GB/T 1094.3-2017Power transformers -- Part 3: Insulation levels, dielectric tests and external clearances in air (English PDF)

Foreword

GB/T 1094 "Power Transformer" is divided into the following parts.

--- Part 1. General;

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

--- Part 3. Insulation level, insulation test and external insulation air gap;

--- Part 4. Guidelines for lightning impulse and operational shock tests of power transformers and reactors;

--- Part 5. Ability to withstand short circuits;

---Part 6. Reactors;

---Part 7. Oil-immersed power transformer load guide;

--- Part 10. Sound level measurement;

--- Section 10.1. Guidelines for the application of sound level determination;

--- Part 11. Dry-type transformers;

--- Part 12. Dry power transformer load guidelines;

--- Part 14. Design and application of liquid immersed transformers using high temperature insulating materials;

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

--- Part 18. Frequency response measurement.

This part is the third part of GB/T 1094.

This part is drafted in accordance with the rules given in GB/T 1.1-2009.

This part replaces GB/T 1094.3-2003 "Power transformers Part 3. Insulation level, insulation test and external insulation air Gap", compared with GB/T 1094.3-2003, the main technical changes are as follows.

--- Adjusted the normative references (see Chapter 2, Chapter 2 of the 2003 edition);

--- Increased the definition of the rated voltage of the winding (see Chapter 3, Chapter 3 of the 2003 edition);

--- Adjusted the insulation level mark (see Chapter 5, Chapter 5 of the 2003 edition);

--- Adjusted the insulation test sequence and test items (see Chapter 7, Chapter 7 of the 2003 edition);

--- Operational impact test for Um=126kV transformers (see Chapter 7, Chapter 7 of the 2003 edition);

--- Inductive withstand voltage (voltage) test adjusted to Ur based, and adjusted pre-applied voltage, measured voltage, measurement of partial discharge measurement Time and partial discharge limits (see Chapter 11, Chapter 12 of the 2003 edition);

--- Added winding insulation level and neutral point insulation level of the system with nominal voltage of 750kV and 1000kV transformer the air gap is added and the relevant test requirements are added (see Chapters 7 and 16 and Chapters 7 and 16 of the 2003 edition);

--- Take the winding line end AC withstand voltage test as a separate test item (see Chapter 7 and Chapter 12, Chapter 7 of the 2003 edition);

--- The requirements for lightning impulse test and operational impact test have been adjusted (see Chapters 13 and 14 and the 13th edition of the 2003 edition).

Chapters 14 and 15);

---The air gap of the external insulation has been adjusted (see Chapter 16, Chapter 16 of the 2003 edition);

--- The appendix has been adjusted, and the appendix "Test Voltage for ACSD Test" has been deleted. The new "Inquiry and Ordering" are required.

"Information on transformer insulation requirements and insulation test" and "Basic principles for determining insulation test, insulation level and insulation clearance" Appendix (see Appendix B and Appendix D, Appendix D of the 2003 edition).

This part uses the redrafting method to modify the use of IEC 60076-3:2013 "Power Transformers Part 3. Insulation Level, Insulation Test and external insulation air gap.

There are technical differences between this part and IEC 60076-3:2013. The terms involved in these differences have been passed on the outer side of the page.

The vertical single line (|) at the white position is identified, and a list of the corresponding technical differences and their causes is given in Appendix A.

This section also made the following editorial changes.

--- The voltage in the full text example has been adjusted according to the actual situation in China;

--- Removed the "Note" of 3.6 in IEC 60076-3:2013;

--- Removed the comment on "Line-end lightning intercept shock test" in 7.1 of IEC 60076-3:2013;

--- Added the suggestive content that the induced voltage between phases may exceed the specified insulation level in the test in 7.3.2.1;

--- The "Lightning Crash Impact Test (LIC)" and "Neutral Terminal Terminal Lightning" in 7.3.2.2 of IEC 60076-3:2013 Test (LIN) is adjusted to type test and as part of 7.3.2.2 of this part, 7.3.2.2 of IEC 60076-3:2013 the other three pilot projects in the series continue to serve as special tests and serve as the content of 7.3.2.3 of this section;

--- "Thunder Cut Shock Test (LIC)" in 7.3.3.1 of IEC 60076-3:2013 and "Neutral Terminal" in 7.3.3.2 the lightning full impact test (LIN) is adjusted to the type test and, as part of 7.3.3.2 of this part, IEC 60076-3.

The other three pilot projects in 7.3.3.1 of 2013 continue to be routine tests and will serve as the content of 7.3.3.1 of this section.

The other two test items in 7.3.3.2 of IEC 60076-3:2013 continue to be special tests and serve as part of this the content of 7.3.3.3;

--- Adjust the contents of Table 1 of IEC 60076-3:2013 to the content of E.1 of this part;

--- Adjust the contents of Tables 2 and 3 of IEC 60076-3:2013 to the content of E.2 of this part;

--- Adjust the contents of 7.4 of IEC 60076-3:2013 to the content of E.3 of this part;

--- Added a fully insulated transformer in 13.4.1, the neutral point is not taken out when the lightning full wave impact test voltage value and Relevant instructions on how to apply;

--- Removed the notes in Chapter 9 of IEC 60076-3:2013 and Note 2 of 16.1;

--- The principle of determining the minimum air gap for external insulation in Chapter 16 of IEC 60076-3:2013 and the minimum air between external insulation the gap value is adjusted to the content of E.4 of this part;

--- Adjust the order of the appendix, add Appendix A to this section, and change Appendix A of IEC 60076-3:2013 to this Part of Appendix F, Appendix B is changed to Appendix C of this part, Appendix C is changed to Appendix D of this part, and Appendix D is changed to this part.

For the contents of Appendix E.5, Appendix E is changed to Appendix B of this part.

This part was proposed by China Electrical Equipment Industry Association.

This part is under the jurisdiction of the National Transformer Standardization Technical Committee (SAC/TC44).

This section was drafted. Shenyang Transformer Research Institute Co., Ltd., Baoding Tianwei Baobian Electric Co., Ltd., China Electric Power Institute of Research, National Transformer Quality Supervision and Inspection Center, Special Transformer Shenyang Transformer Group Co., Ltd., Xi'an Xidian Transformer Ren, Zhengtai Electric Co., Ltd., TBEA Hengyang Transformer Co., Ltd., Changzhou Xidian Transformer Co., Ltd., State Grid Lin Power Co., Ltd. Electric Power Research Institute, Shunte Electric Equipment Co., Ltd., Mingzhu Electric Co., Ltd., Xinhuadu Special Electric Co., Ltd., Electric Power Research Institute of Guangdong Power Grid Co., Ltd., State Grid Shaanxi Electric Power Company Electric Power Research Institute, Guangdong Olympics Ryan Power Technology Co., Ltd., Guangdong Zhongpeng Electric Co., Ltd., Guangzhou Zhongche Junfa Electric Co., Ltd., Baoding Baoling Transformer Limited company, Baoding Tianwei Group Special Transformer Electric Co., Ltd., China Guangdong Nuclear Power Engineering Co., Ltd.

Introduction

This section specifies the insulation requirements and corresponding insulation tests for the specified windings and their terminals. This section also recommends the power transformer outside Air gap at the edge (Chapter 16).

The insulation levels and insulation tests specified in this section apply only to internal insulation. Although the specified rated withstand voltage value of the transformer is insulated as a basis for external insulation is reasonable, but this approach may not meet all the actual conditions. Failure of non-self-recoverable internal insulation it is catastrophic and usually causes the transformer to run out for a long time. When an external flashover occurs, it may only cause a short interruption in operation.

Does not cause permanent damage. Therefore, in order to improve safety, the user can specify the test voltage value of the insulation inside the transformer than the system the outer insulation of his equipment is higher. When there is such a difference, the outer insulation gap of the transformer should be adjusted to fully withstand the internal insulation test.

Inspection requirements.

Appendix B proposes to determine the insulation test, insulation level and external insulation air gap of the transformer according to the highest voltage Um of the equipment.

The basic principle.

Power transformers - Part 3. Insulation levels, Insulation test and external insulation air gap

1 Scope

This part of GB/T 1094 specifies the relevant insulation test and minimum insulation test level used in power transformers. When the user does not when specified, this section recommends the minimum air insulation gap between the live parts of the transformer and their grounding.

This section applies to the power transformer specified in GB/T 1094.1. For certain types of power transformers and electricity with their own standards Reactors, this section only applies if explicitly referenced by these standards.

2 Normative references

The following documents are indispensable for the application of this document. For dated references, only dated versions apply to this article.

Pieces. For undated references, the latest edition (including all amendments) applies to 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 1094.1 Power transformers Part 1. General (GB/T 1094.1-2013, IEC 60076-1:2011, MOD) GB/T 2900.95 Electrotechnical terminology transformers, voltage regulators and reactors (GB/T 2900.95-2015, IEC 60050-421.

1990, NEQ)

GB/T 4109 Insulating bushing with AC voltage higher than 1000V (GB/T 4109-2008, IEC 60137Ed.6.0, MOD) GB/T 7354 partial discharge measurement (GB/T 7354-2003, IEC 60270:2000, IDT) GB/T 16927.1-2011 Part 1 . General definitions and test requirements (IEC 60060-1:2010, MOD) GB/T 16927.2 High Voltage Test Technique Part 2. Measurement System (GB/T 16927.2-2013, IEC 60060-2.

2010, MOD)

3 Terms and definitions

The following terms and definitions as defined in GB/T 1094.1 and GB/T 2900.95 apply to this document.

The highest voltage for the transformer winding equipment highestvoltageforequipmentapplicabletoatransformerwinding Um the rms value of the highest voltage between phases in a three-phase system, the transformer winding insulation is designed according to this.

The rated voltage of the winding is ratedvoltageofawinding Ur Induced during application of voltage or no load between terminals with tapped windings in main tap or between winding terminals without tapping Voltage. For three-phase windings, the voltage between the line terminals.

Note 1. When the voltage applied to one winding is rated, under no-load conditions, all windings have their own rated voltage values at the same time.

Note 2. Phase-phase power is used for single-phase transformers that are to be connected to a three-phase group of star-junctions or to a single-phase transformer between a line and a neutral point of a three-phase system.

The voltage is divided by 3 to indicate the rated voltage. For example 500/3kV.

Note 3. For single-phase transformers to be connected to the network phase, the phase-to-phase voltage is used to indicate the rated voltage.

Note 4. For a series winding of a three-phase series transformer, if the winding is designed as an open winding, the rated voltage is given according to the winding junction into a star junction.

Rated insulation level A set of rated withstand voltages that indicate the dielectric strength characteristics of the insulation.

Rated withstand voltage Used for the test voltage value specified in the standard insulation withstand voltage test to prove that the insulation meets the specified test voltage.

Fully insulateduniforminsofatransformerwinding of transformer windings all outlet ends connected to the transformer winding terminals have the same specified insulation level.

Graded insulation of transformer windings non-uniforminsulationofatransformerwinding when the neutral point terminal of the transformer winding is directly or indirectly grounded, the insulation level of the neutral point design is lower than the insulation specified by the line end.

Level.

4 General

The insulation requirements of the power transformer and the corresponding insulation test are specified in the specified winding and its terminals.

For liquid immersed transformers or gas filled transformers, these requirements apply only to internal insulation. External insulation supplement requirements or tests shall be manufactured the party agrees with the user. If the user has no special requirements for the outer insulation air gap of the transformer, it shall be carried out in accordance with the provisions of Chapter 16. If used If the wiring on the transformer may reduce the original gap distance of the transformer, it should be specified at the time of inquiry.

The casing shall be subjected to type test and routine test in accordance with GB/T 4109 (including appropriate casings to meet the test level of special transformers).

Test level) to verify its relative external and internal insulation.

When the transformer needs to operate at an altitude of more than 1000m, the clearance distance should be designed according to its requirements. It is also necessary to choose Casings with higher insulation levels for casings operating at lower altitudes, see Chapter 16 and GB/T 4109.

During the insulation test, if necessary, the manufacturer can take shielding measures on the bushing terminals, but adjacent to the bushing terminals.

Any shielding of the ground portion shall be considered part of the transformer at the time of operation (except for the shielding required during the partial discharge test).

It is assumed that the bushings and tap-changers used are designed and tested according to the relevant standards, but still need to be carried out on the assembled transformer.

Edge test to check the proper use and installation of these components. If the tap-changer is not in accordance with its manufacturer GB/T 10230.1 for the insulation routine test, the test carried out in accordance with this section can be regarded as the only insulation routine test of the component.

The temperature of the insulation system during the test shall not be lower than 5 ° C, but shall be higher than the test temperature specified in GB/T 1094.1.

Transformers (including various components that may affect their dielectric strength) should be assembled as in operation. normal situation Under the insulating gas or liquid, the transformer does not circulate during the insulation test, so the cooler does not need to be installed. During the test, use Equipment for collecting or detecting insulation failure to generate free gas should be installed and monitored. If a faulty gas is detected in any of the tests, then the type and cause of the fault gas should be investigated and analyzed, and further measures should be taken in consultation with the manufacturer and the user.

Note 1. When testing, external over-voltage protection equipment (such as. lightning arrester) does not need to be installed, and it is advisable to remove the spark discharge gap of the casing or increase the clearance to avoid the test.

A discharge occurs in the middle.

Note 2. Large power transformers usually collect oil samples for dissolved gas analysis before and after the insulation test.

The liquid immersed transformer should be of the same type as the operation (eg mineral oil, ester, silicone oil, etc.) and the same performance parameters (impact performance test) the liquid of the parameter) was tested.

Note 3. Some users will require transformers with OD cooling mode to maintain oil circulation during IVPD test in order to monitor the oil flow of the insulating oil.

Performance, but this is a very special requirement and is outside the scope of this section.

Transformers connected by cable boxes or transformers directly connected to SF6 fully enclosed metal enclosure electrical devices, if required, can be designed Temporary casing is used for temporary joint construction for insulation testing. Similarly, according to the agreement, use a suitable oil/air casing Replace the oil/SF6 casing for testing. In this case, the design of the alternative end of the bushing inside the transformer, including the live part the position and the insulation distance inside the transformer should be the same as the casing in actual operation (the normal deviation of the casing size manufacturing deviation should be Inside) when the manufacturer needs to install nonlinear components (such as arresters or discharge gaps) inside or outside the transformer or tap-changer to limit the transmission when the transient overvoltage is delivered, it should be brought to the attention of the user during the bidding phase and ordering, and it is recommended to indicate it in the circuit diagram on the transformer nameplate.

In the case of live operation, if any terminal of the transformer is designed to be open, it should also be considered that a voltage can be transmitted at the open terminal.

Capability, see Appendix C. All non-tested and neutral terminals are normally grounded in the lightning impulse test, see Chapter 13.

5 Equipment maximum voltage and rated insulation level

The line end and neutral point of each winding are marked with the highest voltage Um of the device (see GB/T 1094.1).

The rules for transformer insulation tests are different depending on the value of Um. When testing the different windings in a transformer in case of conflict, the entire transformer shall adopt the test rules suitable for the winding of the highest Um value.

The test rules for different Um windings are shown in Table 1.

When the rated voltage of series windings (such as autotransformer and phase shifting transformer) is lower than the rated voltage of the system, the Um value should be used and wound.

The rated voltage of the highest voltage of the system connected to the group.

The standard values for Um are given in Table 2. Unless otherwise specified, the Um value used for the transformer windings may be equal to or slightly higher than the rated voltage of the winding.

Note 1. For single-phase transformers that are intended to form a three-phase group of star nodes, divide the phase-to-phase rated voltage by 3, for example. 500/3kV. At this time, the phase voltage value is determined.

The selection of Um is determined, so Um=550kV is selected (see also GB/T 1094.1). This principle also applies to single-phase transformers intended for single-phase systems.

In order to determine the test voltage, the highest relative ground voltage is multiplied by 3 as the equivalent Um.

Note 2. For transformers with two opposite relative ground voltages (eg transformers for railway power supply systems), Um and the phase is related to the voltage between the phases.

Note 3. It may happen that some of the selected tap voltages are slightly higher than the Um standard value, but the highest voltage of the system connected to the winding remains at this standard.

Within the value. Since the insulation requirements are to be matched with the actual system conditions, it is advisable to use this standard value as the Um value of the transformer instead of its closest higher value.

Note 4. In some applications under very special conditions, it may be reasonable to specify other combinations of withstand voltage. In this case, it should be in accordance with the relevant provisions of GB/T 311.1.

Note 5. In some applications, the corner windings are grounded through an external terminal. At this time, the winding can be selected according to the highest voltage Um of the device.

A higher withstand voltage value, and should be determined by the manufacturer and the user.

The highest voltage of the equipment and its rated insulation level (a set of specified rated withstand voltage values) determine the insulation properties of the transformer. These special Verification is performed using a set of insulation tests, see Chapter 7.

The highest voltage value and rated insulation level of the equipment on each winding of the transformer shall be proposed as one of the contents of the inquiry and the signed contract. Such as If there is a winding for grading insulation, the highest voltage value of the equipment at the neutral point and its rated insulation level shall be as specified in Table 3.

The rated insulation level of the winding is marked as follows.

Um/SI/LI/LIC/AC together with the corresponding value for each winding terminal (see example below).

If the winding does not specify the SI or LIC withstand voltage level, the SI or LIC is omitted in the flag, so for the unspecified operation surge voltage the rated insulation levels of the winding wire ends and the neutral point of the h...