SIST EN 50341-2-23:2018

SLOVENSKI STANDARD
01-februar-2018
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Overhead electrical lines exceeding AC 1 kV – Part 2-23: National Normative Aspects
(NNA) for SLOVAKIA (based on EN 50341-1:2012)
Lignes électriques aériennes dépassant 1 kV en courant alternatif - Partie 2-23: Aspects
normatifs nationaux pour la SLOVAQUIE (basé sur l'EN 50341-1:2012)
Ta slovenski standard je istoveten z: EN 50341-2-23:2016
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 50341-2-23
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2016
ICS 29.240.20
English Version
Overhead electrical lines exceeding AC 1 kV - Part 2-23:
National Normative Aspects (NNA) for SLOVAKIA (based on EN
50341-1:2012)
Lignes électriques aériennes dépassant 1 kV en courant
alternatif - Partie 2-23: Aspects normatifs nationaux pour la
SLOVAQUIE (basé sur l'EN 50341-1:2012)
This European Standard was approved by CENELEC on 2016-09-20. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
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
© 2016 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 50341-2-23:2016 E
EN 50341-2-23: 2016 - 2/64 - Slovakia

Contents
Page
1 Scope . 7
1.1 General . 7
1.2 Field of application . 7
2 Normative references, definitions and symbols . 7
2.1 Normative references . 7
2.2 Definitions . 10
2.3 Symbols . 10
3 Basis of design . 12
3.2 Requirements of overhead lines . 12
3.2.2 Reliability requirements . 12
3.2.5 Strength coordination . 12
3.2.6 Additional considerations . 12
4 Actions on lines . 13
4.3 Wind loads . 13
4.3.1 Field of application and basic wind velocity . 13
4.3.2 Mean wind velocity . 13
4.3.3 Mean wind pressure . 13
4.4 Wind forces on overhead line components . 13
4.4.1 Wind forces on conductors . 13
4.4.2 Wind forces on insulator sets . 14
4.4.3 Wind forces on lattice towers . 15
4.4.4 Wind forces on poles . 15
4.5 Ice loads. 15
4.5.1 General . 15
4.6 Combined wind and ice loads . 17
4.6.1 Combined probabilities . 17
4.6.2 Drag factors and ice densities . 17
4.6.5 Wind forces on support for ice covered conductors . 17
4.6.6 Combination of wind velocities and ice loads . 17
4.7 Temperature effects . 18
4.8 Security loads . 18
4.8.1 General . 18
4.8.2 Torsional loads. 18
4.8.3 Longitudinal loads . 19
4.9 Safety loads . 19
4.9.1 Construction and maintenance loads . 19
4.9.2 Loads related to the weight of linesmen . 19
4.10 Forces due to short-circuit currents . 19
4.11 Other special forces . 19
4.11.1 Avalanches, creeping snow . 19
4.11.2 Earthquakes . 20
4.12 Load cases. 20
4.12.1 General . 20
4.12.2 Standard load cases . 20
4.13 Partial factors for actions . 21
5 Electrical requirements . 25
5.3 Insulation coordination . 25
5.4 Classification of voltages and overvoltages . 26
5.4.2 Representative power frequency voltages . 26
5.5 Minimum air clearance distances to avoid flashover . 26

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5.5.2 Application of the theoretical method in Annex E . 26
5.5.3 Empirical method based on European experience . 26
5.6 Load cases for calculation of clearances . 27
5.6.2 Maximum conductor temperature . 27
5.6.3 Wind loads for determination of electric clearances . 27
5.6.4 Ice loads for determination of electric clearances . 28
5.6.5 Combined wind and ice loads . 29
5.7 Coordination of conductor positions and electrical stresses . 29
5.8 Internal clearances within the span and at the top of support . 30
5.9 External clearances . 33
5.9.1 General . 33
5.9.2 External clearances to ground in areas remote from buildings, roads, etc. . 34
5.9.3 External clearances to residential and other buildings . 34
5.9.4 External clearances to crossing traffic routes . 36
5.9.5 External clearances to adjacent traffic routes . 39
5.9.6 External clearances to other power lines or overhead telecommunication lines . 39
5.10 Corona effect . 41
5.10.1 Radio noise . 41
5.11 Electric and magnetic fields . 41
5.11.1 Electric and magnetic fields under a line . 41
5.11.2 Electric and magnetic field induction . 41
5.11.3 Interference with telecommunication circuits . 41
6 Earthing systems . 42
6.1 Introduction . 42
6.1.2 Requirements for dimensioning of earthing systems . 42
6.1.3 Earthing measures against lightning effects . 42
6.1.4 Transferred potentials . 43
6.2 Ratings with regard to corrosion and mechanical strength . 43
6.2.1 Earth electrodes. 43
6.2.2 Earthing and bonding conductors . 44
6.4 Dimensioning with regard to human safety . 44
6.4.1 Permissible values for touch voltages . 44
6.4.3 Basic design of earthing systems with regard to permissible touch voltage . 44
7 Supports . 45
7.3 Lattice steel towers . 45
7.3.6 Ultimate limit states. 45
7.3.7 Serviceability limit states . 45
7.3.8 Resistance of connections . 45
7.3.9 Design assisted by testing . 45
7.4 Steel poles . 45
7.4.6 Ultimate limit states (EN 1993-1-1:2005 – Chapter 6). 45
7.4.7 Serviceability limit states (EN 1993-1-1:2005 – Chapter 7) . 45
7.4.8 Resistance of connections . 46
7.4.9 Design assisted by testing . 46
7.5 Wood poles . 46
7.5.5 Ultimate limit states. 46
7.5.6 Serviceability limit states . 46
7.5.7 Resistance of connections . 46
7.5.8 Design assisted by testing . 46
7.6 Concrete poles . 46
7.6.4 Ultimate limit states. 46
7.6.5 Serviceability limit states . 47

EN 50341-2-23: 2016 - 4/64 - Slovakia

7.6.6 Design assisted by testing . 47
7.7 Guyed structures . 47
7.7.4 Ultimate limit states . 47
7.7.5 Serviceability limit states . 47
7.9 Corrosion protection and finishes . 47
7.9.1 General . 47
7.10 Maintenance facilities . 48
7.10.1 Climbing . 48
7.10.2 Maintainability . 48
7.10.3 Safety requirements . 48
8 Foundations . 48
8.1 Introduction . 48
8.2 Basis of geotechnical design (EN 1997-1:2004 – Section 2) . 48
8.2.2 Geotechnical design by calculation . 48
8.3 Soil investigation and geotechnical data (EN 1997-1:2004 – Section 3) . 48
9 Conductors and earth-wires . 49
9.1 Introduction . 49
9.2 Aluminium based conductors. 49
9.2.2 Electrical requirements . 49
9.2.3 Conductor service temperatures and grease characteristics . 49
9.2.4 Mechanical requirements . 50
9.2.5 Corrosion protection . 50
9.2.6 Test requirements . 50
9.3 Steel based conductors . 50
9.3.1 Characteristics and dimensions . 50
9.3.3 Conductor service temperatures and grease characteristics . 51
9.3.4 Mechanical requirements . 51
9.3.5 Corrosion protection . 51
9.3.6 Test requirements . 51
9.4 Copper base conductors . 52
9.5 Conductors and ground wires containing optical fibre telecommunication circuits . 52
9.5.1 Characteristics and dimensions . 52
9.5.2 Electrical requirements . 52
9.5.3 Conductor service temperatures. 52
9.5.4 Mechanical requirements . 52
9.6 General requirements . 53
9.6.2 Partial factor for conductors . 53
9.6.3 Minimum cross-sections . 53
9.6.4 Sag – tension calculations . 53
10 Insulators . 53
10.1 Introduction . 53
10.4 Pollution performance requirements . 53
10.5 Power arc requirements . 53
10.7 Mechanical requirements . 53
10.10 Characteristics and dimensions of insulators . 54
10.11 Type test requirements . 54
10.11.1 Standard type tests . 54
10.11.2 Optional type tests . 54
11 Hardware . 55
11.1 Introduction . 55
11.6 Mechanical requirements . 55
12 Quality assurance, checks and taking-over . 56

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Annex H/SK (informative) . 56
Installation and measurements of earthing systems . 56
H.2 Basis for the verification . 56
H.2.2 Resistance to earth . 56
H.3 Installation of earth electrodes and earthing conductors . 56
H.3.1 Installation of earth conductors . 56
H.4 Measurements for and on earthing systems . 56
H.4.4 Determination of the earth potential rise . 56
H.4.5 Reduction factor related to earth wires of overhead lines . 56
Annex M/SK (informative) . 57
Geotechnical and structural design of foundations . 57
M.1 Typical values of the geotechnical parameters of soils and rocks . 57
M.1.3 Symbols, definitions and units of some ground parameters . 57
M.3 Sample semi-empirical models for resistance estimation . 63
M.3.1 Geotechnical design by calculation . 63
Annex S/SK (informative) . 64
Map of icing zones in Slovakia . 64

EN 50341-2-23: 2016 - 6/64 - Slovakia

European foreword
1. The Slovak National Committee (NC) is identified by the following address:
SLOVAK OFFICE OF STANDARDS, METROLOGY AND TESTING
Štefanovičova 3
P.O.Box 76
810 05 Bratislava 15
Slovakia
email: unms@normoff.gov.sk
tel:   +421 252 496 847
tel:   +421 252 498 030
2. The Slovak National Committee has prepared this Part 2-23 (EN 50341-2-23) listing the Slovak
National Normative Aspects (NNA) under its sole responsibility and duly passed this document
through the CENELEC and CLC/TC11 procedures.
NOTE The Slovak National Committee also takes sole responsibility for the technically correct co-
ordination of this EN 50341-2-23 with EN 50341-1. It has performed the necessary checks in the frame of
quality assurance/control. However, it is noted that this quality assurance/control has been made in the
framework of the general responsibility of The Slovak National Committee under the national laws/regulations.
3. This EN 50341-2-23 is normative in Slovakia and informative for other countries.
4. This EN 50341-2-23 has to be read in conjunction with EN 50341-1, hereinafter referred as Part 1.
All clause numbers used in Part 2-23 correspond to those of Part 1. Specific subclauses which are
prefixed SK are to be read as amendments to the relevant text in Part 1. Any necessary
clarification regarding the application of Part 2-23 in conjunction with Part 1 shall be referred to the
Slovak Office of Standards, Metrology and Testing that will, in co-operation with CLC/TC11, clarify
the requirements. When no reference is made in Part 2-23 to a specific subclause, then Part 1
applies.
5. In the case of “boxed values“ defined in Part 1, amended values (if any) which are defined in
Part 2-23 shall be taken into account in Slovakia.
However, any “boxed values” whether in Part 1 or Part 2-23, shall not be amended in direction of
greater risk in the Project Specification.
6. The national Slovak standards/regulations, regarding overhead lines exceeding 1 kV AC, are listed
in 2.1/SK.2 and 2.1/SK.3.
NOTE All national standards referred to in this Part 2-23 will be replaced by the relevant European
Standards as soon as they become available and are declared by the Slovak Office of Standards, Metrology
and Testing to be applicable and thus reported to the secretary of CLC/TC11.

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1 Scope
1.1 General
(ncpt) SK.1 New overhead line
As a new overhead line is considered a brand new electric overhead line with nominal
voltage exceeding 1 kV AC, between the points A and B.
The new branch line of the existing overhead line shall be considered as a new overhead
line except for a junction support for which the specific requirements shall be defined in the
Project Specification.
The extent of application of this standard in respect of reconstruction, relaying and extension
of existing overhead lines shall be determined in the Project Specification. Simultaneously,
the Project Specification shall determine, which of the previous national standards shall be
used and to what extent they shall be used for the project in question.
1.2 Field of application
(ncpt) SK.1 Field of application
The requirements of this standard shall be adopted, where applicable (e.g. requirements on
loads, external clearances, etc.), for telecommunication cables as well.
In case of overhead line under the design stage, parties concerned shall agree the extent of
the application of this standard.
Overhead line under construction may be completed according to standards valid during the
design stage of the line. The parties concerned shall agree any possible application of
certain clauses of this standard.
(ncpt) SK.2 Installation of telecommunication equipment on supports
Provisions of this standard also apply to the telecommunication equipment and devices
(aerials, dish antennas, etc.) which are installed on individual supports of overhead power
lines, especially in terms of wind and ice loads on such installed equipment. Design and
installation has to respect requirements of the utility operating the line in question. The
design of such telecommunication equipment has to incorporate such technical solutions and
such precautions, which shall allow safe access and maintenance of both a power line and
telecommunication equipment, and which shall provide protection of persons performing
repairs or maintenance of the power line and/or telecommunication equipment against
electric shock and protection of telecommunication equipment and attached installations
against the influence of the power line (short-circuits, switching and lightning overvoltages
etc.).
2 Normative references, definitions and symbols
2.1 Normative references
(ncpt) SK.1 General
National laws, Government regulations and other binding regulations are included in
following 2.1/SK.2. International and national standards quoted in EN 50341-2-23 and not
included in 2.1 EN 50341-1 are included in 2.1/SK.3.
The set of standards included in 2.1 EN 50341-1 under a common title of Eurocodes is valid
in Slovakia including the Slovak National Application documents related to relevant
standards, unless EN 50341-1 and/or these Slovak National Normative Aspects (EN 50341-
2-23) specify otherwise.
NOTE Some EN, IEC, ISO and CISPR publications implemented as Slovak National Standards
(STN) include informative notes and informative annexes useful in Slovakia.

EN 50341-2-23: 2016 - 8/64 - Slovakia

(A-dev) SK.2 National laws, government decrees and other binding rules of law
Reference Title
22/2001 Z.z. Vyhláška, ktorou sa ustanovujú podrobnosti o zaradení vodných
ciest a ich jednotlivých úsekov do príslušných tried podľa
klasifikácie európskych vodných ciest
Regulation, which establishes the details on classification of
waterways and their individual sections into relevant classes
according to European waterway classification
534/2007 Z.z. Vyhláška o podrobnostiach o požiadavkách na zdroje
elektromagnetického žiarenia a na limity expozície obyvateľov
elektromagnetickému žiareniu v životnom prostredí
Regulation on the details on requirements on electromagnetic
radiation sources and on limits of population exposure to
electromagnetic radiation in the environment
251/2012 Z.z. Zákon o energetike a o zmene a doplnení niektorých zákonov
(energetický zákon)
Act on energetics and on amendment to certain laws (Energy
Act)
FMPE 994/11:1981 Dohoda o postupu při interferenčním ovlivnění
FMD 621/1981-SM zabezpečovacího zařízení celostátních drah zařízeními
elektrizační soustavy
The agreement on the common practice on interference
influence of state railway security equipment by electricity
system devices
(ncpt) SK.3 Standards
Reference Title
STN EN 1991-1-4 Eurokód 1. Zaťaženia konštrukcií. Časť 1-4: Všeobecné
zaťaženia. Zaťaženie vetrom (Národná príloha NA pre SR, Mapa
vetrových oblastí
Eurocode 1: Action on structures. Part 1-4: General actions –
Wind Actions (National Annex NA for Slovakia, Wind zone map)
STN 33 2040 Elektrotechnické predpisy. Ochrana pred účinkami
elektromagnetického poľa 50 Hz v pásme vplyvu zariadenia
elektrizačnej sústavy
Electric engineering regulations. Protection against effects of the
electromagnetic fields 50 Hz in the zone of influence of electric
power system device
STN 33 2160 Elektrotechnické predpisy. Predpisy na ochranu oznamovacích
vedení a zariadení pred nebezpečnými vplyvmi trojfázových
vedení VN, VVN a ZVN
Electric engineering regulations. Rules for the protection of
telecommunication lines and equipment against dangerous
influences of three-phase high voltage, very high voltage and
ultra high voltage lines
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Reference Title
EN 50443 Účinky elektromagnetickej interferencie spôsobenej
vysokonapäťovými elektrickými trakčnými sieťami striedavého
prúdu a/alebo vysokonapäťovými napájacími sieťami striedavého
prúdu na potrubia
Effects of electromagnetic interference on pipelines caused by
high voltage a.c. electric traction systems and/or high voltage
a.c. power supply systems
STN 73 6133 Stavba ciest. Teleso pozemných komunikácií
Road Building – Road embankments and subgrades
EN 13501-1+A1 Klasifikácia požiarnych charakteristík stavebných výrobkov a
prvkov stavieb. Časť 1: Klasifikácia využívajúca údaje zo skúšok
reakcie na oheň
Fire classification of construction products and building elements
– Part 1:Classification using data from reaction to fire tests.
EN 13501-5+A1 Klasifikácia požiarnych charakteristík stavebných výrobkov a
prvkov stavieb. Časť 5: Klasifikácia využívajúca údaje zo skúšok
striech namáhaných vonkajším ohňom
Fire classification of construction products and building
elements - Part 5: Classification using data from external fire
exposure to roofs tests
EN 50522 Uzemňovanie silnoprúdových inštalácií na striedavé napätia
prevyšujúce 1 kV
Earthing of power installations exceeding 1 kV AC.
EN 62305-3 Ochrana pred bleskom. Časť 3: Hmotné škody na stavbách a
ohrozenie života
Protection against lightning – Part 3: Physical damage to
structures and life hazard
EN ISO 14688-1 Geotechnický prieskum a skúšky. Pomenovanie a klasifikácia
zemín. Časť 1: Pomenovanie a opis
Geotechnical investigation and testing - Identification and
classification of soil - Part 1: Identification and description
EN ISO 14688-2 Geotechnický prieskum a skúšky. Pomenovanie a klasifikácia
zemín. Časť 2: Princípy klasifikácie
Geotechnical investigation and testing - Identification and
classification of soil – Part 2: Principles for a classification
EN ISO 14689-1 Geotechnický prieskum a skúšky. Pomenovanie a klasifikácia
skalných hornín. Časť 1: Pomenovanie a opis
Geotechnical investigation and testing - Identification and
classification of rock – Part 1: Identification and description
EN 206 Betón. Špecifikácia, vlastnosti, výroba a zhoda
Concrete. Specification, performance, production and conformity
STN 73 3050 Zemné práce. Všeobecné ustanovenia
Earth works. General requirements

EN 50341-2-23: 2016 - 10/64 - Slovakia

(ncpt) SK.4 Other publications
Reference Title
STN 73 1001: 1988 Zakladanie stavieb. Základová pôda pod plošnými základmi
(withdrawn on 1.4.2010) Foundation of structures. Subsoil under shallow foundations
CIGRE TB 207:2002 CIGRÉ technical brochure No. 207 “Thermal behaviour of
overhead conductors”
CIGRE TB 273:2005 CIGRÉ technical brochure No. 273 “Overhead conductor safe
design tension with respect to Aeolian vibrations”
CISPR TR 18-2 Radio interference characteristics of overhead power lines and
high-voltage equipment. Part 2 : Methods of measurement and
procedure for determining limits
2.2 Definitions
(ncpt) SK.1 span
part of a line between attachment points of a conductor on two consecutive supports
(IEV 466-03-01)
NOTE This definition is included for the reason that the English word “span” corresponds with the
Slovak conversion used in STN IEC 50 (466) which means “a span length”.
(ncpt) SK.2 overhead telecommunication line and equipment
wire or cable line and telecommunication equipment leading above ground and outside
buildings and transmitting information via electromagnetic waves
(ncpt) SK.3 aluminium based conductor
bare conductor made of round or shaped wires being concentric lay stranded with alternating
directions of stranding, with grease or not, produced of materials or various materials
according to one of following alternatives
– aluminium wires
– aluminium alloy wires
– combination of aluminium wires and aluminium alloy wires
– combination of aluminium wires and steel zinc coated wires
– combination of aluminium wires and aluminium clad steel wires
– combination of aluminium alloy wires and steel zinc coated wires
– combination of aluminium alloy wires and aluminium clad steel wires
(ncpt) SK.4 steel based conductor
bare conductor made of round or shaped wires being concentric lay stranded with alternating
directions of stranding, with grease or not, produced of materials or various materials
according to one of following alternatives
– steel zinc coated wires
– aluminium clad steel wires
2.3 Symbols
(ncpt) SK.1 Symbols
Symbols which are contained in EN 50341-2-23 and are not contained in EN 50341-1, or
which are contained in EN 50341-2-23 also with a different meaning than in 2.3 EN 50341-1,
are included below.
Symbol Signification References
b Minimum clearance between conductors within the span 5.8/SK.3
emp
according to empirical formula
c Constant in empirical formula for the minimum clearance 5.8/SK.3
emp
between conductors within the span

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D Minimum clearance required to prevent a disruptive discharge 5.5.3/SK.1
el1
between phase conductor and external object at earth potential
during fast front and slow front overvoltages (external clearance)
D Minimum clearance required to prevent a disruptive discharge 5.5.3/SK.1
el2
between phase conductor and support structure during fast front
and slow front overvoltages (internal clearance)
D Minimum clearance required to prevent a disruptive discharge 5.5.3/SK.1
el3
between phase conductor in window of a support and support
structure during fast front and slow front overvoltages (internal
clearance)
D Minimum clearance required to prevent a disruptive discharge 5.5.3/SK.1
el4
between phase conductor and earth wire during fast front and
slow front overvoltages (internal clearance)
D Horizontal distance of a tree trunk from the most endangered 5.9.2/SK.2
tr
conductor
f Conductor sag under specified conditions 5.8/SK.3
g Self-weight of a conductor per unit length 5.8/SK.3
c
H Height of a tree 5.9.2/SK.2
tr
h
Pole height above ground 7.6.5/SK.2
s
h Height of the most endangered conductor above the horizontal 5.9.2/SK.2
c_tr
plane of the tree base
h Mean height of phase conductors of a given circuit on a support 4.4.1.1/SK.2
pc
I Extreme reference ice load per conductor unit length at 10 m 4.5.1/SK.3
R50
height above ground with return period T = 50 years
K 5.3/SK.2
Altitude factor for altitudes H > 1 000 m
aH
K Altitude factor for altitude H = 1 000 m 5.3/SK.2
a1000
K
Height factor for the ice load 4.5.1/SK.3
h
K Local condition factor for the ice load 4.5.1/SK.3
Ic
k , Factor depending on weight and diameter of a conductor and on 5.8/SK.3
emp
k mutual position of both conductors 5.8/SK.4
emp_r
L
Vertical length of that part of insulator set which may swing 5.8/SK.1
ins
in the direction perpendicular to the line
m Mass of the insulator set 5.8/SK.5
ins
r Horizontal distance between the attachment point of a shorter 5.8/SK.1
insulator set and the point in a span, where the distance between
conductors is checked
t Ice thickness on a conductor with a diameter of 30 mm according 4.6.2/SK.2
I
to the actual load combination
U 5.3/SK.2
Required withstand voltage for altitude H > 1 000 m
rwH
U Required withstand voltage for altitude H = 1 000 m 5.3/SK.2
rw1 000
U Required withstand voltage for lightning impulse 5.3/SK.1
rwLI
U Required withstand voltage for switching impulse 5.3/SK.1
rwSI
U Required withstand voltage for power frequency overvoltage 5.3/SK.1
rw50Hz
V Wind velocity with return period of 2 years 4.6.6.1/SK.1
w Probability factor H.4.4/SK.1

z
Depth of geotechnical soil investigation below the foundation 8.3/SK.1
a
base
EN 50341-2-23: 2016 - 12/64 - Slovakia

Reduction factor of ice load for torsional security loads 4.8.2/SK.1
α
TSL
Reduction factor of ice load for longitudinal security loads 4.8.3/SK.2
α
LSL
Angle describing mutual position of both conductors 5.8/SK.3
δ
φ Insulator set swing angle 5.8/SK.5
Partial factor for resistance (EN 1997-1, Design approach 2) 8.2.2
γ
R
3 Basis of design
3.2 Requirements of overhead lines
3.2.2 Reliability requirements
(ncpt) SK.1 Reliability level of permanent lines
Reliability level 1 (Return period of climatic action 50 years) is considered, unless a higher
reliability level is specified in the Project Specification.
(ncpt) SK.2 Reliability level of temporary lines
Depending on their life duration, the return period of climatic actions for temporary lines, with
duration less than 1 year, may be reduced due to the shorter exposure to climatic effects.
Return periods of climatic loads and additional information is given in the following Table
3/SK.1.
Table 3/SK.1 – Return periods for temporary lines
Life duration Return period (years)
a) c)
≤ 3 days 2
b) c)
≤ 3 months (but > 3 days)
b) c)
≤ 1 year (but > 3 months)
NOTES
a)
For lines, installed for nominal duration of 3 days, it is possible to take into account the
meteorological forecast for the given site
b)
For temporary lines with duration more than 3 days, it is not recommended to use basic mean
wind speed lower than 20 m/s.
c)
Ice loads need not to be considered, provided the line is installed only in the season, when ice
st st
accretion does not occur. This period starts on 1 April and ends on 1 November.
3.2.5 Strength coordination
(ncpt) SK.1 Strength coordination
Only strength coordination for the above-ground part of steel structure of lattice tower stub is
specified in this standard (see 7.3.6.1/SK.3). Additional requirements may be given in the
Project Specification.
3.2.6 Additional considerations
(ncpt) SK.1 Additional considerations
Any further specific requirements, e.g. installation of air
...