1、BRITISH STANDARDBS EN 60034-26:2006Rotating 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 29.160g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g3
2、7g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58Licensed Copy: Wang Bin, na, Wed Apr 11 06:54:16 GMT+00:00 2007, Uncontrolled Copy, (c) BSIBS EN 60034-26:2006This British Standard was published under the
3、authority of the Standards Policy and Strategy Committee on 31 January 2007 BSI 2007ISBN 978 0 580 50036 7National forewordThis British Standard was published by BSI. It is the UK implementation of EN 60034-26:2006. It is identical with IEC 60034-26:2006. It supersedes DD IEC/TS 60034-26:2002, which
4、 will be withdrawn on 1 November 2009. The UK participation in its preparation was entrusted to Technical Committee PEL/2, Rotating electrical machinery.A list of organizations represented on PEL/2 can be obtained on request to its secretary.This publication does not purport to include all the neces
5、sary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments issued since publicationAmd. No. Date CommentsLicensed Copy: Wang Bin, na, Wed Apr 11 06:54:16 GMT+00:00 2007, Uncontrolled Cop
6、y, (c) BSIEUROPEAN STANDARD EN 60034-26 NORME EUROPENNE EUROPISCHE NORM November 2006 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Bru
7、ssels 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 60034-26:2006 E ICS 29.160 Supersedes CLC/TS 60034-26:2004English version Rotating electrical machines Part 26: Effects of unbalanced voltages on the performance of three-
8、phase cage induction motors (IEC 60034-26:2006) Machines lectriques tournantes Partie 26: Effets dun systme de tensions dsquilibres sur les caractristiques de fonctionnement des moteurs cage asynchrones triphass (CEI 60034-26:2006) Drehende elektrische Maschinen Teil 26: Auswirkungen von Spannungsun
9、symmetrien auf das Betriebsverhalten von Drehstrom-Induktionsmotoren (IEC 60034-26:2006) This European Standard was approved by CENELEC on 2006-11-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the st
10、atus 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
11、). 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, Cyprus, th
12、e 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 the United Kingdom. Licensed Copy: Wang Bin, na, Wed Ap
13、r 11 06:54:16 GMT+00:00 2007, Uncontrolled Copy, (c) BSIEN 60034-26:2006 2 Foreword The text of document 2/1391/FDIS, future edition 1 of IEC 60034-26, prepared by IEC TC 2, Rotating machinery, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 60034-26 on 2006-11-01. T
14、his European Standard supersedes CLC/TS 60034-26:2004. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2007-08-01 latest date by which the national standards conflicting with
15、the EN have to be withdrawn (dow) 2009-11-01 Annex ZA has been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 60034-26:2006 was approved by CENELEC as a European Standard without any modification. _ Licensed Copy: Wang Bin, na, Wed Apr 11 06:54:16 GMT+00:00 2007, U
16、ncontrolled Copy, (c) BSI 3 EN 60034-26:2006 CONTENTS INTRODUCTION.4 1 Scope 5 2 Normative references .5 3 Effects of unbalanced voltages on performance.5 3.1 Currents 5 3.2 Heating .5 3.3 Torques.6 3.4 Full-load speed6 4 Derating of motor to prevent overheating.6 Annex A (informative) Determination
17、 of the symmetrical components of the line-to-line voltages U1, U2, U3of a three-phase system 8 Annex B (informative) Approximate determination.10 Annex ZA (normative) Normative references to international publications with their corresponding European publications11 Figure 1 Typical values of derat
18、ing of design N, three-phase cage induction motors within the scope of IEC 60034-127 Figure A.1 Phasor diagram.8 Licensed Copy: Wang Bin, na, Wed Apr 11 06:54:16 GMT+00:00 2007, Uncontrolled Copy, (c) BSIEN 60034-26:2006 4 INTRODUCTION When the line voltages applied to a three-phase cage induction m
19、otor 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 current unbalance. The application of unbalanced voltages to a three-phase induction motor introduces a negative sequence voltage, and this produ
20、ces in the air gap, a flux rotating against the rotation of the rotor, thus tending to produce high currents. A small negative sequence voltage may produce currents in the windings considerably in excess of those present under balanced voltage conditions. Consequently, the temperature rise of the mo
21、tor operating at a particular 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 symmetrical components from the voltage readings of the three phases are we
22、ll-known and can be taken from textbooks. Thus, the calculation 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 modern instrumentation. An approximate evaluation of imbalance is gi
23、ven in the informative Annex B. Licensed Copy: Wang Bin, na, Wed Apr 11 06:54:16 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 5 EN 60034-26:2006 ROTATING ELECTRICAL MACHINES Part 26: Effects of unbalanced voltages on the performance of three-phase cage induction motors 1 Scope This part of IEC 60034 d
24、escribes the effects of unbalanced voltages on the performance of three-phase cage induction motors. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the lat
25、est edition of the referenced document (including any amendments) applies. IEC 60034-12, Rotating electrical machines Part 12: Starting performance of single-speed three-phase cage induction motors 3 Effects of unbalanced voltages on performance The effects of unbalanced voltages on motor performanc
26、e are as described in 3.1 to 3.3. 3.1 Currents The negative sequence components of the voltage produce in the air gap a flux rotating against the rotation of the rotor. A small negative-sequence component of the voltage may produce currents in the windings considerably in excess of those present und
27、er balanced voltage conditions. The frequency of the current in the cage is almost twice rated frequency, thus in the case of cages with current displacement the increase of the rotor winding losses is substantially higher than the increase of the stator winding losses. The currents at normal operat
28、ing speed will be greatly unbalanced in the order of approximately 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 Heating The temperature rise o
29、f the stator winding is always higher than in operation at balanced supply 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 is amplified by the current displacement. Licensed Copy: Wang Bin, na, Wed
30、 Apr 11 06:54:16 GMT+00:00 2007, Uncontrolled Copy, (c) BSIEN 60034-26:2006 6 In addition, unbalance of the voltages 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 currents in stator and roto
31、r. 3.3 Torques The locked-rotor, pull-up and breakdown torques are decreased when the voltages are unbalanced. Should the voltage unbalance be extremely severe, the torques might not be adequate for the application. Voltage unbalance is associated with the generation of an oscillating torque of twic
32、e line frequency. Its amplitude increases linearly with the product of the negative and the positive sequence component of the voltages; 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 sh
33、aft system may be excited, when its critical torsional speed is close to twice line frequency. 3.4 Full-load speed The full-load speed is reduced slightly when the motor operates with unbalanced voltages because of the higher slip associated with the additional rotor losses. 4 Derating of motor to p
34、revent overheating When an a.c. motor for use on a power supply of rated frequency is connected to a three-phase voltage system having a negative-sequence component exceeding 1 % of the positive-sequence component of the voltages over a long period, (at least the thermal time constant of the machine
35、), the permissible power of the motor is less than the rated power to reduce the possibility of damage to the motor. A typical derating factor for motors of design N within the scope of IEC 60034-12 is given in Figure 1 on the supposition that the positive-sequence component of the supply voltage is
36、 close to the rated voltage. Operation of the motor above a 5 % voltage unbalance condition is not recommended. The unbalance factor fuin Figure 1 is defined as: fu= Un/Up where Un is the r.m.s. value of the negative-sequence component of the supply voltage; Up is the r.m.s. value of the positive-se
37、quence component of the supply voltage. Licensed Copy: Wang Bin, na, Wed Apr 11 06:54:16 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 7 EN 60034-26:2006 1,0 0,9 0,8 0,7 0 0,01 0,02 0,03 0,04 0,05 X Y IEC 1328/06 Legend Y = derating factor X = unbalance factor fuFigure 1 Typical values of derating of d
38、esign N, three-phase cage induction motors within the scope of IEC 60034-12 Licensed Copy: Wang Bin, na, Wed Apr 11 06:54:16 GMT+00:00 2007, Uncontrolled Copy, (c) BSIEN 60034-26:2006 8 Annex A (informative) Determination of the symmetrical components of the line-to-line voltages U1, U2, U3of a thre
39、e-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 tri
40、angle upon one of the phasors (U1is chosen in Figure A.1). The connection of the upper corners of the two triangles results in the auxiliary phasor Ui. Draw a straight line, perpendicular to the phasor Uiand meeting with the opposite corner of the triangle built up by U1, U2, U3. The elongation of t
41、his line results in the negative-sequence component Un, when its length 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. Licensed Copy: Wang Bin, na, Wed Apr 11 06:54:16 GMT+00:00 2007, Uncontrolled Copy, (c) BSI
42、 9 EN 60034-26:2006 A.2 Analytical determination The symmetrical components are defined by the equations: Positive-sequence component ( )321p231UaUaUU += Negative-sequence component ( )3221n31UaUaUU += where 32jea = and 012=+ aa . When the values and the phase-angles of the three voltages are known,
43、 the symmetrical components can be calculated directly from the above complex equations. If only the r.m.s. values of the voltages are known, the symmetrical components can be computed from the following equations which contain real quantities only: +=+= +=21232221112123nn1n212np1212221n2cos23sinsin
44、where,cos2,3cos231UUUUUarcUUUarcUUUUUUUUUUnLicensed Copy: Wang Bin, na, Wed Apr 11 06:54:16 GMT+00:00 2007, Uncontrolled Copy, (c) BSIEN 60034-26:2006 10 Annex B (informative) Approximate determination For practical purposes, the following simplified formula may be used for the determination of the
45、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, Uaverage is the average value of the r.m.s. value of all three voltages. NOTE A mathematically correct interrelation between the factors fuand d
46、etermined according to Annexes A and B does not exist. The factor according to Annex B gives only an approximation of the physical reality. Although normally under 3 %, in unusual circumstances the factor according to Annex A may be up to 14 % higher than the approximate value from Annex B resulting
47、 in an maximum deviation of 7 % of the obtained derating factor. ufLicensed Copy: Wang Bin, na, Wed Apr 11 06:54:16 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 11 EN 60034-26:2006 Annex ZA (normative) Normative references to international publications with their corresponding European publications Th
48、e following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. NOTE When an international publication has been mod
49、ified by common modifications, indicated by (mod), the relevant EN/HD applies. Publication Year Title EN/HD YearIEC 60034-12 -1)Rotating electrical machines Part 12: Starting performance of single-speed three-phase cage induction motors EN 60034-12 20022) 1)Undated reference. 2)Valid edition at date of issue. Licensed Copy: Wang Bin, na, Wed Apr 11 06:54:16 GMT+00:00 2007, Uncontrolled Copy, (c)
