SIST EN 50341-2-20:2016

SLOVENSKI STANDARD
SIST EN 50341-2-20:2016
01-april-2016
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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
SIST EN 50341-2-20:2016 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 50341-2-20:2016

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SIST EN 50341-2-20:2016


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

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SIST EN 50341-2-20:2016
EN 50341-2-20:2015 2 / 42 Estonia
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

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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

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SIST EN 50341-2-20:2016
EN 50341-2-20:2015 4 / 42 Estonia
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.

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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
exceeding AC 1 kV and with rated frequencies below 100 Hz. This standard also applies
to D.C. overhead lines in structural aspects.
(NCPT) EE.2 “New overhead line”
A “new overhead line” means a completely new line between two points, A and B. A new
branch line of the existing power line should be considered as a new power line including
the junction support, for which specific requirements should be defined in the Project
Specification.
1.2 Field of application
(A-dev) EE.1 Application to mounting of telecommunication equipment
The Standard EVS-EN 50341:2012 is applicable to fixing of structural elements for tele-
communication (antennas, satellite dishes, All Dielectric Self Supporting (ADSS)
equipment, etc.), if mounted on power line supports (towers), especially regarding wind
forces and ice loads on such fixed elements. The design and installation should be done
under the due control of the line owner and/or the competent authority. Mounting of
telecommunication equipment on power line supports must be coordinated with line
owner and stated in the Project Specification.
If telecommunication equipment (antennas, dishes, etc.) will be installed in the
transmission line supports, and their size, location or mounting will have major effects on
the loads or design of the structures, the requirements of EVS-EN 1993-3 will also have
to be taken into account. If such structures include conductive parts, the requirements on
clearances in Section 5.8 should be applied.
(NCPT) EE.2 Application to existing overhead lines
The Standard EVS-EN 50341:2012 shall not be applied to maintenance, reconductoring,
tee-offs, extensions or diversions to existing overhead lines in Estonia, unless specifically
required in the Project Specification.
In cases of major revisions of existing lines the degree of application of the Standard
EVS-EN 50341:2012 should be agreed upon by the parties concerned and specified in
the Project Specification.
(NCPT) EE.3 Application to installations under construction or design
Installations in the design and construction stage may be completed by using the
standard valid at the beginning of planning unless otherwise agreed with the line owner
and/or any other competent authority.
It must also be determined in the Project Specification which previous National Standard
and to what extent should be applied to the project in question.

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2 NORMATIVE REFERENCES, DEFINITIONS AND SYMBOLS
2.1 Normative references
(A-dev) EE.1 Application of references in Part 1
References in EN 50341-1 apply without change.
(A-dev) EE.2 References to Estonian national laws, regulations and standards
Choice of line route and construction or mounting of high voltage overhead line is
regulated by the following Estonian laws and Government regulations. These laws and
regulations 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. (RT − Riigi Teataja, RTL – Riigi Teataja
Lisa (supplement). Riigi Teataja is the official publication of the Republic of Estonia).
NAME PUBLICATION CITATION
Asjaõigusseadus Law of Property Act (RT I 1993, 39, 590)
Asjaõigusseaduse rakendamise seadus
Law of Property Act Implementation Act (RT I 1993, 72, 1021)
Elektriohutusseadus Electrical Safety Act (RT I 2007, 12, 64)
Elektrituruseadus Electricity Market Act (RT I 2003, 25, 153)
Elektroonilise side seadus Electronic Communications Act (RT I 2004, 87, 593)
1 1
Ehitusseadus Building Act (RT I 2002, 47, 297)
Jäätmeseadus Waste Act (RT I 2004, 9, 52)
Keskkonnajärelvalve seadus Environmental Supervision Act (RT I 2001, 56, 337)
Keskkonnamõju hindamise ja keskkonnajuhtimissüsteemi
seadus
Environmental Impact Assessment and Environmental
Management System Act (RT I 2005, 15, 87)
Lennundusseadus Aviation Act (RT I 1999, 26, 376)
Looduskaitseseadus Nature Conservation Act (RT I 2004, 38, 258)
Maakatastriseadus Land Cadastre Act (RT I 1994, 74, 1324)
Meresõiduohutuse seadus Maritime Safety Act (RT I 2002, 1, 1)
Muinsuskaitseseadus Heritage Conservation Act (RT I 2002, 27, 153)
Planeerimisseadus Planning Act (RT I 2002, 99, 579)
Raudteeseadus Railways Act (RT I 2003, 79, 530)
Teeseadus Roads Act (RT I 1999, 26, 377)
Tööstusheitmete seadus Industrial Emissions Act (RT I, 16.05.2013, 1)
Veeseadus Water Act (RT I 1994, 40, 655)
Võlaõigusseadus Law of Obligations Act (RT I 2001, 81, 487)
Majandus- ja kommunikatsiooniministri määrus
„Elektripaigaldise kaitsevööndi ulatus ja kaitsevööndis
tegutsemise kord“
Regulation of the Minister of Economic Affairs and
Communications “Extent of protection zone for an electrical
installation and practical arrangements in a protection zone” (RTL 2007, 27, 482)

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Sotsiaalministri määrus „Müra normtasemed elu- ja
puhkealadel, elamutes ning ühiskasutusega hoonetes ja
mürataseme mõõtmise meetodid“
Regulation of the Minister of Social Affairs “Audible noise
limits in residential and recreational areas, residential and
social buildings and noise level control methods” (RTL .2002, 38, 511)

The following Estonian standards should be taken into account:
EVS-EN 1991-1-4:2005+NA:2007. Eurokoodeks 1: Ehituskonstruktsioonide koormused.
Osa 1-4: Üldkoormused. Tuulekoormus. Eesti standardi rahvuslik lisa. Eurocode 1:
Actions on structures – Part 1-4: General actions – Wind actions. Estonian National
Annex.
EVS-EN 1991-1-4:2005/A1:2010+A1:2010/NA:2010. Eurokoodeks 1:
Ehituskonstruktsioonide koormused. Osa 1-4: Tuulekoormus. Eesti standardi rahvuslik
lisa. Eurocode 1: Actions on structures – Part 1-4: General actions – Wind actions.
Estonian National Annex
EVS-EN 50522:2010. Üle 1 kV nimivahelduvpingega tugevvoolupaigaldiste maandamine.
Earthing of power installations exceeding 1 kV a.c.
EVS 814:2003. Normaalbetooni külmakindlus. Määratlused, spetsifikatsioonid ja
katsemeetodid. Frost resistance of normal-weight concrete. Definitions, specifications
and test method
EVS 843:2003. Linnatänavad. Town streets
EVS 884:2005. Maagaasitorustik. Projekteerimise põhinõuded üle 16 baarise töörõhuga
torustikele. Natural gas pipeline systems – Pipelines for maximum operating pressure
over 16 bar – General requirements for design
EVS-EN 14229:2010. Ehituspuit. Õhuliinide puitpostid. Structural timber – Wood poles for
overhead lines.
EVS-EN 61773:2002. Overhead lines – Testing of foundations for structures
EVS-EN 1997-1:2005+NA:2006. Eurokoodeks 7: Geotehniline projekteerimine. Osa 1:
Üldeeskirjad. Eurocode 7: Geotechnical design – Part 1: General rules
EVS-EN 1997-1:2005/A1:2013. Eurokoodeks 7: Geotehniline projekteerimine. Osa 1:
Üldeeskirjad. Eurocode 7: Geotechnical design – Part 1: General rules
EVS-EN 60071-1. Insulation co-ordination – Part 1: Definitions, principles and rules
EVS-EN 60071-2. Insulation co-ordination – Part 2: Application guide
EVS-EN 61284:2002. Overhead lines – Requirements and tests for fittings
Other valid relevant normative regulatory documents should also be taken in account.
Internal normative documents of a utility may be referred to in the Project Specification.

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3 BASIS OF DESIGN
3.2 Requirements of overhead lines
3.2.2 Reliability requirements
(NCPT) EE.1 Selection of reliability levels
Three reliability levels are used, as shown in the following Table:
Table EE.3.1 — Reliability levels
Reliability level Lines exceeding AC 1 kV
1 Normal lines
2 Important lines
3 Very important lines
NOTE If line reliability is not specified in the Project Specification, the requirements of Level 1
apply.
(A-dev) EE.2 Wind load on temporary lines
In accordance with the Estonian National Annex of EVS-EN 1991-1-4:2005+NA:2007, the
recommended value of the seasonal coefficient c = 1,0.
season
(NCPT) EE.3 Ice load on temporary lines
When designing temporary lines intended for use between April and October, where ice
accretion does not occur, the ice load need not be considered.
3.2.3 Security requirements
(NCPT) EE.1 Distance between tension supports
In lines with nominal voltage exceeding AC 1 kV up to and including 20 kV, the distance
between tension supports must not be greater than 2 km unless specified otherwise in
the Project Specification. For lines with nominal voltage exceeding AC 20 kV the distance
between tension supports shall be specified in the Project Specification.
3.2.5 Strength coordination
(NCPT) EE.1 Specific requirements
The strength coordination is based on the principles of IEC 60826, which are presented in
Annex A of Part 1 of this Standard. Specific requirements for strength coordination may
be specified in the Project Specification.
3.2.6 Additional considerations
(A-dev) EE.1 Environmental aspects
Consideration of an overhead line as an element in the environment shall take into
account the environmental and legal situations in that particular region of Estonia.
(NCPT) EE.2 Safety and protection of wildlife and livestock
Specific requirements on safety of human beings and protection of wildlife and livestock
(e.g. birds, cattle, etc.) may be specified in the Project Specification, if necessary.
3.2.7 Design working life
(NCPT) EE.1
In general, design working life of lines with nominal voltage exceeding AC 1 kV up to and
including 20 kV is 30 years; for lines with nominal voltage exceeding AC 20 kV it is
50 years. A different design working life may be specified in the Project Specification.

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3.3 Limit states
3.3.3 Serviceability limit states
(NCPT) EE.1 Criteria of serviceability
Criteria of serviceability limit states are defined in clauses relating to particular line
components. Additional requirements may be presented in the Project Specification.
3.4 Actions
3.4.2 Classification of actions by their variation in time
(NCPT) EE.1 Variable actions
Wind loads and ice loads as well as applicable temperatures are assessed by applying
the reliability concept.
3.6 Design values
3.6.3 Design value of a material property
(NCPT) EE.1 Partial factors for actions
Partial factors for a material property higher than those stated in Eurocodes 2, 3, 5, 7, and
8 may be specified in the Project Specification.
4 ACTIONS ON LINES
4.1 Introduction
(snc) EE.1 Climatic data
For assessment of the climatic data to determine numerical values for actions, the first
approach is applied, i.e. Estonian and European standards are used. Specific references
shall be given in the corresponding subsections.
4.3 Wind loads
4.3.1 Field of application and basic wind velocity
(A-dev) EE.1 Basic wind speed
The following value shall be used for basic wind velocity (V ) according to the Estonian
b,0
National Annex of EVS-EN 1991-1-4:2005+NA:2007:
V = 21 m/s
b,0
Other values of basic wind speed based on long-term statistics and local conditions can
be specified in the Project Specification.
4.3.2 Mean wind velocity
(A-dev) EE.1 Wind directional factor
According to the Estonian National Annex of EVS-EN 1991-1-4:2005+NA:2007, the
recommended value of the directional factor c = 1,0.
dir
(A-dev) EE.2 Orography factor
According to the Estonian National Annex of EVS-EN 1991-1-4:2005+NA:2007, the
recommended value of the orography factor c = 1,0.
o
4.3.3 Mean wind pressure
(A-dev) EE.1 Air density
According to EVS-EN 1991-1-4:2005+NA:2007, the conservative value for air density
3
ρ = 1,25 kg/m is used in Estonia.

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4.4 Wind forces on overhead line components
4.4.1 Wind forces on conductors
4.4.1.1 General
(snc) EE.1 Conductors reference height above ground
For lines with nominal voltage up to AC 20 kV, reference height above ground h shall be
taken as 10 m regardless of the actual height, provided that the structure height is a
maximum of 20 m.
For lines with nominal voltage exceeding 20 kV, reference height above ground h for the
calculation of wind forces on conductors shall be determined according to method 2 in
Table 4.3.
(NCPT) EE.2 Mechanical tension in a section
For calculating the mechanical tension in a section, the section length should be used as
the span length.
The mean reference height of spans in the section weighted by their lengths should be
taken as the reference height above ground of the conductors in the section.
4.4.1.3 Drag factor
(snc) EE.1 Drag factor for conductors
The drag factor for the conductor, C , shall be determined by method 1, i.e. C = 1,0.
C C
4.4.2 Wind forces on insulator sets
(NCPT) EE.1 Wind forces on insulator sets
Wind forces due to wind pressure on the insulator sets themselves may be neglected for
the design of supports.
4.4.3 Wind forces on lattice towers
4.4.3.1 General
(snc) EE.1 Method for determining of wind forces
Wind forces on the tower itself can be determined by method 1, by which tower is divided
into sections, or by method 2, by which each individual member of the tower is
considered separately.
(snc) EE.2 The reference height of lattice tower sections or members
The reference height of lattice tower sections or members can be determined by any
method given in Clause 4.4.3.1 of Part 1: either the same value is used for every section
or member of a lattice tower, which is equal to 60 % of the total height of the tower, or the
reference height for every section or member is determined separately as the height of
the geometric centre of the corresponding section or member above ground.
4.4.4 Wind forces on poles
(snc) EE.1 Method for determining the reference height
The reference height to evaluate wind forces on poles can be determined either by
method 1 or method 2.

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4.5 Ice loads
4.5.2 Ice forces on conductors
(snc) EE.1 Extreme ice load per unit length
Extreme ice load per unit length I (N/m) shall be calculated by the following formula:
–3
 I = 9,82 × 10 ρ π b (d + b)
I
where
b is the icing thickness, mm;
d is the diameter of conductor or earthwire, mm;
3
ρ is the ice density, g/cm .
I
Simplified:
I = 0,0277 b (b + d)
Value of the icing thickness should be taken equal to 10 mm and the ice type should be
3
glaze ice with density 0,90 g/cm , unless specified otherwise in the Project Specification.
4.6 Combined win
...