1、Published by theInstitute of Electrical and Electronics Engineers, Inc.5 5 1IEE Recomended Practice forCalculating S h o rt - C i rc u i tC u r rents inIndustrial andC o m m e rcial P o w e rS y s t e m sIEEE Std 551-20060551-2006_VioletBook_frontCover 8/10/06 3:31 PM Page 1Recognized as anAmerican
2、National Standard (ANSI)IEEE Std 551-2006IEEE Recommended Practice for Calculating Short-Circuit Currents in Industrial and Commercial Power SystemsSponsor Power Systems Engineering Committeeof theIEEE Industry Applications SocietyApproved 9 May 2006IEEE-SA Standards BoardApproved 2 October 2006Amer
3、ican National Standards InstituteThe Institute of Electrical and Electronics Engineers, Inc.3 Park Avenue, New York, NY 10016-5997, USACopyright 2006 by the Institute of Electrical and Electronics Engineers, Inc.All rights reserved. Published 17 November 2006. Printed in the United States of America
4、.IEEE is a registered trademark in the U.S. Patent +1 978 750 8400. Permission to photocopy portions ofany individual standard for educational classroom use can also be obtained through the CopyrightClearance Center.iv Copyright 2006 IEEE. All rights reserved.IntroductionThis recommended practice is
5、 intended as a practical, general treatise for engineers on thesubject of ac short-circuit currents in electrical power systems. The focus of this standardis the understanding and application of analytical techniques of short-circuit analysis inindustrial and commercial power systems. However, the s
6、ame engineering principlesapply to all electrical power systems, including utilities and systems other than 60 Hz.More than any other book in the IEEE Color Bookseries, the “Violet Book” covers thebasics of short-circuit currents. To help the reader, the same one-line diagram that is usedin several
7、of the other color books is used in sample calculations. Items covered in theViolet Book that are not covered in the other color book chapters on short-circuit currentsare the contributions of regenerative SCR drives and capacitors to faults. The referencedata chapter in this recommended practice is
8、 quite extensive and should be very useful forany type of power system analysis.Notice to usersErrataErrata, if any, for this and all other standards can be accessed at the following URL: http:/standards.ieee.org/reading/ieee/updates/errata/index.html. Users are encouraged to checkthis URL for errat
9、a periodically.InterpretationsCurrent interpretations can be accessed at the following URL: http:/standards.ieee.org/reading/ieee/interp/index.html.PatentsAttention is called to the possibility that implementation of this standard may require useof subject matter covered by patent rights. By publica
10、tion of this standard, no position istaken with respect to the existence or validity of any patent rights in connection therewith.The IEEE shall not be responsible for identifying patents or patent applications for whicha license may be required to implement an IEEE standard or for conducting inquir
11、ies intothe legal validity or scope of those patents that are brought to its attention.This introduction is not part of IEEE Std 551-2006, IEEE Recommended Practice for CalculatingShort-Circuit Currents in Industrial and Commercial Power Systems.Copyright 2006 IEEE. All rights reserved. vParticipant
12、sTo many members of the working group who wrote and developed the chapters in this rec-ommended practice, the Violet Book has been a labor of love and a long time coming.Over the years, some members have come and gone, but their efforts are sincerely appre-ciated. To all the members past and present
13、, many thanks for your excellent contributions.The following working group members of the Power System Analysis Subcommittee ofthe Power Systems Engineering Committee of the IEEE Industry Applications Societyand some non-members contributed to the existence of the Violet Book: Jason MacDowell, Chair
14、 (2003-2006)S. Mark Halpin, Chair (2000-2003)L. Guy Jackson, Chair (1998-2000)Conrad R. St. Pierre, Chair (1989-1998)Walter C. Huening, Chair (1965-1989)Chapter authors:Chapter reviewers/contributorsChet E. DavisRichard L. DoughtyM. Shan GriffithWilliam R. HaackTimothy T. HoWalter C. HueningDouglas
15、M. KaarcherBal K. MathurElliot RappaportAlfred A. RegottiAnthony J. RodolakisMichael A. SlonimDavid H. SmithConrad R. St. PierreNeville A. WilliamsMichael AimoneJack AlacchiWilliam E. AndersonR. Gene BaggsRoy D. BoyerReuben BurchBernard W. CableW. Fred Carden, Jr.Hari P. S. CheemaNorman R. ConteChet
16、 E. DavisRobert J. DeatonPhillip C. DoolittleRichard L. DoughtyJames W. FeltesKen FleischerPradit FuangfooM. Shan GriffithWilliam R. HaackWilliam HallS. Mark HalpinRobert C. Hay, Sr.Timothy T. HoRobert G. HoeraufWalter C. HueningGuy JacksonDouglas M. KaercherAlton (Gene) KnightJohn A. KroissWei-Jen
17、LeeJason MacDowellBal K. MathurRichard H. McFaddenSteve MillerWilliam J. MoylanRussell O. OlsonLaurie OppelNorman PeachDavid J. PodobinskiLouie J. PowellRalph C. PrichardElliot RappaportAlfred A. RegottiMichael L. ReichardAnthony J. RodolakisWillaim C. RoettgerVincent SaporitaGeorge SchliapnikoffDav
18、id D. ShippFarrokh ShokoohCharles A. ShriveMichael A. SlonimDavid H. SmithJ. R. SmithGary T. SmullinConrad R. St. PierrePeter SutherlandGeorge A. TerryLynn M. ToomanS. I. VenugopalanDonald A. VoltzClaus WiigNeville A. Williamsvi Copyright 2006 IEEE. All rights reserved.AcknowledgmentAppreciation is
19、expressed to the following companies and organizations for contributingthe time and in some cases expenses of the working group members and their support helpto make possible the development of this text.AVCA CorporationBrown it maypresent the advertisers equipment or methods in a best light and sho
20、uld be carefullyevaluated. Manufacturers catalogs are a valuable source of equipment information. Someof the larger manufacturers complete catalogs are very extensive, covering dozens ofvolumes; however, these companies may issue abbreviated or condensed catalogs that areadequate for most applicatio
21、ns. Data sheets referring to specific items are almost alwaysavailable from the sales offices. Some technical files may be kept on microfilm at largerdesign offices for use either by projection or by printing. Manufacturers representatives,both sales and technical, can do much to provide complete in
22、formation on a product.Copyright 2006 IEEE. All rights reserved. 13Chapter 2Description of a short-circuit current2.1 IntroductionElectric power systems are designed to be as fault-free as possible through careful systemand equipment design, proper equipment installation and periodic equipment maint
23、e-nance. However, even when these practices are used, faults do occur. Some of the causesof faults are as follows:a) Presence of animals in equipmentb) Loose connections causing equipment overheatingc) Voltage surgesd) Deterioration of insulation due to agee) Voltage or mechanical stresses applied t
24、o the equipmentf) Accumulation of moisture and contaminantsg) The intrusion of metallic or conducting objects into the equipment such as ground-ing clamps, fish tape, tools, jackhammers or pay-loadersh) A large assortment of “undetermined causes”When a short-circuit occurs in a electric power distri
25、bution system, several things can hap-pen, such as the following:1) The short-circuit currents may be very high, introducing a significant amount ofenergy into the fault.2) At the fault location, arcing and burning can occur damaging adjacent equipmentand also possibly resulting in an arc-flash burn
26、 hazard to personnel working on theequipment.3) Short-circuit current may flow from the various rotating machines in the electricaldistribution system to the fault location.4) All components carrying the short-circuit currents will be subjected to thermal andmechanical stresses due to current flow.
27、This stress varies as a function of themagnitude of the current squared and the duration of the current flow (I2t) andmay damage these components.5) System voltage levels drop in proportion to the magnitude of the short-circuitcurrents flowing through the system elements. Maximum voltage drop occurs
28、 atthe fault location (down to zero for a bolted fault), but all parts of the power sys-tem will be subject to a voltage drop to some degree.2.2 Available short-circuit currentThe “available” short-circuit current is defined as the maximum possible value of short-circuit current that may occur at a
29、particular location in the distribution system assumingthat no fault related influences, such as fault arc impedances, are acting to reduce the faultcurrent. The available short-circuit current is directly related to the size and capacity of theIEEEStd 551-2006 CHAPTER 214 Copyright 2006 IEEE. All r
30、ights reserved.power sources (utility, generators, and motors) supplying the system and is typically inde-pendent of the load current of the circuit. The larger the capacity of the power sourcessupplying the system, the greater the available short-circuit current (generally). The mainfactors determi
31、ning the magnitude and duration of the short-circuit currents are the type offault, fault current sources present, and the impedances between the sources and the pointof the short circuit. The characteristics, locations, and sizes of the fault current sourcesconnected to the distribution system at t
32、he time the short circuit occurs have an influenceon both the initial magnitude and the wave shape of the fault current.Alternating current synchronous and induction motors, generators, and utility ties are thepredominant sources of short-circuit currents. At the time of the short-circuit, synchrono
33、usand induction motors will act as generators and will supply current to the short-circuitbased upon the amount of stored electrical energy in them. In an industrial plant, motorsoften contribute a significant share of the total available short-circuit current.2.3 Symmetrical and asymmetrical curren
34、tsThe terms “symmetrical” current and “asymmetrical” current describe the shape of the accurrent waveforms about the zero axis. If the envelopes of the positive and negative peaksof the current waveform are symmetrical around the zero axis, they are called “symmetri-cal current” envelopes (Figure 2-
35、1). The envelope is a line drawn through the peaks orcrests of the waves.If the envelopes of positive and negative peaks are not symmetrical around the zero axis,they are called “asymmetrical current” envelopes. Figure 2-2 shows a fully offset (non-decaying) fault current waveform. The amount of off
36、set that will occur in a fault currentwaveform depends on the time at which the fault occurs on the ac voltage waveform andthe network resistances and reactances. The current in a purely reactive network couldhave any offset from none to fully offset, depending on the time of its inception, and theo
37、ffset would be sustained (not decaying). A fault occurring in a purely resistive systemwould have no offset in the current waveform. A network containing both resistances andreactances will generally begin with some offset in the current (up to full) and graduallythe current will become symmetrical
38、(because of the decay of the offset) around the zeroaxis.As stated previously, induction and synchronous machines connected on the system sup-ply current to the fault and, because of the limited amount of stored electrical energy inthem, their currents decay with time. Figure 2-3 shows the symmetric
39、al portion of adecaying fault current waveform typical for such equipment.IEEEDESCRIPTION OF A SHORT-CIRCUIT CURRENT Std 551-2006Copyright 2006 IEEE. All rights reserved. 15-2-10120123456Time in Cycles at 60 HertzAmplitude (p.u.)Figure 2-1Symmetrical ac wave01230123456Time in Cycles at 60 HertzAmpli
40、tude (p.u.)Figure 2-2Totally offset ac waveIEEEStd 551-2006 CHAPTER 216 Copyright 2006 IEEE. All rights reserved.Short-circuit currents are nearly always asymmetrical during the first few cycles after theshort circuit occurs and contain both dc and ac components. The dc component is shownin Figure 2
41、-4. The asymmetrical current component (dc) is always at a maximum duringthe first cycle after the short circuit occurs. This dc component gradually decays to zero. Atypical asymmetrical short-circuit current waveform is shown in Figure 2-5.-1010123456Time in Cycles at 60 HertzAmplitude (p.u.)Figure 2-3Decaying symmetrical ac wave0120123456Time in Cycles at 60 HertzAmplitude (p.u.)Figure 2-4Decaying dc wave
