1、BRITISH STANDARDBS EN60034-26:2006Rotating electrical machines Part 26: Effects of unbalanced voltages on the performance of three-phase cage induction motorsThe European Standard EN 60034-26:2006 has the status of a British StandardICS 29.160.30 BS EN Incorporating corrigendum September 2014BS EN 6
2、0034-26:2006ISBN 978 0 580 88012 4Amendments/corrigenda issued since publicationDate Comments30 September 2014 Implementation of IEC corrigendum September 2014: Equation in Annex B updatedThis British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 Jan
3、uary 2007 The British Standards Institution 2014. Published by BSI Standards Limited 2014National forewordThis British Standard is the UK implementation of EN 60034-26:2006. It is identical to IEC 60034-26:2006, incorporating corrigendum September 2014.The UK participation in its preparation was ent
4、rusted to Technical Committee PEL/2, Rotating electrical machinery.A list of organizations represented on this committee can be obtained on request to its secretary.The publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct applicati
5、on.Compliance with a British Standard cannot confer immunity from legal obligations.EUROPEAN STANDARD EN 60034-26NORME EUROPENNE EUROPISCHE NORM November 2006 CENELEC European Committee for Electrotechnical StandardizationComit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektro
6、technische Normung Central Secretariat:rue de Stassart35, B - 1050 Brussels 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELECmembers.Ref. No. EN 60034-26:2006 EICS 29.160 Supersedes CLC/TS 60034-26:2004English version Rotating electrical machines P
7、art 26: Effects of unbalanced voltages on the performance of three-phase cage induction motors(IEC 60034-26:2006)Machines lectriques tournantes Partie 26: Effets dun systme de tensionsdsquilibres sur les caractristiquesde fonctionnement des moteurs cage asynchrones triphass (CEI 60034-26:2006)Drehen
8、de elektrische Maschinen Teil 26: Auswirkungenvon Spannungsunsymmetrien aufdas Betriebsverhalten von Drehstrom-Induktionsmotoren (IEC 60034-26:2006)This European Standard was approved by CENELEC on 2006-11-01. CENELEC members are bound to complywith the CEN/CENELEC Internal Regulations which stipula
9、te 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 onapplication to the Central Secretariat or to any CENELEC member. This European Standard e
10、xists in three official versions (English, French, German). A version in any otherlanguage made by translation under the responsibility of a CENELEC member into its own language and notifiedto the Central Secretariat has the same status as the official versions. CENELEC members are the national elec
11、trotechnical committees of Austria, Belgium, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and t
12、he United Kingdom. EN 60034-26:2006 2 Foreword The text of document 2/1391/FDIS, future edition1 of IEC 60034-26, prepared by IEC TC 2, Rotatingmachinery, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC asEN 60034-26 on 2006-11-01. This European Standard supersedes CLC/TS
13、60034-26:2004. The following dates were fixed: latest date by which the EN has to be implementedat national level by publication of an identical national standard or by endorsement (dop) 2007-08-01 latest date by which the national standards conflictingwith the EN have to bewithdrawn (dow) 2009-11-0
14、1Annex ZA has been added by CENELEC. _Endorsement notice The text of the International Standard IEC 60034-26:2006 was approved by CENELEC as a EuropeanStandard without any modification. _ BS EN 60034-26:2006 3 EN 60034-26:2006CONTENTSINTRODUCTION.41Scope 52Normative references.53Effects of unbalance
15、d voltages on performance.53.1 Currents53.2 Heating.53.3 Torques.63.4 Full-load speed64Derating of motor to prevent overheating.6Annex A (informative) Determination of the symmetrical components of the line-to-linevoltages U1, U2, U3of a three-phase system8Annex B (informative) Approximate determina
16、tion.10 Annex ZA (normative) Normative references to international publications withtheircorresponding European publications11 Figure 1 Typical valuesof derating of design N, three-phase cage induction motorswithin the scope ofIEC 60034-127Figure A.1 Phasor diagram.8BS EN 60034-26:2006EN 60034-26:20
17、06 4 INTRODUCTION When the line voltages applied to a three-phase cage induction motor are not equal, the currents in the stator windings will also be unequal. A small percentage voltage unbalance will result in a much larger percentage currentunbalance. The application of unbalanced voltages toa th
18、ree-phase induction motor introduces a negative sequencevoltage, andthis produces in the air gap, a fluxrotating against the rotation of the rotor, thus tending to producehighcurrents. A small negative sequencevoltage may produce currents in thewindings considerably in excess of those present under
19、balancedvoltage conditions. Consequently, the temperature rise of the motor operating at aparticular load and percentage of voltage unbalance will be greater than for the motor operating under the same conditions with balanced voltages. The analytical and graphical methods used to calculate the symm
20、etrical components from the voltage readings of the three phases arewell-knownand can be taken from textbooks. Thus, thecalculation schemes are not incorporated in this standard, but shown in the informative Annex A. Besides,the evaluation of the symmetrical components can be done automatically by m
21、odern instrumentation. An approximate evaluation of imbalance is given inthe informative Annex B. BS EN 60034-26:2006 5 EN 60034-26:2006ROTATING ELECTRICAL MACHINES Part 26: Effects of unbalanced voltages on the performance of three-phase cage induction motors1 Scope Thispartof IEC 60034 describes t
22、he effects ofunbalancedvoltages onthe performance ofthree-phase cage induction motors. 2 Normative references Thefollowing referenced documents are indispensable for the application of this document. Fordated references, only the edition citedapplies. For undated references, the latesteditionof the
23、referenced document (includingany amendments) applies. IEC 60034-12, Rotating electrical machines Part 12: Starting performance ofsingle-speed three-phasecage induction motors3 Effects of unbalanced voltages on performance The effects ofunbalancedvoltages on motor performance are as described in 3.1
24、 to 3.3.3.1 CurrentsThe negative sequence componentsof the voltage produce in the air gap a flux rotatingagainst the rotation of the rotor. A small negative-sequence component of the voltage may produce currents inthe windings considerably in excess of those present under balanced voltage conditions
25、. The frequency of the current in the cage is almosttwice rated frequency, thus in the case of cages with currentdisplacement the increase of the rotor winding losses issubstantially higher than theincrease of the stator windinglosses.The currents at normal operating speed will be greatly unbalanced
26、 in the order ofapproximately 6 to 10 times the voltage unbalance. The locked-rotor current will be unbalanced to the same degree that the voltages are unbalanced, but the locked-rotor apparent power will increase only slightly. 3.2 HeatingThetemperature rise of the stator winding is always higher t
27、han inoperation atbalancedsupply voltages due to the increase of the losses produced by the negative-sequence components of the currents and voltages. The increase of the rotor losses isamplified by the current displacement.BS EN 60034-26:2006EN 60034-26:2006 6 In addition, unbalance of the voltages
28、 often is associated with a reduction of the positive-sequence component of the voltage, which causes an increase of the positive-sequence components of the currentsin stator and rotor. 3.3 Torques The locked-rotor, pull-up and breakdown torques are decreasedwhen the voltages areunbalanced. Should t
29、he voltage unbalance beextremely severe, the torques might not beadequate for theapplication.Voltage unbalance isassociatedwith the generation ofan oscillating torqueof twice line frequency. Its amplitude increases linearly with the product of the negative and the positivesequence component of the v
30、oltages; at an unbalance factor of fu= 0,05 (see Clause 4) its peak value is in the range of 25 % of the rated torque. Impermissible torsional vibrations of the complete shaft system may be excited, when its critical torsional speed is close totwice line frequency. 3.4 Full-load speedThe full-load s
31、peed isreduced slightly when the motor operateswith unbalanced voltages because of the higher slip associated with the additional rotor losses. 4 Derating of motor to prevent overheating When an a.c. motor for use on a power supply of rated frequency is connected to a three-phase voltage system havi
32、ng a negative-sequence component exceeding 1% ofthe positive-sequence component of thevoltages over along period, (at least the thermal time constant ofthe machine), the permissible power of the motor is less than the rated power toreduce thepossibility of damage to the motor. A typical derating fac
33、tor for motors of design N within the scope of IEC 60034-12 is givenin Figure 1 on the supposition that the positive-sequence component of the supply voltage isclose to the rated voltage. Operation of the motor above a 5% voltage unbalance condition is not recommended. The unbalance factor fuin Figu
34、re1 is defined as: fu= Un/Up where Un is the r.m.s. value of the negative-sequence component ofthe supply voltage;Up is the r.m.s. value of the positive-sequence component of the supply voltage. BS EN 60034-26:2006 7 EN 60034-26:20061,0 0,9 0,8 0,7 0 0,01 0,02 0,03 0,04 0,05X Y IEC 1328/06 Legend Y
35、= derating factor X = unbalance factor fuFigure 1 Typicalvalues of derating of design N,three-phase cage induction motorswithinthe scope of IEC 60034-12BS EN 60034-26:2006EN 60034-26:2006 8 Annex A(informative) Determination of the symmetrical componentsof the line-to-line voltages U1, U2, U3of a th
36、ree-phase system A.1 Graphical determination Ui3Un = j (Ui/ ) U2U3U1UpIEC 1329/06 Figure A.1 Phasor diagram Steps of the graphical determination of the symmetrical components Upand Un: Draw the phasor diagram of the three voltages U1, U2, U3, the sum of which is always zero. Erect an equilaterial tr
37、iangle upon one of the phasors (U1is chosen in Figure A.1). Theconnection of the upper corners of the two triangles results in theauxiliary phasor Ui. Draw a straight line, perpendicular to the phasor Uiand meeting with the opposite cornerof the triangle built up by U1, U2, U3. The elongation of thi
38、s line results in the negative-sequence component Un, when itslength is made 3iU . The connection of the tip of the phasor Unand the tip of the phasor U1is the phasor of the positive sequence component Up. BS EN 60034-26:2006 9 EN 60034-26:2006A.2 Analyticaldetermination The symmetrical components a
39、re defined by the equations: Positive-sequence component ( )321p231UaUaUU +=Negative-sequence component ( )3221n31UaUaUU +=where 32jea = and 012=+ aa . When the values and thephase-angles of the three voltages areknown, the symmetrical components can be calculateddirectly from the above complex equa
40、tions.If only the r.m.s. values of the voltages are known, the symmetrical components can becomputed from the following equations which contain real quantities only:+=+= +=21232221112123nn1n212np1212221n2cos23sinsinwhere,cos2,3cos231UUUUUarcUUUarcUUUUUUUUUUnBS EN 60034-26:2006EN 60034-26:2006 10 Ann
41、ex B(informative) Approximate determination Forpractical purposes, the following simplified formula may be used for the determination ofthe magnitude of imbalance and applied to Figure 1: ufaverageaveragemaxuUUUf= , where Umaxis the r.m.s. value of the greatest value of the voltages U1, U2, U3,Uaver
42、age is the average value of the r.m.s. valueofall three voltages. NOTE A mathematically correct interrelation between the factors fuand determined according to Annexes Aand B does not exist. The factor according to Annex B gives only an approximation of the physical reality. Althoughnormally under 3
43、 %, in unusual circumstances the factor according to Annex A may be up to 14 % higher than theapproximate value from Annex B resulting in an maximum deviation of 7 % of the obtained derating factor. ufBS EN 60034-26:2006September 2014 Septembre 2014 IEC 60034-26 (First edition 2006) Rotating electri
44、cal machines Part 26: Effects of unbalanced voltages on the performance of three-phase cage induction motors IEC 60034-26 (Premire dition 2006) Machines lectriques tournantes Partie 26: Effets dun systme de tensions dsquilibres sur les caractristiques de fonctionnement des moteurs cage asynchrones t
45、riphass CORRIGENDUM 1 In Annex B, replace the mathematical formula and the subsequent two explanations of the symbols by the following new formula and explanations: maxuaverageUf= , where Uaverageis the average value of the r.m.s. value of the three voltages U1, U2, U3, Umaxis the maximum of the dif
46、ferences between Uaverageand the r.m.s. values U1, U2, U3. Dans lAnnexe B, remplacer la formule mathmatique et les deux explications de symboles qui suivent par la nouvelle formule et les explications suivantes: maxuaverageUfU= , o Uaverageest la valeur moyenne de la valeur efficace des trois tensio
47、ns U1, U2, U3, Umaxest la valeur maximale des diffrences entre Uaverageet les valeurs efficaces U1, U2, U3. September 2014 Septembre 2014 IEC 60034-26 (First edition 2006) Rotating electrical machines Part 26: Effects of unbalanced voltages on the performance of three-phase cage induction motors IEC
48、 60034-26 (Premire dition 2006) Machines lectriques tournantes Partie 26: Effets dun systme de tensions dsquilibres sur les caractristiques de fonctionnement des moteurs cage asynchrones triphass CORRIGENDUM 1 In Annex B, replace the mathematical formula and the subsequent two explanations of the symbols by the following new formula and explanations: maxuaverageUfU= , where Uaverageis the average value of the r.m.s. value of the three voltages U1, U2, U3, Umaxis the maximum of the differences between Uaverageand the r.m.s. values U1, U2, U3. Dans lA
