1、BRITISH STANDARD BS 6647:1985 IEC 790:1984 Guide to Oscilloscopes and peak voltmeters for impulse tests UDC 621.317.726 + 621.317.75.004.15BS6647:1985 This British Standard, having been prepared under the directionof the Power ElectricalEngineering StandardsCommittee, was published under the authori
2、ty ofthe Board of BSI and comesintoeffect on 31 October 1985 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference PEL/62 Draft for comment 79/23238 DC ISBN 0 580 14663 4 Committees responsible for this British Standard The preparation of this British Stan
3、dard was entrusted by the Power Electrical Engineering Standards Committee (PEL/-) to Technical Committee PEL/62 upon which the following bodies were represented: Association of Short Circuit Testing Authorities British Industrial Ceramic Manufacturers Association Electric Cable Makers Confederation
4、 Electrical and Electronic Insulation Association (BEAMA Ltd.) Electricity Supply Industry in England and Wales Transmission and Distribution Association (BEAMA Ltd.) Amendments issued since publication Amd. No. Date of issue CommentsBS6647:1985 BSI 09-1999 i Contents Page Committees responsible Ins
5、ide front cover National foreword iii Section 1. General 1 Scope 1 2 Object 1 3 Conditions of use 1 3.1 Range of operating conditions 1 3.2 Reference conditions 2 4 General definitions 2 4.1 Transfer characteristic 2 4.2 Scale factor 2 4.3 Deflection coefficients 2 4.4 Nominal values of the deflecti
6、on coefficients 2 4.5 Non-linearity 2 4.6 Instability 2 4.7 Measuring area or scale 2 4.8 Rated deflection or rated scale 2 4.9 Effective screen areas or effective scale 2 4.10 Warm-up time 3 4.11 Absolute and relative error 3 4.12 Individual error and overall error 3 5 Performance characteristics 3
7、 6 Input characteristics 3 Section 2. Oscilloscopes for impulse tests 7 General 3 7.1 Writing speed 4 7.2 Step response and rise time 4 7.3 Oscilloscope frequency response 4 8 Accuracy requirements 4 8.1 General 4 8.2 Requirements on transfer characteristics 4 8.3 Requirements on the accuracy of the
8、 calibration 4 8.4 Requirements on linearity 5 8.5 Requirements on stability 5 8.6 Requirements on ripple 5 8.7 Requirements on the accuracy of the reading process 5 8.8 Limits on interference 5 9 Record of performance 5 10 Recommended procedure for oscilloscope measurements 6 Section 3. Peak voltme
9、ters for impulse tests 11 General 6 12 Accuracy requirements 6 12.1 General 6 12.2 Requirements on transfer characteristics 7 12.3 Requirements on accuracy of the calibrators 7 12.4 Requirements on linearity 7 12.5 Requirements on stability 7 12.6 Requirements on storage time 7BS6647:1985 ii BSI 09-
10、1999 Page 12.7 Limits on interference 7 13 Record of performance 7 14 Recommendations for measurements with peak voltmeters 7 Appendix A Special recommendations for oscilloscopes 8 Appendix B Precautions in the use of general purpose instruments 9 Appendix C Procedure for performance tests 10 Append
11、ix D Interference tests 12 Figure 1 Effective screen areas 14 Figure 2 Example of procedure for oscilloscope measurements 15 Figure 3 Current injection into the shield of the cable 15 Figure 4 Transient superimposed on the power supply 16 Figure 5 Application of electric and magnetic fields 16 Table
12、 I Normal operating conditions for instruments with a.c. power supplies 1 Table II Reference conditions 2 Table III Limits of stability error (at constant operating conditions) 5 Table A.I Recommended ranges of rated sweep times and minimum writing speed for various standardized impulse tests and me
13、asurements 9 Publications referred to Inside back coverBS6647:1985 BSI 09-1999 iii National foreword This British Standard has been prepared under the direction of the Power Electrical Engineering Standards Committee. It is identical with IEC790:1984 “Oscilloscopes and peak voltmeters for impulse te
14、sts” published by the International Electrotechnical Commission (IEC). Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used
15、 in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker in Figure 1. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Wherever page numbers are quoted they are IEC page numbers. The Techn
16、ical Committee has reviewed the provisions of IEC51-1:1984 and IEC51-2:1984, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. A related BritishStandard to IEC51-1 and IEC51-2 is BS89:1977 “Specification for direct acting indi
17、cating electrical measuring instruments and their accessories”. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity f
18、rom legal obligations. Cross-references International Standard Corresponding British Standard IEC 60 BS 923 Guide on high-voltage testing techniques IEC 60-2:1973 Part 2:1980 Test procedures (Identical) IEC 60-3:1976 Part 3:1980 Measuring devices (Identical) IEC 60-4:1977 Part 4:1980 Application gui
19、de for measuring devices (Identical) IEC 351-1:1976 BS 4739 Method for expression of the properties of cathode-ray oscilloscopes Part 1:1979 General (Identical) IEC 359:1971 BS 4889:1973 Method for specifying the performance of electronic measuring equipment (Technically equivalent) Summary of pages
20、 This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 16, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv
21、 blankBS6647:1985 BSI 09-1999 1 Section 1. General 1 Scope This standard is applicable to analogue oscilloscopes and to peak voltmeters used for measurements during tests with high impulse voltages and high impulse currents. It covers the specific characteristics and calibrations required to meet th
22、e measuring accuracies specified in IECPublication60-3: High-voltage Test Techniques, Part3: Measuring Devices. It does not cover general instrument requirements because they are dealt with in IEC Publication351-1: Expression of the Properties of Cathode-ray Oscilloscopes, and in IEC Publication359:
23、 Expression of the Functional Performance of Electronic Measuring Equipment. 2 Object The object of this standard is: to define the terms specifically related to the oscilloscopes and peak voltmeters used for impulse test; to specify the necessary requirements for such instruments to ensure their co
24、mpliance with the requirements for impulse tests; to indicate the tests and procedures which are necessary in order to fulfil these requirements. 3 Conditions of use 3.1 Range of operating conditions The ranges of operating conditions given in Table I are those under which the instrument should oper
25、ate satisfactorily and should meet the accuracy requirements when it has been calibrated. Any exceptions to the values given in Table I shall be explicitly and clearly stated with an indication that they are exceptions. If the instrument is operated under conditions different from those specified in
26、 Table I, special precautions may be necessary. The mains supply may have transient overvoltages superimposed on it; suitable precautions should be taken to prevent these from affecting the operation of the instrument. If the instrument is supplied by batteries: it shall be capable of operating unde
27、r the above environmental conditions; the manufacturer shall indicate the expected operating time at the reference temperature and also for the two extreme ambient temperature extremes; the manufacturer shall indicate the range of battery voltages over which the instrument will operate satisfactoril
28、y. It is useful to have a device which indicates when the battery voltage is too low. Table I Normal operating conditions for instruments with a.c. power supplies Operating conditions Range Environmental conditions Ambient temperature + 5 C to + 40 C Ambient relative humidity 10 % to 90 % Supply con
29、ditions Mains supply voltage Rated voltage Mains supply frequency Rated frequency 5 % 10 % (r.m.s.) 12 % (a.c. peak)BS6647:1985 2 BSI 09-1999 3.2 Reference conditions The reference conditions are those for which the basic accuracy of the instrument shall be specified and under which investigation of
30、 the basic accuracy shall be made. These conditions are selected from IEC Publication351-1, Table I and are given in Table II below. Table II Reference conditions 4 General definitions 4.1 transfer characteristic the transfer characteristic is the relationship between the input and the output quanti
31、ties of the instrument expressed either as a function of frequency (frequency response) or time (step response). The transfer characteristic is usually presented in a normalized form by assigning the value of unity to the constant portion of the step or frequency response. The requirements on transf
32、er characteristics include the effect of any built-in attenuator 4.2 scale factor the scale factor of the instrument is the factor by which the output indication is multiplied to determine the measured value of the input signal to the instrument. The scale factor includes the ratio of any built-in a
33、ttenuator and is either indicated by the manufacturer or determined by appropriate calibration 4.3 deflection coefficients the deflection coefficient of the instrument is the ratio of the voltage (or time) interval to the corresponding deflection of the instrument. This coefficient refers mainly to
34、oscilloscopes 4.4 nominal values of the deflection coefficients the nominal values of the deflection coefficients are those corresponding to a specific setting of the instrument and are either indicated by the manufacturer or determined by proper calibration if the instrument is linear the nominal v
35、alues of the deflection coefficients are equal and constant over the entire scale or screen of the instrument if the nominal deflection coefficient is only constant over a limited part of the scale or screen, the instrument may still be considered linear provided the measurement is made within this
36、linear portion 4.5 non-linearity non-linearity is any deviation of the actual deflection coefficient at any part on the scale or screen, from the nominal value for that part. It is usually expressed in the form of relative error defined as the ratio of the deviation to the nominal deflection coeffic
37、ient. It does not include the effects of either ripple or limitation in the transfer characteristic of the instrument 4.6 instability instability is any variation of the characteristics of the instrument with time. It is usually expressed in the form of relative error, defined as the ratio of the va
38、riation to the nominal value of the relevant quantity. It does not include the effect of change in the reference conditions 4.7 measuring area or scale the measuring area or scale is the portion of the screen or of the scale within which measurements can be made with defined accuracy. It is indicate
39、d by the manufacturer or determined by calibration NOTEThe use of the word scale in this context applies to analogue and also digital type voltmeters. 4.8 rated deflection or rated scale the rated deflection or rated scale is the maximum value within the limits of the measuring area or scale 4.9 eff
40、ective screen areas or effective scale the effective screen areas are those parts of the measuring area within which measurements can be made with the accuracies specified in Sub-clause8.1. An example of these effective screen areas for both vertical and horizontal deflections is shown in Figure 1,
41、page14 Conditions Reference values Tolerance on reference values Ambient temperature 20 C, 25 C 2 C Ambient relative humidity 45 % to 75 % Supply voltage Rated voltage 1 % (r.m.s.) 2 % (peak) Supply frequency Rated frequency 1 % NOTEThe specific temperature used as reference condition should be indi
42、cated. It is advisable to use the same temperature when checking the basic characteristics of the instrument.BS6647:1985 BSI 09-1999 3 the effective scale is that part of the measuring scale where measurements can be made with the accuracy specified in Sub-clause8.1 measurements can be made outside
43、the effective screen areas or scale but with lower accuracy 4.10 warm-up time the warm-up time is measured under the reference conditions and is the time interval from when the instrument is first switched on, to when the instrument meets all the requirements NOTEThe time interval necessary to compl
44、y with all accuracy requirements may be considerably extended under adverse operating conditions. 4.11 absolute and relative error the absolute error is the difference between the estimated or measured value and the true value. The relative error is the ratio of the absolute error to the true value
45、and it is often expressed as a percentage 4.12 individual error and overall error the individual error is the error of a specific measured quantity or of a specified parameter or characteristic of the instrument the overall error of the instrument is the combination of all its individual errors. In
46、the case of digital peak voltmeters it includes an additional error of 1digit. The overall error does not include known corrections applied to the instrument reading to obtain the measured value the individual or overall errors may be expressed as absolute or relative values 5 Performance characteri
47、stics The performance characteristics of the instrument are divided into two groups. The first is technical data supplied by the manufacturer or determined by the user through appropriate calibration, and the second, the characteristics checked and updated by the user in the performance tests. The p
48、erformance tests are periodic tests carried out to ensure that the instrument meets the specified requirements and that its characteristics have not changed significantly with time. The long-term periodic tests are performed at regular intervals (for example once a year), to check and update those c
49、haracteristics listed under category A (seeClauses9 and13). The short-term tests are checks performed regularly (if necessary, daily) to verify that the instrument is functioning correctly (category B, see Clauses9 and13). After major repairs, more extensive tests are required to ensure satisfactory operation of the instrument and to update those characteristics affected. Some recommendations on the test procedures are outlined inAppendix C andAppendix D. The results of the test (except those of category B) should be r
