SIST EN 50341-2-6:2018

SLOVENSKI STANDARD
01-februar-2018
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Overhead electrical lines exceeding AC 1 kV - Part 2-6: National Normative Aspects
(NNA) for SPAIN (based on EN 50341-1:2012)
Lignes électriques aériennes dépassant 1 kV en courant alternatif - Partie 2-6: Aspects
normatifs nationaux (NNA)pour l'ESPAGNE (basé sur l'EN 50341-1:2012)
Ta slovenski standard je istoveten z: EN 50341-2-6:2017
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 50341-2-6
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2017
ICS 29.240.20
English Version
Overhead electrical lines exceeding AC 1 kV - Part 2-6:
National Normative Aspects (NNA) for SPAIN
(based on EN 50341-1:2012)
Lignes électriques aériennes dépassant 1 kV en courant
alternatif - Partie 2-13: Aspects normatifs nationaux
(NNA)pour l'ESPAGNE (basé sur l'EN 50341-1:2012)
This European Standard was approved by CENELEC on 2017-02-01.
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, Serbia, 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
© 2017 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 50341-2-6:2017 E
Contents
Page
1 SCOPE 6
1.1 General . 6
1.2 Field of application . 6
2 NORMATIVE REFERENCES, DEFINITIONS AND SYMBOLS 6
2.1 Normative references . 6
2.3 Symbols . 6
3 BASIS OF DESIGN 7
3.2 Requirements of overhead lines . 7
3.2.2 Reliability requirements . 7
3.2.5 Strength coordination . 7
3.6 Design values . 7
3.6.2 Design value of an action . 7
3.6.3 Design value of a material property . 7
3.7 Partial factor method and design formula . 7
3.7.2 Basic design formula . 7
4 ACTIONS ON LINES 8
4.1 Introduction . 8
4.2 Permanent loads . 8
4.3 Wind loads . 8
4.3.1 Field of application and basic wind velocity . 8
4.3.5 Wind forces on any overhead line component . 8
4.4 Wind forces on overhead line components . 10
4.5 Ice loads . 10
4.5.2 Ice forces on conductors . 10
4.7 Temperature effects . 10
4.8 Security loads . 10
4.8.1 General . 10
4.8.2 Torsional loads . 11
4.8.3 Longitudinal loads . 11
4.12 Load cases . 12
4.12.1 General . 12
4.12.2 Standard load cases . 12
4.13 Partial factors for actions . 12
5 ELECTRICAL REQUIREMENTS 13
5.2 Currents . 13
5.2.1 Normal current. 13
5.3 Insulation co-ordination . 14
5.4 Classification of voltages and overvoltages . 17

Spain - 3 - EN 50341-2-6:2017
Page
5.4.2 Representative power frequency voltages . 17
5.5 Minimum air clearance distances to avoid flashovers. 18
5.6 Load cases for calculation of clearances . 19
5.6.1 Load conditions . 19
5.8 Internal clearances within the span and at the top of support . 19
5.9 External clearances . 21
5.9.1 General . 21
5.9.2 External clearances to ground in areas remote from buildings, roads, etc. . 22
5.9.3 External clearances to residential and other buildings . 23
5.9.4 External clearances to crossing traffic routes . 24
5.9.5 External clearances to adjacent traffic routes . 25
5.9.6 External clearances to other power lines or overhead telecommunication lines . 26
5.9.7 External clearances to recreational areas (playgrounds, sports areas, etc.) . 29
6 EARTHING SYSTEMS 29
6.1 Introduction . 29
6.1.2 Requirements for dimensioning of earthing systems . 29
6.1.3 Earthing measures against lightning effects . 30
6.2 Ratings with regards to corrosion and mechanical strength . 30
6.2.2 Earthing and bonding conductors . 30
6.3 Dimensioning with regard to thermal strength . 30
6.3.1 General . 30
6.3.2 Current rating calculation . 31
6.4 Dimensioning with regard to human safety . 31
6.4.1 Permissible values for touch voltage . 31
6.4.3 Basic design of earthing systems with regard to permissible touch voltage . 31
6.5 Site inspection and documentation of earthing systems . 32
7 SUPPORTS 33
7.2 Materials . 33
7.2.1 Steel materials, bolts, nuts and washers, welding consumables . 33
7.2.5 Concrete and reinforced steel . 33
7.2.6 Wood . 33
7.3 Lattice steel towers . 33
7.3.1 General . 33
7.3.6 Ultimate limit states . 34
7.3.8 Resistance of connections . 34
7.3.9 Design assisted by testing . 34
7.4 Steel poles . 35
7.4.1 General . 35
7.4.2 Basis of design (EN 1993-1-1:2005 - Chapter 2) . 35
7.4.6 Ultimate limit states (EN 1993-1-1:2005 - Chapter 6) . 35
7.4.8 Resistance of connections . 35

Page
7.4.9 Design assisted by testing . 35
7.5 Wood poles . 36
7.5.1 General . 36
7.5.2 Basis of design . 36
7.5.5 Ultimate limit states . 36
7.6 Concrete poles . 36
7.6.1 General . 36
7.6.4 Ultimate limit states . 36
7.6.5 Serviceability limit states . 36
7.6.6 Design assisted by testing . 36
7.7 Guyed structures . 37
7.7.1 General . 37
7.7.4 Ultimate limit states . 37
7.8 Other structures. 37
8 FOUNDATIONS 37
8.1 Introduction . 37
8.2 Basis of geotechnical design (EN 1997-1:2004 - Section 2) . 37
8.2.2 Geotechnical design by calculation . 37
8.3 Soil investigation and geotechnical data (EN 1997-1:2004 - Section 3) . 39
8.6 Interactions between support foundations and soil . 40
9 CONDUCTORS AND EARTH-WIRES 40
9.2.4 Mechanical requirements . 40
9.6 General requirements . 40
9.6.2 Partial factor for conductors . 40
10 INSULATORS 40
10.2 Standard electrical requirements . 40
10.7 Mechanical requirements . 40
11 HARDWARE 41
11.6 Mechanical requirements . 41
11.9 Characteristics and dimensions of fittings . 41
Tables
Table 5.2.1/ES.1 – Conductor current density .
Table 5.3.1/ES.1 – Standard insulation levels for range I (1 kV < Um ≤ 245 kV) .
Table 5.3.2/ES.1 – Standard insulation levels for range II (Um > 245 kV) .
Table 5.3.3/ES.1 – Recommended air clearances .
Table 5.4/ES.1 – Nominal voltages and highest grid voltages .
Table 5.5/ES.1 – Minimum air clearance distances, D and D , to avoid flashover .
el pp
Table 5.8/ES.1 – Coefficient K based on the oscillation angle .
Table 5.9.6/ES.1 – Additional clearances, D , to other overhead power lines or overhead
add
telecommunication lines .
Table 8.3/ES.1 – Indicative soil characteristics for the calculation of the foundation .
Table G.6/ES.1 – Fault duration related to touch voltage, UTp .

Spain - 5 - EN 50341-2-6:2017
European foreword
1 The Spanish National Committee (NC) is identified by the following address:
Asociación Española de Normalización (UNE)
c/Génova, 6
E 28004 Madrid
Spain
Tel. nº: + 34 915 294 900
Fax nº: + 34 91 310 45 96
Email: info@une.org
Name of the relevant technical body: AEN/CTN 207/SC 7-11 “Líneas eléctricas aéreas” (Overhead
power lines)
2 The Spanish NC and its technical body AEN/CTN 207/SC 7-11 “Overhead power lines” has prepared
this Part 2-6 of EN 50341, listing the Spanish National Normative Aspects (NNA) under its sole
responsibility, and duly passed it through the CENELEC and CLC/TC 11 procedures.
NOTE: The Spanish NC also takes sole responsibility for the technically correct co-ordination of this EN 50341-2-
6 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 2-6 is normative in Spain and informative in other countries.
4 This document shall be read in conjunction with Part 1 (EN 50341-1). All clause numbers used in this
NNA correspond to those of Part 1. Specific sub-clauses that are prefixed “ES”, are to be read as
amendments to the relevant text in Part 1. Any necessary clarification regarding the application of this
combined NNA in conjunction with Part 1 shall be referred to the Spanish NC who will, in co-operation
with CLC/TC 11, clarify the requirements.
When no reference is made in this NNA to a specific sub-clause, then Part 1 applies.
5 In case of “boxed values” defined in Part 1, amended values (if any), which are defined in this NNA,
shall be taken into account in Spain.
However, any “boxed value”, whether in Part 1 or in this NNA, shall not be amended in the direction of
greater risk in a Project Specification.
6 The national Spanish standards/regulations related to overhead electrical lines exceeding 1 kV A.C.
are listed in sub-clause 2.1/ES.1 and ES.2.
NOTE: All national standards referred to in this NNA will be replaced by the relevant European Standards as
soon as they become available and are declared by the Spanish NC to be applicable and thus reported to the
secretary of CLC/TC 11.
7 The Spanish NC declares, in accordance with sub-clause 4.1 of Part 1, that “Approach 3” shall be
used in Spain to stablish numerical values of actions.

1 Scope
1.1 General
(ncpt) ES.1 General
This NNA is applicable to any new line between two points, A and B, its modifications and
extensions.
1.2 Field of application
(A-dev) ES.1 RD 223/2008, ITC-LAT 08, sub-clause 6.3.2

The design and construction of overhead lines with covered conductors and voltages greater than
45 kV shall respect the same electrical clearances as of overhead lines with bare conductors of the
same voltage.
2 Normative references, definitions and symbols

2.1 Normative references
(A-dev) ES.1 National normative regulations

Royal Decree (RD) 223/2008, of 15th February 2008, approving the Regulation on technical and
safety conditions for high voltage electrical lines and its Supplementary Technical Instructions ITC-
LAT 01 to 09
Royal Decree (RD) 337/2014, of 9th May 2014, approving the Regulation on technical and safety
conditions for high voltage power installations and its Supplementary Technical Instructions ITC-
RAT 01 to 23
Royal Decree (RD) 614/2001, of 8th June 2001, establishing the minimum health and safety
requirements for the protection of workers against the electrical risk

Royal Decree (RD) 1955/2000, of 1st December 2000, regulating the activities of transmission,
distribution, marketing and supply of electrical energy and the procedures for the authorization of
installations
(ncpt) ES.2 National normative standards

UNE 207016 “HV and HVH type concrete poles for overhead electrical lines”

UNE 207017 “Lattice steel towers for distribution overhead electrical lines”

UNE 207018 “Plate metallic supports for overhead electrical lines”

2.3 Symbols
(ncpt) ES.1 Additional symbols

a minimum insulator set discharge gap, defined as shortest distance in straight line
som
between live parts and earthed parts
A wind exposed pole area projected in a wind direction perpendicular plane in m
T
CS minimum security factor defined for each element and load case
D clearance between same or different circuits’ phase conductors in metres
F maximum sag in metres, for load cases defined in sub-clause 3.2.3
K coefficient depending on the conductors’ wind oscillation, it shall be selected from Table
5.8/ES.1
K’ coefficient depending on overhead lines nominal voltage. K’ = 0,85 for special category
lines and K’ = 0,75 for other overhead lines
L suspension set length in metres. For conductors attached to the pole with strain or post-
insulator sets L = 0
Spain - 7 - EN 50341-2-6:2017
V reference wind velocity in km/h
V
3 Basis of design
3.2 Requirements of overhead lines

3.2.2 Reliability requirements

(A-dev) ES.1 RD 223/2008, clause 16

For private overhead lines, a competent licensed technician, with the authorization of overhead
line’s owner, may adopt in emergency situations the recommended provisional steps, immediately
advising to the competent Administration body, which shall set the period to restore the regulation
conditions.
(ncpt) ES.2 Reliability levels

The minimum reliability level shall be 1. Actions for wind and ice are defined in section 4.

3.2.5 Strength coordination
(snc) ES.1 Strength coordination

Strength coordination is obtained by matching the security factors (CS) associated to each
component and system of the overhead line.

3.6 Design values
3.6.2 Design value of an action

(A-dev) ES.1 Design value of an action

Actions shall not be affected by partial factors.

3.6.3 Design value of a material property

(A-dev) ES.1 Partial factor for a material property

The partial factor for a material property shall be:

X = X / CS
d K
Where:
X is the design value of the material property
d
XK is the characteristic value of the material property
CS is the minimum security factor for each element and load case defined in sub-clause
4.13/ES.1
3.7 Partial factor method and design formula

3.7.2 Basic design formula
(snc) ES.1 Basic design formula

When considering a limit state of rupture or excessive deformation of a component, element or
connection, it shall be verified that:

R / E ≥ CS
d d
Where:
E is the total design value of the effect of actions, such as internal force or moment, or a
d
representative vector of several internal forces or moments, as defined in sub-clause
3.7.2 of the main body
R is the corresponding structural design resistance, as defined in sub-clause 3.7.2 of the
d
main body
CS is the minimum security factor for each element and load case defined in clause
4.13/ES.1
4 Actions on lines
4.1 Introduction
(snc) ES.1 Introduction
Due to the lack, in general, of official statistical data, in Spain Approach 3 shall be used to stablish
the numerical values of actions.

4.2 Permanent loads
(A-dev) ES.1 RD 223/2008, ITC-LAT 07, sub-clause 3.1.1

Vertical loads on account of own weight of each element shall be taken into account: conductors,
insulators, fittings, ground wires – if they exist –, poles and foundations.

4.3 Wind loads
4.3.1 Field of application and basic wind velocity

(A-dev) ES.1 RD 223/2008, ITC-LAT 07, sub-clause 3.1.2

A minimum reference wind velocity of 120 km/h (33.3 m/s) shall be considered, except in lines with
voltages of 220 kV and above, or lower voltages which are considered part of the transmission grid,
in which a minimum reference wind velocity of 140 km/h (38.89 m/s) shall be considered.

This reference wind velocity (VV) shall mean horizontal, acting perpendicular to the areas
concerned.
4.3.5 Wind forces on any overhead line component

(A-dev) ES.1 RD 223/2008, ITC-LAT 07, sub-clause 3.1.2.4

, shall be at least:
In the case of a flat surface, the wind force, QWx

V
 
V
Q = 100⋅ ⋅ A daN
 
Wx x
 
Where:
V is the reference wind velocity in km/h.
V
A is the area of the flat surface projected in a perpendicular plane to the wind direction, in
x
m
(A-dev) ES.2 RD 223/2008, ITC-LAT 07, sub-clause 3.1.2.5

In the case of a cylindrical surface, the wind force, QWx, shall be, at least:

V
 
V
Q = 70⋅ ⋅ A daN
 
Wx x
 
Spain - 9 - EN 50341-2-6:2017
Where:
V is the reference wind velocity in km/h.
V
A is the area of the cylindrical surface projected in a perpendicular plane to the wind
x
direction, in m
(A-dev) ES.3 RD 223/2008, ITC-LAT 07, sub-clause 3.1.2.1

The wind force over conductors in a suspension pole, in the transversal direction of the line, for
each conductor of the bundle shall be, at least, the following:

QWc_V = qp · d · (L1 + L2) / 2 daN

Where:
q is the wind pressure, with the following value:
p
V 

V
= 60⋅ daN/m for conductors d ≤ 16 mm
 
 
V
 
V
= 50⋅ daN/m for conductors d > 16 mm
 
 
V is the reference wind velocity in km/h.
V
d is the conductor or sub-conductor diameter, in m. In the case of combined wind and ice
load, the thickness of the ice shall be considered, for which a reference value of 7.500
N/m is recommended for the specific volumetric weight of ice.
L , L are the lengths of the adjacent spans, in m.
1 2
Any possible shade effects between conductors, even in the case of phase bundle conductors,
shall be neglected.
For the wind forces over poles with angle, the influence of the direction change and the lengths of
the adjacent spans shall be taken into account.

(A-dev) ES.4 RD 223/2008, ITC-LAT 07, sub-clause 3.1.2.2

The wind forces over the insulator sets shall be taken into account. The force value shall be, at
least, the following:
V
 
V
Q = 70⋅ ⋅ A daN
 
Wins ins
 
Where:
V is the reference wind velocity in km/h.
V
A is the area of the insulator set projected horizontally in a vertical plane parallel to the axis
ins
of the insulator set.
(A-dev) ES.5 RD 223/2008, ITC-LAT 07, sub-clause 3.1.2.3

The total force value of the wind over a lattice tower shall be, at least, the following:

V
 
V
Q = 170⋅ ⋅ A daN
 
Wt T
 
Where:
V is the reference wind velocity in km/h.
V
A is the area of the tower projected in a perpendicular plane to the wind direction, in m
T
4.4 Wind forces on overhead line components

(snc) ES.1 Wind forces on overhead line components

Due to the use in Spain of an alternative method to define the wind forces on overhead line
components (Approach 3), the structural factors described in sub-clause 4.4 are not applicable.

4.5 Ice loads
4.5.2 Ice forces on conductors

(A-dev) ES.1 RD 223/2008, ITC-LAT 07, sub-clause 3.1.3

In Spain the ice load per length of the conductor, I (in daN per linear metre), shall be, at least:

• In zones with an altitude over the sea up to 500 m, I = 0
• In zones with an altitude over the sea between 500 and 1.000 m, I = 1,8 √𝑑𝑑
• In zones with an altitude over the sea higher than 1.000 m, I = 3, 6 𝑑𝑑
√
Where:
d is the conductor diameter, in mm.

4.7 Temperature effects
(A-dev) ES.1 RD 223/2008, ITC-LAT 07, sub-clause 3.2.1

In Spain, the following design situations shall be taken into account:

a) Minimum temperature, without other climatic action:
Not relevant.
b) Extreme wind velocity at next temperature:
• In zones with an altitude over the sea less than 500 m, T = -5 ºC
• In zones with an altitude over the sea between 500 and 1.000 m , T = -10 ºC
• In zones with an altitude over the sea more than 1.000 m, T = -15 ºC

c) Minimum temperature combined with a reduced wind velocity:
Not relevant.
d) Ice load at next temperature:
• In zones with an altitude over the sea between 500 and 1.000 m , T = -15 ºC
• In zones with an altitude over the sea more than 1.000 m, T = -20 ºC

e) Ice load combined with a reference wind velocity of, at least, 60 km/h, at next temperature:
• In zones with an altitude over the sea between 500 and 1.000 m , T = -15 ºC
• In zones with an altitude over the sea more than 1.000 m, T = -20 ºC
This situation shall only be taken into account in overhead lines with voltages of 220 kV and
above, or lines with less voltage that belong to the transmission grid.

4.8 Security loads
4.8.1 General
(snc) ES.1 General
The security loads shall be taken into account in Spain for lines of nominal voltage up to 45 kV.

Spain - 11 - EN 50341-2-6:2017

4.8.2 Torsional loads
(A-dev) ES.1 RD 223/2008, ITC-LAT 07, sub-clause 3.1.5

The breakage of (one or more) conductors of a single phase or ground wire shall be taken into
account. This load shall be applied in a point producing the most unfavourable situation for any
element of the pole, taking into account the torsion produced in the case this load is eccentric. In
poles placed in a point in which the trace of the line suffers a direction change, the resultant load
due to the tension angle of conductors and ground wires shall be additionally taken into account.

• Conductor breakage in poles with suspension sets.
One sided load shall be taken into account, corresponding to the breakage of just one
conductor or ground wire.
This load could be reduced by special devices adopted to this purpose and due to the deviation
of the suspension insulator set, but in this last case the minimum value to take into account
shall be 50% of the broken conductor tension with one or two conductors per phase, the 75% of
the broken conductor tension with three conductors per phase and 100% of the broken
conductor tension in lines with four or more conductors per phase.
• Conductor breakage in poles with strain sets.
One sided load shall be taken into account, corresponding to the breakage of just one
conductor or ground wire without any reduction of its tension.
• Conductor breakage in anchor poles.
The load corresponding to the breakage of a ground wire or conductor shall be taken into
account in lines with one conductor per phase, with no reduction of its tension and, in lines with
bundles the breakage of a ground wire or all the conductors of the bundle, but supposed those
with a 50% tension reduction, without any other reduction.
• Conductor breakage in dead end poles.
The load corresponding to the breakage of a ground wire or conductor shall be taken into
account in lines with one conductor per phase and in lines with bundles the breakage of a
ground wire or all the conductors of the bundle. In both cases without any reduction of its
tension.
• Conductor breakage in special poles.
It shall be considered depending on the purpose of each circuit installed in the pole, considering
the load producing the most unfavourable situation for any element of the pole.

4.8.3 Longitudinal loads
(A-dev) ES.1 RD 223/2008, ITC-LAT 07, sub-clause 3.1.4

The unbalanced loads to be considered are applied in the conductor and ground wire attach point
and shall take into account, therefore, the torsional loads that could be produced.

In poles placed in a point in which the trace of the line suffers a direction change, in addition, the
resultant load due to the tension angle of conductors and ground wires shall be taken into account.

• Unbalance in poles with suspension sets.
For lines with nominal voltage over 66 kV a longitudinal load equivalent to 15% the one sided
tension of all conductors and ground wires shall be considered.
For lines with nominal voltage up to and 66 kV a longitudinal load equivalent to 8% the one
sided tension of all conductors and ground wires shall be considered. This load may be
considered spread out in the axis of the pole at the height of the attach points of conductors and
ground wires.
• Unbalance in poles with strain sets.
For lines with nominal voltage over 66 kV a longitudinal load equivalent to 25% the one sided
tension of all conductors and ground wires shall be considered.
For lines with nominal voltage up to and 66 kV a longitudinal load equivalent to 15% the one
sided tension of all conductors and ground wires shall be considered. This load may be
considered spread out in the axis of the pole at the height of the attach points of conductors and
ground wires.
• Unbalance in anchor poles.
A longitudinal load equivalent to 50% the one sided tension of all conductors and ground wires
shall be considered.
For lines with nominal voltage up to and 66 kV, this load may be considered spread out in the
axis of the pole at the height of the attach points of conductors and ground wires.
• Unbalance in dead end poles.
A longitudinal load equivalent to 100% the one sided tension of all conductors and ground wires
shall be considered.
• Very pronounced unbalance in poles.
In poles of any type which have a pronounced unbalance load of adjacent spans, the conductor
tension unbalance shall be analysed in the most unfavourable situations of them. If the result of
this analysis is more unfavourable than the values fixed previously, the resulting values shall
apply.
• Unbalance in special poles.
In case of special poles, the designer shall assess the most unfavourable unbalance load which
the conductors and ground wires can produce over the pole, taking into account the purpose of
each of those circuits. This load shall be applied in the point producing the most unfavourable
situation for any element of the pole.

4.12 Load cases
4.12.1 General
(A-dev) ES.1 RD 223/2008, ITC-LAT 07, sub-clause 3.5.3

For lines with nominal voltage over 66 kV, in suspension poles and angle poles with suspension
sets and strain sets with conductors with rated tensile strength less than 6600 daN, the
consideration of torsional loads defined in sub-clause 4.8.2/ES.1 may be neglected when the
following conditions are confirmed simultaneously:

a) Conductors and ground wires have a security factor greater than 3.
b) The security factor of poles and foundations in load case 5b is the correspondent to cases 1a,
2a and 3.
c) Anchor poles are installed every 3 km (maximum).

4.12.2 Standard load cases
(snc) ES.1 Standard load cases

In Spain there are no climatic conditions associated to load cases 2b, 2c and 2d defined in Table
4.6 of the main body. Therefore, reduction factors applied to ice load per length defined in sub-
clause 4.12.2 may have the next values:
α = 1;  α1 = 1;  α2 = 1;  α3 = 1;  α4 = 1

4.13 Partial factors for actions

(A-dev) ES.1 RD 223/2008, ITC-LAT 07, sub-clause 3.5.4

Normal load cases shall be 1a, 2a, 2b, 2c, 2d, 3 and 4 defined in Table 4.6 of the main body.

Abnormal load cases shall be 5a y 5b defined in Table 4.6 of the main body.

The security factor CS of poles shall be, at least, the following:

• Metallic elements: the security factor to the yield stress shall not be less than 1,5 for normal
load cases and 1,2 for abnormal load cases.
• When the mechanical strength of complete poles is verified by a full scale test, the previous
values may be reduced to 1,45 and 1,15 respectively.
• Reinforced concrete elements: The security factor of poles and reinforced concrete elements
shall be the mentioned in standard UNE 207016. In abnormal load cases the security factor
may be reduced 20%.
• Wooden elements: The security factors shall not be less than 3,5 for normal load cases and 2,8
for abnormal load cases.
• Guys: The wires or bars used in guys shall have a security factor not less than 3 for normal load
cases and 2,5 for abnormal load cases.

Spain - 13 - EN 50341-2-6:2017

(A-dev) ES.2 RD 223/2008, ITC-LAT 07, clause 5.3

In some situations such as crossings and parallelisms with other lines or with communication
routes or over urban zones, and with the intention of reducing the probability of accident increasing
the security of the line, the security factors in normal load cases shall be a 25% bigger than the
ones mentioned in clause 4.13/ES.1.

This increase of the security factor is not applicable to lines of 220 kV and above or lower than 220
kV which belong to the transmission grid, because the mechanical strength of poles is determined
taking into account a minimum reference wind velocity of 140 km/h and a combined load case of
ice and wind.
5 Electrical requirements
5.2 Currents
5.2.1 Normal current
(A-dev) ES.1 RD 223/2008, ITC-LAT 07

The maximum current densities under permanent rating conditions shall not exceed the values
indicated in the following table.

If the project includes a study of temperatures attained in the conductors, taking into account
climatological conditions and load line, different values may be acceptable.

Table 5.2.1/ES.1 – Conductor current density

Rated Current density
cross section
2 2
mm Amperes/mm
Copper Aluminium Aluminium alloy

10 8,75 -- --
15 7,60 6,00 5,60
25 6,35 5,00 4,65
35 5,75 4,55 4,25
50 5,10 4,00 3,70
70 4,50 3,55 3,30
95 4,05 3,20 3,00
125 3,70 2,90 2,70
160 3,40 2,70 2,50
200 3,20 2,50 2,30
250 2,90 2,30 2,15
300 2,75 2,15 2,00
400 2,50 1,95 1,80
500 2,30 1,80 1,70
600 2,10 1,65 1,55
The values shown in the previous table refer to materials having the following values of resistivity at
20ºC:
• Copper 0,017241 Ω.mm /m,
• Harden aluminium 0,028264 Ω.mm /m,
• Aluminium alloy 0,03250 Ω.mm /m.

For galvanized steel a resistivity of 0,192 Ω.mm /m may be considered and for aluminium clad
steel 0,0848 Ω.mm /m.
In the case of aluminium-steel cables, the value taken from the table shall be the current density
corresponding to the total cross section, as though it were aluminium, this value then being
multiplied by a reduction coefficient which, depending on composition, will be:

• 0,916 for 30 + 7 composition;
• 0,937 for 6 + 1 and 26 + 7 compositions;
• 0,95 for 54 + 7 composition;
• 0,97 for 45 + 7 composition.

The resulting value will be applied to the entire cross section of the cable.

For aluminium-steel alloy cables, the process is analogous, on the basis of the current density
corresponding to aluminium alloy and using the same reduction coefficients depending on
composition.
For other cable types, the maximum permissible density will be obtained by multiplying the value
shown in the table for the same cross section of copper by a coefficient equal to:

1,724
ρ
Where:
ρ is the resistivity at 20° C of the conductor in question, expressed in microohms/centimetre.

5.3 Insulation co-ordination
(A-dev) ES.1 RD 223/2008, ITC-LAT 07

The insulation coordination comprises the selection of dielectric strength of the materials, taking
into account the voltages that may arise in the grid to which these materials are used in and taking
also into account the ambient conditions and the characteristics of the available protective devices.

The dielectric strength of the materials is here considered in the standard insulation level sense.

The principles and rules of insulation co-ordination are described in EN 60071-1 and EN 60071-2.
The procedure for insulation co-ordination involves the selection of a set of standard withstand
voltages which characterise the insulation.

The minimum standard insulation levels corresponding to the highest voltage of the line, as this
one is defined in clause 5.4, shall be those in Tables 5.3.1/ES.1 and 5.3.2/ES.1.

These tables give the standard withstand voltages for range I and II. In both tables, the standard
withstand voltages are grouped in standard insulation levels associated to the values of the highest
voltage for equipment Um.
In range I, the standard withstand voltages include the power frequency withstand voltages and
fast front withstand voltages. In range II, the standard withstand voltages include the low front
withstand voltages and the fast front withstand voltages.

For other values of the highest voltage not included in the table, standards EN 60071-1 and EN
60071-2 shall be used.
In the case of design lines with a voltage higher than the ones included in these tables, in order to
determine the insulation levels, standards EN 60071-1 and EN 60071-2 shall be used.

Spain - 15 - EN 50341-2-6:2017

Table 5.3.1/ES.1 – Standard insulation levels for range I
(1 kV < Um ≤ 245 kV)
Highest voltage for Standard power frequency Standard fast front withstand
equipment withstand voltage voltage
Um kV kV
kV (effective) (peak)
(effective)
3,6 10
7,2 20
12 28 75
17,5 38
24 50 125
36 70
52 95 250
72,5 140 325
(185) 450
230 550
(185) (450)
145 230 550
275 650
(230) (550)
170 275 650
325 750
(275) (650)
(325) (750)
245 360 850
395 950
460 1050
Note: If the values between brackets are not enough to probe the specific withstand voltages between phases are fulfilled,
more additional withstand voltages between phases tests are required.

Table 5.3.2/ES.1 – Standard insulation levels for range II
(Um > 245 kV)
Standard slow front withstand voltage Standard fast front

Highest voltage for withstand voltage
equipment kV
(
...