CLC/TS 50544:2010
(Main)Low voltage d.c. surge protective device for traction systems - Selection and application rules for surge arresters
Low voltage d.c. surge protective device for traction systems - Selection and application rules for surge arresters
This Technical Specification applies to non linear metal-oxide resistor type surge arresters (MO surge arresters) without spark gaps designed to limit voltage surges on d.c. traction systems with nominal voltage up to 1 500 V. This Technical Specification applies to protection of equipment. Same principles for selection and application apply for MO surge arresters on d.c. traction systems with nominal voltage 3 000 V.
Überspannungsschutzgeräte für Niederspannungs-Gleichstrom-Bahnsysteme - Auswahl und Anwendungsregeln für Überspannungsableiter
Parafoudres basse tension courant continu pour traction - Principes de choix et d’application pour les parafoudres
Nizkonapetostni enosmerni prenapetostni odvodniki za sisteme električne vleke - Izbira in pravila uporabe za prenapetostne odvodnike
Ta tehnična specifikacija se uporablja za prenapetostne odvodnike z nelinearnimi upori iz kovinskega oksida brez iskrišč za omejevanje valovnih napetostnih udarov v sistemih električne vleke enosmernega toka z nazivno napetostjo do 1500 V. Ta tehnična specifikacija se uporablja za zaščito opreme. Enaka načela za izbor in uporabo veljajo za prenapetostne odvodnike z nelinearnimi upori iz kovinskega oksida v sistemih električne vleke enosmernega toka z nazivno napetostjo 3000 V.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2014
1L]NRQDSHWRVWQLHQRVPHUQLSUHQDSHWRVWQLRGYRGQLNL]DVLVWHPHHOHNWULþQHYOHNH
,]ELUDLQSUDYLODXSRUDEH]DSUHQDSHWRVWQHRGYRGQLNH
Low voltage d.c. surge protective device for traction systems - Selection and application
rules for surge arresters
Parafoudres basse tension courant continu pour traction - Principes de choix et
d’application pour les parafoudres
Ta slovenski standard je istoveten z: CLC/TS 50544:2010
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.
TECHNICAL SPECIFICATION
CLC/TS 50544
SPÉCIFICATION TECHNIQUE
February 2010
TECHNISCHE SPEZIFIKATION
ICS 29.120.50; 29.280
English version
Low voltage d.c. surge protective device for traction systems -
Selection and application rules for surge arresters
Parafoudres basse tension courant Überspannungsschutzgeräte
continu pour traction - für Niederspannungs-Gleichstrom-
Principes de choix et d’application Bahnsysteme -
pour les parafoudres Auswahl und Anwendungsregeln
für Überspannungsableiter
This Technical Specification was approved by CENELEC on 2009-12-25.
CENELEC members are required to announce the existence of this TS in the same way as for an EN and to
make the TS available promptly at national level in an appropriate form. It is permissible to keep conflicting
national standards in force.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: Avenue Marnix 17, B - 1000 Brussels
© 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. CLC/TS 50544:2010 E
Foreword
This Technical Specification was prepared by the Technical Committee CENELEC TC 37A,
Low voltage surge protective devices.
It also concerns the expertise of SC 9XC, Electric supply and earthing systems for public transport
equipment and ancillary apparatus (Fixed installations), of Technical Committee CENELEC TC 9X,
Electrical and electronic applications for railways.
The broad subject of overvoltage protection in d.c. traction systems need to address the approaches,
requirements and definitions of several disciplines and TC’s. Concerned European Standards are
referenced for generic definitions.
This Technical Specification reflects the common practise of overvoltage protection in the d.c. traction
community, as far as protection of equipment in the primary power supply is concerned (e.g. feeders,
overhead contact lines, return circuits, power side of rolling stock).
Therefore, definitions and approaches in this Technical Specification, covering a specific application in
line with EN 50526-1, are different for some aspects from the definitions and approaches in the
EN 61643 series.
The text of the draft was circulated for voting in accordance with the Internal Regulations, Part 2,
Subclause 11.3.3.3. and was approved by CENELEC as CLC/TS 50544 on 2009-12-25.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent
rights.
The following date is proposed:
– latest date by which the existence of the CLC/TS
has to be announced at national level
(doa) 2010-06-25
1)
This Technical Specification will be withdrawn once the SC 9XC document on the same subject is
published.
__________
———————
1)
Under development at the time of issue.
– 3 – CLC/TS 50544:2010
Contents
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
3.1 System voltages . 5
3.2 Arrester . 7
4 Systems and equipment to be protected . 9
4.1 General . 9
4.2 Substations . 9
4.3 Overhead contact line system .10
4.4 Return circuit .11
4.5 Rolling stock .12
5 Supply voltages .13
6 Overvoltages .13
6.1 Lightning overvoltages .13
6.2 Switching overvoltages .14
7 Function and characteristics of MO surge arresters .14
7.1 Basic function .14
7.2 Characteristics .15
7.3 Classification .16
8 Insulation co-ordination and application of MO surge arresters .17
8.1 General .17
8.2 Principles of insulation co-ordination .17
8.3 Protective distance .19
8.4 Protection level .22
8.5 Surge arresters connected in parallel .22
9 Selection of MO surge arresters .23
9.1 Continuous operating voltage U .23
c
9.2 Arrester class .23
9.3 Mechanical considerations .23
Annex A (informative) Supply voltages .24
Bibliography .25
Figures
Figure 1 – Protective circuit in a substation (principle arrangement) .10
Figure 2 – Principle of a protective circuit of a line (outdoor system) .11
Figure 3 – Installation of surge arresters on the overhead contact line and the running rails .12
Figure 4 – Surge arrester arrangement on a vehicle .13
Figure 5 – Current-voltage characteristic of an MO surge arrester .15
Figure 6 – Requirements and design of surge arresters .17
Figure 7 – Assumption for the calculation of the voltage at the open end of a line and for the
determination of the protective distance L .20
Figure 8 – Voltage funnel and illustration of protective distance .21
Tables
Table 1 – Arrester classification and related parameters. .16
Table 2 – Insulation levels .18
Table A.1 – Supply voltages .24
– 5 – CLC/TS 50544:2010
1 Scope
This Technical Specification applies to non linear metal-oxide resistor type surge arresters (MO surge
arresters) without spark gaps designed to limit voltage surges on d.c. traction systems with nominal
voltage up to 1 500 V.
This Technical Specification applies to protection of equipment.
Same principles for selection and application apply for MO surge arresters on d.c. traction systems
with nominal voltage 3 000 V.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 50122-2 Railway applications – Fixed installations – Part 2: Protective provisions against
the effects of stray currents caused by d.c. traction systems
EN 50124-1 Railway applications – Insulation coordination – Part 1: Basic requirements –
Clearances and creepage distances for all electrical and electronic equipment
EN 50163 Railway applications – Supply voltages of traction systems
1)
EN 50526-1 Railway applications – Fixed installations – D.C. surge arresters and voltage
limiting devices – Part 1: Surge arresters
EN 60071-1 Insulation co-ordination – Part 1: Definitions, principles and rules (IEC 60071-1)
EN 62305-3 Protection against lightning – Part 3: Physical damage to structures and life
hazard (IEC 62305-3, mod.)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 System voltages
3.1.1
nominal voltage
U
n
designated value for a system
[EN 50163]
3.1.2
highest permanent voltage
U
max1
maximum value of the voltage likely to be present indefinitely
[EN 50163]
———————
1)
At draft stage.
3.1.3
highest non permanent voltage
U
max2
maximum value of the voltage likely to be present as highest non permanent voltage for a limited
period of time
[EN 50163]
3.1.4
highest long term overvoltage
U
max3
voltage defined as the highest value of the long-term overvoltage for t = 20 ms. This value is
independent from frequency
[EN 50163]
3.1.5
rated insulation voltage
U
Nm
d.c. withstand voltage value assigned by the manufacturer to the equipment or part of it, characterizing
the specified permanent (over five minutes) withstand capability of its insulation
[EN 50124-1, mod.]
3.1.6
rated impulse voltage
U
Ni
impulse voltage value assigned by the manufacturer to the equipment or a part of it, characterizing the
specified withstand capability of its insulation against transient overvoltages
[EN 50124-1]
3.1.7
overvoltage
any voltage having a peak value exceeding the corresponding peak value (including recurrent
overvoltages) of maximum steady-state voltage at normal operating conditions
[EN 50124-1]
3.1.8
long-term overvoltage
overvoltage higher than U lasting typically more than 20 ms, due to low impedance phenomena
max2
e.g. a rise in substation primary voltage
[EN 50163]
3.1.9
transient overvoltage
short duration overvoltage of a few milliseconds or less due to current transfers
[EN 50124-1]
3.1.10
switching overvoltage
transient overvoltage at any point of the system due to specific switching operation or fault
[EN 50124-1]
3.1.11
lightning overvoltage
transient overvoltage at any point of the system due to a specific lightning discharge
[EN 50124-1]
– 7 – CLC/TS 50544:2010
3.2 Arrester
3.2.1
surge protective device
SPD
device that is intended to limit transient overvoltages and divert surge currents. It contains at least one
nonlinear component
[EN 61643-11]
3.2.2
voltage limiting type SPD
SPD that has a high impedance when no surge is present, but will reduce it continuously with
increased surge current and voltage. Common examples of components used as nonlinear devices
are varistors and suppressor diodes. These SPDs are sometimes called “clamping type”
[EN 61643-11]
3.2.3
surge arrester
device intended to limit transient overvoltages to a specified level
NOTE Surge arrester, or shorter “arrester”, is a more general term for metal-oxide surge arrester (see 3.2.4). Surge arresters
contain one or more nonlinear metal-oxide resistors (MO resistor). A nonlinear metal-oxide resistor (MO resistor) is the same as
a variable metal-oxide resistor (MO varistor).
[EN 50526-1]
3.2.4
metal-oxide surge arrester without gaps
arrester having non-linear metal-oxide resistors connected in series and/or in parallel without any
integrated series or parallel spark gaps
[EN 60099-4]
3.2.5
maximum continuous operating voltage of an arrester
U
c
designated permissible value of d.c. voltage that may be applied continuously between the arrester
terminals
[EN 60099-4, mod.]
3.2.6
rated voltage of an arrester
U
r
voltage by which the arrester is designated. For d.c. traction systems the rated voltage is the
maximum continuous operating voltage
[EN 60099-4, mod.]
3.2.7
charge transfer capability
maximum charge per impulse that can be transferred during the charge transfer test and during the
operating duty test
[EN 50526-1, mod.]
3.2.8
discharge current of an arrester
impulse current which flows through the arrester
[EN 50526-1]
3.2.9
nominal discharge current of an arrester
I
n
peak value of lightning current impulse which is used to classify an arrester
[EN 60099-4]
3.2.10
high current impulse of an arrester
peak value of discharge current having a 4/10 µs impulse shape
[EN 60099-4]
3.2.11
steep current impulse
current impulse with a virtual front time of 1 µs with limits in the adjustment of equipment such that the
measured values are from 0,9 µs to 1,1 µs, and the virtual time to half value on the tail shall be not
longer than 20 µs
[EN 60099-4]
3.2.12
lightning current impulse
8/20 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
[EN 60099-4]
3.2.13
direct lightning current impulse
impulse defined by the charge Q and the peak value of the current impulse I
imp
[EN 50526-1]
3.2.14
long duration current impulse
rectangular impulse which rises rapidly to maximum value, remains substantially constant for a
specified period and then falls rapidly to zero
[EN 60099-4]
3.2.15
switching current impulse of an arrester
the peak value of discharge current having a virtual front time greater than 30 µs but less than 100 µs
and a virtual time to half value on the tail of roughly twice the virtual front time
[EN 60099-4]
3.2.16
continuous current of an arrester
I
c
current flowing through the arrester when energized at the continuous operating voltage
[EN 60099-4]
3.2.17
reference current of an arrester
I
ref
d.c. current defined by the manufacturer used to determine the reference voltage of the arrester
[EN 60099-4, mod.]
– 9 – CLC/TS 50544:2010
3.2.18
reference voltage of an arrester
U
ref
d.c. voltage applied to the arrester to obtain the reference current
[EN 60099-4, mod.]
3.2.19
residual voltage of an arrester
U
res
peak value of voltage that appears between the terminals of an arrester during the passage of
discharge current
[EN 60099-4]
4 Systems and equipment to be protected
4.1 General
Electrical traction d.c. systems should be protected against overvoltages by surge arresters. Main field
of application are in substations, at sectioning posts and at singular points along the contact lines.
The terminations of the insulated cables connected to the contact line system and the electronic
apparatuses connected to the return pole of the rectifier in the substations should be protected by
surge arresters.
4.2 Substations
An important element of a lightning protection concept is the protection of the line feeders and return
conductors in the substations with arresters (see Figure 1). The arresters have the following functions.
• The arresters A1, which are connected in the substation between the feeder circuit-breakers
(cable connection) and the return circuit, reduce the overvoltages at the feeder circuit-breakers
and the rectifiers, inclusive of their measuring and monitoring devices, in case of positive lightning
strokes. In case of negative lightning strokes the diodes of the rectifier are conductive, but this
does not endanger the elements.
• The arrester A2 between the return circuit and the structure earth is to limit overvoltages of the
running rails. The arrester A2 is also important in case of direct lightning strokes into the running
rails, e.g. if lines above earth have a conductor rail. The arrester A2 is not intended for protection
against electric shock coming from impermissible rail potential.
NOTE Protection against electric shock is considered in EN 50526-2. When arresters A2 and protective devices as per
EN 50526-2 are used at the same place, a coordination of both low voltage protective devices is needed (under consideration).
Key
1 feeder
2 return conductor
3 arrester A1
4 arrester A2
5 MEB
6 earth resistance
Figure 1 – Protective circuit in a substation (principle arrangement)
4.3 Overhead contact line system
Surge arresters should be installed between the overhead contact line system or return circuit and
earth where discontinuities in the line are present and reflections of the overvoltage waves can occur,
in particular (see Figure 2):
• at each feeding switch-disconnector or disconnector;
• along the line, at both sides of a normally open switch-disconnector or disconnector (bridging a
section-insulator);
• in the line, at a normally closed switch-disconnector or disconnector (bridging a section-insulator);
• at the ends of a section;
• at power demand points (e.g. for switch heating).
Additional arresters can be necessary for track sections where frequent lightning strokes are likely, for
instance on bridges or on elevated lines, and cross country lines.
– 11 – CLC/TS 50544:2010
The arresters A1 are preferably fitted at the height of the overhead contact line so that the electrical
connection to the overhead contact line can be led in a short, straight way. Moreover, the arresters A1
are connected to the earth electrodes as directly as possible (see Figure 3). The arresters A1 and the
cable between the arresters and the earth electrodes are insulated against the mast of the overhead
contact line or the structure earth.
Key
1 arrester A1
2 current tap, e.g. switch heater
3 feeder from the substation
Figure 2 – Principle of a protective circuit of a line (outdoor system)
4.4 Return circuit
For stray current reasons the return circuit is not connected to earthing installations or earth according
to EN 50122-2.
Running rails
To reduce the stray current corrosion, the resistance to earth of the running rails has to be high for d.c.
traction systems. Consequently, the running rails are not suited as earth electrodes for lightning
protection. Therefore, either low-resistance pole foundations, driven pipes as well as the reinforcement
of tracks of reinforced concrete or separate buried earth electrodes are to be used as earth electrodes
for lightning protection along the line dependent on the local conditions. Earthing resistance ≤ 10 Ω is
regarded as sufficient (see for instance EN 62305-3).
It has to be born in mind that the discharged lightning energy may also appear on the tracks and that
this can endanger the electrical or electronic equipment (e.g. switch controllers, signalling equipment,
switch heaters) that is fitted near the tracks or in the tracks. This hazard can only be minimised if the
equipment is provided with additional surge arresters against overvoltages.
a) Protection of the overhead contact line b) Protection of the overhead contact line and the
running rail (return conductor)
Key
1 arrester A1
2 arrester A2
In both cases the running rails are insulated against earth.
Figure 3 – Installation of surge arresters on the overhead contact line and the running rails
4.5 Rolling stock
Surge arresters are installed on the vehicle roof close to the current collector, as shown in Figure 4.
– 13 – CLC/TS 50544:2010
Key
1 overhead contact line
2 current collector
3 arrester A1
4 main circuit breaker
5 electrical equipment of traction vehicle
6 vehicle body
Figure 4 – Surge arrester arrangement on a vehicle
5 Supply voltages
The relevant values for the supply voltages of the traction systems with the relevant admissible
voltage ranges are given in EN 50163. See Table A.1.
6 Overvoltages
6.1 Lightning overvoltages
Traction systems can be treated the same as medium voltage distribution systems with respect to
overvoltages and insulation co-ordination.
Lightning parameters are derived from statistical analysis of worldwide lightning measurements. The
mostly occurring negative cloud-to-ground flashes have current peak values between 14 kA (95 %
probability) an
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