EN 50526-2:2014

SLOVENSKI STANDARD
01-maj-2014
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Railway Applications - Fixed Installations - D.C. surge arresters and voltage limiting
devices - Part 2: Voltage limiting devices
Bahnanwendungen - Ortsfeste Anlagen - Überspannungsableiter und
Niederspannungsbegrenzer - Teil 2: Spannungsbegrenze
Applications ferroviaires - Installations fixes - Parafoudres et limiteurs de tension - Partie
2:Limiteurs de tension
Ta slovenski standard je istoveten z: EN 50526-2:2014
ICS:
29.120.50 9DURYDONHLQGUXJD Fuses and other overcurrent
PHGWRNRYQD]DãþLWD protection devices
29.280 (OHNWULþQDYOHþQDRSUHPD Electric traction equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 50526-2
NORME EUROPÉENNE
February 2014
EUROPÄISCHE NORM
ICS 29.120.50; 29.280
English version
Railway applications -
Fixed installations -
D.C. surge arresters and voltage limiting devices -
Part 2: Voltage limiting devices

Applications ferroviaires -  Bahnanwendungen -
Installations fixes - Ortsfeste Anlagen -
Parafoudres et limiteurs de tension pour Überspannungsableiter und
systèmes à courant continu - Spannungsbegrenzungseinrichtungen -
Partie 2: Limiteurs de tension Teil 2:
Spannungsbegrenzungseinrichtungen

This European Standard was approved by CENELEC on 2013-12-30. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the CEN-CENELEC Management Centre or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the CEN-CENELEC Management Centre has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany,
Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

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

CEN-CENELEC Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2014 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50526-2:2014 E
Contents Page
Foreword . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Classes of VLD . 8
5 Characteristics and requirements of the VLDs . 9
5.1 Marking . 9
5.2 Service requirements . 9
5.2.1 Normal outdoor service conditions . 9
5.2.2 Normal indoor service conditions . 9
5.2.3 Abnormal service conditions . 10
5.3 General characteristics . 10
5.4 Minimum requirements . 10
5.4.1 Response time . 10
5.4.2 Additional requirements for VLDs of class 1 . 10
5.4.3 Additional requirements for VLDs of classes 3 and 4 . 10
5.5 Electrical characteristics and thermal rating . 11
5.6 Protection of VLDs against lightning . 11
5.7 Command and control (class 3 and 4 only) . 12
5.7.1 Local control . 12
5.7.2 Remote signalling . 12
5.7.3 Operation and alarm recordings . 12
6 Type tests . 13
6.1 General . 13
6.2 Nominal triggering voltage U and non-triggering voltage U . 14
Tn W
6.2.1 Procedure for welding shutspark gap VLDs (Class 1) . 14
6.2.2 Procedure for thyristor type VLDs (Class2) . 14
6.2.3 Procedure for mechanical switching VLDs and for combined thyristors with mechanical
switching devices VLDs (Class 3 and Class 4) . 15
6.3 Leakage current . 15
6.4 D.C. current withstand . 15
6.4.1 General . 15
6.4.2 Procedure to determine the rated current. 15
6.4.3 Procedure to determine short time withstand current . 16
6.5 A.C. current withstand characteristics (optional) . 17
6.6 Response time characteristics . 18
6.6.1 Response time for d.c. voltage . 18
6.6.2 Response time for combined a.c.-d.c. voltage . 20

- 3 - EN 50526-2:2014
6.7 Lightning current withstand characteristics for VLDs exposed to direct lightning strikes . 21
6.8 Recovery test (Class 3, 4) . 23
6.9 Reverse voltage test (Class 2.1) . 23
6.10 Dielectric tests for panel type voltage limiting devices (Class 3 and 4) . 24
6.10.1 Test conditions . 24
6.10.2 Power-frequency voltage withstand test. 24
6.11 Degree of protection. 24
6.12 Environmental tests for outdoor equipment . 25
6.13 Determination of minimum current for safe short circuiting of Class 1 VLDs . 25
7 Routine tests . 26
7.1 General . 26
7.2 VLDs of classes 3 and 4 . 26
7.3 Dielectric tests for panel type voltage limiting devices. 26
Annex A (informative) Preferred ranges of the principal properties of the VLDs . 27
Bibliography . 31

Figures
Figure 1  Test circuit for testing of response time . 19
Figure 2  TR evaluation. 19
Figure 3  Response time characteristic . 20
Figure 4 Test circuit for testing of response time T for combined a.c.-d.c. voltage . 21
R
Figure 5  Evaluation of response time T for combined a.c.-d.c voltage . 21
R
Figure 6  Circuit for the Recovery Voltage test . 23

Tables
Table 1  Classes of voltage-limiting device . 8
Table 2  Type tests . 13
Table 3  Maximum response time as a function of d.c. voltages . 18
Table 4  Maximum response time for combined a.c.-d.c. voltages . 20
Table A.1  Nominal Triggering voltage U . 27
Tn
Table A.2  Instantaneous Triggering Voltage U . 27
TI
Table A.3  Rated current I . 28
r
Table A.4  Short time withstand current I . 28
W
Table A.5  Leakage current I . 28
L
Table A.6  Making and breaking capacity . 28
Table A.7  Nominal lightning current (8/20 µs) I . 29
imp-n
Table A.8  High current impulse 8/20 μs and 4/10 μs I . 29
imp-high
Table A.9  High charge impulse I . 29
imp-hc
Table A.10  Current-time characteristic for safe short circuiting of Class 1 VLDs . 30

Foreword
This document (EN 50526-2:2014) 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:

(dop) 2014-12-30
• latest date by which this document
has to be implemented at national
level by publication of an identical
national
standard or by endorsement
(dow) 2016-12-30
• latest date by which the national
standards conflicting with this
document have to be withdrawn
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.

This European Standard, Railway applications — Fixed installations — D.C. surge arresters and voltage
limiting devices, is in three parts:
— Part 1: Surge arresters deals with metal oxide arresters without gaps for d.c. railway traction systems
(fixed installations) and is based on EN 60099-4, Ed. 2.2, 2009-5;
— Part 2: Voltage limiting devices [the present text] deals with voltage limiting devices for specific use in
d.c. railway traction systems (fixed installations);
— Part 3 Application guide [currently at Enquiry stage] deals with a guide of application of metal-oxide
arresters and of voltage limiting devices.

- 5 - EN 50526-2:2014
1 Scope
This European Standard applies to Voltage Limiting Devices (VLDs) to be applied in d.c. traction systems in
order to comply with protective provisions against electric shock from d.c., and mixed a.c. – d.c. voltages, in
accordance with the EN 50122 series, taking into account stray current provisions.
VLDs operate in such a way as to connect the track return circuit of d.c. railway systems to the earthing
system or to conductive parts within the overhead contact line zone or current collector zone.
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 50122-1:2011, Railway applications  Fixed installations  Electrical safety, earthing and the return
circuit  Part 1: Protective provisions against electric shock
EN 50122-3:2010, Railway applications  Fixed installations  Electrical safety, earthing and the return
circuit  Part 3: Mutual Interaction of a.c. and d.c. traction systems
 Fixed installations  D.C. switchgear  Part 1: General
EN 50123-1:2003, Railway applications
EN 50123-7 (all parts), Railway applications  Fixed installations  D.C. switchgear  Part 7-x:
Measurement, control and protection devices for specific use in d.c. traction systems
 Insulation coordination  Part 1: Basic requirements  Clearances
EN 50124-1, Railway applications
and creepage distances for all electrical and electronic equipment
EN 50125-2, Railway applications  Environmental conditions for equipment  Part 2: Fixed electrical
installations
EN 50163:2004, Railway applications  Supply voltages of traction systems
EN 50526-1:2012, Railway applications  Fixed installations  D.C. surge arresters and voltage limiting
 Part 1: Surge arresters
devices
EN 60060-1, High-voltage test techniques  Part 1: General definitions and test requirements (IEC 60060-1)
EN 60085, Electrical insulation  Thermal evaluation and designation (IEC 60085)
EN 60529:1991, Degrees of protection provided by enclosures (IP Code) (IEC 60529:1989)
EN 61643-311, Components for low-voltage surge protective devices  Part 311: Performance
requirements and test circuits for gas discharge tubes (GDT) (IEC 61643-311)
 Surface texture: Profile method  Terms,
EN ISO 4287, Geometrical product specifications (GPS)
definitions and surface texture parameters (ISO 4287)
EN ISO 4892-1, Plastics  Methods of exposure to laboratory light sources  Part 1: General guidance
(ISO 4892-1)
EN ISO 4892-2, Plastics  Methods of exposure to laboratory light sources  Part 2: Xenon-arc lamps
(ISO 4892-2)
EN ISO 4892-3, Plastics  Methods of exposure to laboratory light sources  Part 3: Fluorescent UV lamps
(ISO 4892-3)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 50526-1:2012 and the following
apply.
3.1
voltage-limiting device
VLD
protective device whose function is to prevent existence of an impermissible high touch voltage
[SOURCE: EN 50122-1:2011, 3.1.20]
3.2
recoverable VLD
VLD that recovers after triggering
3.3
non-recoverable VLD
VLD remaining in its low resistance state permanently after triggering
3.4
welding shut spark gap
voltage fuse
VLD which triggers by electrical discharge across a gap causing a permanent short-circuit by welding shut of
metallic parts
3.5
rated current
I
r
maximum value of the direct current that may flow for the specified long term through the VLD in specified
environmental conditions without exceeding the temperature rise limits
3.6
short time withstand current
I
W
current that a VLD can carry in closed status, during a specified short time under prescribed conditions of
use and behavior
3.7
making capacity
I
NSS
value of prospective making current that a switching device is capable of making at a stated voltage under
prescribed conditions of use and behavior
Note 1 to entry: The conditions to be prescribed are dealt with in the relevant specifications.
[SOURCE: IEV 441-17-09, modified — The beginning of the Note has been changed.]
3.8
breaking capacity
maximum current that a recoverable VLD can interrupt at a stated voltage
3.9
leakage current
I
L
current which flows through the terminals when the VLD is in open status

- 7 - EN 50526-2:2014
3.10
lightning current impulse
I
imp-n
8/20 µs current impulse with limits on the adjustment of equipment such that the measured values are from
7 µs to 9 µs for the virtual front time and from 18 µs to 22 µs for the time to half value on the tail
[SOURCE: EN 60099-4:2004]
3.11
high current impulse
I
imp-high
peak value of discharge current having a 4/10 µs or 8/20 µs impulse shape which is used to test the ability of
the VLD to withstand direct lightning strikes from the dielectric point of view
3.12
high charge impulse
I
imp-hc
peak value of high charge impulse having a 10/350 µs shape, or a waveshape with the same charge drained
and similar duration, which is used to test the ability of the VLD to withstand direct lightning strikes from the
energy capability point of view
3.13
triggering voltage
U
T
voltage at which a VLD becomes conductive
3.14
nominal triggering voltage
U
Tn
voltage at which the VLD becomes conductive when a d.c. voltage is applied for long term
Note 1 to entry: This voltage is used to identify the VLD.
3.15
instantaneous triggering voltage
U
Ti
minimum triggering voltage at which the VLD becomes conductive shortly after its application
Note 1 to entry: A maximum delay of 5 ms is taken in this standard.
3.16
non-triggering voltage
U
W
maximum voltage below which the VLD will not trigger for any duration of the applied voltage
3.17
residual voltage
U
res
value of voltage that appears between the terminals of the VLD during the passage of a specified current
3.18
mixed voltage
voltage having significant a.c. and d.c. components
3.19
response time
T
R
time between the application of a voltage until VLD becomes conductive

4 Classes of VLD
This European Standard identifies the properties and the technology of a VLD using the classes of VLD
which are defined in Table 1.
Table 1  Classes of voltage-limiting device
Auxiliary
Able to
Method for switching power supply
Maximum Recoverable interrupt
Class between the high and necessary Polarity
response time T or not the current
R
low resistance status for normal
in the VLD
operation
Can be
recoverable in
Welding shut of
1 No Bidirectional 5 ms No
some
metallic parts
a
conditions
Passive at
5 ms
natural zero
2.1 Triggering of thyristors No Unidirectional (for voltages equal to or Yes
crossing of
higher than U )
TI
current
Passive at
5 ms
natural zero
2.2 Triggering of thyristors No Bidirectional (for voltages equal to or Yes
crossing of
higher than U )
TI
current
Voltage dependent and not
exceeding the limits given in
Contactor only
3.1 Yes Bidirectional EN 50122-1:2011, 9.3.2.2 or Yes Yes

EN 50122-3:2010, 7.2
through 7.5
Voltage dependent and not
Contactor only exceeding the limits given in
3.2 Yes Bidirectional Yes Yes
EN 50122-1:2011, 9.3.2.3,
EN 50122-3:2010, 7.6
Specified by the
3.3 Contactor only Yes Bidirectional Yes Yes
manufacturer
For voltages up to U ,
TI
voltage dependent and not
exceeding the limits given in
Combination of
EN 50122-1:2011, 9.3.2.2 or
4.1 thyristors and Yes Bidirectional Yes Yes
EN 50122-3:2010, 7.2
contactor
through 7.5.
For voltages equal to or
higher than U 5 ms.
Ti
For voltages up to U ,
TI
voltage dependent and not
Combination of exceeding the limits given in
4.2 thyristors and Yes Bidirectional EN 50122-1:2011, 9.3.2.3, Yes Yes
contactor EN 50122-3:2010, 7.6.
For voltages equal to or
higher than U 5 ms
Ti
Combination of
Specified by the
4.3 thyristors and Yes Bidirectional Yes Yes
manufacturer
contactor
NOTE EN 50122-1 defines two functionalities for VLDs, VLD-O and VLD-F. In this European Standard a
discrimination is not necessary; the functionalities will be described in prEN 50526-3.
a
For transient low currents associated with low energy dissipation no welding shut may occur.

- 9 - EN 50526-2:2014
5 Characteristics and requirements of the VLDs
5.1 Marking
VLDs shall be identified by the following minimum information which shall appear on the rating plate
(nameplate):
− manufacturer's name or trademark and manufacture type designation;
− class of VLD according to EN 50526-2 (optional);
− rated current I in A;
r
− short time withstand current I in kA;
w
− nominal triggering voltage U ;
Tn
− year of manufacture;
− serial number.
The terminals of unidirectional devices shall be marked with the symbols + and -.
In case of small VLDs not having space for a rating plate with all information, the devices shall be marked
with the manufacturer’s name or trademark, the type designation and the nominal triggering voltage. The
remaining information shall be given in a data-sheet.
5.2 Service requirements
5.2.1 Normal outdoor service conditions
VLDs which conform to this part of the standard shall be suitable for operation under the following normal
service conditions:
− ambient temperature within the range of -40 °C to +40 °C;
− solar radiation lower than 1 120 W/m as given in EN 50125-2;
− altitude not exceeding 1 400 m (from Annex B in EN 50123-1:2003);
− any pollution not exceeding PD 4 as given in EN 50124-1.
The equipment shall be suitable for installation in the vicinity of a rail track on foundations designed so as to
damp the main effects of the passage of the trains. Nevertheless a limited vibration or limited shocks may
affect the equipment, which shall be capable of operating satisfactorily when subjected to the following
conventional accelerations separately applied:
− g : vertical acceleration:5 m/s ;
v
− g : horizontal acceleration:5 m/s .
h
5.2.2 Normal indoor service conditions
VLDs which conform to this standard shall be suitable for operation under the following normal service
conditions:
− ambient temperature within the range of -5 °C to +40 °C (from Annex B in EN 50123-1:2003);

− altitude not exceeding 1 400 m (from Annex B in EN 50123-1:2003);
− any pollution not exceeding PD3 as given in EN 50124-1.
5.2.3 Abnormal service conditions
The following are examples of abnormal service conditions which require special consideration in the
manufacture or application of VLD and should be brought to the attention of the supplier:
− temperature in excess of +40 °C or below -5 °C for indoor installations or below -40 °C for outdoor
installations;
− application at altitudes higher than 1 400 m; in this case the temperature-rise tests and dielectric tests (for
VLDs inside a cabinet), carried out at laboratories at lower levels, shall take into account a correction in
the temperature-rises and dielectric test values to be agreed between the involved parties;
− all excessive environmental conditions that may degrade insulating surface or mounting hardware: fumes,
vapours dirt, salt spray or other conducting materials; moisture, humidity, dropping water or steam;
− explosive mixtures of dust, gases or fumes;
− special mechanical requirements (earthquakes, vibrations, high ice loads, high cantilever stresses);
− unusual transportation or storage;
− heat sources near the VLD.
5.3 General characteristics
The following characteristics shall be defined to identify each VLD:
− the class of VLD;
− if relevant, the auxiliary power supply voltage, with its tolerances.
The manufacturer shall specify whether the device is recoverable or non-recoverable at defined currents and
durations.
5.4 Minimum requirements
5.4.1 Response time
A VLD shall become conductive in a time not greater than the specified response time depending on the
applied voltage. The response time of the VLD shall be stated as function of the applied voltage.
For VLDs of Classes 2, 3 and 4 the triggering may be delayed intentionally in order that unwanted triggering
will not take place due to switching transients and similar phenomena.
5.4.2 Additional requirements for VLDs of class 1
If gas discharge tubes are used in VLDs, they shall comply with EN 61643-311.
5.4.3 Additional requirements for VLDs of classes 3 and 4
The VLD shall not open if the current through it exceeds its breaking capacity.
The VLD shall open at an adjustable time after it has closed unless the breaking capacity is exceeded. The
range of variation of this time setting shall be specified.

- 11 - EN 50526-2:2014
If the VLD re-opens automatically and then re-triggers, after a set number of operations in a given time
interval either:
− it shall be prevented from re-opening and a warning or an alarm shall be signalled; or
− only a warning or an alarm shall be signalled.
The VLD shall provide the possibility to be manually operated at site.
If the VLD requires a power supply for operation, the VLD shall be provided with a failsafe function such that
it turns into the conductive state in case of failure of the power supply.
5.5 Electrical characteristics and thermal rating
In addition to the general characteristic indicated in 5.3, the manufacturer shall state the following electrical
characteristics of each type of VLD if applicable. In case of adjustable parameters, the setting ranges shall
be stated:
− for VLDs of Classes 3 and 4, the nominal voltages of the electric traction systems in which the VLDs are
to be installed;
− the nominal triggering voltage U ;
Tn
− the non-triggering voltage U ;
w
− the maximum response time as function of the voltage;
− the instantaneous triggering voltage U ;
Ti
− the maximum leakage current I at U , when the VLD is in its non-conducting state;
L w
− the short-time withstand current I and the duration of the current flow;
w
− the rated current I ;
r
− the maximum residual voltage at the short-time withstand current;
− the maximum residual voltage at the rated current;
− the conditions in which the VLD is recoverable;
− the lightning current impulse, or sequence of lightning impulses, which the VLD can withstand in the
specified test conditions;
− for VLDs of Classes 3 and 4, the breaking capacity, determined in accordance with 6.8;
− for VLDs of Classes 3 and 4, the making capacity, in accordance with 6.4.3.
5.6 Protection of VLDs against lightning
If requested by the purchaser the VLD shall withstand the effects of the specified lightning surges. The
requirements can be different according to the class of VLD. If necessary a surge arrester, according to
EN 50526-1, may be integrated into the VLD.

5.7 Command and control (class 3 and 4 only)
5.7.1 Local control
On the cabinet, the following characteristics and measuring indications should be foreseen to provide a
monitoring and control locally:
1) the instantaneous d.c. voltage across the terminals of the VLD;
2) the instantaneous d.c. current flowing through the device;
3) the operating state of the VLD (open or closed);
4) a push or touch button to manually command the closing and the opening of the device;
5) a push or touch button to start a manual self test (if possible);
6) access to recorded data as given in 5.7.3, the activations, warnings, alarms,… in the past and stored
in a register file (if applicable).
NOTE 1 Conventionally the voltage in Item 1) is the voltage on the rails relative to earth. This means that if the rail
potential is positive the figure displayed is positive.
NOTE 2 The manual self test procedure in Item 5 will trigger the thyristor and will also close the contactor for a limited
time (typically 1 s).
5.7.2 Remote signalling
If remote signalling is requested at least the following signals shall be offered:
1) contactor open;
2) contactor closed;
3) warnings, alarms.
5.7.3 Operation and alarm recordings
Recordings are optional. A list of the recordings that can be stored is indicated as an example in the
following:
a) operation recordings:
1) the status of the VLD;
2) the total number of operations (1 operation = 1 x CLOSE + 1 x OPEN);
b) alarm recordings with time stamp:
1) interruption of the auxiliary power supply of
...