SIST EN 50155:2002

Railway applications - Electronic equipment used on rolling stock

Applies to all electronic equipment for control, regulation, protection, supply etc. associated with the accumulator battery of the vehicle or a low voltage power supply source with or without the direct connection to the contact system. Does not apply however to electronic power circuits which conform to IEC 61287-1. It covers the conditions of operation, design, construction and testing of electronic equipment as well as basic hardware and software requirements. This consolidated version consists of the second edition (1998) and its amendment 1 (2006). Therefore, no need to order amendment in addition to this publication.

Bahnanwendungen - Elektronische Einrichtungen auf Schienenfahrzeugen

Applications ferroviaires - Equipements électroniques utilisés sur le matériel roulant

S'applique à tous les équipements électroniques de commande, de régulation, de protection, d'alimentation etc., reliés à la batterie d'accumulateurs du véhicule ou à une source d'alimentation basse tension avec ou sans liaison galvanique avec la ligne de contact. Ne s'applique pas toutefois aux circuits électroniques de puissance qui doivent être conforme à la CEI 61287-1. Couvre les conditions de fonctionnement, la conception, la construction mécanique et les essais des équipements électroniques ainsi que les exigences de base du matériel et logiciel.  Cette version consolidée comprend la deuxième édition (1998) et son amendement 1 (2006). Il n'est donc pas nécessaire de commander  l'amendement avec cette publication.

Železniške naprave – Elektronska oprema na voznih sredstvih

General Information

• Status: Withdrawn
• Publication Date: 28-Feb-2002
• Withdrawal Date: 13-Sep-2007
• ICS: 29.280 - Electric traction equipment
• ICS: 45.060.10 - Tractive stock
• Technical Committee: ŽEN - Electrical applications for railways
• Current Stage: 9900 - Withdrawal (Adopted Project)
• Start Date: 13-Sep-2007
• Due Date: 06-Oct-2007
• Completion Date: 14-Sep-2007
• Directive: 2008/57/EC - Directive 2008/57/EC of the European Parliament and of the Council of 17 June 2008 on the interoperability of the rail system within the Community (Recast)
• Directive: 96/48/EC - Interoperability of the trans-European high-speed rail system
• Ref Project: EN 50155:2001 - Railway applications - Electronic equipment used on rolling stock

Relations

• Replaced By: SIST EN 50155:2007 - Railway applications - Electronic equipment used on rolling stock
• Effective Date: 29-Jan-2023
• Amended By: SIST EN 50155:2002/A1:2003 - Railway applications - Electronic equipment used on rolling stock
• Effective Date: 21-Sep-2010
• Revises: SIST EN 50155:1998 - Railway applications - Electronic equipment used on rolling stock
• Effective Date: 28-Jan-2023
• Revised: SIST EN 50155:1998 - Railway applications - Electronic equipment used on rolling stock
• Effective Date: 07-Jun-2022
• Revised: SIST EN 50155:1998 - Railway applications - Electronic equipment used on rolling stock
• Effective Date: 06-May-2014

Standards Content (Sample)

SLOVENSKI SIST EN 50155:2002
prva izdaja
STANDARD
marec 2002
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Railway applications – Electronic equipment used in rolling stock
ICS 5HIHUHQþQDãWHYLOND
29.280; 45.060.10
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EUROPEAN STANDARD EN 50155
NORME EUROPÉENNE
EUROPÄISCHE NORM August 2001
ICS 29.280; 45.060.10 Supersedes EN 50155:1995
English version
Railway applications -
Electronic equipment used on rolling stock
Applications ferroviaires - Bahnanwendungen -
Equipements électroniques utilisés Elektronische Einrichtungen auf
sur le matériel roulant Schienenfahrzeugen
This European Standard was approved by CENELEC on 2000-08-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway,
Portugal, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2001 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50155:2001 E
Foreword
This European Standard was prepared by the CENELEC Technical Committee TC 9X, Electrical and
electronic applications in railways.
The text of the draft was submitted to the Unique Acceptance Procedure and was approved by
CENELEC as EN 50155 on 2000-08-01.
This European Standard supersedes EN 50155:1995.
This second edition of EN 50155 has the purpose to technically align the European Standard to the
International Standard IEC 60571:1998, keeping however the reference to the European needs, mainly
expressed in the requirements of horizontal European standardisation.
The following dates were fixed:
- latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2002-02-01
- latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2003-08-01
Annexes designated “normative” are part of the body of the standard. Annexes designated “informative”
are given for information only. In this standard annex A is informative, and contains a list of clauses
where agreement between the parties (e.g. user and manufacturer) is mentioned. Annex B is also
informative and lists a number of Standard documents which may assist in this standard.
____________
- 3 - EN 50155:2001
Contents
1 General .5
1.1 Scope.5
1.2 Normative references.5
1.3 Definitions.7
2 Environmental service conditions of operation .9
2.1 Normal service conditions .9
2.2 Special service conditions .10
3 Electrical service conditions .10
3.1 Power supply.10
3.2 Supply overvoltages              .12
3.3 Installation.12
3.4 Surges and electrostatic discharge      .13
3.5 Electromagnetic compatibility.14
4 Reliability, maintainability and expected useful life.14
4.1 Equipment reliability.14
4.2 Useful life.14
4.3 Maintainability.14
4.4 Maintenance levels .15
4.5 Built-in diagnostics .15
4.6 Automatic test equipment.15
4.7 Alternative methods for fault diagnosis.15
4.8 Purpose built test equipment and special tools .16
5 Design.16
5.1 General .16
5.2 Detailed practices - Hardware.16
5.3 Detailed practices - Software.18
5.4 System features.20
6 Components.21
6.1 Procurement.21
6.2 Application.22
7 Construction.22
7.1 Equipment construction.22
7.2 Component mounting.22
7.3 Electrical connections.23
7.4 Internal flexible wiring (electrical and optical) .24
7.5 Flexible printed and strip wiring .24
7.6 Printed board-flexible and rigid.25
7.7 Protective coatings for printed board assemblies.25
7.8 Identification.26
7.9 Mounting .26
7.10 Cooling and ventilation.27
7.11 Materials and finishes.27

8 Safety.27
8.1 General .27
8.2 Functional safety.27
8.3 Personnel safety.27
9 Documentation.27
9.1 Supply and storage of documentation.27
9.2 Hardware and software documentation.28
9.3 Documentation requirements.29
10 Testing.30
10.1 Categories of tests .30
10.2 List of tests.31
Tables
1 Ambient temperature.9
2 List of tests.31
Figures
1 System interfacing with the typical EMC areas A, B and C .17
2 Supply overvoltage .35
3 Alternative test for supply overvoltage.36
4 Capacitor discharge surge test .37
Annex A (informative) List of subclauses in which agreement between the parties
(e.g. user and manufacturer) is mentioned .43
Annex B (informative) Bibliography.44

- 5 - EN 50155:2001
1 General
1.1 Scope
This standard applies to all electronic equipment for control, regulation, protection, supply, etc., installed
on rail vehicles and associated with:
- either the accumulator battery of the vehicle;
- or a low voltage power supply source with or without a direct connection to the contact system
(transformer, potentiometer device, auxiliary supply);
with the exception of electronic power circuits, which conform to EN 50207.
This standard covers the conditions of operation, design, construction, and testing of electronic
equipment, as well as basic hardware and software requirements considered necessary for competent,
reliable equipment.
Additional requirements in other standards or individual specifications may complement this standard, if
they are justified.
Specific requirements related to practices necessary to assure defined levels of functional safety
(integrity level equal to or higher then one) are to be found in EN 50126, EN 50128, and ENV 50129.
For the purpose of this standard, electronic equipment is defined as equipment mainly composed of
semiconductor devices and recognized associated components. These components will mainly be
mounted on printed boards.
NOTE  Sensors (current, voltage, speed, etc.) and firing unit printed board assemblies for power electronic devices are covered by this
standard. Complete firing units are covered by EN 50207.
1.2 Normative references
This European standard incorporates by dated or undated references, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of
these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
EN 29000-3 1998 Quality management and quality assurance standards
Part 3: Guidelines for the application of ISO 9001 to the development, supply
and maintenance of software (ISO 9000-3:1993)
EN 50121-3-2 2000 Railway Applications - Electromagnetic compatibility
Part 3-2: Rolling stock - Apparatus
EN 50126 1999 Railway Applications - Dependability for guided transport systems (RAMS)
EN 50128 2001 Railway Applications - Software for railway control and protection systems
ENV 50129 1998 Railway Applications - Safety related electronic railway control and protection
systems
EN 50163 1995 Railway Applications - Supply voltages of traction systems
EN 50207 2000 Electronic power convertors for rolling stock

EN 60068 Environmental testing (IEC 60068 series)
EN 60068-2-1 1993 Part 2: Tests - Test A: Cold (IEC 60068-2-1:1990)
EN 60068-2-2 1993 Part 2: Tests - Test B: Dry heat (IEC 60068-2-2:1974)
EN 60068-2-30 1999 Part 2: Tests - Test Db and guidance: Damp heat, cyclic (12+12 hour cycle)
(IEC 60068-2-30:1980 + A1:1985)
EN 60249 Base materials for printed circuits (IEC 60249 series)
EN 60249-2-5 1994 Part 2: Specifications - Specification No.5: Epoxide woven glass fabric
copper-clad laminated sheet, of defined flammability (vertical burning test)
(IEC 60249-2-5:1987 + A2:1992)
EN 60249-2-10 1994 Specification No.10: Epoxide non woven/woven glass reinforced copper-clad
laminated sheet of defined flammability (vertical burning test)
(IEC 60249-2-10:1987 + A2:1990)
EN 60249-2-12 1994 Specification No.12: Thin epoxide woven glass fabric copper-clad laminated
sheet, of defined flammability, for use in the fabrication of multilayer printed
boards (IEC 60249-2-12:1987 + A1:1989)
EN 60249-2-15 1994 Specification No.15: Flexible copper-clad polyimide film, of defined
flammability (IEC 60249-2-15:1987)
EN 60297/ Series Dimensions of mechanical structures of the 482,6 mm (19 in) series
HD 493 (IEC 60297, series)
EN 60352 Solderless connections (IEC 60352 series)
EN 60352-1 1997 Part 1: Solderless wrapped connections - General requirements, test methods
and practical guidance (IEC 60352-1:1997)
EN 60352-2 1994 Part 2: Solderless crimped connections - General requirements, test methods
and practical guidance (IEC 60352-2:1990)
EN 60529 1991 Degrees of protection provided by enclosures (IP Codes)
(IEC 60529:1989)
EN 60617 Series Graphical symbols for diagrams (IEC 60617 series)
EN 61000-4-4 1995 Electromagnetic compatibility (EMC) - Part 4: Testing and measurement
techniques - Section 4: Electrical fast transient/burst immunity test (IEC
61000-4-4:1995)
EN 61082 Series Preparation of documents used in electrotechnology (IEC 61082 series)
EN 61373 1999 Shock and vibration requirements for rolling stock equipment
(IEC 61373:1999)
EN 123000 1991 Generic specification - Printed boards
EN 123200 1992 Sectional specification - Single and double sided printed boards with plated-
through holes
EN 123300 1992 Sectional specification - Multi-layer printed boards
EN 123400 1992 Sectional specification - Flexible printed boards without through connections
EN 123500 1992 Sectional specification - Flexible printed boards with through connections

- 7 - EN 50155:2001
EN ISO 9001 Quality systems - Model for quality assurance in design/ development,
production, installation and servicing
EN ISO 9002 Quality systems - Model for quality assurance in production and installation
IEC 60077 1968 Rules for electric traction equipment
IEC 60249-3-1 1981 Base materials for printed circuits - Part 3: Special materials used in
connection with printed circuits - Specification No. 1: Prepreg for use as
bonding sheet material in the fabrication of multilayer printed boards
IEC 60321 1970 Guidance for the design and use of components intended for mounting on
boards with printed wiring and printed circuits
IEC 60326 Printed boards
IEC 60326-3 1991 Part 3: Design and use of printed boards
IEC 60326-7 1981 Part 7: Specification for single and double sided flexible printed boards without
through connections
IEC 60326-8 1981 Part 8: Specification for single and double sided flexible printed boards with
through connections
IEC 60605 (series) Equipment reliability testing
1.3 Definitions
For the purposes of this standard, the following definitions apply:
1.3.1
printed board
base material cut to size containing all holes and bearing at least one conductive pattern. Printed boards
are typically subdivided according to:
- their structure (e.g. single and double-sided, multilayers)
- the nature of the base material (e.g. rigid, flexible)
1.3.2
printed board assembly
printed board with electrical and mechanical components and/or other printed boards attached to it with
all manufacturing processes, soldering, coating, etc., completed
1.3.3
plug-in unit
unit which plugs into a subrack and is supported by guides. These units can be of various types, ranging
from a printed board with components mounted in a frame or box type unit, designed with a plug-in
connection
1.3.4
subrack
structural unit for housing printed board assemblies and/or plug-in units
1.3.5
rack
free-standing or fixed structure for supporting electrical or electronic equipment (e.g. subracks)
1.3.6
cubicle
any enclosure for housing electrical and/or electronic equipment

1.3.7
line replaceable unit
unit designed to be exchanged as a result of on-vehicle fault diagnosis, e.g. a subrack, or plug-in unit
1.3.8
performance check
short form performance test which is carried out during and after environmental tests, sufficient to prove
that the equipment is within its operational limits, and that it has survived an environmental test
1.3.9
control system voltage supply
voltage supply used to power the vehicle control equipment.
The supply may be derived from a vehicle battery. The battery may be charged from battery chargers,
auxiliary inverters and motor-alternator or motor-generator sets with associated electronic regulations.
Where the control system voltage supply is derived from a battery, the nominal and rated control system
voltages are defined in 3.1. Where no battery is fitted, the nominal control system voltage is the normal
controlled level of that voltage.
1.3.10
vehicle wiring
all wiring which can be connected to the control system voltage supply, wherever located, and all other
wiring external to the electronic equipment under consideration
1.3.11
supply overvoltage
electrical disturbance to the control system voltage supply caused by equipment controlling that supply.
A supply overvoltage will occur as an increase in the level of the control system voltage supply
1.3.12
surge
non-periodic and relatively short positive or negative (or both) variable (voltage or current) between two
steady states.
It may be produced by the normal operation of equipment within the vehicle, caused generally by the
discharge of energy when inductive circuits are switched.
It may be present either on the control system voltage supply, or on wiring connected directly to
switched inductive circuits, or coupled electrostatically or electromagnetically from such wiring into other
wiring.
The effective value of the source impedance of a transient will depend upon the manner of its
generation and coupling.
1.3.13
burst
repetitive pulses occurring during a fixed time interval.
They may occur during normal operation of the vehicle, typically resulting from unstable arc conditions.
1.3.14
failure
inability of an item of equipment to continue to perform its intended function.
A temporary malfunction will not be considered a failure provided that:
a) The equipment recovers normal operation automatically following malfunction
b) The malfunction is not apparent to the vehicle operating staff; for example, fault indicators do not
light up.
NOTE  Attention is drawn to the possibility of a consequential failure of a second item of equipment resulting from a temporary
malfunction of another item of equipment connected to it.

- 9 - EN 50155:2001
1.3.15
damage
any change in visual appearance or alteration of mechanical integrity
1.3.16
useful life
period from a stated time, during which, under stated conditions, an item has an acceptable failure rate,
or until an unrepairable failure occurs
NOTE  For a repairable item the individual useful life may be ended by a failure which is not considered as repairable for any reason.
2 Environmental service conditions of operation
2.1 Normal service conditions
2.1.1 Altitude
The altitude at which the equipment is normally to function does not exceed 1 200 m. When it exceeds
this figure, compliance with the requirements shall be defined by agreement between manufacturer and
user.
2.1.2 Ambient temperature
Electronic equipment shall be designed and manufactured to meet the full performance specification
requirement for the selected temperature categories as stated in table 1.
The design shall take into account temperature rises within cubicles to ensure that the components do
not exceed their specified temperature ratings.
In addition, the equipment shall meet the special short-term start up thermal conditions as stated in
column 3. In this interval the full performance ratings may be relaxed, but the maximum air temperature
surrounding the printed board assembly according to column 4 shall not be exceeded.
Table 1 - Ambient temperature
Column 1 Column 2 Column 3 Column 4
Air temperature
External ambient Internal cubicle Internal cubicle surrounding the
temperature temperature overtemperature printed board
during 10 min assembly
°C °C °C °C
T1 -25  +40 -25  +55 +15 -25  +70
T2 -40  +35 -40  +55 +15 -40  +70
T3 -25  +45 -25  +70 +15 -25  +85
TX -40  +50 -40  +70 +15 -40  +85
For peripheral units (measuring transducers,etc.), or if the equipment is in a decentralized configuration,
then if the above ambient temperature ranges are exceeded, the actual temperatures occurring at the
location of the equipment concerned shall be used in the design.
Rapid external ambient temperature variations resulting from running through tunnels shall be taken into
account. For this purpose the rate of change of external temperature shall be assumed to be 3 °C/sec,
with a maximum variation of 40 °C .

2.1.3 Shock and vibration
The equipment shall be able to withstand, without deterioration or malfunction, vibrations and shocks
that occur in service.
In order to provide some reasonable degree of confidence that it will survive the specified useful life
under service conditions, it shall be capable of meeting the vibration, shock and bump test as described
in 10.2.11.
For these purposes the equipment is specified as having the electronic units installed complete, and
supported in their designed fixings, with anti-vibration mounts where fitted.
For the typical values of shocks and vibrations in real service, reference is made to EN 61373.
2.1.4 Relative humidity
The equipment shall be designed for the following humidity stresses (limit values) over the relevant
range of the external ambient temperature as defined in 2.1.2:
- yearly average ≤ 75% rel. humidity,
- 30 consecutive days in the year: 95% relative humidity.
In addition, any moisture condensation during operation shall not lead to any malfunction or failure
especially when running through tunnels.
For peripheral units (measuring transducers etc.), or if the equipment is in a decentralized configuration,
then if the above humidity stresses are exceeded, the actual humidity occurring at the location of the
equipment concerned shall be used in the design.
2.2 Special service conditions
Special arrangements shall be agreed between the appropriate parties involved when service conditions
can be proved to be different from those mentioned in 2.1 (e.g. electronic equipment mounted on the
bogie or integrated within a power converter etc.). Checks for the effectiveness of such arrangements
can, if required, form the subject of optional type tests which can be carried out on the vehicle itself in
accordance with methods to be agreed between the user and the manufacturer.
2.2.1 Atmospheric pollutants
The equipment may be expected to be exposed throughout its life to various pollutants (e.g. oil mist, salt
spray, conductive dust, sulphur dioxide.). The types of pollutants and their concentration should be
defined in the tender documents.
3 Electrical service conditions
3.1 Power supply
3.1.1 Supply from accumulator battery
The nominal voltage of equipment (U ) so supplied shall be selected from amongst the following values:
n
24 V, 48 V, 72 V, 96 V, 110 V
NOTE 1  These nominal voltage values are given only as standardising values for the design of equipment. They should not be
considered as the off load battery voltages since these are determined by the types of battery, the number of cells and the operating
conditions.
NOTE 2  Different voltage variations may be used, following IEC 60077. In this case compliance with the requirements should be
defined by agreement between manufacturer and user.

- 11 - EN 50155:2001
3.1.1.1 Variations of voltage supply
Electronic equipment supplied by accumulator batteries without a voltage stabilizing device shall
operate satisfactorily for all the values of the supply voltage within the range defined below (measured
at the input terminals of the equipment).
The supplier of the electronic equipment shall specify its power consumption in order to enable
calculations for the battery cabling.
Minimum voltage: 0,7 U
n
Nominal voltage: U
n
Rated voltage: 1,15 U
n
Maximum voltage: 1,25 U
n
Voltage fluctuations (e.g. during start-up of auxiliary equipment or voltage oscillations of battery
chargers) lying between 0,6 U and 1,4 U and not exceeding 0,1 s shall not cause deviation of
n n
function.
Voltage fluctuations lying between 1,25 U and 1,4 U and not exceeding 1 s shall not cause damage:
n n
equipment may not be fully functioning during these fluctuations.
In the case of thermal engines, see also 3.1.1.3.
3.1.1.2  Interruptions of voltage supply.
Interruptions of up to 10 ms may occur on input voltage as defined below:
- Class S1: no interruptions
- Class S2: 10 ms interruptions
This shall not cause any equipment failure.
The time values specified are for nominal voltage and the choice of classes shall be defined by the
system designer
3.1.1.3  Variations of voltage supplies for rolling stock powered by thermal engines
At start-up of thermal engines the voltage supply system shall be designed to guarantee the supply to
the essential electronic equipment during the whole starting sequence.
3.1.1.4  D.C. ripple factor
All batteries on charge have a pulsating voltage, the d.c. ripple factor of which, unless otherwise stated,
shall not be greater than 15% calculated from the equation:
U - U
max min
d.c. ripple factor =  x 100
U + U
max min
where U and U are the maximum and minimum values, respectively, of the pulsating voltage.
max min
The minimum and maximum voltages as defined in 3.1.1.1 however shall not be exceeded.

3.1.2 Supply by a static converter or a rotating set
In the case of equipment supplied with power from a stabilized source, (e.g. a static converter or a
rotating motor-generator set provided with a regulator), electronic equipment shall operate satisfactorily
for values of the supply voltage lying between 0,9 and 1,1 U , where U is the nominal voltage and can
n n
be either d.c. or a.c.
In addition, for operating equipment, voltage fluctuations lying between 0,7 U and 1,25 U not
n n
exceeding 1 s and also between 0,6 U and 1,4 U not exceeding 0,1 s are allowed.
n n
3.1.3 Supply change over
In the case of equipment supplied with power alternatively from an accumulator battery and a stabilized
source (d.c.), the equipment shall operate satisfactorily under the conditions stated in 3.1.1, 3.1.1.1,
3.1.1.4 and 3.1.2.
- Class C1: at 0,6 U during 100 ms (without interruptions).
n
- Class C2 during a supply break of 30 ms.
3.1.4 Supply with overhead line or third rail
In the case of electronic equipment with a supply derived directly from the overhead line or third rail
(e.g. control electronics of a self starting static converter), the equipment shall operate satisfactorily for
values of contact line voltage as described in EN 50163.
3.2 Supply related surge
All connections to electronic equipment capable of being connected to the control system voltage supply
shall withstand:
a) the supply overvoltages as specified in 3.1.1.1 and/or 3.1.2 (as appropriate);
b) the application of supply overvoltage as specified in 10.2.6.1.
Surges shall be assumed to be generated with respect to the control system voltage supply return
potential and to be present only as an increase to the level of the control system voltage, which shall be
assumed to be present before and after the application of the surge. Surges of opposite polarity to the
control system voltage supply need not be considered.
Surges exceeding 1,25 U longer than 0,1 s shall be assumed to occur only in the case of a failure in
n
the control system voltage supply.
3.3 Installation
The supply to the electronic equipment should be provided by a separate conductor connected as
directly as possible to the source. This conductor should be used only for the supply to electronic
circuits.
The installation of the electronic equipment shall be arranged so as to reduce, as far as possible, the
effects of external electrical disturbances.
Suppression should be provided at the source of electrical interference.
If one pole of the battery of the vehicle is connected to the vehicle body, this shall be specified.
Where several manufacturers supply electronic equipment having common direct connections, a single
reference point of equi-potential shall be established by mutual agreement.

- 13 - EN 50155:2001
3.4 Surges and electrostatic discharge
3.4.1 Requirements
All electronic equipment shall withstand surges, either directly induced or indirectly coupled such that no
damage or failure occurs during operation on the vehicle.
It may be assumed that the equipment will be used only for its intended purpose and it will be operated
over all representative modes.
In order to provide some reasonable degree of confidence that it will survive the specified useful life
under service conditions, the electronic equipment shall be capable of meeting the surges and
electrostatic discharge tests as described in 10.2.6.
Surges may be assumed to be non repetitive and they should not occur at a time interval of less than
10 s.
The surges shall be considered to be generated by an ideal voltage source in series with the specified
source impedance switched to the electronic equipment by an ideal switch for the specified duration, in
place of the normal control system voltage supply, if present. This supply shall not be assumed to be
capable of absorbing any of the transient energy. However for certain applications it may be assumed
that other loads are connected in parallel with the equipment (See 10.2.6).
Surges shall be assumed to be applied to the electronic equipment at the equipment wiring interface.
Where connections to the electronic equipment are made via multipole connectors, such connectors and
associated wiring harnesses shall be considered to be part of the electronic equipment.
If separate transient protection equipment is not provided locally (typically within one metre of the
equipment), then the requirements of 3.4.2 shall apply.
3.4.2 Surge levels
For design purposes, electronic equipment shall be considered to be subject to one or more forms of
electrical disturbance:
a) all connections to electronic equipment capable of being connected to the control system voltage
supply shall withstand the application of the surge waveform as described in 10.2.6.2.;
b) all connections to electronic equipment not connected to the control system voltage supply but
connected to vehicle wiring and liable to be affected by electromagnetic coupling from other wiring
shall withstand the application of the surge waveform as described in 10.2.6.2.
Where wiring to electronic equipment is shielded (e.g. screened cables), these connections shall be
exempt from the above requirements.
The surges appear irrespective of the value of the control system supply voltage.
The surges are of either polarity, and shall be assumed to occur with the control system supply voltage
both present and absent.
If the input impedance of the circuit is high (with respect to the source impedance of the transient), then
the transient will be a voltage waveform, but if the impedance is low, then it will be a current waveform.

3.5 Electromagnetic compatibility
The equipment shall be protected so as not to be adversely affected by conducted or radiated
interference, and shall be capable of meeting the relevant interference test requirement as described in
10.2.7 and 10.2.8.1.
In addition the equipment shall not emit radio frequency interference (RFI) in excess of the level defined
in 10.2.8.2.
4 Reliability, maintainability and expected useful life
4.1 Equipment reliability
4.1.1 Predicted reliability
The user may require the manufacturer to predict his reliability figure or meet the user's reliability target.
The method of calculation shall be agreed at the time of tendering between the manufacturer and the
user, and shall be in accordance with a recognized standard.
4.1.2 Proof of reliability
Where the user has specified a required reliability level, the following actions are necessary.
The equipment performance shall be carefully monitored.
The equipment manufacturer and the user shall agree to record all actions carried out on the equipment.
To demonstrate the reliability level of the equipment a defect report will be presented at the end of a
mutually agreed period (km or service hours) identifying the components replaced (circuit reference
number, type, manufacturer, number of manufacturing lot, kilometres and/or operating hours etc.), the
definition and cause of faults (design weakness, software, component problems etc.).
In order to show whether the equipment meets its stated reliability requirements, the equipment should
be subjected to a reliability evaluation.
IEC 60605 may be used as a guide.
The detailed reliability evaluation procedure shall be stated in the contract.
4.2 Useful life
The useful life of the electronic equipment, unless otherwise agreed at the time of tendering between the
equipment manufacturer and the user, shall be taken as 20 years.
When the manufacturer intends to use components with a known life less than the useful life of the
electronic equipment, their use and procedures for their regular replacement shall be agreed between
the involved parties.
4.3 Maintainability
Unless otherwise agreed, equipment shall be designed such that regular periodic maintenance shall not
be necessary.
Special maintenance requirements, if any, shall be defined by the user at the time of tendering.
Printed board assemblies, and/or subracks shall be capable of being individually tested.
In addition, the equipment manufacturer shall advise what maintenance procedures are necessary or
prohibited.
NOTE   Maintenance processes such as ultrasonic cleaning, connecting of diagnostic test equipment, electrical insulation testing, and
transportation packaging arrangements, can reduce the equipment reliability level, through additional stressing of the assembly and
components.
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4.4 Maintenance levels
4.4.1 On-vehicle diagnosis
The user and manufacturer shall agree on the nature of units (e.g. subracks or plug-in units) to be
exchanged as a result of on-vehicle fault diagnosis.
These units, defined as line replaceable units, shall be designed to be easily exchanged.
The user and manufacturer shall also agree on the use of any specialised tools required in this
maintenance procedure.
Equipment shall be designed such that a failed line replaceable unit can be identified by the use of
either suitable portable test equipment or built-in diagnostics, both with associated test instructions.
Maintenance or diagnostic procedures at this level shall not require the removal or replacement of any
component of the Line Replaceable Unit.
4.4.2 Off-vehicle diagnosis and repair
Equipment shall be designed such that test equipment with associated test instructions shall enable the
full diagnosis and validation of performance of each type of train-borne equipment in repair centres by
qualified personnel.
Equipment shall be constructed such that access necessary for diagnosis and repair can be achieved
without damage or undue disturbance to the components or wiring.
In addition, printed board assemblies shall have test facilities (e.g test plugs, test pads etc.) to aid the
diagnosis and repair process.
4.5 Built-in diagnostics
Indicators to assist diagnostic maintenance shall be used where appropriate, in order to display status of
input data, output data, main control functions, power supplies, etc.
Self test routines shall be capable of providing clear indication of the operational status of the
equipment.
Any built-in diagnostic facilities capable of exercising rather than monitoring the equipment shall be
suitably interlocked to prevent interruption of the normal operation of the equipment other than under
test conditions.
The use of extra components for built-in diagnostics shall not considerably influence the reliability of the
equipment, and shall be taken account of in reliability calculations.
4.6 Automatic test equipment
The user may require to use a specific type of automatic test equipment for fault location either on or off
the vehicle.
If this is required, details of such test equipment and its interfacing with train-borne equipment, e.g. bed
of nails or guided probe (for off-vehicle repair), or equipment connector (for on vehicle diagnosis), shall
be provided by the user at the time of tendering.
It is permitted to remove plug-in units which do not contribute to the function of the equipment, to
facilitate the connection of Automatic Test Equipment.
4.7 Alternative methods for fault diagnosis
Where train-borne electronic equipment has been developed or tested using proprietary test equipment
the manufacturer may offer this as an alternative for fault diagnosis within repair centres, provided that
use of such equipment is practical to the installation and all support details are made available to the
user.
4.8 Purpose built test equipment and special tools
The prior approval of the user shall be obtained regarding the use of items requiring tools other than
readily available industrial tools.
Where purpose built test equipment and/or special tools are required to carry out the user's formal
maintenance procedures, this equipment, or alternatively the manufacturing and procurement details for
it, shall be offered for sale to the user.
Test equipment does not necessarily have to comply with this standard.
5 Design
5.1 General
5.1.1 Quality management
All design shall proceed according to EN ISO 9001.
The design process shall be visible and auditable.
If the user requires details of this process for tender evaluation, he shall define this in the tender
documents.
Particular attention is drawn to the need implicit in the use of EN ISO 9001, for all system, hardware,
and software design to proceed according to clearly laid down functional and interface specifications.
5.1.2 Life-cycle
All design shall proceed according to a defined life cycle model, which shall be laid down in the quality
plan.
5.2 Detailed practices - Hardware
5.2.1 Interfacing
All interfaces shall be so implemented as to allow the equipment to meet its requirements in respect of:
- electromagnetic compatibility;
- potential differences;
- personnel safety
and to control propagation of damage arising from external faults.
The user may require galvanic isolation to meet the above. In this case the requirement and particular
areas for its application shall be declared at the tender stage.
An example of system interfacing with various EMC areas is given in Figure 1.
5.2.2 Fault protection
Outgoing cables shall be rated to at least the current limit value of the protective device for that circuit.
Equipment shall be protected against external faults (e.g. short circuit or open circuit conditions as
appropriate).
Regulated power supply units for electronic equipment shall incorporate current limiting to minimise the
use of fuse elements.
If the user wishes to forbid the use of fuses internal to the equipment, this shall be declared at the time
of tendering.
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Figure 1 - System interfacing with the typical EMC-areas A, B and C

Where protective devices of the tripping type are incorporated in the output circuits, the available
current under short circuit conditions shall be sufficient to operate them. In addition, devices with
manual resetting shall be easily accessible.
Any protective devices used shall be so arranged that the risk of fire within the equipment is minimised.
5.2.3 Referencing power supplies
The output of galvanically isolated power supply units should not be allowed to float.
When the outputs are not referenced to a voltage source (e.g. battery or voltage supply) then one of the
supply rails should be connected to the vehicle frame or a defined earth point.
This reference and the means of connection should be defined and mutually agreed.
5.2.4 Interchangeability
All individual printed board assemblies forming part of a system shall be functionally complete and fully
interchangeable with any other unit of the same functional type without the need for any recalibration of
the hardware after the board has been inserted in the system.
5.2.5 Reduction of supply voltage
The equipment shall not suffer damage, when the supply is, or falls, below the lowest limit of its
specified source voltage, irrespective of the
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