GB 20840.1-2010Instrument transformers - Part 1: General technical requirements (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents".

Drafting.

This document is Part 1 of GB/T (Z)20840 "Mutual Inductors". GB/T (Z)20840 has the following parts published.

---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 Instrument Transformers;

---Part 5: Supplementary Technical Requirements for Capacitive Voltage Transformers;

---Part 7: Electronic Voltage Transformers;

---Part 8: Electronic Current Transformers;

---Part 9: Digital Interface of Instrument 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 102: Ferromagnetic Resonance in Substations with Electromagnetic Voltage Transformers;

---Part 103: Application of instrument transformers in power quality measurement.

This document supersedes GB/T 20840.1-2010 "Electrical Transformers - Part 1: General Technical Requirements" and GB/T 20840.6-2017 "Electrical Transformers - Part 1: General Technical Requirements".

"Instruments - Part 6: Supplementary General Technical Requirements for Low-Power Instrument Transformers". This document is based on GB/T 20840.1-2010 and integrates...

The content of GB/T 20840.6-2017.Compared with GB/T 20840.1-2010, apart from structural adjustments and editorial changes, the main technical differences are...

The changes are as follows.

---Added all the content of GB/T 20840.6-2017 (see full text);

---The scope of application has been changed to apply to AC systems with a nominal voltage greater than 1kV or DC systems with a rated frequency of [missing information].

DC high-voltage equipment for 15Hz~400Hz or DC applications (see Chapter 1, Chapter 1 of GB/T 20840.1-2010);

---Terms and definitions are changed to directly reference the terms and definitions defined in GB/T 20840.99 (see Chapter 3, GB/T 20840.1-).

Chapter 3 (2010)

---Rated value.

- The high-voltage insulation level of Um=1100kV has been increased (see 5.2);

- The DC insulation resistance requirement for secondary terminals has been added (see 5.4.5.3);

---Design or structural changes or additions.

- Clarify the altitude correction and insulation test for external insulation (see 6.6, GB/T 20840.1-2010 6.6);

- Specify the maximum value of dissolved gases in the oil before multiple cutoff impact tests (see Table 16 in 6.8);

- Simplify the acceptance rules for internal arc fault protection levels (see 6.9, GB/T 20840.1-2010 6.9);

---Added mechanical strength requirements for products with Um > 800kV (see Table 15 in 6.7);

- Temperature rise test. Further clarify the test duration (see 7.2.2, 7.2.2 of GB/T 20840.1-2010);

- Lightning impulse test. The test criteria for other types of instrument transformers have been modified (see 7.2.3.2.3, GB/T 20840.1-2010).

7.2.3.2.1);

- Breaking impact test. changed from a special test to a type test (see 7.2.3.3, 7.4.1 of GB/T 20840.1-2010);

- Operational impact test. It is specified that gas-insulated instrument transformers shall be tested under two polarities (see 7.2.3.4, GB/T 20840.1-).

(2010, 7.2.3.3)

- Accuracy test. The test shall be conducted within the temperature range and frequency of interest (see 7.2.6, GB/T 20840.1-2010).

7.2.6);

- Mechanical strength test. changed from a special test to a type test (see 7.2.10, 7.4.4 of GB/T 20840.1-2010);

- Overvoltage transmission test. The test procedure has been improved (see 7.4.2, 7.4.3 of GB/T 20840.1-2010);

- Internal arc fault test. The test procedure is defined (see 7.4.3, 7.4.5 of GB/T 20840.1-2010);

- It is stipulated that "gas dew point measurement" should not only be a routine test, but also a commissioning test item (see 7.3.1 and 7.5.3).

GB/T 20840.1-2010, 7.3.1);

---Added experiments.

- Storage climate environment test (see 7.2.12);

- Partial discharge measurement. The requirement to record the partial discharge initiation voltage and extinction voltage has been added (see 7.3.3.2);

- Measurement of insulation resistance of secondary terminals (see 7.4.5);

- Thermomechanical endurance test (see 7.4.8);

- Seismic performance verification (see 7.4.11);

---Added requirements for transportation and storage environments (see 8.2);

---Added technical requirements and verification procedures for the seismic performance of instrument transformers (see Appendix C).

This document is modified to adopt IEC 61869-1:2023 "Instrument transformers - Part 1: General requirements".

This document has undergone several structural adjustments compared to IEC 61869-1:2023.A table comparing the structural numbering of the two documents can be found here.

Appendix A.

This document differs significantly from IEC 61869-1:2023.The relevant clauses are indicated in vertical margins.

Single lines (|) are indicated. A summary of these technical differences and their causes can be found in Appendix B.

The following editorial changes have been made to this document.

---All formulas in the text have been numbered;

---The scope has been reorganized, and IEC 61850 has been replaced with the informative reference DL/T 860 (see Chapter 1);

---IEC 61869-9 (see Chapter 1, Table 9, 7.2.6.2.1 and...) has been replaced by GB/T 20840.9-2017 (see Chapter 1, Table 9, 7.2.6.2.1 and...).

Appendix I);

---IEC 60068-2-1 is corrected to IEC 60068-2-1:2007 (see Chapter 2);

---IEC 60068-2-17 is corrected to IEC 60068-2-17:1994 (see Chapter 2 and 7.2.8);

---The URL for the terminology database has been removed (see 3.1);

---Added "Iepr. Rated primary current increase" and "Kepr. Rated primary current increase multiple" (see 3.2);

---IEC TS60815-1:2008 has been replaced by GB/T 26218.1-2010 (see 4.2.4), which is used for informational purposes.

---IEC 62271-1 has been replaced with GB/T 11022 (see note 2 in 4.3.3) for informational reference;

---The header content has been adjusted. "(Root Mean Square Value)" has been added after "Power Frequency Voltage Withstand Capability" and "(Impulse Voltage Withstand Capability)" has been updated.

---IEC 60044-8 has been replaced with GB/T 20840.8 (see 5.6.2) for informational reference;

---The table header format has been adjusted, and "error limit" has been added after the table title (see Table 8);

---The table header format has been adjusted, and "Error Limit" has been added after the table title. Additionally, paragraphs within the table have been changed to footnotes (see...).

Table 9);

---The format of the table header has been adjusted (see Table 10);

---IEC 60480 has been replaced with GB/T 8905 (see 6.2.2) for informational purposes;

---IEC 62271-203 has been replaced with GB/T 7674 (see note 6.2.5) for informational reference;

---IEC 62217 has been replaced with GB/T 22079 (see note 6.3 and C.4.2.5) for informative reference;

---Correct "maximum allowable value" to "minimum allowable value" in the last paragraph (see 6.4.1);

---The description of deltaTh is corrected from "temperature rise at altitude h" to "temperature rise limit at altitude h" (see 6.4.2);

---The references GB/T 26218.1-2010, GB/T 26218.2-2010, and GB/T 26218.3-2011 are used to replace the references respectively.

The standards IEC TS60815-1, IEC TS60815-2, and IEC TS60815-3 were replaced, with "the previous definition" replacing the obsolete standards.

IEC TR60815:1986 (see Table 14);

---IEC TS60815-2:2008 has been replaced by GB/T 26218.2-2010 and GB/T 26218.3-2011, respectively, which are used for informational reference.

And IEC TS60815-3:2008 (see 6.6.1);

---The phrase "power frequency wet test withstand voltage" in the explanation of formula m is corrected to "power frequency withstand voltage" (see 6.6.2);

---Adjust the "Minimum Detection Level" in the table header to "Equipment Minimum Detection Level" (see Table 16);

---The phrase "EMC testing on the terminals of the Sensor Electronic Data Sheet (TEDS) will be specified in IEC 61869-16" has been changed to "Sensing..." EMC testing on the terminals of the Electronic Data Sheet (TEDS) shall be conducted in the relevant section of the forthcoming GB/T 20840 (all parts).

---The test ports for conducted immunity testing (0kHz~150kHz) have been changed from "Binary input ports only" to "3, 4, 5, 6, 7".

(See Table 18);

---Correct "ISO/IEC 8802-3" to "ISO/IEC/IEEE8802-3" in the first paragraph (see 6.14.1.2);

---IEC 60812 is changed from informative reference to normative reference (see 6.20);

---Adjust "Withstand voltage test of low-voltage components and secondary terminals" and "Seismic performance" to "Impact withstand voltage test of low-voltage components and secondary terminals" respectively.

The sections "Test" and "Seismic Performance Verification" have been revised, and the sections "Casing Sealing Performance Test at Ambient Temperature" and "Casing Sealing at Low and High Temperatures" have been removed.

The word "shell" in "performance test" has been changed, and the headings of the corresponding test clauses have also been adjusted accordingly (see Tables 21 and 23).

7.2.8, 7.2.11, 7.3.9, 7.4.4 and 7.4.11);

---The phrases "in some countries" and "this issue has been discussed in CIGRE" in footnote b have been removed (see Table 22);

---The table title was changed from "Required Routine Tests" to "Required Routine Tests After Type Testing," the table format was adjusted, and some fields were deleted.

The clause numbers corresponding to the test items, as well as the two routine tests "Inspection of Markings" and "Pressure Resistance Test of Inflatable Shell," are added.

Added a note (see Table 23);

---Note 1 has been rewritten, with the following added. "For liquid-insulated transformers, this does not apply if tested in a third-party laboratory." "Test sequence restrictions" (see 7.1.3);

---IEC 60060-1 has been replaced with GB/T 16927.1 (referenced for informational purposes). The description of M in Figure 9 has been changed from "measuring device, input..." the resistance value of "RM" should be changed to "measuring device" (see 7.2.5.1);

---Adjust the symbol for the test voltage generator to a commonly used domestic symbol (see Figures 9, 11-13);

---IEC 62271-203:2022 has been replaced with GB/T 7674-2020 (see 7.2.9) for informational reference;

---IEC 62155 has been replaced with GB/T 23752 (see 7.2.9, 7.3.10 and C.4.2.5) for informational reference;

---Correct "±2°C" and "±3°C" in the table to "±2K" and "±3K" respectively (see Tables 25 and 26);

---IEC TR61869-103 (see 7.2.15) has been replaced by GB/T 20840.103 (reference standard).

---Adjust the test voltage applied from "between primary terminals (for phase-to-phase VT)" to "between primary terminals (for ungrounded voltage inductance)".

(See 7.3.2)

---Added supplementary explanation on partial discharge. "Note 2.For electromagnetic voltage transformers, in order to prevent core saturation, program A and program B..." the power frequency withstand voltage test in Section B refers to the induced withstand voltage test at a frequency higher than the rated frequency (see 7.3.3.2);

---Sub-map numbers have been added (see Figure 18);

---Item a) has been adjusted to a segment, and the item numbers have been adjusted accordingly (see 8.5.2);

---Columns a) and b) have been adjusted to segments, and the column numbers have been adjusted accordingly (see 8.5.3);

---The "Select" field in the table header has been changed to "Selected Seismic Resistance Level," and the guiding text "Test parameters are as follows." has been added (see Table C.1 and...).

C.4.3.6);

---IEC TS60815-2 has been replaced by GB/T 26218.2-2010 and GB/T 26218.3-2011, respectively, which are used for informational reference.

and IEC TS60815-3 (see D.1);

---IEC TS60815 has been replaced with GB/T 26218 (see Table F.1) for informational purposes;

---The heading has been changed from "Short-time Current and Dynamic Stability Current Withstand Tests" to "Short-time Current Tests" (see F.3.3);

---Added the guiding text "The following information was provided by the manufacturing testing laboratory". and "The drawings provided by the manufacturing testing laboratory..." See Table G.1 for examples. (See G.2 and G.3);

---Change the text below the figure from the main text to a figure caption (see Figures I.2 and I.6);

---Change the figure title from "Experimental Circuit for LPCT Digital Accuracy Measurement" to "LPCT Accuracy Measurement with A/D Converter" Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents.

This document was proposed by the China Electrical Equipment Industry Association.

This document is under the jurisdiction of the National Technical Committee on Standardization of Instrument Transformers (SAC/TC222).

1 Scope

This document only specifies general technical requirements for the ratings, design, structure, testing, transportation, storage, installation, and maintenance of various types of instrument transformers.

Technical requirements, and other supplementary technical requirements for various types of instrument transformers are specified in the dedicated sections of their respective product standards.

This document applies to measuring instruments and protection or control devices, systems with a nominal voltage greater than 1kV AC or 1.5kV DC.

Newly manufactured current transformers with analog or digital outputs and a rated frequency of 15Hz~400Hz or for DC applications. The nominal voltage is less than or equal to...

This document is for reference when using low-voltage instrument transformers for 1kV AC or 1.5kV DC systems.

Note 1.Bushing-type current transformers, although they do not have a primary insulation level themselves, are typically placed in AC systems with a nominal voltage greater than 1kV or DC systems with a nominal voltage greater than 1.5kV.

Therefore, it also falls within the scope of this document.

Example. Current transformers placed in GIS, high-voltage bushings, or cables.

Note 2.This document contains error limit requirements for analog or digital outputs. Other characteristics of the digital interface of the instrument transformer are specified in GB/T 20840.9-2017.

The standard, together with DL/T 860 (all parts), is applied to communication networks and systems for power automation.

Note 3.This document takes into account bandwidth requirements. Harmonic accuracy requirements and anti-aliasing filter requirements are specified in section 5.7.

Note 4.Figure 1 shows a general block diagram of a single-phase low-power instrument transformer (LPIT). Depending on the technology used, not all components listed in Figure 1 are required for the transformer.

Indispensable.

Note. The secondary power supply can be combined with the primary power supply or the power supply of other current transformers.

Figure 1 General block diagram of a single-phase LPIT

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included.

This document.

GB/T 311.1 Insulation coordination – Part 1: Definitions, principles and rules (GB/T 311.1-2012, IEC 60071-1) 2006, MOD) GB/T 1984 High-voltage AC circuit breakers (GB/T 1984-2024, IEC 62271-100:2021, MOD) GB/T 2423.1-2008 Environmental testing of electrical and electronic products – Part 2: Test methods – Test A. Low temperature (IEC 60068-2-1.

2007, IDT)

GB/T 2423.2-2008 Environmental testing of electrical and electronic products – Part 2: Test methods – Test B. High temperature (IEC 60068-2-2.

2007, IDT)