IEC61000-3-12 Harmonic Measurements Up To 75A
Contents
1. O Advanced Test Equipment Rentals Established 1981 www atecorp com 800 404 ATEC 2832 1EC61000 3 12 Harmonic Measurements Up To 75A VPN 104 120 1 IEC 61000 3 12 HARMONIC MEASUREMENTS UP To 75A Introduction The legislative requirement to measure Harmonics and Flicker on equipment rated up to 16A rms is well known to organizations selling any type of electrical and electronic equipment in the European Community IEC61000 3 12 defines limits for for levels of harmonic current in equipment rated up to 75A This technical note provides guidance for making measurements in accordance with the 61000 3 12 standard An example spreadsheet for use with Voltech IEC software data is available from our website at www voltech com Relationship to 61000 3 2 Harmonics lt 16A The 61000 3 12 lt 75A standard uses the same basic methods limit types and measurement methods of 61000 3 2 lt 16A and an understanding of those is assumed in this technical note See the references for more information 2003 Voltech Instruments All rights reserved a Nils no Ae ee Pa ES Nr IEC 61000 3 12 OL Ti gt A On XT Compliance Testing to 3 12 Method 1 Connect up the power analyzer as shown in figure 1 The PM3000A power analyzer is suitable for direct measurements up to 30A rms A precision current transformer such as the Voltech CT1000 100 1 may be used to extend the measurement range up to 75A AC Source Vol2. equipment is acceptable based on the Rsce level and the predicted impact on the existing level of voltage harmonic distortion Stage 3 For equipment complying neither with stage 1 or stage 2 the manufacturer shall state in the instruction manual and in a document available to a prospective user before purchasing the equipment that it is necessary for the user to consult the supply authority for consent to connect the equipment Consent is required before connection and the measurements of harmonics THD and PWHD described here must be available to the electricity supplier 61000 3 12 Testing Summary Measure 1 5s smoothed harmonics and their averages Calculate THD PWHD and In harmonic Less than limits Yes gt Simplified connection of Stage 1 j No Less than limits Yes gt Connect but specify Min Rsce of Stage 2 No Y Requires supply authority acceptance before connection 2003 Voltech Instruments All rights reserved IEC 61000 3 12 A Practical Example A piece of single phase equipment is rated at 230V 40A at 50Hz The harmonics are measured using a PM3000A power analyzer and its associated PC software The percentage individual currents and THD PWHD are calculated according to the instructions given here An example spreadsheet showing how the calculations are done on data exported from Voltech software is available
3. row then the requirements corre sponding to that row have been met Also every individual not smoothed harmonic result must not exceed 150 of the limit just as in 61000 3 2 The requirements are split into three stages 1 2 and 3 as described below Stage 1 Limits u e u Js le 7 e e ho i uz hs 7o pwn a asla 107 13 72 les los e1 or 2 a a If all measured values are below those given in the table above then the require ment is that the instruction manual of the product shall state Equipment conform ing to IEC61000 3 12 provided Rsce min 33 Rsce is defined later but Regge is generally at least 33 for most commercial installations Stage 2 If the equipment does not meet the stage 1 requirements compare the measured values against the appropriate table below Start at the top of the table and work downwards until all the measured values are lower than those given on a particular row Note the minimum Rsce for that row It is acceptable to linearly interpret between table values in order to obtain an intermediate value of Regge if required Balanced Three phase Equipment Limits mee ee ele Rsce vas le a orje 72 2 se fan lia l2 e ie e e Ja J1 27 jo 2 fie s 13 Ja e 25 ale e Mo 27 2 2 he r 19 e e e amwe a erlo 2 is mis 7 8 so se me fer fe ee fis fs fo fee 2003 Voltech Instruments All rights reserved IEC 61000 3 12 Equipment Other Than B
4. 39 437 3841 E mail sales voltech com www voltech com Note While every care has been taken in compiling the information for this publication Voltech Instruments cannot accept legal liabil ity for any inaccuracies Voltech Instruments reserves the right to alter product specifications without notice and whenever necessary to ensure optimum performance from its product range VPN 104 120 1
5. alanced Three phase Limits ml EE EB Be oes molar Rsce 33 je farefa to7 27 72 2 fas 1e 31 13 2 23 Jos ee e J24 Ja Js 27 Jae J2 s Js a 13 3 J 26 120 e Jaz a fis faz ho 2 fe 16 5 fis la fso 30 _ wo fs s s a7 2 e hele 1a e 0 o ap a ee a7 fe e fe fee io as fea lar Balanced Three phase Equipment Under Specified Conditions Limits Min jlo l4 Is I7 lagi lay l42 l43 THD PWHD Rsce wee a horar rap esta ee ofe e ho 27 s 2 re s ha ho e ls This table may be used only if one of the following conditions is met a The phase angle of the 5th harmonic current is in the range of 90 to 150 typical of an uncontrolled diode bridge and smoothing capacitor b The design of the equipment is such that the phase angle of the 5th harmonic current has no preferential value over time and can take any value in the whole interval of 0 to 360 typical of converters with fully controlled bridges c The 5th and 7th harmonic currents are each less than 5 of the reference fundamental current 2003 Voltech Instruments All rights reserved IEC 61000 3 12 ILTECHNOTES INT When a table value of Rsce can be found the instruction manual of the product shall state Equipment conforming to IEC61000 3 12 provided Rsce min xx where xx is the value found in the table In addition the user manual shall state that there is a need for the supply authority to verify that the connection of this
6. f the relevant standard IEC61000 3 12 Limits Limitation for harmonic currents produced by equip ment connected to public low voltage systems with input current lt 5A per phase and subject to restricted connection Note 61000 3 12 is due for publication in 2004 and is the standard that will implement the following technical report IEC61000 3 4 1998 Limits Limitation of emission of harmonic currents in low voltage power supply systems for equipment with rated current greater than 16A IEC documents are available from www iec ch 3 The Voltech IEC Software This PC software includes extensive reference and background material to the IEC harmonics and flicker standards within its help system Fully working trial version available free of charge from www voltech com 2003 Voltech Instruments All rights reserved IEC 61000 3 12 VOLTECHNOTES a a 2000 200 1000 100 500 50 200 20 oo NOTES 50 5 0 on 2 0 10 1 0 8 0 5 5 0 2 1 0 1 0 5 0 enenaa BEBBE gogia The Voltech PM Series of Power Analyzers 2003 Voltech Instruments All rights reserved VOLTECHNOTES Voltech Instruments Ltd 148 Sixth Street Harwell International Business Centre Didcot Oxon OX11 ORA UK Telephone 44 0 1235 834555 Facsimile 44 0 1235 835016 E mail sales voltech co uk Voltech Instruments Inc 11637 Kelly Road Suite 306 Fort Myers FL 33908 USA Telephone 1 239 437 0494 Facsimile 1 2
7. from the support area of www voltech com ven fe e e es e 7 le e oo in ho vo THO pwna Limit Value When these average measured values are compared with those of table 1 each of the measured value is below the limit Also every individual result shown on the complete spreadsheet is less than 150 of the limits in accordance with part 4 2 4 of the stan dard Thus these results comply with the requirements of Stage 1 Simplified Connection All that is required is that the stage 1 declaration is made in the product s instruction manual Significance of Rgce min The short circuit ratio Rsce is related to the output impedance of the supply to which the equipment will be connected Rsce min 230 Z x lequ Z 230 Rgce min X equ Where Z supply output impedance lequ rated line current In this case Zmax 230 33 x 40 Zaa 2 mO 2003 Voltech Instruments All rights reserved IEC 61000 3 12 OLTECHNOTES In terms of short circuit current lsc the supply must be rated at greater than lee min Zmax lsc min 230 0 1742 im 1320A Pre compliance Testing The full compliance testing methods described above use equipment and tech niques that are in strict accordance with the requirements of the standard Full compliance techniques are used by test houses and larger organizations to provide traceable certification that the tested equipment meets the standard Pre compliance testin
8. g is often used during product design and development phases to provide useful measurements using a less expensive test environ ment The Voltech PM3000A may be used without a fully compliant ac source to provide pre compliance measurements When making pre compliance measure ments always ensure there is an adequate margin between the results and the limits before submitting the product for compliance testing Conclusions Products rated at up to 75A per phase for connection within the European Community will need to comply with the harmonic limits described by IEC61000 3 12 The test method is basically identical to that of IEC61000 3 2 although different limits have been specified Versatile power measurement equipment such as the Voltech PM3000ACE can be used to making 61000 3 12 measurements simply with the addition of current transformers and some spreadsheet calculations No hardware modifications are required The PM3000ACE is ideal for making either pre compliance measurements from the normal ac supply or full compliance measurements if used with a suitable ac source 2003 Voltech Instruments All rights reserved IEC 61000 3 12 References 1 Voltech technical note Understanding EN61000 3 2 item no 104 007 2 This technical note is written as a guide to implementing the following stan dard and must be read in conjunction with it In case of doubt always refer to the latest available version o
9. tech PM3000A Power Analyzer CT1000 100 1 RS232 IEEE Figure 1 Measuring power and harmonics 2 Make measurements as usual using the power analyzer software The class and other set up details of the software are unimportant at this stage although current scaling should be set if a current transformer has been used At the end of the test export the results from the software The results may now be opened in a spreadsheet for manipulation in accordance with 61000 3 12 as follows 3 Using the spreadsheet calculate the following a Total Harmonic Distortion THD 2003 Voltech Instruments All rights reserved gt VOLTECHNOTES IEC 61000 3 12 a a o a i _ ae ae gt A b Partial Weighted Harmonic Distortion PWHD Be n 7 c Percentage individual harmonics lo l3 l4 I5 143 Where is the average current harmonic n over the duration of the t 3 spreadsheet A of l4 is the average fundamental 1st harmonic current over the duration of test from the spreadsheet 4 Compare the results with the tables in the next section 2003 Voltech Instruments All rights reserved ao w IEC 61000 3 12 OLTECHNOTES y eN AC Applying the Limits Each of the calculated measurements is now compared with values given in rows of limits taken from tables of the standard The comparison is made row by row If every measured value is less than those in the
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