1、 IEC/TS 62758 Edition 1.0 2012-09 TECHNICAL SPECIFICATION Calibration of space charge measuring equipment based on the pulsed electro- acoustic (PEA) measurement principle IEC/TS 62758:2012(E) colour inside THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2012 IEC, Geneva, Switzerland All rights re
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9、ion of space charge measuring equipment based on the pulsed electro- acoustic (PEA) measurement principle INTERNATIONAL ELECTROTECHNICAL COMMISSION V ICS 17.220.99; 29.035.01; 29.080.30 PRICE CODE ISBN 978-2-83220-336-1 Registered trademark of the International Electrotechnical Commission Warning! M
10、ake sure that you obtained this publication from an authorized distributor. colour inside 2 TS 62758 IEC:2012(E) CONTENTS FOREWORD . 4 INTRODUCTION . 6 1 Scope 7 2 Normative references . 7 3 Terms and definitions . 7 4 Basic theory for measurement . 8 4.1 Permittivity and induced charge density . 8
11、4.2 Charge in dielectrics and Poissons law 8 4.3 Coulombic force of charge in electric field 9 4.4 Reflection and transmission of pressure wave 9 4.5 Maxwell stress . 9 4.6 Response of linear system . 10 5 Procedure to calibrate the space charge measurement 10 5.1 Principle of calibration . 10 5.1.1
12、 General . 10 5.1.2 Typical result of calibration measurement . 11 5.2 Sample preparation . 12 5.2.1 Sample for calibration measurement . 12 5.2.2 Sample placement . 13 5.3 Data acquisition . 13 5.3.1 Pulse voltage test 13 5.3.2 Averaging 13 5.3.3 Data acquisition for calibration . 14 5.3.4 Signal o
13、btained under short circuit condition . 15 5.4 Data processing and calibration . 15 5.4.1 Deconvolution 15 5.4.2 Calibration for horizontal axis and calculation of waveform for electric field distribution . 16 5.4.3 Calibration for electric field and charge density distributions . 16 5.4.4 Confirmat
14、ion of linearity of measurement 17 5.4.5 Typical test results by expert members of project team . 17 Annex A (informative) Theory of PEA method . 21 Bibliography . 35 Figure 1 Theoretical distributions for calibration measurement 11 Figure 2 Typical result of calibration measurement . 12 Figure 3 Dr
15、op of silicone oil and sample placement 13 Figure 4 Pulse voltage application test . 13 Figure 5 Dependence of averaging number 14 Figure 6 Measurement of waveform for calibration 15 Figure 7 Confirmation of absence of space charge accumulation during d.c. voltage application for calibration 15 Figu
16、re 8 Deconvolution and calibration . 16 Figure 9 Calibration for electric field and charge density distributions 17 TS 62758 IEC:2012(E) 3 Figure 10 Confirmation of linearity measurement 17 Figure 11 Results of calibration test by research Group A . 18 Figure 12 Results of calibration test by resear
17、ch Group B . 18 Figure 13 Results of calibration test by research Group C . 19 Figure 14 Results of calibration test by research Group D . 19 Figure 15 Results of calibration test by research Group E . 19 Figure A.1 Principle of acoustic wave generation in PEA method 22 Figure A.2 Pressure wave prop
18、agation in PEA measurement system 24 Figure A.3 Response of piezo-transducer . 25 Figure A.4 Transform from pressure to amount of charge induced on piezo- transducer 25 Figure A.5 Relationship between the pulse width and thickness of piezo-transducer . 26 Figure A.6 Adequate spatial resolution . 27
19、Figure A.7 Example of two types of signal 29 Figure A.8 Calculation flow for deconvolution . 30 Figure A.9 Effect of Gaussian filter . 31 Figure A.10 PEA measurement apparatus 32 Figure A.11 Equivalent circuit for voltage application 33 Figure A.12 Equivalent circuit for signal detection . 34 Table
20、1 Measurement resolution 20 4 TS 62758 IEC:2012(E) INTERNATIONAL ELECTROTECHNICAL COMMISSION _ CALIBRATION OF SPACE CHARGE MEASURING EQUIPMENT BASED ON THE PULSED ELECTRO-ACOUSTIC (PEA) MEASUREMENT PRINCIPLE FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization
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33、subject to review within three years of publication to decide whether they can be transformed into International Standards. IEC 62758, which is a technical specification, has been prepared by technical committee 112: Evaluation and qualification of electrical insulating materials and systems. TS 627
34、58 IEC:2012(E) 5 The text of this technical specification is based on the following documents: Enquiry draft Report on voting 112/206/DTS 112/219/RVC Full information on the voting for the approval of this technical specification can be found in the report on voting indicated in the above table. Thi
35、s publication has been drafted in accordance with the ISO/IEC Directives, Part 2. The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under “http:/webstore.iec.ch“ in the data related to the specific publication
36、. At this date, the publication will be transformed into an International Standard, reconfirmed, withdrawn, replaced by a revised edition, or amended. A bilingual version of this publication may be issued at a later date. IMPORTANT The colour inside logo on the cover page of this publication indicat
37、es that it contains colours which are considered to be useful for the correct understanding of its contents. Users should therefore print this document using a colour printer. 6 TS 62758 IEC:2012(E) INTRODUCTION The pulsed electro-acoustic (PEA) method has been used to measure space charge distribut
38、ion in dielectric materials by many researchers, and it has been accepted, in general, as a useful method to understand the electrical properties of dielectric materials. However, since PEA measurement equipments have been developed/used independently by different researchers over the world, there h
39、as not yet been any standard way to evaluate whether a system works properly. The IEC has therefore established a project team to create a standard procedure to evaluate PEA measurement equipment. This technical specification is the result. TS 62758 IEC:2012(E) 7 CALIBRATION OF SPACE CHARGE MEASURIN
40、G EQUIPMENT BASED ON THE PULSED ELECTRO-ACOUSTIC (PEA) MEASUREMENT PRINCIPLE 1 Scope IEC 62758, which is a technical specification, presents a standard method to estimate the performance of a pulsed electro-acoustic (PEA) measurement system. For this purpose, a systematic procedure is recommended fo
41、r the calibration of the measurement system. Using the procedure, users can estimate whether the system works properly or not. 2 Normative references None. 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 space charge accumulated charge in mat
42、erials Note 1 to entry: This technical specification deals with the space charge in bulk and on surfaces of dielectric materials. 3.2 pulsed electro-acoustic method PEA technique for measuring space charge density distribution in solid dielectric materials Note 1 to entry: In this technique, the pre
43、ssure wave that is generated from the charge layer in a material specimen by applied pulse voltage to the specimen is observed using piezo-electric transducer attached behind an electrode contacted to the specimen. Details of measurement theory are described in Clause A.1. 3.3 piezo-electric transdu
44、cer sensor to detect the intensity of the pressure wave Note 1 to entry: By applying the pressure wave, the charge is proportionally induced on the surface of the transducer. By connecting an adequate external circuit, the induced charge is converted to voltage signal. In the PEA measurement, the fi
45、lm or plate shaped piezo-electric transducer is usually used. The pressure wave intensity is measured as a voltage signal across the transducer when the wave propagates through the transducer. Details of the measurement procedure are described in A.1.3. 3.4 calibration set of operations that establi
46、sh, under specified conditions, the relationship between values of quantities indicated by measuring instrument or measuring system, or values represented by a material measure of a reference material, and the corresponding values obtained by a theoretical model SOURCE: IEC 60050-394:2007, definitio
47、n 394-40-43, modified the words “obtained by a theoretical model“ replace “realized by standards“. Note 1 to entry: This is the standard way to estimate the performance of a PEA measurement system. In the PEA measurement, the pressure wave generated from the charge layer in the material is measured
48、as a voltage signal. To obtain the charge density distribution, it is necessary to calibrate the measured voltage signal to the charge 8 TS 62758 IEC:2012(E) density distribution. Therefore, in this technical specification, the calibration means the procedure to calculate the charge density distribu
49、tion from the measured voltage signal. 3.5 deconvolution procedure to recover the voltage signal from the distorted one Note 1 to entry: The measured voltage signal is usually distorted by the reflection of the pressure wave at the interfaces between materials constituting the measurement system, the characteristic of the voltage signal detecting circuit and the induced noise with applied pulse voltage. To recover the voltage measured signal, a so-
