EN 50341-2-20:2015

SLOVENSKI STANDARD
01-april-2016
1DG]HPQLHOHNWULþQLYRGL]DL]PHQLþQHQDSHWRVWLQDGN9GHO1DFLRQDOQD
QRUPDWLYQDGRORþLOD11$]D(VWRQLMRQDSRGODJL(1
Overhead electrical lines exceeding AC 45 kV - Part 2-20: National Normative Aspects
(NNA) for ESTONIA (based on EN 50341-1:2012)
Ta slovenski standard je istoveten z: EN 50341-2-20:2015
ICS:
29.240.20 Daljnovodi Power transmission and
distribution lines
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 50341-2-20

NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2015
ICS 29.240.20
English Version
Overhead electrical lines exceeding AC 45 kV -
Part 2-20: National Normative Aspects (NNA) for ESTONIA
(based on EN 50341-1:2012)
This European Standard was approved by CENELEC on 2015-01-06.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 50341-2-20:2015 E
CONTENTS
0 Introduction .5
0.7 Language .5
1 Scope .5
1.1 General .5
1.2 Field of application .5
2 Normative references, definitions and symbols .6
2.1 Normative references.6
3 Basis of design .8
3.2 Requirements of overhead lines .8
3.3 Limit states .9
3.4 Actions .9
3.6 Design values .9
4 Actions on lines .9
4.1 Introduction .9
4.3 Wind loads .9
4.4 Wind forces on overhead line components . 10
4.5 Ice loads . 11
4.6 Combined wind and ice loads . 11
4.7 Temperature effects . 11
4.8 Security loads . 11
4.9 Safety Loads . 12
4.10 Forces due to short-circuit currents . 13
4.11 Other special forces . 13
4.12 Load cases . 13
4.13 Partial factors for actions . 14
5 Electrical requirements . 16
5.1 Introduction . 16
5.2 Currents . 16
5.4 Classification of voltages and overvoltages . 16
5.5 Minimum air clearance distances to avoid flashover . 17
5.6 Load cases for calculation of clearances . 17
5.8 Internal clearances within the span and at the top of support . 18
5.9 External clearances . 18
5.10 Corona effect . 26
6 Earthing systems . 27
6.1 Introduction . 27
6.2 Ratings with regard to corrosion and mechanical strength. 27
6.4 Dimensioning with regard to human safety . 27
7 Supports . 28
7.2 Materials . 28
7.3 Lattice steel towers . 28
7.4 Steel poles . 29
7.5 Wood poles . 29
7.9 Corrosion protection and finishes . 30
7.10 Maintenance facilities. 30
8 Foundations . 30
8.1 Introduction . 30
8.2 Basis of geotechnical design . 30
8.3 Soil investigation and geotechnical data. 31
9 Conductors and earth-wires . 32
9.2 Aluminium based conductors . 32
9.3 Steel based conductors . 32
9.5 Conductors and ground wires containing optical fibre telecommunication circuits . 32

Estonia 3 / 42 EN 50341-2-20:2015
9.6 General requirements . 32
10 Insulators . 32
10.2 Standard electrical requirements . 32
10.4 Pollution performance requirements . 33
10.7 Mechanical requirements. 33
10.10 Characteristics and dimensions of insulators . 33
11 Hardware . 34
11.6 Mechanical requirements. 34
12 Quality assurance, checks and taking-over . 34
Annex B (informative) Conversion of wind velocities and ice loads . 35
Annex C (informative) Application examples of wind loads – Special forces . 36
Annex E (normative) Theoretical method for calculating minimum air clearances . 37
Annex F (informative) Empirical method for calculating mid span clearances . 38
Annex G (normative) Calculation methods for earthing systems . 39
Annex H (informative) Installation and measurements of earthing systems . 40
Annex M (informative) Geotechnical and structural design of foundations . 42

FOREWORD
1 The Estonian National Committee (NC) is identified by the following address
Estonian Centre for Standardisation
Estonian National High Voltage Committee (HVC)
Aru str. 10, 10317 Tallinn, Estonia
Phone: +372 605 5050
Fax: +372 605 5070
e-mail: info@evs.ee
2 The Estonian NC has prepared this Part 2-20 of EN 50341, listing the Estonian national normative
aspects under its sole responsibility, and has duly passed it through the CENELEC and CLC/TC 11
procedures.
NOTE: The Estonian NC also takes sole responsibility for the technically correct co-ordination of this NNA with
EN 50341-1. It has performed the necessary checks in the frame of quality assurance / control. However, it is noted
that this quality control has been made in the framework of the general responsibility of a standards committee under
the national laws / regulations.
3 This Part 2-20 is normative in Estonia and informative for other countries.
4 This Part 2-20 has to be read in conjunction with EN 50341-1, referred to hereafter as Part 1. All
clause numbers used in this Part 2-20 correspond to those in Part 1. Specific subclauses, which
are prefixed “EE”, are to be read as amendments to the relevant articles in Part 1. Any necessary
clarification regarding the application of Part 2-20 in conjunction with Part 1 shall be referred to the
Estonian NC that will, in cooperation with CLC/TC 11, clarify the requirements.
When no reference is made in Part 2-20 to a specific subclause, Part 1 applies.
5 In the case of “box values” defined in Part 1, amended values (if any), which are defined in Part
2-20, shall be taken into account in Estonia.
However any boxed value, whether in Part 1 or Part 2-20, shall not be amended in the direction of
greater risk in the Project Specification.
Terms with prepositions “from” and “up to”, denoting boundaries of values, always include the
boundary values itself, as it is common in other Estonian normative documents.
6 The national Estonian standards/regulations related to overhead electrical lines exceeding AC 1 kV
are identified/listed in Clause 2 of this Part 2-20.
NOTE All national standards referred to in this Part 2-20 will be replaced by the relevant European Standards as
soon as they become available and are declared by the Estonian Centre for Standardisation to be applicable and
thus reported to the secretary of CLC/TC 11.

Estonia 5 / 42 EN 50341-2-20:2015
0 INTRODUCTION
0.7 Language
(snc) EE.1 Language
This Part 2-20 is published in English and in Estonian.
1 SCOPE
1.1 General
(NCPT) EE.1 Application to new lines
This Part 2-20 applies to all new overhead electric lines with nominal system voltages
exc
...