SIST EN 50443:2012

Effects of electromagnetic interference on pipelines caused by high voltage a.c. electric traction systems and/or high voltage a.c. power supply systems

The presence of ac power supply systems or of a.c. electric traction systems (in this standard also indicated as a.c. power systems) may cause voltages to build up in pipeline systems,(in this standard indicated as interfered systems) running in the close vicinity, due to one or more of the following mechanisms:
   inductive coupling,
   conductive coupling,
   capacitive coupling.
Such voltages may cause danger to persons, damage to pipelines or connected equipment or disturbance to the electrical/ electronic equipment connected to the pipeline.
This European Standard deals with the situations where these effects may arise and with the maximum tolerable limits of the interference effects, taking into account the behaviour of the ac power systems both in normal operating condition and/or during faults.
NOTE In the worst case, the pipe may not disperse current to ground. As a consequence, the prospective touch voltage coincides with the interference voltage.
This European Standard applies to all metallic pipelines irrespective of the conveyed fluid, e.g. liquid or gas, liable to be interfered by high voltage a.c. railway and high voltage a.c. power supply systems.
The objective of this standard is to establish:
   the procedure for evaluating the e.m. interference;
   the interference distance to be considered;
   the types of coupling to be considered for operating and fault conditions of the high voltage a.c. electric traction systems and high voltage a.c. power supply systems;
   the configurations to be considered for both metallic pipeline and high voltage a.c. electric traction systems or high voltage a.c. power systems;
   the limits of the voltages due to the electromagnetic interference;
   information on interference situations, calculation methods, measuring methods, mitigation measures, management of interference.
This European Standard is applicable to all new metallic pipelines and all new high voltage a.c. electric traction systems and high voltage a.c. power supply systems and all major modifications that may change significantly the interference effect.
This European Standard only relates to phenomena at the fundamental power frequency (e.g. 50 Hz or 16,7 Hz).
This European Standard does not apply to:
   all aspects of corrosion,
   the coupling from a.c. railway and power supply systems with nominal voltages less than or equal to 1 kV,
   interference effects on the equipment not electrically connected to the pipeline.

Auswirkungen elektromagnetischer Beeinflussungen von Hochspannungswechselstrombahnen und/oder Hochspannungsanlagen auf Rohrleitungen

Effets des perturbations electromagnétiques sur les canalisations causées par les systèmes de traction électrique ferroviaire en courant alternatif et/ou par les réseaux électriques H.T. en courant alternatif

Učinki elektromagnetne interference na cevovode, ki jih povzročajo visokonapetostni sistemi izmeničnega toka električne vleke in/ali visokonapetostni izmenični napajalni sistemi

Prisotnost izmeničnih napajalnih sistemov ali sistemov izmeničnega toka električne vleke (v tem standardu označeni tudi kot »izmenični napajalni sistemi«) lahko povzroči nabiranje napetosti v sistemih cevovodov (v tem standardu označeni kot »interferirani sistemi«), ki potekajo v neposredni bližini, zaradi enega naslednjega mehanizma ali več:
– induktivno sklapljanje,
– konduktivno sklapljanje,
– kapacitivno sklapljanje.
Takšne napetosti lahko ogrožajo osebe, povzročijo škodo na cevovodih ali povezani opremi ali so vzrok motenj električne/elektronske opreme, povezane s cevovodom.
Ta evropski standard obravnava situacije, v katerih lahko takšni učinki nastanejo, ter najvišje sprejemljive meje interferenčnih učinkov z upoštevanjem obnašanja izmeničnih napajalnih sistemov v običajnih delovnih pogojih in/ali med okvarami.
OPOMBA: V najslabšem primeru cev morda ne prevaja toka v tla. Zato pričakovana napetost dotika sovpada z interferenčno napetostjo.
Ta evropski standard velja za vse kovinske cevovode, na katere lahko vplivajo visokonapetostni železniški sistemi izmeničnega toka in visokonapetostni izmenični napajalni sistemi, ne glede na snov, ki jo prenašajo, npr. tekočino ali plin.
Namen tega standarda je vzpostavitev:
– postopka za vrednotenje elektromagnetne interference;
– razdalje interference, ki jo je treba upoštevati;
– tipov sklapljanja, ki jih je treba upoštevati za obratovanje in stanja napak visokonapetostnih sistemov izmeničnega toka električne vleke in visokonapetostnih izmeničnih napajalnih sistemov;
– konfiguracij, ki jih je treba upoštevati pri kovinskih cevovodih in visokonapetostnih sistemih izmeničnega toka električne vleke ali visokonapetostnih izmeničnih napajalnih sistemih;
– omejitev napetosti zaradi elektromagnetne interference;
– informacij o interferenčnih situacijah, metodah za izračun, metodah za merjenje, ukrepih za ublažitev, upravljanju interference.
Ta evropski standard velja za vse nove kovinske cevovode, za vse nove visokonapetostne sisteme izmeničnega toka električne vleke in visokonapetostne izmenične napajalne sisteme ter za vse večje spremembe, ki bi lahko znatno spremenile učinek interference.
Ta evropski standard velja le za pojave pri osnovni obratovalni frekvenci (npr. 50 Hz ali 16,7 Hz).
Ta evropski standard se ne uporablja:
– pri vseh pojavih korozije;
– za sklapljanje iz železniških sistemov izmeničnega toka in izmeničnih napajalnih sistemov z nominalnimi napetostmi, ki so manjše ali enake 1 kV;
– za učinke interference v opremi, ki ni električno povezana s cevovodom.

General Information

• Status: Published
• Publication Date: 22-Dec-2011
• ICS: 23.040.99 - Other pipeline components
• ICS: 29.280 - Electric traction equipment
• Technical Committee: ŽEN - Electrical applications for railways
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 14-Dec-2011
• Due Date: 18-Feb-2012
• Completion Date: 23-Dec-2011
• Ref Project: EN 50443:2011 - Effects of electromagnetic interference on pipelines caused by high voltage a.c. electric traction systems and/or high voltage a.c. power supply systems

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 50443:2012
01-februar-2012
8þLQNLHOHNWURPDJQHWQHLQWHUIHUHQFHQDFHYRYRGHNLMLKSRY]URþDMR
YLVRNRQDSHWRVWQLVLVWHPLL]PHQLþQHJDWRNDHOHNWULþQHYOHNHLQDOLYLVRNRQDSHWRVWQL
L]PHQLþQLQDSDMDOQLVLVWHPL
Effects of electromagnetic interference on pipelines caused by high voltage a.c. electric
traction systems and/or high voltage a.c. power supply systems
Auswirkungen elektromagnetischer Beeinflussungen von
Hochspannungswechselstrombahnen und/oder Hochspannungsanlagen auf
Rohrleitungen
Effets des perturbations electromagnétiques sur les canalisations causées par les
systèmes de traction électrique ferroviaire en courant alternatif et/ou par les réseaux
électriques H.T. en courant alternatif
Ta slovenski standard je istoveten z: EN 50443:2011
ICS:
23.040.99 Drugi sestavni deli za Other pipeline components
cevovode
29.280 (OHNWULþQDYOHþQDRSUHPD Electric traction equipment
SIST EN 50443:2012 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 50443:2012

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SIST EN 50443:2012

EUROPEAN STANDARD
EN 50443

NORME EUROPÉENNE
December 2011
EUROPÄISCHE NORM

ICS 23.040.99; 29.280; 33.100.01


English version


Effects of electromagnetic interference on pipelines caused by high
voltage a.c. electric traction systems and/or high voltage a.c. power
supply systems



Effets des perturbations électromagnétiques sur Auswirkungen elektromagnetischer
les canalisations causées par les systèmes de Beeinflussungen von
traction électrique ferroviaire en courant alternatif Hochspannungswechselstrombahnen und/oder
et/ou par les réseaux électriques H.T. en courant Hochspannungsanlagen auf Rohrleitungen
alternatif






This European Standard was approved by CENELEC on 2011-10-24. 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels


© 2011 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50443:2011 E

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SIST EN 50443:2012
EN 50443:2011 – 2 –
Contents
Foreword . 4
1 Scope. 5
2 Normative references . 5
3 Terms and definitions . 6
4 Procedure . 9
5 Interference distance . 9
5.1 General . 9
5.2 Interference distance for normal operating conditions . 10
5.2.1 overhead a.c. power systems . 10
5.2.2 underground a.c. power systems . 10
5.3 Interference distance for fault condition . 10
5.3.1 General . 10
5.3.2 overhead a.c. power systems . 10
5.3.3 underground a.c. power systems . 10
5.4 Summary of the interference distances . 10
6 Interference situations. 11
7 Coupling types . 11
8 Interference . 12
9 Interference results . 13
10 Limits for permissible interference . 13
10.1 General . 13
10.2 Limits related to electrical safety of persons . 13
10.2.1 General . 13
10.2.2 Operating conditions . 13
10.2.3 Fault conditions . 14
10.3 Limits related to damage to the pipeline system . 14
10.3.1 Fault conditions . 14
10.3.2 Operating conditions . 14
10.4 Limits related to disturbance of the pipeline system . 14
11 Evaluation of the interference results . 14
12 Mitigation measures . 15
Annex A (informative) Indications to select interference situations . 16
Annex B (informative) Guidance for interference investigations . 17
B.1 Introduction . 17
B.2 Configuration of the a.c. electric traction system . 17
B.3 Configuration of the a.c. power supply system . 18
B.4 Configuration of the pipeline . 18
B.5 Calculation methods . 19
B.6 Calculation of independent interfering systems . 20
Annex C (informative) Measuring methods. 21
C.1 General . 21
C.2 Measurement methods for interference voltages at steady state . 21
Annex D (informative) Mitigation measures . 22
D.1 General . 22
D.2 Mitigation measures at the pipeline side . 22
D.3 Mitigation measures at the a.c railway system side . 23
D.4 Mitigation measures at the a.c. power supply system side. 23
Annex E (informative) Management of interference . 24
E.1 General . 24
E.2 Plant life . 24
E.3 Exchange of information . 24
E.4 Plant documentation . 24

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SIST EN 50443:2012
– 3 – EN 50443:2011
Annex F (informative) A-deviations . 26
Bibliography . 27

Tables
Table 1  Interference distances . 11
Table 2  Coupling types and distances to be considered . 12
Table 3  Limits for interference voltage related to danger to (electrically) instructed persons . 14

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SIST EN 50443:2012
EN 50443:2011 – 4 –
Foreword

This document (EN 50443:2011) has been prepared by Technical Committee CLC/TC 9XC "Electric
supply and earthing systems for public transport equipment and ancillary apparatus (Fixed installations)".

This European Standard gives limits relevant to the electromagnetic interference produced by high
voltage a.c. railway and power supply systems on metallic pipelines.
Limits are relevant to the interference which can be tolerated on the metallic pipeline, by the equipment
connected to it and by persons working on them or in contact with them.

This European Standard indicates the electromagnetic interference situations to which the limits must be
related.

Suggestions concerning the interference situations to be examined are given in Annex A. Suggestions
concerning the appropriate calculation methods are given in Annex B. Suggestions concerning the
appropriate measurement methods are given in Annex C. Suggestions about the use of mitigation
measures are given in Annex D. Suggestions for management of interference are given in Annex E.

The following dates are fixed:

– latest date by which the amendment has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2012-10-24

– latest date by which the national standards conflicting
with the amendment have to be withdrawn (dow) 2014-10-24

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent
rights.

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SIST EN 50443:2012
– 5 – EN 50443:2011
1 Scope
The presence of a.c. power supply systems or of a.c. electric traction systems (in this standard also
indicated as a.c. power systems) may cause voltages to build up in pipeline systems, (in this standard
indicated as interfered systems) running in the close vicinity, due to one or more of the following
mechanisms:
− inductive coupling,
− conductive coupling,
− capacitive coupling.

Such voltages may cause danger to persons, damage to pipelines or connected equipment or
disturbance to the electrical/ electronic equipment connected to the pipeline.

This European Standard deals with the situations where these effects may arise and with the maximum
tolerable limits of the interference effects, taking into account the behaviour of the a.c power systems
both in normal operating condition and/or during faults.

NOTE In the worst case, the pipe may not disperse current to ground. As a consequence, the prospective touch voltage
coincides with the interference voltage.

This European Standard applies to all metallic pipelines irrespective of the conveyed fluid, e.g. liquid or
gas, liable to be interfered by high voltage a.c. railway and high voltage a.c. power supply systems.

The objective of this standard is to establish:
− the procedure for evaluating the electromagnetic interference;
− the interference distance to be considered;
− the types of coupling to be considered for operating and fault conditions of the high voltage a.c.
electric traction systems and high voltage a.c. power supply systems;
− the configurations to be considered for both metallic pipeline and high voltage a.c. electric traction
systems or high voltage a.c. power systems;
− the limits of the voltages due to the electromagnetic interference;
− information on interference situations, calculation methods, measuring methods, mitigation measures,
management of interference.

This European Standard is applicable to all new metallic pipelines and all new high voltage a.c. electric
traction systems and high voltage a.c. power supply systems and all major modifications that may change
significantly the interference effect.

This European Standard only relates to phenomena at the fundamental power frequency (e.g. 50 Hz or
16,7 Hz).

This European Standard does not apply to:
− all aspects of corrosion,
− the coupling from a.c. railway and power supply systems with nominal voltages less than or equal to
1 kV,
− interference effects on the equipment not electrically connected to the pipeline.

2 Normative references
The following referenced documents 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.

IEC 60050-161, International Electrotechnical Vocabulary  Chapter 161: Electromagnetic
compatibility

IEC 60050-195, International Electrotechnical Vocabulary  Part 195: Earthing and protection
against electric shock

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SIST EN 50443:2012
EN 50443:2011 – 6 –

IEC 60050-826, International Electrotechnical Vocabulary  Part 826: Electrical installations

3 Terms and definitions
For the purposes of this document, the terms and definitions given in the International Electrotechnical
Vocabulary (IEV) apply, unless they are defined in this European Standard:

3.1
a.c. electric traction system
a.c. railway electrical distribution network used to provide energy for rolling stock
NOTE The system may comprise:
- contact line systems,
- return circuit of electric railway systems,
- running rails of non-electric railway systems, which are in the vicinity of, and conductively connected to the running rails of an
electric railway system.

3.2
a.c power supply system
a.c. electrical system devoted to electrical energy transmission and including overhead lines, cables,
substations and all apparatus associated with them
NOTE This includes HV transmission lines with 16,7 Hz.

3.3
a.c. power system
a.c. electric traction system or a.c. power supply system
NOTE Where it is necessary to differentiate, each interfering system is clearly indicated with its proper term.

3.4
interfering system
general expression encompassing an interfering high voltage a.c. electric traction system and/or high
voltage a.c. power supply system

3.5
interfered system
system on which the interference effects appear
NOTE In this standard pipeline system.

3.6
pipeline system
system of pipe network with all associated equipment and stations
NOTE 1 In this standard pipeline system refers only to metallic pipeline system.
NOTE 2 The associated equipment is the equipment electrically connected to the pipeline.

3.7
earth
conductive mass of the earth, whose electric potential at any point is conventionally taken as equal to
zero
[IEC 60050-826-04-01]

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SIST EN 50443:2012
– 7 – EN 50443:2011
3.8
operating condition
fault free operation of any system
NOTE Transients are not to be considered as an operating condition.

3.9
fault condition
non intended condition caused by short-circuit to earth, the fault duration being the normal clearing time
of the protection devices and switches
NOTE The short circuit is an unintentional connection of an energized conductor to earth or to any metallic part in contact with
earth.

3.10
conductive coupling
coupling which occurs when a part of the current belonging to the interfering system returns to the system
earth via the interfered system or when the voltage to the reference earth of the ground in the vicinity of
the influenced object rises because of a fault in the interfering system, and the results of which are
conductive voltages and currents

3.11
inductive coupling
phenomenon whereby the magnetic field produced by a current carrying circuit influences another circuit;
the coupling being quantified by the mutual impedance of the two circuits, and the results of which are
induced voltages and hence currents that depend for example on the distances, length, inducing current,
circuit arrangement and frequency

3.12
capacitive coupling
phenomenon whereby the electric field produced by an energized conductor influences another
conductor, the coupling being quantified by the capacitance between the conductors and the
capacitances between each conductor and earth, and the results of which are interference voltages into
conductive parts or conductors insulated from earth, these voltages depending for example on the
voltage of the influencing system, distances and circuit arrangement

3.13
interference
phenomenon resulting from conductive, capacitive, inductive coupling between systems, and which can
cause malfunction, disturbance, danger, damage, etc.

3.14
disturbance
malfunction of an equipment loosing its capability of working properly for the duration of the interference
NOTE When the interference disappears, the interfered system starts again working properly without any external intervention.

3.15
damage
permanent reduction in the quality of service which can be offered by the interfered system
NOTE 1 Examples of damages are: coating perforation, pipe pitting, pipe perforation, permanent malfunction of the equipment
connected to the pipes, etc.
NOTE 2 A reduction in the quality of service may be also the complete cancellation of service.

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SIST EN 50443:2012
EN 50443:2011 – 8 –
3.16
interference situation
situation in which an interference may appear (permanently or intermittently) between an a.c. power
system and a metallic pipeline system, a given interference situation being defined by the geometrical
and electrical data of the a.c. power system and of the metallic pipeline system as well as defined by the
data describing the medium between the two systems
NOTE An interference situation may cause:
− danger to persons;
− damage to the pipeline and/or to the connected equipment;
− disturbance of the electrical and/or electronic equipment connected to the pipeline.

3.17
interference distance
maximum distance between the pipeline system and a.c. power system for which an interference shall be
considered

3.18
interfering current
vectorial sum of the currents flowing through the conductors relevant to the a.c. power system (i.e.
catenaries, feeders, return conductors, phase conductors, earth wires)
NOTE This interfering current is used to simplify the calculations when the distances between the interfering system and the
interfered system is high as compared to the distances between the conductors of the interfering system.

3.19
interference voltage
voltage caused on the interfered system by the conductive, inductive and capacitive coupling with the
nearby interfering system between a given point and the earth or across an insulating joint

3.20
prospective touch voltage
voltage between simultaneously accessible conductive parts when those conductive parts are not being
touched by a person or an animal
NOTE In the case dealt in this standard the prospective touch voltage coincides with the interference voltage. This is due to the
fact that in the worst case the interfered pipe may not disperse current to ground.
[IEC 60050-195-05-09]
3.21
skilled person
person with relevant education and experience to enable him or her to perceive risks and to avoid
hazards which electricity can create
[IEC 60050-195-04-01]

3.22
(electrically) instructed person
person adequately advised or supervised by electrically skilled persons to enable him or her to perceive
risks and to avoid hazards which electricity can create
[IEC 60050-195-04-02]
3.23
immunity
ability of a device, equipment or system to perform without degradation in the presence of an
electromagnetic disturbance
[IEC 60050-161]

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SIST EN 50443:2012
– 9 – EN 50443:2011
3.24
environmental reduction factor
factor which represents the reduction of interference voltage associated with the presence of extended
earthed extraneous metallic structures
NOTE The value of the environmental reduction factor depends on many parameters (e.g. impedance of the circuit made of the
structure and the earth).

3.25
reduction factor
factor which represents the reduction of interference voltage associated with the presence of the current
flowing through the tracks, the return conductors, the cable shields, the shield wires, etc.

3.26
rural area
area which has a low density of local metallic structures in direct electrical contact with the soil

3.27
urban area
area which contains a high density of local metallic structures in direct electrical contact with the soil such
as water pipes, cables with bare metal sheaths, railway tracks, earthing structures of buildings, masts
and foundations

4 Procedure
In order to evaluate the acceptability of an interference produced by an a.c. power system on a metallic
pipeline system, the following design steps apply:
a) define the interference distance to be considered, according to Clause 5;
b) define the interference situations to be examined (worst cases of interference), according to
Clause 6;
c) select the involved coupling type(s) to be considered, according to Clause 7;
d) select the involved interference effect(s) to be considered, according to Clause 8;
e) assess the interference result(s) for each effect selected in the previous step, according to Clause 9;
f) select the acceptable limit for each of the results assessed in the previous step, according to
Clause 10;
g) determine the interference results on the metallic pipeline system by calculation or measurement,
according to Clause 11;
h) compare the interference results with the relevant limits; if the comparison shows that the
interference situation is unacceptable, mitigation measures shall be applied, according to Clause 12.

The procedure shall be carried out twice, i.e. considering short term interference (due to a.c. power
system in fault conditions) and long term interference (due to a.c. power system in operating conditions).

The design steps shall be supported and agreed by the involved parties.

5 Interference distance
5.1 General
The a.c. power systems located at a distance less than or equal to the interference distance from a given
metallic pipeline system shall be considered as interfering systems for this pipeline system.

The objective of interference distance is to limit the number of interfering systems to be considered and
for which assessing the interfering currents/voltages is necessary.

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SIST EN 50443:2012
EN 50443:2011 – 10 –

National rules, recommendations and guidelines determining other interference distances may be
applied.

NOTE 1 An alternative method for evaluating the interfering distances is presented in Annex A of Recommendation
ITU-T K.68:2008.
NOTE 2 The soil resistivity to be taken into account in defining the value of the interference distance is the one of the deep layers
of soil (as deep as needed for interference calculations).

5.2 Interference distance for normal operating conditions
5.2.1 overhead a.c. power systems
In rural areas, for soil resistivity below 3 000 Ωm, an interference distance of 1 000 m between the
interfering system and the metallic pipeline system should be considered. In case of soil resistivity value
greater than 3 000 Ωm, the interference distance value, in metres, should be equal to the soil resistivity
value, in Ωm, divided by 3.

In urban areas, the previous interference distance may be decreased, taking into account the
environmental reducing factor of the metallic structures existing in these areas. The interference distance
should not be less than 300 m.

NOTE Typical values for the environmental reducing factor are 0,1 to 0,7 (see ITU-T K.68:2008, Appendix II).

5.2.2 underground a.c. power systems
For underground a.c. power systems the interference distance should be 50 m.

5.3 Interference distance for fault condition
5.3.1 General
For a.c. power supply systems, the hereunder distances apply in the case of neutral solidly earthed or
earthed through small impedance.

The fault current values associated with insulating and resonant earthed systems are low and do not
result in danger or in significant risk of damage or disturbance and calculations or measurements are only
required when interference occurs.

5.3.2 overhead a.c. power systems
In rural areas, for soil resistivity below 3 000 Ωm, an interference distance of 3 000 m between the
interfering system and the metallic pipeline system should be considered. In case of soil resistivity value
greater than 3 000 Ωm, the interference distance value, in metres, should be equal to the soil resistivity
value in Ωm.

In urban areas, for soil resistivity below 3 000 Ωm, the interference distance should not be less than
300 m. For soil resistivity greater than 3 000 Ωm the interference distance, in metres, should be equal to
the soil resistivity value, in Ωm, divided by 10.

5.3.3 underground a.c. power systems
For underground a.c. power systems the interference distance should be 50 m.

5.4 Summary of the interference distances
Table 1 summarises the above statements.

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SIST EN 50443:2012
– 11 – EN 50443:2011
Table 1  Interference distances
a
Interference distance
ρρρρ
Type of a.c. power
m
Areas
systems
Ω m
Normal operation Fault condition
> 3 000
ρ/3 ρ
overhead Rural
≤ 3 000 1 000 3 000
> 3 000
ρ/10
overhead Urban
≥ 300
≤ 3 000
≥ 300
underground all all 50 50
a
National rules, recommendations and guidelines determining other interference distances may be applied.

6 Interference situations
When dealing with a metallic pipeline system interfered by an a.c. power system, only interferences
below the limits indicated in chapter 10 are acceptable.

In general, several interference situations within the interference distance should be investigated, in order
to be sure that all the possible unacceptable interferences, if any, are turned into acceptable ones, by
adopting suitable mitigation measures as indicated in Annex D.

In Annex A suggestions are given on how to select the set of interference situations to be investigated.
Some suggestions about configuration and input data are given in informa
...