DL/T 1980-2019Test method of average moisture content in transformer insulation paper and paperboard Frequency domain dielectric spectroscopy method (English PDF)
变压器绝缘纸（板）平均含水量测定法频域介电谱法
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Issued by
National Energy Administration
Level / Type
National · Recommended
Issue date
June 4, 2019
Implementation date
October 1, 2019
Scope
DL/T 1980-2019 is the English-translated version of 变压器绝缘纸（板）平均含水量测定法频域介电谱法.
DL/T 1980-2019 — This standard specifies the method for measuring the average moisture content of insulating paper (board) of equipment such as oil-immersed transformers, reactors and bushings by frequency domain dielectric spectroscopy.
Method summary, instruments and materials used, measurement methods, etc. This standard applies to the determination of the average moisture content of the insulating paper (board) of equipment such as oil-immersed transformers, reactors and bushings, including the Insulating paper (board), new paper (board) sample testing and overall testing of non-sampling field equipment.
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Document preview — DL/T 1980-2019
National Standard of the People's Republic of China
- ICS
- 27.140
- Classification
- F 20
Issued by: National Energy Administration
Contents
- Foreword
- 1 Scope
- 2 Normative references
- 3 Method overview
- 4 Terms and definitions
- 5 Apparatus and materials
- 6 Measurement method
- 7 Precision
- 9 Report
- Appendix A (Normative Appendix) Measurement and Wiring Method of Transformer, Reactor and Bushing
- Appendix B (informative appendix) Frequency domain dielectric spectrum database of oil-impregnated insulating paper (board) with different water content
- Appendix C (informative appendix) XY model to evaluate the moisture content of insulation paper (board) of transformers, reactors and bushings
- Appendix D (informative appendix) Water content criterion for oil-immersed transformer and reactor insulation Error Undefined bookmark.
Foreword
This standard is formulated in accordance with the rules of GB/T 1.1-2009 "Standardization Guidelines Part 1: Standard Structure and Compilation".
Please note that certain contents of this document may involve patents. The issuing agency of this document is not responsible for identifying these patents.
This standard was proposed by the China Electricity Council.
This standard is under the jurisdiction of the National Electrochemical Standardization Technical Committee (TC322).
Drafting organizations of this standard. Xi'an Jiaotong University, Shenzhen Power Supply Bureau Co., Ltd., State Grid Shaanxi Electric Power Research Institute, State Grid Jiangsu Electric Power Co., Ltd. Electric Power Research Institute, China Nuclear Wuhan Nuclear Power Operation Technology Co., Ltd., China Southern Power Grid Research Institute Limited Liability Company, Xi'an Thermal Power Research Institute Co., Ltd., State Grid Shandong Electric Power Company Electric Power Research Institute, China Electric Power Research Institute Co., Ltd., Nanjing Predi Electric Technology Co., Ltd.
1 Scope
This standard specifies the method for measuring the average moisture content of insulating paper (board) of equipment such as oil-immersed transformers, reactors and bushings by frequency domain dielectric spectroscopy.
Method summary, instruments and materials used, measurement methods, etc.
This standard applies to the determination of the average moisture content of the insulating paper (board) of equipment such as oil-immersed transformers, reactors and bushings, including the Insulating paper (board), new paper (board) sample testing and overall testing of non-sampling field equipment.
2 Normative references
The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this document.
For undated references, the latest version (including all amendments) applies to this document.
GB/T 1410 Test method for volume resistivity and surface resistivity of solid insulating materials DL/T 449 Determination of water content of oil-impregnated fibrous insulating materials DL/T 474.3 Implementation guidelines for on-site insulation test Dielectric loss factor tandelta test DL/T 596 Preventive test procedures for electrical equipment
3 Method overview
Conduct frequency domain dielectric spectroscopy on insulating paper (board) and new paper (board) samples of oil-immersed transformers, reactors and bushings, and field equipment for measurement, compare the measurement curve with the standard curve database to obtain the average moisture content of the insulation paper (board) in the sample or device under test.
4 Terms and definitions
The following terms and definitions apply to this standard.
4.1 Dielectric response
The response characteristics of the electrical performance parameters of the dielectric with time and frequency under the applied voltage are called time domain dielectric response and frequency domain dielectric response, respectively.
Electric response.
4.2 Frequency domain dielectric spectrum
The response curve of dielectric parameters such as dielectric coefficient and dielectric loss factor changing with frequency.
4.3 XY model
Simplify the model according to the proportions of the dimensional relationship between the oil gap, stays and cardboard in the oil-immersed transformer and reactor, X represents the insulation system There is the ratio of the sum of the thickness of the cardboard to the sum of the thickness of all the stays, Y represents the sum of the width of all the stays and the sum of all the widths of the cardboard in the insulation system Ratio.
5 Apparatus and materials
5.1 Frequency domain dielectric spectrum tester
Including low-voltage broadband signal source, high-voltage broadband amplifier and micro-current detection module. After the instrument runs stably, the following indicators should be reached.
a) The frequency measurement range is 0.1mHz~5kHz;
b) Dielectric loss measurement range 0~10;
c) The capacitance measurement range is 10pF~100µF;
d) The maximum value and resolution of current measurement is 20mA/10pA;
e) Support the water content evaluation function of transformer insulation paper (board).
5.2 Measuring electrode
The measuring electrode (used for measurement in the laboratory) is a three-electrode structure, including a high-voltage electrode, a protected electrode and a protective electrode, as shown in the figure
Table 1 shows the typical dimensions. The measuring electrode should be kept clean, dry and stored in a desiccator.
5.3 Reagents
Petroleum ether. analytically pure, boiling range 60°C~90°C.
Anhydrous ethanol. analytically pure.
6 Measurement method
6.1 Sampling and testing
6.1.1 Sample preparation
For paper (board) samples (oil-containing) and new paper (board) samples taken from oil immersion equipment, pre-dried sharp metal work can be used Use a razor blade or scissors to cut the sample. The sample size should be larger than the outer diameter of the high-voltage electrode. Then put the sample into a clean plastic with self-sealing function.
The material is sealed in a sealed bag, after air is discharged, sealed, and stored in a sealed bottle. The samples should be tested as soon as possible after collection, and the recommended storage time should not exceed 7 days.
6.1.2 Measurement procedure
6.1.2.1 Take out the measuring electrode from the desiccator, use tweezers to put the sample under test into the measuring electrode, make the sample and the high-voltage electrode, the protected electric the electrode and the protective electrode are in full contact to ensure that there is no air gap, and then the measuring electrode is placed in a metal shielding box. The sample should completely cover the protective electrode, and it does not touch the inner wall of the shielding box.
6.1.2.2 Connect the protected electrode of the three electrodes to the measuring terminal of the tester, the high-voltage electrode to the high-voltage terminal of the tester, and the protective electrode to the screen the shielding box and the shielding end of the tester are connected, and the test connecting wires are all coaxial shielded wires.
6.1.2.3 Record the ambient temperature, turn on the tester, and start measurement after 5 minutes of stable operation to obtain the frequency domain dielectric spectrum curve of the tested sample.
The water content of the tested sample is calculated according to the standard curve database equipped with the instrument.
6.1.2.4 After the test is completed, turn off the power of the test instrument, clean the measuring electrode with petroleum ether, dry it and store it in a desiccator.
6.2 Overall inspection of field equipment without sampling
6.2.1 Test preparation
Before the test, remove all the leads connected to the end of the casing of the device under test, remove the debris around the device, and fully discharge the device.
If necessary, clean or dry the outer insulating surface of the equipment.
6.2.2 Measurement procedure
6.2.2.1 Wire the device under test. The wiring method of double winding, three winding and autotransformer, reactor and bushing is in accordance with norms Appendix A.
6.2.2.2 Turn on the tester and run it stably for 5 minutes, then measure the frequency domain dielectric spectrum curve of the device under test and record the top of the device under test.
Layer oil temperature data.
6.2.2.3 When the frequency domain dielectric spectrum curve shows negative values or obvious fluctuations, check whether the wiring is reliable, the grounding is good, and the Re-measure whether the pipe surface is dirty or damp or other interference factors.
6.2.2.4 Convert the frequency domain dielectric spectrum curve of the tested equipment to the standard temperature (25°C), according to the X and Y parameters of the insulation structure of the tested equipment, Fitting to get the moisture content of the insulation paper (board) of the equipment under test.
6.2.2.5 After the test is completed, turn off the test instrument, fully discharge the tested device and remove all test wiring.
7 Precision
The difference between the two determination results of this standard should not exceed 10% of the average value.
8 Reports
For the insulating paper (board) samples of oil-immersed transformers, reactors, bushings and other equipment, take the average of the two test results. For transformers, Take a single test result for equipment such as reactors and bushings.
Appendix A
(Normative appendix) Measuring wiring method of transformer, reactor and bushing A.1 Single-phase dual-winding transformer for the dielectric response test of the insulation between the high-voltage and low-voltage windings of a single-phase dual-winding transformer, the high-voltage winding and the neutral point are short-circuited and connected to the dielectric response the high-voltage end and low-voltage winding of the tester should be short-circuited and connected to the measuring end of the dielectric response tester, and the shielded wire should be connected to the transformer housing. Test wiring They are shown in Figure A.1.
A.2 Single-phase three-winding transformer for the dielectric response test of the insulation between the high, medium, and low voltage windings of a single-phase three-winding transformer, the medium voltage winding and the neutral point are short-circuited and connected to the dielectric the high voltage end of the electrical response tester, the low voltage winding is shorted and connected to the measuring end 1 of the dielectric response tester, the high voltage winding and the neutral point are shorted and connected Connect to the measuring terminal 2 of the dielectric response tester, and connect the shielded wire to the transformer housing. The test wiring is shown in Figure A.2.
A.3 Single-phase autotransformer for the dielectric response test of autotransformer insulation, the high-voltage winding, low-voltage winding and neutral point are short-circuited and connected to the dielectric response tester.
At the measuring end, the transformer housing is connected to the high voltage end of the dielectric response tester, and the shielding wire is suspended. The test wiring is shown in Figure A.3.
A.4 Three-phase transformer for three-phase dual-winding transformers, three-phase three-winding transformers, and three-phase autotransformers, short windings in each phase of A, B, and C Join together.
A.5 Reactor
The connection for the dielectric response test of the oil-immersed reactor is shown in Figure A.4.The common ground terminal (high voltage terminal) is connected to the shell, and the winding is shorted and connected Connected to the measuring terminal, and the shielding wire of the measuring line is suspended.
A.6 Casing
The connection for the dielectric response test of oil-immersed casing is shown in Figure A.5.The high voltage end is connected to the conductive rod of the casing, and the lead of the last screen is connected to the measurement at the end, the shielding wire of the measuring line is grounded.
Appendix B
(Informative appendix) Frequency domain dielectric spectrum database of oil-impregnated insulating paper (board) with different water content the standard curve of frequency domain dielectric spectrum of insulating paper (board) with a moisture content of 0.5%-6% at a temperature of 25°C is shown in Figures B.1, B.2 and B.3.among them
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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 11 pages — is available in the English PDF.
Referenced standards
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