08-30190022-DC.pdf
a Date: 23 September 2008 Origin: European Latest date for receipt of comments: 30 November 2008 Project no.: 2008/03002 Responsible committee: PEL/73 Short circuit currents Interested committees: Title: Draft BS EN 60865-1 Short-circuit currents - Calculation of effects Part 1: Definitions and calculation methods Supersession information: If this document is published as a standard, the UK implementation of it will supersede BSEN60865-1 : 1994 and partially supersede. NONE If you are aware of a current national standard which may be affected, please notify the secretary (contact details below). WARNING: THIS IS A DRAFT AND MUST NOT BE REGARDED OR USED AS A BRITISH STANDARD. THIS DRAFT IS NOT CURRENT BEYOND 30 November 2008. This draft is issued to allow comments from interested parties; all comments will be given consideration prior to publication. No acknowledgement will normally be sent. See overleaf for information on commenting. 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Direct tel: 020 8996 7009 Responsible Committee Secretary: Committee Service Centre (BSI) E-mail: cscbsigroup.com Draft for Public Comment Head Office 389 Chiswick High Road London W4 4AL Telephone: +44(0)20 8996 9000 Fax: +44(0)20 8996 7001 Form 36 Version 8.0 DPC: 08/30190022 DC Licensed CopyChinese University of Hong Kong, 21/10/2008 08:43, Uncontrolled Copy, (c) BSI b Introduction This draft standard is based on European discussions in which the UK took an active part. Your comments on this draft are welcome and will assist in the preparation of the consequent British Standard. If no comments are received to the contrary, then the UK will approve this draft and implement it as a British Standard. Comment is particularly welcome on national legislative or similar deviations that may be necessary. Even if this draft standard is not approved by the UK, if it receives the necessary support in Europe, the UK will be obliged to publish the official English Language text unchanged as a British Standard and to withdraw any conflicting standard. UK Vote Please indicate whether you consider the UK should submit a negative (with reasons) or positive vote on this draft. Submission The guidance given below is intended to ensure that all comments receive efficient and appropriate attention by the responsible BSI committee. Annotated drafts are not acceptable and will be rejected. All comments must be submitted, preferably electronically, to the Responsible Committee Secretary at the address given on the front cover. Comments should be compatible with Version 6.0 or Version 97 of Microsoft® Word for Windows, if possible; otherwise comments in ASCII text format are acceptable. Any comments not submitted electronically should still adhere to these format requirements. All comments submitted should be presented as given in the example below. Further information on submitting comments and how to obtain a blank electronic version of a comment form are available from the BSI web site at: http:/www.bsigroup.com/en/Standards-and-Publications/Current-work/DPCs/ Template for comments and secretariat observations Date: xx/xx/200x Document: ISO/DIS xxxxx 1 2 (3) 4 5 (6) (7) MB Clause No./ Subclause No./ Annex (e.g. 3.1) Paragraph/ Figure/Table/ Note (e.g. Table 1) Type of com- ment Comment (justification for change) by the MB Proposed change by the MB Secretariat observations on each comment submitted 3.1 Definition 1 ed Definition is ambiguous and needs clarifying. Amend to read . so that the mains connector to which no connection . 6.4 Paragraph 2 te The use of the UV photometer as an alternative cannot be supported as serious problems have been encountered in its use in the UK. Delete reference to UV photometer. Microsoft and MS-DOS are registered trademarks, and Windows is a trademark of Microsoft Corporation. Licensed CopyChinese University of Hong Kong, 21/10/2008 08:43, Uncontrolled Copy, (c) BSI 73/147/CD COMMITTEE DRAFT (CD) IEC/TC or SC: TC 73 Project number IEC 60865-1 Ed. 3.0 Title of TC/SC: Short-circuit currents Date of circulation 2008-09-19 Closing date for comments 2008-12-19 Also of interest to the following committees Supersedes document 73/143/MCR Functions concerned: Safety EMC Environment Quality assurance Secretary: Gunne Hegglid THIS DOCUMENT IS STILL UNDER STUDY AND SUBJECT TO CHANGE. IT SHOULD NOT BE USED FOR REFERENCE PURPOSES. RECIPIENTS OF THIS DOCUMENT ARE INVITED TO SUBMIT, WITH THEIR COMMENTS, NOTIFICATION OF ANY RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE AND TO PROVIDE SUPPORTING DOCUMENTATION. Title: IEC 60865-1: Short-circuit currents - Calculation of effects - Part 1: Definitions and calculation methods (Titre) : CEI 60865-1: Courants de court-circuit - Calcul des effets - Partie 1: Définitions et méthodes de calcul Introductory note FORM CD (IEC) 2001-07-01 © International Electrotechnical Commission, IEC Licensed CopyChinese University of Hong Kong, 21/10/2008 08:43, Uncontrolled Copy, (c) BSI 60865-1/Ed.3 © IEC:200X 2 73/147/CD CONTENTS 1 Scope and object4 2 Normative references .4 3 Definitions, symbols and units 5 3.1 Definitions.5 3.2 Symbols and units.6 4 General 10 5 Rigid conductor arrangements11 5.1 General.11 5.2 Calculation of electromagnetic forces 11 5.3 Effective distance between main conductors and between sub-conductors12 5.4 Calculation of stresses in rigid conductors.13 5.5 Structure loads due to rigid conductors .15 5.6 Consideration of automatic reclosing.15 5.7 Calculation with special regard to conductor oscillation .15 6 Flexible conductor arrangements17 6.1 General.17 6.2 Effects on horizontal main conductors .18 6.3 Effects on vertical main conductors (droppers) 24 6.4 Effects on bundled conductors 25 6.5 Structure loads due to flexible conductors .27 7 The thermal effect on bare conductors28 7.1 General.28 7.2 Calculation of temperature rise28 7.3 Calculation of thermal equivalent short-circuit current .28 7.4 Calculation of temperature rise and rated short-circuit withstand current density for conductors .29 7.5 Calculation of thermal short-circuit strength for different durations of the short-circuit .29 Annex A (normative) Equations for calculation of diagrams48 Bibliography52 Figure 1 Factor k1s for calculating the effective conductor distance.34 Figure 2 Loading direction and bending axis for multiple conductor arrangements .35 Figure 3 factor c for the influence of connecting pieces in equation (17) 36 Figure 4 Factors VF, V and Vs to be used with the three-phase and line-to-line short circuits.37 Figure 5 Factors Vr and Vrs to be used with three-phase automatic reclosing38 Figure 6 Maximum swing out angle m for a given maximum short-circuit duration Tk1.39 Figure 7 Factor for tensile force in flexible conductors40 Figure 8 Geometry of a dropper. 40 Figure 9 2 as a function of 1.41 Figure 10 3 · sin n °180 as a function of as/ds42 Licensed CopyChinese University of Hong Kong, 21/10/2008 08:43, Uncontrolled Copy, (c) BSI 60865-1/Ed.3 © IEC:200X 3 73/147/CD Figure 11 as a function of j and st43 Figure 12 a) as a function of j and st for 2.5 R S | | T | | for for (26) where 6 fin 2 N 50 10 m = (27) fin is the lowest value of when Young's modulus becomes constant. The final Young's modulus E for stranded conductors shall be used. The stress factor of the main conductor is given by: () NF lmng 3 st 2 sn 24 = (28) During or at the end of the short-circuit current flow, the span will have oscillated out of the steady-state position to the angle given by: k 1 k1 res k1 res 1 k1 res 1 cos 3600,5 20,5 = ° F H G I K J L N M M O Q P P R S | | T | | T T T T T T for for (29) Insofar as the duration of the first short-circuit current flow Tk1 as defined in 3.1 is known, the maximum swing-out angle m may be determined as per figure 6 or calculated as given below. Otherwise, or if Tk1 is greater than the value 0,4 T, then the value 0,4 T shall be used for Tk1 in equations (29), (32) and (35). During or after the short-circuit current flow the span will have oscillated to the maximum swing-out angle m which is obtained as follows: = ° ° R S T 1 sin 090 190 kk k r r for for (30) and m 1,25 arccos 0,7661 10 arccos 0,9850,766 1800,985 = ° + ° 6; 0,17 · 10-18 m4/(A2s) for aluminium/steel conductors with a cross section ratio of Al/St 6; 0,088 · 10-18 m4/(A2s) for copper. In the case of two-line single-phase systems, replace Ik3 in equation (37) by Ik2. The factor CD allows for sag increases caused by elastic and thermal elongation of the conductor and is given by () thela 2 c D 8 3 1+ += b l C (36) The factor CF allows for a possible increase in the dynamic sag of the conductor caused by a change in shape of the conductor curve and is given by: Licensed CopyChinese University of Hong Kong, 21/10/2008 08:43, Uncontrolled Copy, (c) BSI 60865-1/Ed.3 © IEC:200X 22 73/147/CD Cr r r r F 1,05 0,97+0,1 1,15 0,8 0,81,8 1,8 = 0,6 if m 70° and with a dropper in the middle of the span additionally max 60°. In this case the drop force is given by: ° += 180 8121 m stf FF, (43) NOTE In short spans the bending stiffness of the span reduces the span drop, which means that the span drop is calculated to be too large if the span length is less than approximately 100 times the diameter of the single conductor, i.e. l 6,0 1,0 * If 1,6 then = 1,6 shall be used. The factor V is given by: fc/f Factor V 0,8 1 * If 1,6 then = 1,6 shall be used. In the case of Vs, the same equations shall be used as for V, but fc/f shall be replaced by fcs/f. Licensed CopyChinese University of Hong Kong, 21/10/2008 08:43, Uncontrolled Copy, (c) BSI 60865-1/Ed.3 © IEC:200X 50 73/147/CD A.5 Figure 5 The factor Vr is given by: 1,8 for fc/f 0,05 Vr = 1,0 0,615 lg (fc/f) for 0,05 fc/f 1,0 1,0 for fc/f 1,0 1,8 for fcs/f 0,05 Vrs =1,0 0,615 lg (fcs/f) for 0,05 fcs/f 1,0 1,0 for fcs/f 1,0 A.6 Figure 7 Factor is a function of and . It may be calculated as the real solution of the equation 232 21220+=b g b g b g with 0 1. A.7 Figure 8 The factor 2 is given by: () + + = 2 pipi pi 2 sin1 4 2sin 24sin 1 pi 2 f Tf e Tf f Tf Tf () ()() + + + + f Tf e Tf Tf Tf Tf f f fc pi 2 pi pi pi pi 2 2 2sin 2 2sin 2 cos 2 21 sin 8 pi 2 cos 2sin Tf f where is the time constant of the network and can be calculated according to IEC 60909-0: 980 021 ln 3 21 , , = f with 1,1 and = arctan (2f) If 1,1 then = 1,1 shall be used. f Tpi is the solution of the equation 2pi1 Tf= A.8 Figure 10 The factor 3 is given by () ()1arctan 1 180 sin ss ssss 3 ° = da da n ad Licensed CopyChinese University of Hong Kong, 21/10/2008 08:43, Uncontrolled Copy, (c) BSI 60865-1/Ed.3 © IEC:200X 51 73/147/CD A.9 Figure 11 is the real solution of the equation 3 st 2 st 0+=j21bg with j 2/3 j A.10 Figure 12 The function in Figure 12 maybe calculated numerically by solving the cubic equation with nonlinear coefficients 3 stst 0+=jf 2 1bg with 0 1, and f aa = 3 sws aa ya ya ya ya ya n sws as 180 as as as as = 2 sin 12 2 arctan 12 2 / / / / / ° 211yada asss =bg A.11 Figure 13 The rated short-circuit withstand current density Sthr is given by S T c thr kr 20 20 20e 20b = ln 1 + - 20 C 1 + - 20 C 1 ° ° bg bg with the following data of material: Symbol SI-unit Copper Aluminium Alloy, Aluminium Conductor Steel Reinforced (ACSR) Steel c J(kg°C) 390 910 480 kg/m 3 8 900 2 700 7 850 20 1/(m) 56 106 34,8 106 7,25 106 20 1/°C 0,0039 0,004 0,0045 If base-temperatures other than 20 °C are used, the equation for Sthr must be changed. Licensed CopyChinese University of Hong Kong, 21/10/2008 08:43, Uncontrolled Copy, (c) BSI 60865-1/Ed.3 © IEC:200X 52 73/147/CD Bibliography 1 CIGRÉ: The mechanical effects of short-circuit currents in open air substations (Rigid and flexible conductors). Vol. 105. Paris: CIGRÉ SC 23, WG 11, 1996. 2 CIGRÉ: The mechanical effects of short-circuit currents in open air substations (Part II). Vol. 214. Paris: CIGRÉ SC 23, WG 03, 2002. Licensed CopyChinese University of Hong Kong, 21/10/2008 08:43, Uncontrolled Copy, (c) BSI
