CLC TR 50480-2011 Determination of cross-sectional area of conductors and selection of protective devices.pdf

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1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationPD CLC/TR 50480:2011Determination of cross-sectional of protective devicesarea of conductors and selection National forewordThis Published Document is the UK implementation of CL

2、C/TR 50 :2012.The requirements for electrical installations are given in BS 7671:2008. This Technical Report sets out a uniform approach to the calculations required for the determination of cross-sectional area of conductors and the selection of the appropriate protective devices to meet the requir

3、ements of BS 7671. The main body of the technical report was developed by CENELEC TC 64. National Annex NA provides details of additional and alternative calculation methods that are used in the UK.The UK participation in its preparation was entrusted to Technical Committee JPEL/64, Electrical insta

4、llations of buildings Joint committee.A list of organizations represented on this committee can be obtained on request to its secretary. The British Standards Institution 2012. Published by BSI Standards Limited 2012.ISBN 978 0 580 64478 8ICS 29.050Compliance with a British Standard cannot confer im

5、munity from legal obligations.This was published under the authority of the Standards Policy and Strategy Committee on 31 December 2012.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDPD CLC/TR 50480:2011This publication does not purport to include all the necessary p

6、rovisions of a contract. Users are responsible for its correct application.Published Document 480TECHNICAL REPORT CLC/TR 50480 RAPPORT TECHNIQUE TECHNISCHER BERICHT February 2011 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisch

7、es Komitee fr Elektrotechnische Normung Management Centre: Avenue Marnix 17, B - 1000 Brussels 2011 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. CLC/TR 50480:2011 E ICS 29.050 Supersedes R064-003:1998English version Determination

8、of cross-sectional area of conductors and selection of protective devices Dtermination des sections des conducteurs et choix des dispositifs de protection Festlegung von Leiterquerschnitten und Auswahl von Schutzeinrichtungen This Technical Report was approved by CENELEC on 2011-01-02. CENELEC membe

9、rs are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, 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

10、, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. - 2 - Foreword This Technical Report was prepared by CENELEC Technical Committee 64, Electrical installations and protection against electric shock. The text of the draft was circulated for voting in accordance with the Internal Regulati

11、ons, Part 2, Subclause 11.4.3.3 (simple majority) and was approved by CENELEC as CLC/TR 50480 on 2011-01-13. This Technical Report supersedes R064-003:1998. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and CENELEC shall not

12、 be held responsible for identifying any or all such patent rights. _ PD CLC/TR 50480:2011 CLC/TR 50480:2011 (E)- 3 - Contents Foreword . - 2 - Introduction - 5 -1 Scope . - 6 -2 Reference documents - 7 -3 Symbols . - 8 -4 Parameters - 13 -4.1 General - 13 -4.2 Conductor resistances . - 15 -4.3 Cond

13、uctor reactances - 15 -5 Characteristics of installations . - 16 -6 Characteristics of the supply source . - 19 -6.1 Voltage . - 19 -6.2 Supply by HV/LV transformers - 19 -6.3 Supply by generators . - 20 -6.4 Contribution of asynchronous motors - 20 -6.5 LV supply . - 21 -6.6 Capacitors - 21 -7 Char

14、acteristics of protective devices. - 21 -7.1 Circuit-breakers . - 21 -7.2 Fuses . - 22 -8 Protection against overload currents. - 22 -8.1 Current-carrying capacity . - 22 -8.2 Coordination between conductors and overload protective devices - 22 -9 Determination of breaking capacity of protective dev

15、ices - 24 -9.1 General . - 24 -9.2 Three line maximum short-circuit current - 24 -9.3 Line-to-line maximum short-circuit current - 25 -9.4 Line-to-neutral maximum short-circuit current . - 26 -10 Ability to withstand electro-dynamic stresses for busbar trunking systems - 27 -11 Fault protection (pro

16、tection against indirect contact) - 28 -11.1 Disconnecting time - 28 -11.2 Calculation of earth fault current Ief- 28 -12 Verification of thermal stress in conductors . - 29 -12.1 Thermal stress . - 29 -12.2 Minimum short-circuit current - 30 -12.3 Calculation of the minimum short-circuit current .

17、- 31 -13 Voltage drop . - 32 -Annex A Conductor resistances . - 34 -Bibliography . - 44 - National Annex NA (informative)UK National Practice. - -35PD CLC/TR 50480:2011 CLC/TR 50480:2011 (E)- 4 - Figures Figure 1 Examples of installation configurations and impedances used in this document . - 13 -Fi

18、gure 2 Examples of installation configurations and impedances used in this clause - 25 -Tables Table 1 Resistivity at 20 C in accordance with IEC 60909, in mmm / m - 13 -Table 2 Resistivity at various temperatures - 14 -Table 3 Reactance per metre of conductors of cables ( x ) - 14 -Table 4 Selectio

19、n of resistivity and reactance for insulated conductors and cables. - 16 -Table 5 Selection of resistance and reactance for busbar trunking systems . - 17 -Table 6 Elements to take into account when calculating maximum and minimum short circuit currents and earth fault currents. - 18 -Table 7 Voltag

20、e factor c - 19 -Table 8 Values of kM. - 21 -Table 9 Peak factor (n) . - 27 -Table 10 Maximum disconnecting time for TN and TT systems and for IT systems in case of a second fault - 28 -Table 11 Values of the factor k . - 30 -Table A.1 Conductor AC resistances at 20 C, m / m . - 3 -5PD CLC/TR 50480:

21、2011 CLC/TR 50480:2011 (E)- 5 - Introduction The harmonised rules for the erection of electrical low voltage installations, HD 384/HD 60364, require selection, dimensioning and calculation for the components of an electrical installation. In complex installations long and detailed calculations may b

22、e needed. The rules of HD 384/HD 60364 give the basic principles without the details necessary for an accurate application. Computers with appropriate software enable the applicable rules for the determination of conductor cross-section area and selection of protective devices to be applied readily.

23、 It is important that the results of such software programs are in accordance with the harmonised rules. Therefore this Technical Report defines the different reference parameters necessary for the calculation of the cross-sectional area of the conductors and for the selection of the protective devi

24、ces. It also gives the reference methods for calculation according to the different safety rules defined in the Harmonisation Documents of the series HD 384/HD 60364. PD CLC/TR 50480:2011 CLC/TR 50480:2011 (E)- 6 - 1 Scope This Technical Report applies to low-voltage installations with a nominal sys

25、tem frequency of 50 Hz in which the circuits consist of insulated conductors, cables or busbar trunking systems. It defines the different parameters used for the calculation of the characteristics of electrical wiring systems in order to comply with rules of HD 384/HD 60364. These rules are mainly t

26、he following: - current-carrying capacities of the conductors; - characteristics of protective devices in regard to protection against overcurrent; - verification of thermal stress in conductors due to short-circuit current or earth fault current; - fault protection (protection against indirect cont

27、act) in TN systems and IT systems; - limitation of voltage drop; - verification of mechanical stresses during short-circuit in busbar trunking systems (BTS) according to EN 60439-2 or powertrack systems according to EN 61534 series. The calculations provided in this Technical Report are only applica

28、ble where the characteristics of the circuits are known. For the purpose of this document, when referring to Busbar Trunking Systems, Powertrack Systems are also considered. NOTE 1 Mechanical stress during short-circuit is covered by IEC 60865. NOTE 2 In general these calculations concern supply by

29、HV/LV transformer, but they are also applicable to supply by LV/LV transformer and LV back-up generators. NOTE 3 Effects of harmonics currents are not covered by this document. This Technical Report is also applicable for checking the compliance of the results of calculations performed by software p

30、rograms for calculation of cross-sectional area of insulated conductors, cross-sectional area of cables and characteristics for selection of busbar trunking systems with HD 384/HD 60364. PD CLC/TR 50480:2011 CLC/TR 50480:2011 (E)- 7 -2 Reference documents The following referenced documents are indis

31、pensable 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. EN 60076 series Power transformers (IEC 60076 series) EN 60228 Conductors of insulated cables

32、 (IEC 60228) EN 60269 series Low voltage fuses (IEC 60269 series) EN 60269-1 Low-voltage fuses - Part 1: General requirements (IEC 60269-1) HD 60269-2 Low-voltage fuses - Part 2: Supplementary requirements for fuses for use by authorized persons (fuses mainly for industrial application) - Examples o

33、f standardized systems of fuses A to J (IEC 60269-2) HD 60269-3 Low-voltage fuses - Part 3: Supplementary requirements for fuses for use by unskilled persons (fuses mainly for household or similar applications) - Examples of standardized systems of fuses A to F (IEC 60269-3) EN 60439-1 1999 Low-volt

34、age switchgear and controlgear assemblies - Part 1: Type-tested and partially type-tested assemblies (IEC 60439-1:1999) EN 60439-2 2000 Low-voltage switchgear and controlgear assemblies - Part 2: Particular requirements for busbar trunking systems (busways) (IEC 60439-2:2000) EN 60898 series Electri

35、cal accessories - Circuit-breakers for overcurrent protection for household and similar installations (IEC 60898 series) EN 60947-2 Low-voltage switchgear and controlgear - Part 2: Circuit-breakers (IEC 60947-2) EN 61439-1 2009 Low-voltage switchgear and controlgear assemblies - Part 1: General rule

36、s (IEC 61439-1:2009, mod.) EN 61534 series Powertrack systems (IEC 61534 series) HD 384/HD 60364 series Low-voltage electrical installations (IEC 60364 series) HD 60364-4-41 2007 Low-voltage electrical installations - Part 4-41: Protection for safety - Protection against electric shock (IEC 60364-4-

37、41:2005, mod.) HD 60364-4-43 2010 Low-voltage electrical installations - Part 4-43: Protection for safety - Protection against overcurrent (IEC 60364-4-43:2008, mod. + corrigendum October 2008) HD 60364-5-52, 2010 Low-voltage electrical installations - Part 5-52: Selection and erection of electrical

38、 equipment - Wiring systems (IEC 60364-5-52:2009, mod. ) HD 384-5-54 Electrical installation of buildings - Part 5: Selection and erection of electrical equipment - Chapter 54: Earthing arrangements and protective conductors (IEC 60364-5-54) IEC 60909 series Short-circuit currents in three-phase a.c

39、. systems (IEC 60909 series) PD CLC/TR 50480:2011 CLC/TR 50480:2011 (E)- 8 - 3 Symbols In this Technical Report, the following symbols are used: I2Current ensuring effective operation in conventional time of the protective device and generally given in the product standard, A IBDesign current of the

40、 circuit being considered, A (IEV 826-11-10) IefEarth fault current, kA InNominal current of the protective device (fuse rating or breaker setting), A IncRated current of busbar trunking system, at an ambient temperature of 30 C, A IpMaximum peak value of highest short-circuit current, kA kQI Initia

41、l symmetrical short-circuit current at the feeder connection point Q kA Ik1 Steady state short-circuit current for a line-to-neutral short circuit kA Ik2 Steady state short-circuit current for a line-to-line short circuit kA Ik3 Steady state short-circuit current for a three line short circuit kA NO

42、TE 1 In some cases the Ik1can be higher than the Ik3(e.g. at the terminals of the delta-star transformer). IZContinuous current-carrying capacity of cable, insulated conductors or busbar trunking system as applied in a circuit A (020tI ) Thermal stress capacity of line, neutral or PE (PEN) conductor

43、 given in general for one second, A.s, (IEV 447-07-17) (cw2cwtI ) Thermal stress capacity of line, neutral or PE (PEN) conductor given in general for one second for busbar trunking systems, A.s, (EN 60439-2, 4.3) l1Route length (insulated conductors and cables), m, subscript u: upstream subscript d:

44、 downstream l2Length of BTS (Busbar Trunking System), m subscript u: upstream subscript d: downstream RCResistance of the conductor between the transformer and the main switchboard m Rc1 phResistance of line conductor per metre, consisting of insulated conductor or cable, at steady-state operating t

45、emperature, m/m Rc1 N Resistance of neutral conductor per metre, consisting of insulated conductor or cable, at steady-state operating temperature, m/m Rc1 PE Resistance of protective earthing conductor per metre, consisting of insulated conductor or cable, at steady-state operating temperature, m/m

46、 RNResistance of the neutral conductor upstream of the circuit being considered, neutralN= RR , m RPEResistance of the protective conductor from the main equipotential bonding to the origin of the circuit being considered, conductor protectivePE= RR , m RPENResistance of the PEN conductor from the m

47、ain equipotential bonding to the origin of the circuit being considered, conductor PENPENR= R , m PD CLC/TR 50480:2011 CLC/TR 50480:2011 (E)- 9 - RQResistance of the HV network, m RSUP Resistance of the LV upstream network, m RT Resistance of the transformer, m Rb0 phMean ohmic resistance of BTS (Bu

48、sbarTrunking System) per meter, per line, at 20 C, m / m Rb1 phMean ohmic resistance of BTS per meter, per line, at rated current Inc, at the steady-state operating temperature, m / m PD CLC/TR 50480:2011 CLC/TR 50480:2011 (E)- 10 - Symbols used for resistances in the context of short-circuits in busbar trunking systems 123PENRbxphThree-line short-circuit 123PENRbxph phLine to line short-circuit between L1 and L2, note may be between any two lines 123PENRbxph-NLine to neutral short-circuit between L1 and N 123PENRbxph-PEfault between L1 and PE NOTE 2 The value of x depends on t