CLC/TR 50480:2011
(Main)Determination of cross-sectional area of conductors and selection of protective devices
Determination of cross-sectional area of conductors and selection of protective devices
This Technical Report applies to low-voltage installations with a nominal system 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 the 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 contact) 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 applicable 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 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 programs 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.
Festlegung von Leiterquerschnitten und Auswahl von Schutzeinrichtungen
Détermination des sections des conducteurs et choix des dispositifs de protection
Določanje prereza vodnikov in izbira zaščitnih naprav
To tehnično poročilo velja za nizkonapetostne inštalacije z nazivno frekvenco sistema 50 Hz, pri katerih so vezja sestavljena iz izoliranih prevodnikov, kablov ali zbiralčnih razdelilnih sistemov.
Opredeljuje različne parametre, ki se uporabljajo za izračun značilnosti električnih inštalacijskih sistemov, da ustrezajo pravilom HD 384/HD 60364.
Pravila so v glavnem naslednja:
- zmožnosti prevodnikov za prenos toka;
- značilnosti zaščitnih naprav v zvezi z zaščito pred nadtokom;
- preverjanje termične napetosti v prevodnikih zaradi kratkega stika ali toka zaradi napake pri ozemljitvi;
- zaščita pred okvaro (zaščita pred posrednim stikom) v sistemih TN in sistemih IT;
- omejitev padca napetosti;
- preverjanje mehanske napetosti med kratkim stikom v zbiralčnih razdelilnih sistemih (BTS) v skladu z EN 60439-2 ali tračnih napajalnih sistemih v skladu s serijo EN 61534.
Izračuni, ki jih zagotavlja to tehnično poročilo, veljajo le tam, kjer so znane značilnosti vezja.
Za namen tega dokumenta zbiralčni razdelilni sistemi pomenijo tudi tračne napajalne sisteme.
OPOMBA 1 Mehansko napetost med kratkim stikom zajema IEC 60865.
OPOMBA 2: Na splošno ti izračuni veljajo za napajanje prek transformatorjev VN/NN, veljajo pa tudi za napajanje prek transformatorjev NN/VN in rezervnih generatorjev NN.
OPOMBA 3: Ta dokument ne zajema učinkov harmonskih tokov.
To tehnično poročilo velja tudi za preverjanje skladnosti rezultatov izračunov, ki so jih izvedli računalniški programi za izračun prereza izoliranih prevodnikov, prereza kablov in značilnosti za izbiro zbiralčnih razdelilnih sistemov, s HD 384/HD 60364.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-maj-2011
1DGRPHãþD
SIST R064-003:2000
'RORþDQMHSUHUH]DYRGQLNRYLQL]ELUD]DãþLWQLKQDSUDY
Determination of cross-sectional area of conductors and selection of protective devices
Festlegung von Leiterquerschnitten und Auswahl von Schutzeinrichtungen
Détermination des sections des conducteurs et choix des dispositifs de protection
Ta slovenski standard je istoveten z: CLC/TR 50480:2011
ICS:
29.060.01 (OHNWULþQHåLFHLQNDEOLQD Electrical wires and cables in
VSORãQR general
91.140.50 Sistemi za oskrbo z elektriko Electricity supply systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
TECHNICAL REPORT
CLC/TR 50480
RAPPORT TECHNIQUE
February 2011
TECHNISCHER BERICHT
ICS 29.050 Supersedes R064-003:1998
English version
Determination of cross-sectional area of conductors and selection of
protective devices
Détermination des sections des Festlegung von Leiterquerschnitten und
conducteurs et choix des dispositifs de Auswahl von Schutzeinrichtungen
protection
This Technical Report was approved by CENELEC on 2011-01-02.
CENELEC members 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, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für 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
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 Regulations, 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 be held responsible for identifying any or all such patent
rights.
__________
- 3 - CLC/TR 50480:2011
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 Conductor 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 Characteristics 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 devices . - 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 (protection against indirect contact). - 28 -
11.1 Disconnecting time . - 28 -
11.2 Calculation of earth fault current I . - 28 -
ef
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 . - 31 -
13 Voltage drop . - 32 -
Annex A Conductor resistances . - 34 -
Bibliography . - 34 -
Figures
Figure 1 – Examples of installation configurations and impedances used in this document . - 13 -
Figure 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 mΩ⋅mm² / m . - 13 -
Table 2 − Resistivity at various temperatures . - 14 -
Table 3 − Reactance per metre of conductors of cables ( x ) . - 14 -
Table 4 − Selection 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 − Voltage factor c . - 19 -
Table 8 − Values of k . - 21 -
M
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, mΩ / m . - 34 -
- 5 - CLC/TR 50480:2011
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 be 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.
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 devices.
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.
1 Scope
This Technical Report applies to low-voltage installations with a nominal system 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 the 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 contact) 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 applicable 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 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 programs 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.
- 7 - CLC/TR 50480:2011
2 Reference documents
The 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.
EN 60076 series Power transformers (IEC 60076 series)
EN 60228 Conductors of insulated cables (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
of 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-voltage 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
...
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