Earthing of power installations exceeding 1 kV a.c.
Nationalforeword
supersedes BS EN 50522:2010 which is withdrawn. This British Standard is the UK implementation of EN 50522:2022. t
The UK participation in its preparation was entrusted to TechnicalCommittee PEL/99 Erection and operation of power installations.
Alist oforganizations represented on this mittee can be obtained onrequest to its mittee manager.
and NC which provide further guidance to assist users n the application The UK mittee draws users' attention to National Annexes NA NBof this standard.
Contractual and legal considerations
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This publication is not intended to constitute a contract Users areresponsible for its correct application.
@ The British Standards Institution 2023Published by BSI Standards Limited 2023
ISBN 978 0 539 03985 6
ICS 29.120.50
Compliance with a British Standard cannot confer immunity fromlegal obligations.
Standards Policy and Strategy Committee an 28 February 2023. This British Standard was published under the authority of the
Amendments/corrigenda issued since publication
Date
EN50522
English Version
Earthingofpowerinstallationsexceeding1kVa.c.
Prises de lerre des installations electriques de puissance en courant altematif de tension supBrieure 3 1 kV
Nennwechselspannungen Uber 1 kV Erdung von Starkstromanlagen mil
This European Standard was approved by CENELEC on 2022-01-10. CENELEC members ae bound o ply wih the CENICENELECIntemal Regulations which stipulate the condrions for gving this European Standard the status of a national standard without any aleration.
Management Centre or to any CENELEC member. Up-to-date ists and bibiographical references conceming such nafional standards may be obtained on application Io the CEN-CENELEC
This European Standard exists hthree offical versions (Engish French Geman). A version ary oher language made by translationunder the responsbity of a CENELEC member inlo is own language and notifed to the CEN-CENELEC Management Cenitre has he same status as the official versions.
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Contents
Page
European foreword. .51 Scope ..2 Normative references .3 4 Fundamental requirements. Terms and definitions 15 .84.1 General requlrements... 154.2 4.2.1 Methods of neutral earthing Electrical requirements 15 154.2.2 4.3 Short-circuit current.... Safety criteria 15 154.4 Functional requirements ..165 51 Design of earthing systems General. 165.2 5.2.1 Dimensioning with respect to corrosion and mechanical strength Earth electrodes. ..16 165.2.2 Earthing conductor.. 165.2.3 5.3 Bonding conductors... Dimensioning with respect to thermal strength 175.3.1 5.3.2 General Current rating calculation.... 175.4 5.4.1 Dimensioning with regard to touch voltages. Permissible values5.4.2 Measures for the observance of permissible touch voltages. 195.4.3 Design procedure9 61 Transferred potential from highvoltage systems to low voltage systems Measures to avoid transferred potential .23 236.1.1 6.1.2 High and low voltage earthing systems LV supply only within HV substations 236.1.3 6.1.4 LV supply leaving or ing to HV substations. LVin theproximity of HV substation. 23 236.2 Transferred potentials to telemunication and other systems 247 7.1 Installation of earth electrodes and earthing conductors Construction of earthing systems 25 257.2 Lightning and transients. .257.3 8 Measures for earthing on equipment and installations . Measurements. 25 269 Maintainability. ..69.1 9.2 Inspections Measurements. 26 2610 Inspection and documentation of earthing systems 26Annex A (normative) Methods of calculating permissible touch voltages .27A.1 Method of calculating permissible touch voltages UTp. .27A.2 Method of calculating prospective permissible touch voltages UvTp ...8A.3 Method of calculating permissible step voltages. 29
Annex B (normative) Calculation of Permissible touch voltage Urp Prospective permissible touch voltage Uvrp....B.1 General . 30 OEB.2 Calculation of permissible touch voltage . 30B.3 Calculation of the permissible touch voltage Urp curve values of Figure 8. 30B.4 Calculation of prospective permissible touch voltage ...mechanical strength and corrosion resistance ....Annex D (normative) Current rating calculation of earthing conductors and earth electrodes .. 37 Annex E (normative) Description of the recognized specified measures M. 42Annex F (normative)Measures on earthing systems to reduce the effects of high frequencyinterference....Annex G (normative) Detailed measures for earthing of equipment and installations.... ...46G.1 G.2 Fences around substation installations.. Pipes . ... 46G.3 Traction railsG.4 Pole mounted transforming and/or switching installations. 47G.5 Secondary circuits of instrument transformers 48Annex H (normative) Measuring touch voltagesAnnex I(informative)Reduction factors related to earth wires of overhead lines and metal sheaths of underground cables. . 5011 General 5012 Typical values of reduction factors of overhead lines and cables (50 Hz).13 Influence of the resistances to earth on current in cable sheath 52Annex J(informative)Basis for the design of earthing systems.J.1 SoilresistivityJ.2 Resistance to earth 53Annex K (informative) Installing the earth electrodes and earthing conductors K1 Installation of earth electrodes .59 .59K.1.1 Horizontal earth electrodes ..59K.1.2 Verticalor inclined driven rods.K.1.3 Jointing the earth electrodes..K.2 Installation of earthing conductors .59K.2.1 General 59K.2.2 Installing the earthing conductors .59K.2.3 Annex L (informative) Measurements for and on earthing systems. Jointing the earthing conductors 61 60L.1 Soilresistivity measurement and analysis 61L.1.1 Introduction. 61L.1.2 Soil resistivity measurement..
