00311103 PDF BRITISH STANDARD BS EN 60868 1993 Flickermeter — Functional and design specifications The European Standard EN 60868 1993 has the status of a British Standard UDC 621 317 7 BS EN 60868 19[.]
BRITISH STANDARD Flickermeter — Functional and design specifications The European Standard EN 60868:1993 has the status of a British Standard UDC 621.317.7 BS EN 60868:1993 BS EN 60868:1993 Cooperating organizations The European Committee for Electrotechnical Standardization (CENELEC), under whose supervision this European Standard was prepared, comprises the national committees of the following countries: Austria Belgium Denmark Finland France Germany Greece Iceland Ireland Italy Luxembourg Netherlands Norway Portugal Spain Sweden Switzerland United Kingdom This British Standard, having been prepared under the direction of the General Electrotechnical Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 August 1993 Amendments issued since publication © BSI 08-1999 Amd No The following BSI references relate to the work on this standard: Committee reference GEL/110 Drafts for comment 84/22884 DC, 88/24779 DC ISBN 580 22455 Date Comments BS EN 60868:1993 Contents Page Cooperating organizations Inside front cover National foreword ii Foreword Text of EN 60868 National annex NA (informative) Appendix D to IEC 255-8:1978 17 National annex NB (informative) Committees responsible 22 National annex NC (informative) Cross-references Inside back cover © BSI 08-1999 i BS EN 60868:1993 National foreword This British Standard has been prepared under the direction of the General Electrotechnical Standards Policy Committee and is the English language version of EN 60868:1993, Flickermeter — Functional and design specifications, published by the European Committee for Electrotechnical Standardization (CENELEC) It is identical with IEC 868:1986 + A1:1990 published by the International Electrotechnical Commission (IEC) This British Standard supersedes BS 6796:1986 which is withdrawn BS EN 60868-0:1993 is complementary to this standard as it covers statistical evaluation of flicker severity NOTE The reference in note to Table IV should refer to Appendix D of IEC 255-8:1978 This appendix was deleted in the 1990 revision of IEC 255-8 and it has therefore been reproduced in National annex NA 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 from legal obligations Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages to 22, 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 ii © BSI 08-1999 EUROPEAN STANDARD EN 60868 NORME EUROPÉENNE April 1993 EUROPÄISCHE NORM UDC 621.317.7 Supersedes HD 498 S2:1992 Descriptors: Measuring instrument, flickermeter, design, performance, specification, test English version Flickermeter — Functional and design specifications (IEC 868:1986 + A1:1990) Flickermètre — Spécifications fonctionnelles et de conception (CEI 868:1986 + A1:1990) Flickermeter — Funktionsbeschreibung und Auslegungsspezifikation (IEC 868:1986 + A1:1990) This European Standard was approved by CENELEC on 1993-03-09 CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels © 1993 Copyright reserved to CENELEC members Ref No EN 60868:1993 E EN 60868:1993 Foreword Contents At the request of 72 Technical Board, HD 498 S2:1992 (IEC 868:1986 + A1:1990) was submitted to the CENELEC voting procedure for conversion into a European Standard The text of the International Standard was approved by CENELEC as EN 60868 on March 1993 The following dates were fixed: Page Foreword Introduction Scope and object Description of the instrument 3 Specification Type test specifications Appendix A Evaluation of flicker severity on the basis of the output of the IEC flickermeter 14 Annex ZA (normative) Other international publications quoted in this standard with the references of the relevant European publications 16 Figure — Functional diagram of UIE flickermeter 12 Figure — Basic illustration of the time-at-level method 13 Table I — Normalized flickermeter response for sinusoidal voltage fluctuations Table II — Normalized flickermeter response for rectangular voltage fluctuations Table III Table IV 11 Table A.I — Test specifications for flickermeter classifier 15 — latest date of publication of an identical national standard (dop) 1994-03-01 — latest date of withdrawal of conflicting national standards (dow) — Annexes designated “normative” are part of the body of the standard In this standard, Annex ZA is normative © BSI 08-1999 EN 60868:1993 INTRODUCTION This report gives a functional and design specification for flicker measuring apparatus intended to indicate the correct flicker perception level for all practical voltage fluctuation waveforms Sufficient information is presented to enable such an instrument to be constructed The method of flicker severity assessment from flickermeter output data will form the subject of other publications In its present form, this report is not intended to be an appendix to IEC Publications 555-3: Disturbances in Supply Systems Caused by Household Appliances and Similar Electrical Equipment, Part 3: Voltage Fluctuations This report is based on specifications prepared by the Disturbances Study Committee of the International Union for Electroheat (UIE) Scope and object The purpose of this report is to provide basic information for the design and the implementation of an analogue or digital flicker measuring apparatus It does not specify the method of calculating a flicker severity value, or give tolerable limit values Description of the instrument The description given below is based on an analogue implementation A partly or completely digital meter is equally acceptable provided that it offers the same functional characteristics The flickermeter architecture is described by the block diagram of Figure 1, page 12, and can be divided into two parts, each performing one of the following tasks: — simulation of the response of the lamp-eye-brain chain; — on-line statistical analysis of the flicker signal and presentation of the results The first task is performed by blocks 2, and of Figure 1, whilst the second task is accomplished by block Although this last block is not mandatory, as flicker signal analysis can be performed off-line using a suitable recording medium, its inclusion is recommended because it will allow a more complete and efficient use of the instrument 2.1 Block — Input voltage adaptor and calibration checking circuit This block contains a signal generator to check the calibration of the flickermeter on site and a voltage adapting circuit that scales the mean r.m.s value of the input mains frequency voltage down to an internal reference level In this way flicker measurements can be made independently from the actual input carrier voltage level and expressed as a percent ratio Taps on the input transformer establish suitable input voltage ranges to keep the input signal to the voltage adaptor within its permissible range 2.2 Block — Square law demodulator The purpose of this block is to recover the voltage fluctuation by squaring the input voltage scaled to the reference level, thus simulating the behaviour of the lamp 2.3 Blocks and — Weighting filters, squaring and smoothing Block is composed of a cascade of two filters and a measuring range selector, which can precede or follow the selective filter circuit The first filter eliminates the d.c and double mains frequency ripple components of the demodulator output The second does the shaping of the flickermeter frequency response to the modulating fluctuation, as follows: the weighting filter block simulates the frequency response to sinusoidal voltage fluctuations of a coiled coil filament gas filled lamp (60 W – 230 V) combined with the human visual system The response function is based on the perceptibility threshold found for each frequency on 50 % of the persons tested1) 1) A reference filament lamp for 100–130 V systems would have a different frequency response and would require a corresponding adjustment of the weighting filter The characteristics of discharge lamps are totally different, and wider modifications of this report would be necessary to take them into account © BSI 08-1999 EN 60868:1993 Block is composed of a squaring multiplier and a first order low-pass filter The human flicker sensation via lamp, eye and brain is simulated by the combined non-linear response of blocks 2, and Block alone is based on the borderline perceptibility curve for sinusoidal voltage fluctuations; the correct weighting of non-sinusoidal and stochastic fluctuations is achieved by an appropriate choice of the complex transfer function for blocks and Accordingly the correct performance of the model has also been checked with periodic rectangular signals as well as with transient signals The output of block represents the instantaneous flicker sensation 2.4 Block — On-line statistical analysis Block incorporates a microprocessor that performs an on-line analysis of the flicker level, thus allowing direct calculation of significant evaluation parameters A suitable interface allows data presentation and recording The use of this block is related to methods of deriving measures of flicker severity by statistical analysis The statistical analysis, whether performed on-line by block or off-line on a recording of the output of block 4, shall be made by subdividing the amplitude of the flicker level signal into a suitable number of classes The flicker level signal is sampled at a constant rate Every time that the appropriate value occurs, the counter of the corresponding class is incremented by one In this way, the frequency distribution function of the input values is obtained By choosing a scanning frequency sufficiently higher than the maximum flicker frequency, the final result at the end of the measuring interval represents the distribution of flicker level duration in each class Adding the content of the counters of all classes and expressing the count of each class relative to the total gives the probability density function of the flicker levels From this, one obtains the cumulative probability function used in the time-at-level statistical method Figure 2, page 13, schematically represents the statistical analysis method, limited for simplicity of presentation to 10 classes From the cumulative probability function, significant statistical values can be obtained such as mean, standard deviation, flicker level being exceeded for a given percentage of time or, alternatively, the percentage of time an assigned flicker level has been exceeded The observation period is defined by two adjustable time intervals: Tshort and Tlong The long interval defines the total observation time and is always a multiple of the short interval: (Tlong = n · Tshort) For on-line processing, immediately after conclusion of each short time interval, the statistical analysis of the next interval is started and the results for the expired interval are made available for output In this way, n short time analyses will be available for a given observation period Tlong, together with the results for the total interval Cumulative probability function plots should preferably be made by using a Gaussian normal distribution scale 2.5 Outputs The flickermeter diagram in Figure 1, page 12, shows a number of outputs between blocks and The outputs marked with an asterisk are not essential, but may allow a full exploitation of the instrument potential for the investigation of voltage fluctuations Further optional outputs may be considered 2.5.1 The aim of optional output and associated r.m.s meter is to display the voltage fluctuation waveform in terms of changes in r.m.s value of the input voltage This can be achieved by squaring, integrating between zero crossings on each half-cycle and square rooting the signal In order to observe small voltage changes with good resolution, an adjustable d.c offset and rectification should be provided 2.5.2 Output is mainly intended for checking the response of block and making adjustments 2.5.3 Output gives an instantaneous linear indication of the relative voltage change %V expressed as per V cent equivalent of an 8.8 Hz sinusoidal wave modulation This output is useful to select the proper measuring range 2.5.4 Output gives the integral of the instantaneous flicker sensation © BSI 08-1999 EN 60868:1993 2.5.5 Output represents the instantaneous flicker sensation and can be recorded on a strip-chart recorder for a quick on-site evaluation, or on magnetic tape for long duration measurements and for later processing 2.5.6 Output in block is connected to a serial digital interface suitable for a printer and a magnetic tape recorder Using another digital to analogue converting interface, analogue plots of the cumulative probability function can be obtained directly from this block Specification 3.1 Analogue response The overall analogue response from the instrument input to the output of block is given in Table I and Table II for sinusoidal and rectangular voltage fluctuations as defined in IEC Publication 555-3 One unit output from block corresponds to the reference human flicker perceptibility threshold The response is centred at 8.8 Hz for sinusoidal modulation The prescribed accuracy is achieved if the input values for sine and square-wave modulations are within ± % of the tabulated values, for an output of one unit of perceptibility Table I — Normalized flickermeter response for sinusoidal voltage fluctuations Input relative voltage fluctuation %V for one unit of perceptibility V at output Voltage fluctuation Hz 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.8 (%) 2.340 1.432 1.080 0.882 0.754 0.654 0.568 0.500 0.446 0.398 0.360 0.328 0.300 0.280 0.266 0.256 0.250 © BSI 08-1999 Hz 9.5 10.0 10.5 11.0 11.5 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0 20.0 21.0 22.0 23.0 24.0 25.0 Voltage fluctuation (%) 0.254 0.260 0.270 0.282 0.296 0.312 0.348 0.388 0.432 0.480 0.530 0.584 0.640 0.700 0.760 0.824 0.890 0.962 1.042 EN 60868:1993 Table II — Normalized flickermeter response for rectangular voltage fluctuations Input relative voltage fluctuation %V for one unit of perceptibility V at output Hz u 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.8 Voltage fluctuation (%) 0.514 0.471 0.432 0.401 0.374 0.355 0.345 0.333 0.316 0.293 0.269 0.249 0.231 0.217 0.207 0.201 0.199 Hz 9.5 10.0 10.5 11.0 11.5 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0 20.0 21.0 22.0 23.0 24.0 Voltage fluctuation (%) 0.200 0.205 0.213 0.223 0.234 0.246 0.275 0.308 0.344 0.380 0.421 0.461 0.506 0.552 0.603 0.657 0.713 0.767 3.2 Input transformer The input voltage transformer must accept a wide range of nominal mains voltages and adapt them to the maximum level compatible with the operation of the following circuits The most common rated voltages, assuming a – 30 % to + 20 % deviation are listed in Table III Table III Rated input voltage – 30 % + 20 % (V r.m.s.) (V r.m.s.) (V r.m.s.) 57.7 100 115 127 160 220 230 240 380 420 40 70 80.5 89 112 154 161 168 266 294 68 120 138 152 192 264 276 288 456 504 The prescribed total range shall therefore be 40 V r.m.s to 504 V r.m.s It is advisable to keep the variations of secondary voltage within a maximum excursion of to 3.5 times and therefore the transformer should have at least two taps with transforming ratios 504 for primary to VR 276 138 secondary and and for the taps, where VR is the reference carrier level VR VR The pass bandwidth of the transformer shall not introduce a significant attenuation of the modulation sidebands at ± 25 Hz Insulation level shall be kV r.m.s for and kV peak for an 1.2/50 4s impulse An electrostatic shielding shall be provided between windings and suitably connected © BSI 08-1999 EN 60868:1993 The maximum delay between damp heat and cold tests shall not exceed h Dry heat test — Temperature: 40 ± °C — Duration: 16 h Damp heat test — Temperature: 40 ± °C — Duration: 24 h Under steady temperature conditions, relative humidity will be brought to 93 +2 % –3 Cold test — Temperature: ± °C — Duration: 16 h Change of temperature test — Starting temperature: 40 ± °C — Final temperature: ± °C Permanence at starting temperature for h before proceeding to temperature change Maximum temperature gradient of the test chamber shall not exceed °C/min averaged over not more than 10 © BSI 08-1999 EN 60868:1993 Table IV Test No Interference immunity tests (provisional) Notes Test voltage1) Application mode a kV r.m.s — Insulation resistance kV d.c 0.5 — Impulse voltage 1.2/50 4s kV peak Mains frequency V r.m.s 2) 250 — Impulse voltage 1.2/50 4s kV peak 7) Low-voltage trains (1 kHz to MHz) V peak 8) 100 — Damped oscillatory waves at MHz kV peak 3) 0.5 Fast transients with low energy kV peak 6) 2 Interruption of a.c power supply ms 8) to 10 10 Static electricity discharges kV 4) 15 11 Mains frequency A/m 8) 500 Impulse 8/20 4s A/m peak 8) 500 Damped oscillatory wave at MHz A/m peak 8) 50 Radiated H.F (20 MHz to 500 MHz) V/m 5) 10 12 13 14 Conducted interference Insulation tests Dielectric Electromagnetic fields b Explanatory notes 1) Application mode of test voltage: a) between the terminals of each circuit and the earthed equipment case (common mode); b) between the terminals of a same circuit (differential mode) 2) Value prescribed for the time necessary to extinguish a fault; other values may be adopted according to the national safety rules 3) For this test, see Appendix C of IEC Publication 255-8: Electrical Relays, Part 8: Thermal Electrical Relays 4) For this test see IEC Publication 801-2: Electromagnetic compatibility for Industrial-process Measurement and Control Equipment, Part 2: Electrostatic Discharge Requirements 5) For this test see IEC Publication 801-3:Part 3: Radiated Electromagnetic Field Requirements 6) Tests under consideration in IEC Technical Committee No 65 7) Tests under consideration in IEC Technical Committee No 65 8) Tests under consideration in IEC Technical Committee No 77 © BSI 08-1999 11 EN 60868:1993 12 Figure — Functional diagram of UIE flickermeter © BSI 08-1999 EN 60868:1993 Figure 2a — Flicker level as a time-varying function Signal permanence in class No is indicated as an example: Figure 2b — Cumulative probability function of signal permanence in classes to 10 Figure — Basic illustration of the time-at-level method © BSI 08-1999 13 EN 60868:1993 Appendix A Evaluation of flicker severity on the basis of the output of the IEC flickermeter A.1 Short-term flicker evaluation The measure of severity based on an observation period Tst = 10 is designated Pst and is derived from the time-at-level statistics obtained from the level classifier in block of the flickermeter The following formula is used: where the percentiles P0.1, P1, P3, P10 and P50 are the flicker levels exceeded for 0.1, 1, 3, 10 and 50 % of the time during the observation period The suffix s in the formula indicates that the smoothed value should be used; these are obtained using the following equations: P50 s = (P30 + P50 + P80)/3 P10 s = (P6 + P8 + P10 + P13 + P17)/5 P3 s = (P2.2 + P3 + P4)/3 P1 s = (P0.7 + P1 + P1.5)/3 The 0.3 s memory time-constant in the flickermeter ensures that P0.1 cannot change abruptly and no smoothing is needed for this percentile A.2 Long-term flicker evaluation The 10 period on which the short-term flicker severity evaluation is based is suitable for assessing the disturbances caused by individual sources with a short duty-cycle Where the combined effect of several disturbing loads operating randomly (e.g welders, motors) has to be taken into account or when flicker sources with long and variable duty cycles (e.g arc furnaces) have to be considered, it is necessary to provide a criterion for the long-term assessment of the flicker severity For this purpose, the long-term flicker severity Plt, shall be derived from the short-term severity values, Pst, over an appropriate period related to the duty cycle of the load or a period over which an observer may react to flicker, e.g a few hours, using the following formula: where Psti (i = 1, 2, 3, ) are consecutive readings of the short-term severity Pst A.3 Techniques to improve accuracy of evaluation Various techniques are available to achieve accurate flicker evaluation over a wide range of conditions Some of these techniques are given below Any of them may be used alone or in combination provided that the specified accuracy of ± % is obtained over a sufficient range of depth of modulation of the input voltage In most cases the values of particular percentile points, Pk, required to calculate Pst will not correspond with a single class and must be derived by interpolation (or extrapolation) from the actual classes available A.3.1 Linear interpolation Linear classification is arranged so that the full scale, Fs, of the classifier has N equal discrete steps giving a class width of Fs/N Let n be the number of the class to which percentile Pk belongs Class n includes flickermeter output levels between (n – 1) Fs/N, which is exceeded by yn – percent of the samples and nFs/N, which is exceeded by yn percent of the samples By linear interpolation the percentile Pk corresponding to yk percent is: 14 © BSI 08-1999 EN 60868:1993 A.3.2 Non linear interpolation When linear interpolation does not give sufficient accuracy, non-linear interpolation shall be used The recommended procedure is to it a quadratic formula to the levels corresponding to three consecutive classes on the cumulative probability function, CPF The CPF level is obtained from the relationship: where: Fs/N = Class width H1 = 3/2 yn – – yn + 1/2 yn + H2 = 1/2 yn – – yn + 1/2 yn + H3 =H – 4H2 (yn – – yk) where yn is the percent probability corresponding to class n and so on (see Sub-clause A.3.1) A.3.3 Pseudo zero intercept It may happen that one or more percentiles of interest, Pk, lie in the interval of the first class of the classifier Experience has shown that interpolating between zero and the upper end point of the first class gives poor results, because this makes the implicit assumption that a level of zero will be exceeded with a 100 % probability In practice a typical cumulative probability function can meet the probability axis well below the 100 % mark and then move vertically up the axis A way of reducing errors in this region is to extrapolate the cumulative probability function back to the y axis to provide a pseudo zero intercept value, yo A suitable algorithm to give yo is: yo = (3y1 – 3y2 + y3) A.3.4 Non-linear classification A classifier may be used more efficiently and more accurately if the class intervals are graduated in width For instance, a logarithmic classification may be used and this usually permits the use of linear interpolation, avoids the need for zero extrapolation and allows the full dynamic range of input signals to be covered without range switching Alternatively a linear classifier may be applied to output of the flickermeter but this still requires some range selection A.4 Performance testing Each flickermeter, with its classifier, shall be subjected to the regular trains of rectangular voltage changes given in Table A.I below: Table A.I — Test specifications for flickermeter classifier Voltage changes %V/V % Changes per minute 39 110 620 2.724 2.211 1.459 0.906 0.725 0.402 In each case, the flicker severity, Pst, shall be 1.00 ± 0.05 In addition, the manufacturer shall determine the range of the magnitude of voltage changes for which the corresponding Pst values are given with an accuracy of % or better To make these tests, the magnitude of %V/V % given in the table shall be increased and decreased while keeping the repetition rate constant, and the value of Pst shall be obtained If, for instance, at a repetition rate of seven changes per minute the input voltage changes are increased by a factor of from 1.459 % to 4.377 %, then Pst should increase from 1.0 ± % to 3.0 ± % The range over which the accuracy of ± % is maintained is the working range of the classifier If selectable sensitivity ranges are employed in the flickermeter, then similar tests should be performed for each range © BSI 08-1999 15 EN 60868:1993 Annex ZA (normative) Other international publications quoted in this standard with the references of the relevant European publications When the international publication has been modified by CENELEC common modifications, indicated by (mod), the relevant EN/HD applies IEC publication Date Title EN/HD 68-2-2 1974 Basic environmental testing procedures Part 2: Tests — Tests B: Dry heat EN 60068-2-2 68-2-3 1969 Test Ca: Damp heat, steady state HD 323.2.3 S2a 68-2-14 1984 Test N: Change of temperature 255-8 1978 Electrical relays — Part 8: Thermal electrical — relays 555-3 1982 Disturbances in supply systems caused by household appliances and similar electrical equipment — Part 3: Voltage fluctuations EN 60555-3 1987 801-2 1984 Electromagnetic compatibility for industrial-process measurement and control equipment — Part 2: Electrostatic discharge requirements HD 481.2 S1a 1987 801-3 1984 Part 3: Radiated electromagnetic field requirements HD 481.3 S1 1987 HD 323.2.14 Date a S2a 1993 1987 1987 — a EN 60068-2-2 includes supplement A:1976 to IEC 68-2-2 HD 323.2.3 S2 includes A1:1984 to IEC 68-2-3 HD 323.2 14 S2 includes A1:1986 to IEC 68-2-14 HD 481.2 S1 is superseded by EN 60801-2:1993 which is based on IEC 801-2:1991 16 © BSI 08-1999