protection devices, especially for currents up to several times the rated current.

In addition, the transient accuracy of the passive LPCT during a fault is given if required.

Accuracy.

Note 3.Passive LPCTs have only analog voltage outputs (for digital outputs or using any type of active electronic components, refer to the technical reference GB/T 20840.8). Such a passive LPCT may include a secondary signal cable (transmission cable). Appendix 10C gives the use of air-core coils (Ro Appendix 10D gives the working principle of the derivative type LPCT using an integrated shunt resistor.

Working principle of LPCT.

2 Normative references

The contents of the following documents constitute the 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.

Chapter 2 of GB/T 20840.6-2017 and the following supplements are applicable.

GB/T 762 standard current level (GB/T 762-2002, IEC 60059:1999, MOD) GB/T 20840.1 Transformers Part 1: General Technical Requirements (GB/T 20840.1-2010, IEC 61869-1:2007, MOD) GB/T 20840.6 Transformers Part 6: Supplementary general technical requirements for low power transformers (GB/T 20840.6-2017, IEC 61869-6:2016, MOD)

3 Terms and definitions

The terms and definitions defined in GB/T 20840.1 and GB/T 20840.6 and the following supplements and modifications apply to this document.