EN 50562:2018

SLOVENSKI STANDARD
01-september-2018
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SIST-TS CLC/TS 50562:2011
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Railway applications - Fixed installations - Process, protective measures and
demonstration of safety for electric traction systems
Bahnanwendungen - Ortsfeste Anlagen - Prozess, Schutzmaßnahmen und
Nachweisführung für die Sicherheit in der Bahnstromversorgung
Applications ferroviaires - Installations fixes - Processus, mesures de prévention et
démonstration de la sécurité pour les installations fixes de traction électrique
Ta slovenski standard je istoveten z: EN 50562:2018
ICS:
29.280 (OHNWULþQDYOHþQDRSUHPD Electric traction equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 50562
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2018
ICS 29.280 Supersedes CLC/TS 50562:2011
English Version
Railway applications - Fixed installations - Process, protective
measures and demonstration of safety for electric traction
systems
Applications ferroviaires - Installations fixes - Processus, Bahnanwendungen - Ortsfeste Anlagen - Prozess,
mesures de prévention et démonstration de la sécurité pour Schutzmaßnahmen und Nachweisführung für die Sicherheit
les installations fixes de traction électrique für elektrische Bahnanlagen
This European Standard was approved by CENELEC on 2017-08-21. 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, 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: Rue de la Science 23, B-1040 Brussels
© 2018 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 50562:2018 E
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Abbreviations. 11
5 Risk assessment process . 12
5.1 General. 12
5.2 System definition . 13
5.3 Identification of additional hazards for the system under consideration . 14
5.4 Risk assessment . 16
5.5 Demonstration of safety . 17
6 Definition of the generic reference system of an electric traction system . 18
6.1 General. 18
6.2 Electric traction system . 18
6.3 Substations and switching stations . 19
6.4 Contact line system . 22
6.5 Return circuit . 22
6.6 Interfaces to the electric traction system . 23
6.7 Interfaces to substations and switching stations . 24
6.8 Interfaces to contact line system . 25
6.9 Interfaces to return circuit. 26
7 Protective measures of the generic electric traction system . 27
7.1 General. 27
7.2 General protective measures . 27
7.3 Substations and switching stations . 29
7.4 Contact line system . 30
7.5 Return circuit . 31
Annex A (informative) Explanation of the risk assessment process for the generic reference
system . 32
Annex B (informative) Documents related to EN 50562 . 52
Annex C (informative) Combination of risk acceptance principles . 58
Annex D (informative) Guidance on software for safety functions on system level . 60
Annex ZZ (informative) Relationship between this European standard and the essential
requirements of EU Directive 2008/57/EC [2008 OJ L191] aimed to be covered . 62
Bibliography . 63

European foreword
This document (EN 50562:2018) has been prepared by CLC/SC 9XC “Electric supply and earthing
systems for public transport equipment and ancillary apparatus (Fixed installations)”.
The following dates are fixed:
• latest date by which this document has to be (dop) 2018-07-26
implemented at national level by publication of
an identical national standard or by
endorsement
• latest date by which the national standards (dow) 2021-01-26
conflicting with this document have to
be withdrawn
This document supersedes CLC/TS 50562:2011.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a mandate given to CENELEC by the European Commission
and the European Free Trade Association, and supports essential requirements of EU Directive(s).
For the relationship with EU Directive(s) see informative Annex ZZ, which is an integral part of this
document.
Introduction
This European Standard provides a code of practice (CoP) for the process, protective measures and
demonstration of safety for the conventional electric traction systems which supports the application of
EN 50126. Within this standard “safety” is used with respect to harm to people and environment. Safety in
terms of harm to assets is covered in the relevant product and application standards.
This standard includes a systems description for the generic reference system for a conventional electric
traction system (refer to Figure 3) and the related subsystems. The interfaces with respect to safety at the
system borders and the respective aspects to be coordinated are described. Based on the list of top-level
hazards and endangered groups protective measures for risk mitigation and hazard control are derived
and indications for the verification and validation procedures are given. The list of standards given in
Annex B can serve as a reference.
During the preparation of this European Standard it became obvious, that the risks associated with
conventional electric traction systems are broadly accepted. This conclusion is based on long term
experience from several European railways. The technical systems used by these European railways in
their conventional electric traction systems are equivalent to the generic reference system described in
this standard. Confidential field data that were taken into account represent more than 1 200 000 year km
operational experience. To exemplify, the equivalent would be a network size of about 80 000 km and the
operational experience laid down in traceable field data would cover a period of 15 years of service. No
fatality was reported caused by a product property or a failure of a specified function of the conventional
electric traction systems.
This standard has been developed specifically to support the realization of EN 50126 within the context of
safety for electric traction systems. It provides generic building blocks which assists the fulfilment of the
requirements of life cycle steps given in EN 50126. Product and application standards are traditionally
applied in fixed installations to ensure safety and performance in terms of e.g. reliability and cost
efficiency. Within this standard the link between existing product and application standards, technical
specification for interoperability and EN 50126 is given.
This standard complies with the principles of the life cycle modelling according to EN 50126 by tailoring
the risk assessment process. This means that this standard encompasses the entire safety process
ranging from the system description, hazards identification to the verification and validation of the
implemented protective measures according to EN 50126 and it is not just a summation of product and
application standards.
This standard has been developed so that it can also be used for assessing risks arising from technical
changes within the legal framework of the European Union.
This standard also supports the decision making regarding the assessment of changes, e.g. with respect
to the significance of changes in technologies. It includes in particular the risk acceptance principle
regarding the application of codes of practice. It also supports the application of the risk acceptance
principles similar reference systems and explicit risk estimation for electric traction systems in the
framework of EN 50126.
When applying TSIs, e.g. TSI Energy, this standard supports the demonstration of the inherent safety of
the conventional electric traction system and supports the safe integration at overall system level.
Amongst others this standard can be used as a code of practice for conventional electric traction
systems. This does not exclude consideration of other codes of practice even from other fields of
application.
The interrelation between the legal framework, the standards traditionally applied and the set of standards
confined to safety is shown in Figure 1.
Figure 1 — Interrelationship between standards and the legal framework
1 Scope
This European Standard defines the process, protective measures and demonstration of safety in
accordance with EN 50126 for conventional electric traction systems for railways. This standard can also
be applied to guided mass transport systems and trolleybus systems. All these systems can be elevated,
at-grade and underground.
Other systems including those listed below were not assessed and therefore are outside the scope of this
European Standard:
– underground mine traction systems,
– cranes, transportable platforms and similar transportation equipment on rails, temporary structures
(e.g. exhibition structures) in so far as these are not supplied directly or via transformers from the
contact line system and are not endangered by the traction power supply system,
– suspended cable cars,
– funicular railways,
– magnetic levitated systems,
– railways with inductive power with inductive contactless transmission of the energy from the electric
traction power supply system to the electrically powered traction unit,
– railways with buried contact line system that is required to be energised only below the train to
ensure safety,
For similar technology and similar hazardous scenarios, the safety considerations of this standard can be
used as a guideline. This European Standard applies to conventional electric traction systems, which are
new or are undergoing major changes.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document including any amendments applies.
EN 50110 (series), Operation of electrical installations
EN 50119, Railway applications - Fixed installations - Electric traction overhead contact lines
EN 50122 (series), Railway applications – Fixed installations – Electrical safety, earthing and the return
circuit
EN 50123 (series), Railway applications – Fixed installations – DC switchgear
EN 50124 (series), Railway applications – Insulation coordination
EN 50126 (series), Railway applications – The specification and demonstration of Reliability, Availability,
Maintainability and Safety (RAMS)
EN 50152 (series), Railway applications – Fixed installations – Particular requirements for AC switchgear
EN 50153, Railway applications - Rolling stock - Protective provisions relating to electrical hazards
EN 50163, Railway applications - Supply voltages of traction systems
EN 50388, Railway Applications - Power supply and rolling stock - Technical criteria for the coordination
between power supply (substation) and rolling stock to achieve interoperability
EN 50633, Railway applications - Fixed installations - Protection principles for AC and DC electric traction
systems
CLC/TR 50488, Railway applications - Safety measures for the personnel working on or near overhead
contact lines
EN 60255 (series), Measuring relays and protection equipment (IEC 60255)
EN 61508 (series), Functional safety of electrical/electronic/programmable electronic safety-related
systems (IEC 61508)
EN 62305 (series), Protection against lightning (IEC 62305)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
contact line system
support system and contact line supplying electric energy to vehicles through current collecting
equipment
Note 1 to entry: The contact line system can comprise.
- the contact line,
- masts and foundations,
- supports and any components registering the conductors,
- cross-spans or cables,
- tensioners,
- other along track conductors such as feeders, earth wires and return conductors when supported from the same
masts as the contact line,
- conductors connected permanently to the contact line for supplying other electrical equipment such as lighting,
signal operation, point control and point heating.
[SOURCE: IEC 60050-811:2017, 811-33-59]
3.2
conventional electric traction system
electric traction system constructed, operated and maintained according to relevant standards and
common practice
3.3
current collector zone
CCZ
zone whose limits are in general not exceeded by an energized collector no longer in contact with the
contact line or broken collector and its fragments
[SOURCE: EN 50122-1:2011, 3.5.10]
3.4
effective touch voltage
U
te
voltage between conductive parts when touched simultaneously by a person or an animal
Note 1 to entry: The value of the effective touch voltage can be appreciably influenced by the impedance of the
person or the animal in electric contact with these conductive parts.
Note 2 to entry: The conductive path through the body is conventionally from hand to both feet (horizontal distance of
1 m) or from hand to hand.
[SOURCE: IEC 60050-195:1998, 195-05-11, modified - “(effective)” replaced with “effective”, Note 2 to
entry has been added.]
3.5
electric safety
freedom from unacceptable risk of harm caused by electrical systems
[SOURCE: EN 50122-1:2011, 3.1.1]
3.6
electric shock
physiological effect resulting from an electric current passing through a human or animal body
[SOURCE: IEC 60050-195:1998, 195-01-04]
3.7
electric traction system
railway electric distribution network used to provide energy for rolling stock
Note 1 to entry: The system includes
– contact line systems,
– return circuit of electric traction systems,
– running rails of non-electric traction systems, which are in the vicinity of, and conductively connected to the running
rails of an electric traction system,
– electric installations, which are supplied from contact lines either directly or via a transformer,
– electric installations in power plants and substations, which are utilized solely for generation and distribution of
power directly to the contact line,
– electric installations of switching stations.
[SOURCE: IEC 60050-811:2017, 811-36-21]
3.8
hazard
potential source of harm
Note 1 to entry: The In English, the term “hazard” can be qualified in order to define the origin of the hazard or the
nature of the expected harm (e.g. “electric shock hazard”, “crushing hazard”, “cutting hazard”, “toxic hazard”, “fire
hazard”, “drowning hazard”).
Note 2 to entry: In French, the synonym “risque” is used together with a qualifier or a complement to define the origin
of the hazard or the nature of the expected harm (e.g. “risque de choc électrique”, “risque d'écrasement”, “risque de
coupure”, “risque toxique”, “risque d'incendie”, “risque de noyade”).
Note 3 to entry: In French, the term “risque” also denotes the combination of the probability of occurrence of harm
and the severity of that harm, in English “risk” (see 903–01–07).
[SOURCE: IEC 60050-903:2013, 903-01-02]
3.9
overhead contact line zone
OCLZ
zone whose limits are in general not exceeded by a broken overhead contact line
[SOURCE: EN 50122-1:2011, 3.5.9]
3.10
protection
provisions for detecting faults or other abnormal operating conditions in a power system, for enabling fault
clearance, for terminating abnormal operating conditions, and for initiating signals or indications
Note 1 to entry: The term “protection” is a generic term for protection equipment or protection systems.
Note 2 to entry: The term “protection” may be used to describe the protection of a complete power system or the
protection of individual plant items in a power system e.g. transformer protection, line protection, generator protection.
Note 3 to entry: Protection does not include items of power system plant provided, for example, to limit overvoltages
on the power system. However, it includes items provided to control the power system voltage or frequency
deviations such as automatic reactor switching, load-shedding, etc.
[SOURCE: IEC 60050-448:1995, 448-11-01, modified – abnormal condition becomes abnormal operating
conditions]
3.11
protective measure
measure intended to achieve adequate risk reduction, implemented:
- by the designer (inherent design, safeguarding and complementary protective measures,
information for use) and
- by the user (organization: safe working procedures, supervision, training; permit-to-work systems;
provision and use of additional safeguards; use of personal protective equipment)
[SOURCE: IEC 60050-903:2013, 903-01-17]
3.12
return cable
conductor connecting the running rails or other parts of the return circuit to the substation
Note 1 to entry: Similar to IEC 60050-811-35–04.
[EN 50122-1:2011, 3.3.5]
3.13
return circuit
all conductors which form the intended path for the traction return current and the current under fault
conditions
Note 1 to entry: The conductors may be for example:
– running rails;
– return conductor rails;
– return conductors;
– return cables.
Note 2 to entry: The definition applies to return currents during operation and fault conditions.
[SOURCE: IEC 60050-811:2017, 811-35-01, modified - Note 2 to entry has been added]
3.14
return conductor
conductor paralleling the track return system and connected to the running rails at periodic intervals
[SOURCE: IEC 60050-811:2017, 811-35-13]
3.15
return conductor rail
conductor rail used instead of the running rail for the traction return currents
[SOURCE: IEC 60050-811:2017, 811-34-10]
3.16
safety
freedom from unacceptable risk
[SOURCE: ISO/IEC Guide 116:2010, 3.16], [SOURCE: IEC 60050-903:2013, 903-01-19]
3.17
switchgear and controlgear
switching devices and their combination with associated control, measuring, protective and regulating
equipment, also assemblies of such devices and equipment with associated interconnections,
accessories, enclosures and supporting structures, intended in principle for use in connection with
generation, transmission, distribution and conversion of electric energy
[SOURCE: IEC 60050-441:2000, 441-11-01]
3.18
system hazard
unintended condition within a technical system which contributes to a top-level hazard
Note 1 to entry: A system hazard can include defects and deficiencies of functions and properties.
3.19
top-level hazard
physical situation that provides a potential source of harm where no further barriers are specified
3.20
track circuit
electrical circuit of which the rails of a track section form a part, with usually a source of current connected
at one end and a detection device at the other end for detecting whether this track section is clear or
occupied by a vehicle
Note 1 to entry: In a continuous signalling system, the track circuit may be used to transmit information between the
ground and the train.
[SOURCE: IEC 60050-821:2017, 821-03-01]
4 Abbreviations
Table 1 — Abbreviations and acronyms
Abbreviation and Explanation
acronym
AC Alternating Current
ACRC Automated Connection to the Return Circuit
CCZ Current Collector Zone
CoP Code of Practice
CSM RA Common Safety Methods - Risk Assessment
DC Direct Current
EMC Electromagnetic Compatibility
ERE Explicit Risk Estimation
HD CEN/CENELEC harmonization document
HMI Human Machine Interface
O&M Operation and Maintenance
OCLZ Overhead Contact Line Zone
OTHERS Other groups of persons besides PAX, PUB and STAFF, such as trespasser,
vandals etc. characteristic: knowing that there are residual risks when entering
the vicinity of tracks, power lines and contact line systems
PAX Passengers of the railway. characteristic: not expecting a risk
PUB General public, e.g. neighbourhood, passer-by, but not passengers.
characteristic: not expecting a risk
SIM Comparison with a similar reference system
S-SIL Software Safety Integrity Level
STAFF Competent persons having the permission for access to and work on railway
assets, e.g. railway personnel, civil workers for railway construction, search
and rescue etc. Characteristic: knowing that there are residual risks when
entering electrical rooms or the vicinity of tracks, power lines and contact line
systems
TLH Top Level Hazard
TSI Technical Specification for Interoperability
T&C Testing and Commissioning
WHO World Health Organization of the United Nations
5 Risk assessment process
5.1 General
Precondition for the application of this European Standard as a code of practice is that the design,
construction, operation and maintenance of electric traction systems follow the relevant standards to
ensure safety. For applications where no specific standards exist, safety shall be established by the
application of the risk acceptance principles 'comparison with a similar reference system' and 'explicit risk
estimation'. If explicit risk estimation is applied the safety process shall follow EN 50126 or EN 61508 or
equivalent.
NOTE The risk assessment process for application of code of practice or comparison with similar reference
system the process is a part of a hazard management process, e.g. with respect to life cycle.
This clause describes how to:
– define the system under consideration and the relevant interfaces,
– apply gap analysis and perform risk assessment,
– apply protective measures,
– demonstrate safety.
Clause 6 of this standard describes an electric traction system that serves as a generic reference system.
When using this standard for the risk acceptance principles application of a code of practice and for the
comparison with a similar reference system the risk assessment shall be focused on the differences of
the reference system and the system under consideration. The reference system can be derived from the
generic reference system defined in Clause 6 or from an existing system that is proven in use and has an
acceptable safety level within a similar conditions and operational context.
In case the generic reference system is chosen, the protective measures (Clause 7) identified shall be
evaluated regarding their applicability for the system under consideration and protective measures for
new hazards shall be added. For other reference systems this applies in analogy but based on the
protective measures of the generic reference system in clause 6 of this standard.
The risk assessment process for an electric traction system is a process tailored from EN 50126 and
consists of the following steps shown in Figure 2.
Figure 2 — Risk assessment process for an electric traction system
5.2 System definition
The system under consideration, operational conditions and procedures, environment and its interfaces
shall be described in a level of detail that enables the analysis to be undertaken. The system may be
structured in subsystems as far as it is necessary. The main functions and components shall be included
in the system definition. Application conditions shall be documented and taken into account.
The system definition of the system under consideration shall be comparable to the system definition of
the reference system. The reference system serves as a bench mark for the system under consideration
in terms of design, operational context, protective measures, environmental conditions etc. The reference
system can be an existing system or the generic reference system described in this standard.
5.3 Identification of additional hazards for the system under consideration
5.3.1 General
The hazard identification for the system under consideration shall be performed and documented.
Annex A can be used as a guideline. Table 2 summarizes the top-level hazards and related foreseeable
accidents of Annex A. If the approach used for the hazard identification of the reference system provides
a complete and detailed analysis, this approach is recommended to be followed in order to ensure
consistency. In all other cases the hazard identification approach provided by this standard shall be used.
5.3.2 New technologies
Solutions using new technologies can introduce specific hazards. The hazards shall be addressed firstly
at the product level and this serves as an input to the system hazard analysis. Where standards for new
technologies exist they are assumed to be applied.
5.3.3 Hazard identification approach
Hazard identification shall be performed following a structured approach and results in a list of system
hazards for the system under consideration in its operational context. The results of the hazard
identification shall be documented, e.g. in a hazard log.
NOTE 1 The content of the hazard log in Annex A provides parts of the requirements of hazard logs, e.g. in
accordance with EN 50126-1:2017, 6.3.3.3, only.
NOTE 2 It is not intended to define a normative structure of the hazard log. The structure of the hazard log can be
chosen according to the project's needs. For orientation an example is given in the informative Annex A.
The hazard identification shall start with the list of top-level hazards set out in Table 2, to ensure that the
basis for the identification of system hazards is comprehensive. All components shall be taken into
account, but components may be grouped, e.g. catenary comprising of contact wire, messenger wire and
droppers, where practicable. The question to be answered is, how the component or set of components
could contribute to a top level hazard. This includes functions and properties, e.g. behaviour in the case
of fire, typical locations and operational situations.
NOTE 3 Figure A.1 in Annex A shows the relation between accidents, top-level hazards and system hazards.
Table 2 — List of top-level hazards and foreseeable accidents
Top-level hazard Foreseeable accident Identification
code of
foreseeable
top-level
hazard
Exposure of persons to situations where Harm due to electric shock TLH 1
they have access to hazardous voltages
Exposure of persons to situations where Harm due to striking / collision TLH 2
they experience relative movement between
objects and persons in direct vicinity
Exposure of persons to unexpected or Harm due to striking / collision with TLH 3
heavy acceleration or deceleration surroundings or due to slipping, tripping
and falling
Exposure of persons to heat source Harm due to arcs, hot surfaces, fire TLH 4
Top-level hazard Foreseeable accident Identification
code of
foreseeable
top-level
hazard
Exposure of persons and the environment to Harm due to smoke, acids, toxic TLH 5
hazardous amount and duration of substances
aggressive or toxic substances (local
regulations)
Exposure of persons to severe pressure Harm due to explosion, overpressure TLH 6
waves
Exposure of persons to hazardous Harm due to electromagnetic fields TLH 7
electromagnetic fields
Exposure of persons to situations where the Harm due to falling parts, trapping, TLH 8
design or condition of equipment is clamping, cutting
inappropriate for nearby persons, e.g. by
sharp edges, slippery surface.
Exposure of persons to excessive sound Harm due to reduction or loss of hearing TLH 9
levels
NOTE 4 At the beginning of the hazard identification it is recommended to agree on terms like hazardous voltage
or excessive sound levels. Standards, related directives or local regulations may be used as reference for the
associated limits.
NOTE 5 For conventional electric traction systems the top-level hazard list is regarded as comprehensive. The
top-level hazard “exposure to radio-active substances or hazardous radiation” can be excluded a priori as in electric
traction system such scenarios do not apply. When using the approach of EN 50562 for other applications, it is
necessary to assess whether additional top-level hazards may be applicable.
The following groups of persons shall be taken into account during the hazard identification:
– PAX
passengers of the railway. Characteristic: awareness of the generic risks but not expecting a risk
originating from an electric traction system;
– STAFF
a person whose duties can require them to be in such proximity to the electric traction system that
danger may arise. Characteristic: awareness of the generic risks to persons originating from an
electric traction system;
NOTE 6 The expression STAFF includes railway staff, contractor's employees, emergency services etc.
– PUB
general public, e.g. neighbourhood, passer-by, level crossing users, but not passengers.
Characteristic: awareness of the generic risks but not expecting a risk originating from an electric
traction system;
– OTHERS
trespasser, vandals etc. This group is not intended to be in a given location, but places themselves at
risk. Characteristic: Most of the group is aware of but disregards or underestimates the risks
originating from an electric traction system when entering the vicinity of tracks, power lines and
contact line systems.
5.3.4 Reference to existing analyses
If the system under consideration or its modification is equivalent to the generic reference system or a
previous system used as reference system, the analyses, e.g. performed according to EN 50562 on the
previous system, may be used as safety argument to avoid repeating analyses without additional
information in terms of risks.
5.4 Risk assessment
5.4.1 General
During risk assessment, the identified system hazards shall be assessed with regard to the foreseeable
accidents and groups at risk. The objective is to decide whether the risk is acceptable or not. The
following aspects shall be considered:
a) consider the extent to which the risk assessment of the reference system is comparable to the
system under consideration and determine if further analysis of these aspects is necessary, and
b) assess any additional hazards which have been identified and are associated with the system under
consideration and analyse them;
c) assess the adequacy of the risk acceptance principles chosen and the effectiveness of the protective
measures to address the identified risks;
d) assess the interfaces and associated aspects. If necessary the interface requirements shall be
agreed between interface partners.
5.4.2 Risk acceptance principles
For each hazard or groups of hazards the decision shall be made which risk acceptance principle:
— application of codes of practice or additional codes of practice;
— similarity analysis with a reference system also from other applications;
— explicit risk estimation.
The risk acceptance principles lead to the identification of protective measures.
5.4.3 Protective measures
Protective measures shall be identified that control the risks to ensure an acceptable risk level.
NOTE In practice most of the protective measures can be taken from Clause 7 of this standard as they are
supplemented by the relevant product and system standards.
5.4.4 Risk assessment for the generic reference system
5.4.4.1 General
The risk assessment for the generic reference system and related subsystems identified in Clause 6 is
based on field data experience. The protective measures in Clause 7 of this standard are supported by
product and application standards which include also requirements for safety and ensure that the related
risks are broadly acceptable. The use of product and application standards and the protective measures
is common practice in all conventional electric traction system for railway applications.
The risk assessment for the generic reference system has been done within the framework of EN 50126.
Under the precondition of the application of the relevant standards the protective measures identified in
EN 50562 Clause 7 are sufficient to demonstrate the compliance with safety requirements and ensure a
broadly acceptable level of safety.
Additionally, components designed, produced, tested and applied according to widely recognized
standards like EN, HD and IEC respectively are regarded as sufficiently safe. No additional safety
analysis on components is required as long as the permissible application conditions and the intended
use are met. The safety margins have already been included in the relevant standards.
The protective measures resulting from this risk assessment are considered to be a code of practice for
the design, operation and maintenance of conventional electric traction systems within the scope of this
standard. The protective measures provide the necessary risk reduction with regard to the hazards
identified.
5.4.4.2 Residual risks
A single component can fail when performing the intended function. In general, a single point failure in a
well-designed system does not cause an incident leading to injuries or fatalities with some exceptions or
limitations. The residual risks are widely accepted because service experience indicates that no fatality
has been reported in large networks over many years of operation due to these exceptions or limitations.
EXAMPLE 1 With a high probability the breakage of a contact line system, e.g. catenary wire, leads to a short
circuit. To ensure this, there are certain requirements regarding earthing and bonding e.g. of adjacent structures like
fences. The short circuit is detected and switched off. The presence of risk during the time between the mechanical
failure and switching off cannot be avoided. There is a small residual risk that the catenary wire breaks undetected
without causing a short circuit.
EXAMPLE 2 A switchgear for feeding the contact line system can fail to switch off a short circuit in its protection
area. The next back up level switchgear will switch off the current, but will need more time. Components like cables or
catenary wires are rated for this scenario; nevertheless, there is a risk that the permissible short-term touch voltages
are not maintainable during those rare and short duration events.
5.5 Demonstration of safety
The demonstration of safety shall document the implementation of the applicable standards and identified
protective measures. As far as applicable it shall be based on the safety demonstration of the reference
system. If there is no safety demonstration of a reference system available it shall include:
a) a statement that EN 50562 has been applied and all requirements have been taken into account;
b) a statement that either
i) the system under consideration is equivalent to the generic reference system as defined in
Clause 6. By this, it is accepted that the same hazards are applicable as identified in this
standard. Or
ii) the system under consideration is similar to a reference system. In case of differences, these
differences shall be described. The results of the process in Clause 5 applied for the differences
shall be documented in the statement.
c) listing of all protective measures in accordance with Clause 7 or the equivalent protective measures
of the reference system that are assessed to be applicable to the system under consideration;
d) selecting and tailoring of the applicable protective measures regarding scope and responsibility of the
entity using this standard including related arguments;
e) listing of all protective measures within the scope and responsibility of the entity using this standard
that were modified including related arguments;
f) documentary evidence or justification providing assurance that the protective measures falling within
the scope of the entity using the standard have been implemented successfully;
g) statement that all protective measures within the scope and responsibility of the entity using this
standard have been implemented successfully. The statement should reference the documented
evidence or arguments;
h) listing of all the remaining protective measures to be transferred as safety related application
conditions to and implemented by another entity responsible for safe integration of the system under
consideration with other subsystems and its placing into operation.
For the documented evidence or arguments, the safety demonstration shall provide the link to the project
documentation. It should not repeat or summarize content. Such project documentation can for example
comprise:
i) engineering input data (environmental conditions and isokeraunic level, field of application etc.);
j) O&M manuals (intended use, instructions for use, basic switching procedures etc.);
k) operational documentation (operator's supplementary documentation to the O&M manuals);
l) drawings;
m) wiring manuals;
n) equipment documentation (equipment drawings, O&M manual, T&C manuals etc.);
o) test reports (routine or factory acceptance tests of equipment, commissioning test reports etc.);
p) studies and calculations (insulation coordination, protection coordination, earthing concept, load flow,
short circuit calculation, dimensioning of components etc.);
The entity applying this standard and completing the set of documents and arguments can declare the
system to be sufficiently safe.
NOTE The demonstration of safety could vary from a simple product certification up to a comprehensive
submission for an overall project.
The documents used for safety demonstration should describe the reasons for or the origin of the
identified protective measures in order to facilitate the assessment of modifications.
6 Definition of the generic reference system of an electric traction system
6.1 General
The following subclauses describe the generic reference system for the application of EN 50562. When
using this standard as a code of practice the system under consideration shall be described in such a way
that the comparison with the reference system is supported. It is recommended using the same structure
of the description for the comparison with similar systems or explicit risk estimation.
6.2 Electric traction system
6.2.1 Function
The electric traction system controls, converts and transmits electric energy to the trains and other
installations along the line via the contact line system and return
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