international harmonization of standards[1]. detailed report [power apparatus

7/30/2019 International Harmonization of Standards[1]. Detailed Report [Power Apparatus

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1318 IEEE Transactions on Energy Converbion, Vol. 14, No 4, December 1999International Harmonization of StandardsDetailed Rep ort

P. I. NippesNippes-Bell Associates, Inc.2135 Highway 35Holmdel, New Jersey 07733 USAAbstract - Now that the market for electrical apparatus ha sbecome global, there are efforts underway to comparestandard s with an inten t to harmonize these standard s. TheInstitute of Electrical and Electronics Engineers (IEEE) hasmade strides in this area. Specifically, he Electric MachineryComm ittee (EMC ) of the IEEE Power Engineering Society isat the fore front of the IEEE ha rmonization effort. This paperwill give some historical background and summarize thedetails of this effort.

I. INTRODUCTIONAt the 1994 IEEE Winter Power Meeting in New YorkCity, the IEEE EMC Task Force on standardsharmonization met on February 2 to assign specificdocuments for comparison. IEC documents representingthe international standards were to be compared with theAmerican standards including IEEE, ANSI and NEMAdocuments. Ad hoc committees were established for ninecategories of electric machinery. These categories were I -Induction Machines (large), I1 - Induction Machines(medium size), I11 - Cylindrical Rotor SynchronousMachines, IV - Salient Pole Hydro Synchronous Machines,V - Other Salient Pole Synchronous Machines, VI - DCMachines, VI1 - Permanent Magnet Machines andControllers, VI11 - Electrical Machine Insulation and IXwhich is a General category. Note that Table 1 is tabulated

by category. The Task Force has reconvened annually atthe IEEE WPM to report progress on the assignedcomparisons. This paper will summarize the results of thecomparisons by category. Additionally, two papers havebeen authored recently by Task Force members describingthe details of two specific comparisons. They will also besummarized. This work will serve as the basis for hrtherharmonization efforts. Two routes to harmonization arediscussed. Whatever route is taken, the process will beslow, perhaps requiring as long as ten years.11. THE IEC STAN DAR DS PROCESS

The International Electrotechnical Commission (IEC) isan international organization with headquarters in Geneva,Switzerland. Equipment is classified into variouscategories superintended by a Technical Committee (TC).PE-1226-EC-0-2.1998 A paper recommended and approved by theIEEE Electric Machinery Committee of the IE EE Power E ngineeringSociety for publication n the IEEE Transactions on Energy Conversion.Manuscript submitted August 27, 1997: made available for printingFebruary 18, 1998.

N. E. NilssonOhio Edison Company7 6 South Main StreetAkron, Ohio 44308 USAFor example, TC 2 covers rotating machinery and TC 98 isresponsible for Electrical Insulation Systems. Fifty-one(51) nations are represented by a national committee. Thepresentation of material is a formal process that involvescomment cycles and balloting. Once a document isapproved, it becomes available in a dual languagepublication, French and English.

III. THE IEEE STANDAR DS PROCESSThe Institute of Electrical Electronics Engineers (IEEE)is a transnational society with membership worldwide. TheIEEE has its headquarters in the United States in New Y orkCity. Standards activities are overseen by the StandardsBoard. Standards project sponsors are appointed to revise,reaffirm or establish standards, and the spon sor is the chairof a working group affiliated with an IEEE technicalcommittee. For example, most IEEE electric machinerystandards are overseen by working groups reporting tosubcommittees of the IEEE Power Engineering Society(PES) Electric Machinery Committee (EMC). The typicalcycle of a standard is five years, after which the standardshould he reviewed for reaffirmation or revision. Theaffiliation of working group members must be diverse.That is, a standard developed by a working group withmore than fifty percent of its membership composed ofrepresentatives from manufacturers or users wiIl not beapproved by the Standards Board.It should be noted that the IEEE EMC HarmonizationTask Force, in a few cases, compared IEC standards withANSI and NEMA standards. The American NationalStandards Institute (ANSI) presently does not generate anyof its own rotating machinery standards. It approves otherstandards, such as those of IEEE and NEMA, as ANSIstandards. Many ANSI standards ca ny a dual IEEE/ANSIdesignation.NEMA is the National Electrical ManufacturersAssociation and is the sponsor of NEMA Std. MG-1(Motors and Generators). This is not an industly consensusdocument as only manufacturers are permitted to send

delegates to NEMA standards activities. It should be notedthat NEMA is the Secretariat for the ANSI C50 C ommittee(Rotating Electric Machinery).

0885-8969/99/$10,00 0 1998 IEEE


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Category

TABLE 1S U M M A R Y OF THE NINE CATEGORIES(See the Introduction of this paper for a description ofeac h category)

Not Completed orNo Comparisonomparison s Identical Similar DifferentIEC 34-1 IEEE 112 6 1 1 0IEC 34-1 ,2,14 ANSI C50.41 3 IO 29

II IEC 892 NEMA MG-I 3 3 0IEC 34-1 IEEE 112, Sec. 8 3 I 0Ill IEC 34-1 ANSI C50.14.15 2 IO 21IEC 34-2 IEEE 1 1 5 . 0 6 12IEC 34-3 ANSlC50 3 6 4IV None Yet None Yet

91904241912V IEC34-1,2, 14,15 NEMAMG-1,IEEE 115 3 I5 23 IOVI IEC 34- 1,2, 19 IEEE 113 11 25 5 28VI1 None Yet None YetVlll IEC 34-15 IEEE 522 0 6 1 9IEC 34-18 IEEE 275 ,43 4 3 4 9 IIX IS 0 1680 IEEE 85 2 IO 8 I 1TOTALS 39 127 112 153(PERCENT) (9.0%) (29.0%) (26.0%) (36.0%)

IV. SUMMARYOF CATEGORIESProgress has been made by members of the IEEE EMCTask Force on Standards Harmonization. Accordingly, itwould he of interest to know how much similarity existsbetween the IEEE standards and IEC standards prior tomajor efforts at harmonization. Table I summarizes thecomparisons by machine categoty.To put the information in Table I into perspective, notethat six categories of machines are considered complete.One category is similar to categories already completed andso the work required to finish it will be minimal. No workhas been done in one category. In the last category, general

comparisons remain to be done. Also, note that due to thecontent of IEC Std. 892, NEMA Std. MG-1 was used forthe comparison.Two conclusions can be drawn from this table. First,there are opportunities for harmonization. Twenty-sixpercent of the standards are different while thirty-eightpercent are identical, or similar. Secondly , some processwill be needed to address the fact that there is nocomparison for thirty-six percent of the standards. In otherwords, there is a standard requirement in either the IEEEstandards or the IEC standards for which there is noequivalent in the other set of standards.V. IEEE AN D IEC STA NDAR DS FOR INSULATION

Two early papers have been presented discussing theresults of some of the comparisons illustrated in Table 1.They are discussed in Sections V and VI .The paper, Harmonization of IEEE & IEC ElectricalInsulation Standards, by R. F. Weddleton and E. J. VanVooren [2] was presented in September of 1995 at the

Electrical Electronics Insulation Con ference in Rosemont,Illinois. Effort in this area is overseen by the IEEEStandards Coordinating Committee 4 (SCC 4): ElectricalInsulation. The related IEC body is Technical Committee(TC) 98: Electrical Insulation Systems. A specificcomparison is made of IEC Std. 85-1984, ThermalEvaluation and Classification of Electrical Insulation,IEEE Std. 1-1986, General Principles for TemperatureLimits in Rating of Electric Equipment and for theEvaluatio n of Electrical Insulation. IEC Std. 85 relates theThermal Class to the maximum temperature at rated load,while the IEEE Standard relates it to normal operatingconditions and permissible emergency temperaturelimits or peak load operation. How ever, the IECStandard may cover expected excursions with the statementmaking due allowance for factors, peculiar to the productin question. The IEC Standard maintains the letter classes,including Class E (120C) not included in IEEE Standards.It also extends the classes to 250 and above. IEEE Std. 1states that insulating system classes may be designated byletters, but does not list them. The numerical MaterialTemperature Classes given deal specifically with insulatingmaterials, not systems.One of the major contributions of this paper on thesubject of standards harmonization is the discussion ongoals of and routes to harmonization. The outcome of theharmonization process is not clear cut. One goal might beto retain two sets of standards, IEEE and IEC, identifyingsimilarities and differences. This might be beneficial incases where a customer buys a product specified to bothstandards. In that case, common tests would have to heperformed only once. On the other hand, goal 2 would beto have a single set of standards. While more far reachingand more complex, this is probably the logical goal for


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1320harmonization. How does an entity arrive at one set ofstandards? RouleA is to make a detailed comparison of thestandards and resolve the differences. Route B is simply tochoose the better standard. Whatev er route is taken, theprocess will be slow, perhaps requiring as long as ten years.

VI. ANSI AND IEC STANDARDS FOR INDUCTIONMOTORSThe paper, A comparison of ANSI and IEC Standardsfor Power Station Polyphase Induction (Asynchronous)Motors, by N. E. Nilsson [ l ] was presented at the 1996Winter Power Meeting in Baltimore, Maryland. ANSI

C50.41-1982, Polyphase Induction Motors for PowerStations, is compared with the polyphase asynchronousmotor (hereinafter referred to as motor) requirements ofthe following IEC standards:1) 34-1: 1994, Rating and Performance2) 34-2: 1972, Methods for Determining Losses and3) 34-5:1991, Classification of Degrees of Protection4) 34-8: 1990, Terminal Markings and Direction of5) 34-9:1990, Noise Limits6) 34-12:1980, Starting Performance of Induction7) 34-14:1988, Measu rement, Evaluation and Limits of8) 72-1: 1991, Dimen sions and Output Series

Efficiency.Provided by EnclosuresRotation

MotorsVibration Severity

While there are a number of similarities, there are issuesthat are addressed by one standard hut not by the other. Forexample, ANSI is silent on the issue of harmonic voltages,but IEC 34-1.12.2.1 specifies that motors shall be suitablefor operation on a supply voltage having a harmonicvoltage factor (HVF) not exc eeding 0.02. This value is 0.03per unit for normal torque motors. During temperature risetesting, the HVF shall not exceed 0.015. The HVF can becomputed as follows:

where n is the order of the harmonicVn is the per unit value of the harmonic voltageOn the other hand, IEC is silent on the issue of bustransfer limits. ANSI Std. C50.41.8 states that the windingend turns shall he adequately braced and supported towithstand the starting capab ilities and to w ithstand the bustransfer of 1.33 per unit volts per hertz.

ANSI Std. (30.41.25 specifies that high potential (hipot)tests shall he performed hut does not specify the test level.ANSI does, however, specify in Section 8 that W - I andW-I1 frame motors shall have sealed insulation systemswith sufficient moisture resistance to withstand animmersion test. In addition to spec ifying one minute testlevels, IEC Std. 34-1:1994 permits a five second test at 120percent of the normal test voltage. IEC also specifies hipotlevels for motors after repair or refurbishmentIEC is silent on continuous loading above nameplaterating. ANSI Std. CS0.41.9.3.1 contem plates a continuousloading above nameplate by specifying that the m otor maybe procured with a service factor (SF) rating. A typicaloverload rating is 1.15 service factor. When a motor isoperated at 1.15 SF, it may have efficiency, power factorand speed values different from those at rated load.Although not explicitly stated, it should be clear that a 1.15SF m otor operated at nameplate rating (1.0 SF) will havelower temperature rises than the maxim um specified levelsfor unity SF motors. At this time, no SF ratings arespecified for motors used with various adjustable speeddrives (ASDs) such as six pulse, twelve pulse and PWMtype ASDs. Nevertheless, it is comm on practice to usemotors with SFs greater than unity to provide margin forheating in the motor caused by the k(6n i 1) harmonicsgenerated by the A SD.

VII. RECENT STANDARD S COMPARISONSRecently IEEE Std. 113-1985, Test Procedures forDirect Current Machines has been compared with theappropriate sections of IEC Std. 34 -1 ,3 44 and 34-19. Thisnew material has been included in Table 1of this paper andsupplements the information in Table 1 of the d igest paper

presented at the International Electric Machine s and D rivesConference (IEMD C97) presented in Milwaukee, May 18-21, 1997. There are a number of similarities between thetwo sets of standards, particularly in the area ofidentification of sp ecific losses, measurem ent of currentand voltage ripple, measurement of inductances and speedregulation. There are significant differences in thefollowing areas:1) Brush drop loss: IEC defines brush voltage drop as0.6 volts for metal-carbon brushes and 2 volts forcarbon or graphite brushes. IEEE Std. 113 definesbrush voltage drop as 0.5 volts for metal-carbonbrushes, 2 volts for carbon or graphite brushes with

shunts attached or 3 volts for carbon or graphitebrushes without shunts attached.2) Definitions: IEC gives a list of terms and definitionswhile IEEE Std. 113 refers to a dictionary standard.3) Ripple: IEEE Std. 113 specifies ripple free operationas being less than 6 percent peak-to-peak AC (2


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1321cooling systems, the IEC standards appear to impose lessstringent constraints.When designing a machine to comply with IECstandards, it is possible to design for higher electricalwinding current densities than is the case for ANSIstandards. In one exa mple involving relatively low voltageair cooled generators, when limiting 60 Hz operation byANSI standards for a given temperature classification andlimiting 50 Hz operation by IEC standards for an equivalentclass, the designers discovered that it is possible to raise 50Hz torque nearly 20 percent above 60 Hz torque resultingin 50 Hz output power being essentially equal to 60 Hzoutput despite the lower speed.

VI11 ONGOING ACTIVITIESThe harmonization process is not static. There areactivities in process at this time to close the gap betweenthe IEEE and IEC. The EMC Harmonization Task Forcehas recommended the following action to the EMC:I) IEC Std 34-17, ,Guide fo r the Application of CageInduction Motors When Fed From Converters.This recent IEC document should be evaluated bythe appropriate IEEE subcomm ittee.2) Provisional Methods fo r Determining Losses an dEflciency of Converter Fed Induction Machines.This document was submitted to the IEC CentralOffice in Final Form in June of 1995. Interestingly ,much of the work that went into the preparation ofthis document was performed in the United States.This material should be adopted by IEEE directlyfrom the IEC document when it becomes available.The harmonization effort is working in both directions.

IEEE Std. 112, Test Procedure for Polyphase InductionMotors and Generators, which was recently revised, hasbeen submitted to IEC for Member Nation comments inconsideration for adoption as an IEC document. The IECSubcommittee 2G (SCZG), Rotating Machinery TestMethods and Procedures, convened in Helsinki in June of1996 and it was reported that 10 pages of comm ents weresubmitted by 9 different nations pertaining to IEEE Std.112. These comments will be reviewed by SC2G forpossible inclusion within planned revisions of IEC 34-2.The IEC does not have a standard that addresses testprocedures for induction machines and IEEE Std. 112 hasalready been embraced by the international community asthe sem inal document on this subject.The IEC does not presently have a standard on insulationresistance testing. Accordingly, it has been suggested whenthe latest revision has been completed for IEEE Std. 43,Recommended Practice for Testing Insulation Resistanceof Rotating Machinery, that it be considered forsubmission by the U S . National Committee to the IEC.

percent RMS) for components greater than 500hertzwhile IEC does not specify ripple free operationNevertheless, IEEE uses the term on rectifiedpower for m otor conditions not meeting the ripple-free criteria.Both standards indicate that stray load loss varies asthe square of current. Where they differ is that IECspecifies stray load loss as 1 percent of full load foruncompensated machines and 0.5 percent of full loadfor compensated machines. The IEEE standardidentifies test procedures for determination of strayload loss and recommends 1 percent of full load beused only in the absence of test data.

The IEEE standard covers vibration testing, insulationresistance, magnetic saturation, audio noise,electromagnetic interference, exciter response, shaftcurrents and moment o f inertia, while IEC does not.Additionally, a com parison of standards for salient-polesynchronous machines excluding hydro machines wascompleted recently. IEC 34-1, 2, 14 and 15 are comparedwith IEEE Std. 115 and NEMA Std. MG-1. There wereportions of IEEE Std. 522 included in this comparison. Apaper summ arizing the results was submitted for review forthe 1997 IEEE Sum mer Power Meeting in Berlin, Germanyby N. K. Ghai of MagneTek.A number of the comparisons are the same as thosedescribed for other categories of machines; however, someof the m ore interesting differences are as follows:

1) There is a significant variation in voltage surgecapability requirements. For a 2.3 kV machine, the1.2 microsecond capability required by IEC is 7.6per unit. IEEE requires 5.0 per unit and NEMArequires 4.5 per unit. The requirement atapproximately 0.2 microseconds also varies. IECrequires 4.9 per unit, IEEE requires 3.5 per unit andNEMA requires 2.0 per unit.2) The greatest difference between NEMA and IECstandards concerns machine performance standards.The IEC requires tolerances on the order of ten tofifteen percent. Nevertheless, the tolerance for thepeak value of generator short circuit current is plusor minus 30 percent. NEMA does not recognizetolerances on stated performance. It is usually amatter of agreement between the owner and themanufacturer whether the stated performance isnominal or guaranteed.

Also, since the original draft of this paper was completed,a paper summarizing the comparison of IEC and ANSIstandards for synchronous generators that was presented ina panel discussion at a recent IEEE Winter Power Meetinghas been published. The authors conclude that both sets ofstandards are similar; however, in the design of thermal


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1322Finally, it should be noted that the harmonization effortwithin the IEEE EMC has been headed by P. I. Nippessince its inception. There will be a changing of the guard in1997. C. Kaminski is the new Chairman of the EMC TaskForce in Standards Harmon ization.

IX. REFERENCESN. E. Nilsson, A Comparison of ANSI and IECStandards for Power Station Polyphase Induction(Asynchronous) Motors, presented at the 1996 IEEEWinter Power Meeting, January 22, 1996, Baltimore,Maryland, paper 96WM 32-1-EC.R. F. Weddleton and E. J. Van Vooren,Harmonization of IEEE C IEC Electrical InsulationStandards, Technical Paper TP-95132, July 14, 1995.

X. BIOGRAPHYN. E. Nilsson (M-1971, SM-1982, F-1996) holds aBSEEdegree from the University of Cincinnati (1971), an MSEEdegree from the University of Akron (1975), and a JurisDoctor degree from the University of Akron (1986). He isa Principal Engineer in the Ohio Edison Technical ServicesDepartmen t Project Services Section. His workassignments have included preparation of major equipmentspecifications, development of engineering computerprograms to support technical analyses, development ofrelay protection schemes, and development of specializedtesting programs to evaluate plant equipment and systems.Mr. Nilsson is a registered Professional Engineer inKentucky, Ohio and Pennsylvania, and a member of EtaKappa Nu and Tau B eta Pi. He is licensed as an attorney in

Ohio and is a licensed Patent Attorney.Paul I. Nippes, P.E. president of Nippes-Bell Associates,Inc. and Magnetic Products and Services, Inc., has beeninvolved with electrical machinery as a designer andconsultant for over 47 years. During the past 20 years, Mr.Nippes has concentrated on solving shaft current problemsand designing corrective products, including machinecondition monitors. Prior to consulting, Mr. Nippes careeras an Electrical Engineer included the followingcompanies: ElectroDynamicMjeneral DynamicsCorporation, the Elliott Company, and the Allis ChalmersManufacturing Company. He had also been an AssociateProfessor of Electrical Engineering at the University ofWisconsin. Mr. Nippes is a Fellow of IEEE, and hasserved as Chairman of ANSI C50 and IEC SC2G. He holdsa BSEE. from Penn State (1950) and an MSEE from theUniversity of Wisconsin (1955).

international harmonization of standards[1]. detailed report [power apparatus

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