INSTRUCTION HANDBOOK
ELECTRONIC INTERLOCKING AND GRADE
CROSSING SIGNALLING SYSTEM PROTECTION
AGAINST EFFECTS OF THE LIGHTNING CURRENT
H-SPD-06-04-2015-ENG
Surge
Protection
Device
HAKEL spol. s r.o.
Bratri Stefanu 980
500 03 Hradec Kralove
Czech Republic
tel.: +420 494 942 300
fax: +420 494 942 303
e-mail: info@hakel.cz
www.hakel.com
Surge
Protection
Device
Insulation
Monitoring
Device
ELECTRONIC INTERLOCKING AND GRADE CROSSING
SIGNALLING SYSTEM PROTECTION AGAINST EFFECTS OF
THE LIGHTNING CURRENT
With a gradual introduction of electronic protection systems sensitive to the overvoltage into the railway traffic, it is necessary to address
also their protection, especially against dangerous effects of lightning strokes that may cause extensive damages to this equipment.
A railway electronic signalling and interlocking system is a complex system that must be highly reliable and responsive in accordance
with the needs of safe railway traffic. Individual functional units are located both inside and outside buildings, at the railway stations and
on the lines, i.e. in the open environment where the induction from the lightning (impulse) currents has a great effect, both from the short
and long-distance discharges.
Seeking the optimum overvoltage protection thus requires a very special approach that is influenced mainly by the two basic aspects:
• The overvoltage protection installation must not influence a functional reliability and operational safety of the electrical signalling
circuits.
• Acquisition and operating costs should not be excessive.
On electrified tracks the overhead lines act as a protective lightning network and the lightning strokes are mostly caught by exposed
parts of the overhead lines. By this the outdoor parts of the interlocking boxes are protected to a great extent.
It must be, however, taken into account that the effects of the lightning impulses may be transferred via a decentralized electronic
interlocking power supply system from the overhead line not only to the UNZ power supply source but also to the interlocking electric
circuits.
General principles of the protection against a lightning stroke
The lightning impulse releases a huge energy in a short time (in the order of milliseconds or less). The current flowing in the earth-leakage
line to the air terminals after a direct lightning stroke is usually up to 100 kA or even 200 kA in the extreme cases. A typical idealized curve
is shown in the Fig. 1.
This earth-leakage lightning current may induce dangerous voltages up to tens of kV in the earthing system. Moreover, it can destroy the
electronic equipment located close to the strong electromagnetic field created around the earth-leakage conductor.
virtual impulse beginning
Current impulse, definition of front time and time to half-value
6.21. Normalized curve of a test current impulse
This is why a special attention is paid to the earthing systems of buildings of all categories and system solutions are recognized in this area.
A general earthing system should fulfil the three general requirements:
• It must protect the user from destructive impacts of lightning (impulse) and short-circuit currents.
• It must drain the lightning (impulse) or short-circuit current into the earth without creating dangerous contact or step voltages.
• It must ensure the operation and maximum reliability of the electronic equipment.
The effective solution requires a co-ordinated collaboration of several professions which is often negatively influenced by mutual
misunderstanding.
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Scope of protection
A complex protection against effects of lightning strokes consists of the external and internal protection. It includes the
following:
• Potential equalization (inner potential differences) using:
- A grid-type interconnection of all large passive conductive parts (e.g. PE conductors, building reinforcement, metal piping,
lifts and metal cable trays).
- Furnishing the active conductors (e.g. data lines, power grid conductors including PEN and N conductors) with a protection system
or individual protecting elements.
• Reduction of coupling (overvoltage reduction on the active conductors)
- Double-sided earthing of the cable sheaths or channels.
- Removing conductive loops.
- Increasing the distance between parallel conductors.
- Installation of isolation transformers.
• Tapping the overvoltage (controlled overvoltage limitation).
Internal protection against the lightning stroke
The internal protection against the lightning stroke must hinder insulation breakdown between live parts (conductors) and earthed parts
of the equipment, or between live conductors. The dielectric strength of currently used electronic devices is not high due to a high
packing density in the computer circuits. For this reason it is necessary to ensure that the increased voltage that may cause a breakdown
and subsequently a failure or destruction of the device is decreased or removed.
When the lightning strikes to the outer protection, a building potential is significantly increased (see Fig. 2). Therefore a particular emphasis
is given to the potential equalization of all the conductive parts of the equipment. This is also the reason why both the internal and
external protection systems must be solved as one issue considering the following:
• The price of the equipment or object.
• The importance of the equipment for the business.
• The risk of loss of data.
• Local conditions (e.g. availability of the external protection against the lightning stroke).
The internal protection against the lightning stroke includes a whole range of measures and therefore it must be implemented as
balanced as possible with respect to the costs and utilization.
Concerning the solution economy, a compromise should be found since e.g. a complex grid-type system of the potential equalization
shall be very expansive for the existing buildings. The protection of all the live conductors is practical only in exceptional cases.
6.22 Galvanic effect of the lightning (impulse) current
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Implementation of the protective measures against the lightning stroke in the electronic interlocking
and grade crossing signalling system
A complete protection of the electronic equipment against the impulse overvoltage is very expensive. When a conception
of the equipment overvoltage protection is elaborated, an optimum solution must be sought. A failure of a certain instrument
or a limited part of the equipment may be acceptable, e.g. in the locations where the overvoltage occurs occasionally.
When designing and implementation of the investment the protection against the lightning stroke must be already taken into
account so that the general measures can be implemented without additional costs (foundation earth, earthing system for equalizing
potentials, wall reinforcement, etc.). It is also important to establish so called lightning protection zones (LPZ) of the protected object
that are specified in the IEC 1312-1. Protecting element locations should be carefully designed since their efficiency is influenced by their
selection and location.
Internal protection
One of the most important elements of the internal protection of the electronic interlocking boxes is the overvoltage protection system
that limits the dangerous overvoltage leaking from power lines (main and backup HV feeders) to the value specified in the standard.
It is so called concatenation where the first stage includes a spark-gap- or varistor-type surge protection device and 2nd and 3rd stages
consist of the varistor-type surge protection devices.
This connection enables stepwise limitation of the high energy of the lightning impulse current, see Fig. 3.
3. Stepwise limitation of the lightning surge
The electronic interlocking box input lines (main and backup feeders) are equipped with a two-stage cascade (concatenated). The first
stage usually includes a spark-gap-type while the second stage is varistor-type of SPD. Nowadays there are power gas discharge tubes
combined with varistors available.
The experience gained to date has shown that this solution is efficient enough to protect interlocking boxes against dangerous voltages
leaking from the public mains network or from the overhead lines.
Another protection stage against inductive effects of the lightning stroke that is located in some of the internal power supply circuits
(400 V) of the electronic interlocking box consists of varistor protecting elements connected to the earth.
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4. Wiring diagram of the overvoltage protection in the 24 V battery power distribution circuit
To protect the 24 V battery power distribution circuit for microprocessors mainly against the induced atmospheric surge, both lines of the
24 V DC are fitted with an overvoltage protection system connected to the earth (see Fig. 4).
This system represents one of possible solutions consisting of a double gas discharge tube GDT 150 combined with a PIII-230 DS surge
arrester and an earth-leakage monitor (HIS).
The HIS and PIII status signals (signal contacts of both devices are connected in series) are directed to the processing computer via an
auxiliary relay. The signals are then evaluated as a 24 VDC overvoltage protection system failure.
In addition, transient voltage suppressors are connected between the microprocessor supply voltage lines. The schematics representation
of protecting elements location in the AZD electronic interlocking unit is shown in the Fig. 5.
Examples of positions of the lightning surge protection devices and the overvoltage surge protection devices in the power supply and
protection circuits of the 24 V voltage distribution circuit in the electronic interlocking box are shown in the Fig. 6 to Fig. 11. To keep the
internal protection efficient, it is also important to follow the general principles below:
• Careful elaboration of the project documents of the overvoltage protection system. New buildings must be evaluated with respect
to the implementation of appropriate measures already at the construction design stage (foundation earth, reinforcement part
interconnection, and earthing system for equalizing potentials).
• Space separation of the source of interference (e.g. heavy current equipment separated from the sensitive devices of the protecting
system).
• Thoroughly implemented potential equalization system (grid network with short connections) that is connected to all of the exposed
conductive parts of the equipment (earth electrode, external protection against lightning strokes, metal water piping, metal cable
sheaths, reinforcements, PE conductor).
• Earthing system connection between buildings that form parts of the equipment and are interconnected via lines. Under special
conditions, the earthing connection may be left open (breakdown fuse).
• Avoiding loops in power supply and data lines.
• Wires that conduct the surge current (e.g. leads from collectors, conductors for the potential equalization) or the mains network with a
large portion of harmonics must not be routed in parallel to the data lines without shielding.
• It is recommended to use TN-S system that limits interferences.
• Electronic equipment must be supplied from the mains network via isolated lines.
• The shielded lines are earthed on both ends or are routed in the conductive trays that are connected and earthed on both ends.
• It is possible to utilize shielding of devices, equipment or their parts.
• The overvoltage protections must be installed on both ends of the endangered line.
• Separate routing of protected and non-protected lines and their perpendicular crossing.
• If possible, the cable and piping inlets into buildings must be located in a limited area.
Potential equalization protection
An extensive quality system of the potential equalization substantially decreases a risk of overvoltage. However, the quality of the
potential equalization system may by sufficient only in case that it is considered already at the project design stage or during the building
construction (either new or reconstructed). Later solutions are inconvenient and expensive.
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6.27.Location of the protecting elements in the AZD electronic interlocking box
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6. An example of location of the surge protection devices in
the feeders
7. An example of location of the overvoltage protection devices
in UNZ
8. An example of location of the overvoltage protection
devices in certain supply voltage circuits inside the electronic
interlocking box
9. The location of the overvoltage protection device on the
train dispatcher’s console (JOP)
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10. The location of the 24 V battery
power distribution circuit
11. Interstitial protection of the
track circuit power supply cables
(Rohatec railway station)
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Electronic interlocking within the railway network is in most cases installed in the existing objects where the optimum conditions
for the protection against lightning strokes cannot be achieved. In such cases it is possible only to implement a quality system
of the potential equalization in the interlocking room (for examples see Fig. 12 and Fig. 13).
If the interlocking box is installed in a new building, the potential equalization network design must respect the economical
aspect as well as the following criteria:
• An extensive potential equalization system should be implemented only at the locations where the equipment needing
protection is installed or will be installed.’
A protection system range may be limited to a certain area.
• The active functionality of the most of overvoltage protections require a quality potential equalization system.
A full potential equalization is achieved when all the passive parts of the equipment (external protection against lightning strokes, metal
piping, metal cable sheaths, etc.) and the protective conductor of the active parts (power supply and data lines) are connected in case
of overvoltage. If the lightning strikes on the external protection, the potential of all the conductive pars of the equipment increases at
the same level.
If the equipment is installed in more than one building, the earthing systems of all the buildings must be connected.
Since the lightning surge current in the interlocking room contains a strong high-frequency part, the induction of the conductors of the
potential equalization is playing a significant role and thus increasing the wire cross-section to decrease the resistance is not efficient
enough. The inductance may be decreased mainly by implementation of short connecting wires that are connected in parallel.
12. Potential equalization network
13. The main earthing bus
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The parallel connection is achieved by interconnection of all the potential buses and by using of all available conductive
path (e.g. reinforcement). The existing buildings must be often equipped with radial potential equalization systems.
A grid potential network may be implemented only in the cases that are allowed by the building construction stage.
Electronic grade crossing signalling protection
There are the same protection principles against lightning strokes as for the electronic crossing signalling. The only difference
is in the protection of the power input from the local public mains network that is equipped with a 3-stage protection concatenation
(see an example in Fig. 14). If the crossing signalling is supplied from the nearest station via a 6 kV cable or from the overhead line, the
overvoltage protection is only two-stage.
In the electronic grade-crossings that are installed on the non-electrified tracks without the track circuits, both the stretches of rails from
both sides (minimum 40 m from the ASE file connection) are conductively connected and are connected to the individual conductors.
Earthing of the tracks at the electronic grade crossing on the non-electrified line without the track circuits.
When designing the overvoltage protection in the IT systems that are often used with the grade crossings, it is important to check that
the protections between working conductors and earthing points do not decrease the IT insulation level below the level of the earthleakage monitor.
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recommended HAKEL products for
TNC-S network
3 x PI-L xxx
UN = 500 V
IN = xxx A
TYPE 3
DECOUPLING
INDUCTOR
DECOUPLING
INDUCTOR
PIII(M)-275/3+0
UC = 275 V
In = 20 kA (8/20)
UP < 1,3 kV
3-pole arrester
3-phases network TN-C
Imax 50 kA
M - replaceable module
DS – remote monitoring (optional)
SPC25/3+0
UC = 275 V
Imax = 50 kA (8/20)
Iimp = 25 kA (10/350)
In = 25 kA (8/20)
UP < 1,2 kV
UT = 335 V/5 sec (L/N)
3-pole arrester
3-phases network TN-C
Itotal 75 kA
”V”– connection 125 A
DS – remote monitoring (optional)
3 x PI-L xxx
UN = 500 V
IN = xxx A
PI-3k xxx
UC = 275 V
IN = (xxx) A*
UOC = 6 kV
UP < 850 V
TYPE 3
3 x PI-L xxx
UN = 500 V
IN = xxx A
TYPE 2
DECOUPLING
INDUCTOR
TYPE 1
PIV(M)12,5-275/3+0
UC = 275 V
Imax = 40 kA (8/20)
Iimp = 12,5 kA (10/350)
In = 20 kA (8/20)
UP < 1,2 kV
UT = 335 V/5 sec
3-pole arrester
3-phases network TN-C
Itotal 37,5 kA
M - replaceable module
DS – remote monitoring (optional)
P-3k230
UC = 275 V
UOC = 6 kV (8/20)
UP < 1,2 kV
PI-3k xxx
UC = 275 V
IN = (xxx) A*
UOC = 6 kV
UP < 850 V
TYPE 3
TYPE 3
2) switchboard can be equipped
TYPE 1+2
1) switchboard can be equipped
P-3k230
UC = 275 V
UOC = 6 kV (8/20)
UP < 1,2 kV
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recommended HAKEL products for
IT network
DECOUPLING
INDUCTOR
1) switchboard can be equipped
3 x PI-L xxx
UN = 500 V
IN = xxx A
PI-k8 IT
UN = 230 V/ 50Hz
UC = 275 V/ 50Hz
IN = 8 A
Imax = 8 kA (8/20)
UP < 840 V
DS – remote monitoring (optional)
TYPE 1+2
DECOUPLING
INDUCTOR
TYPE 1+2
SPC3.0 90 kA
UN = 3 x 500 V/ 50Hz
UC = 3 x 600 V/ 50Hz
Imax = 90 kA (8/20)
Iimp = 12 kA (10/350)
UP < 2 kV
DS – remote monitoring (optional)
3 x PI-L xxx
UN = 500 V
IN = xxx A
L1 L2 L1 L2 L1 L2
TYPE 1+2
TYPE 3
PI-k8 IT
UN = 230 V/ 50Hz
UC = 275 V/ 50Hz
IN = 8 A
Imax = 8 kA (8/20)
UP < 840 V
DS – remote monitoring (optional)
TYPE 3
PI-k8 IT
UN = 230 V/ 50Hz
UC = 275 V/ 50Hz
Imax = 8 kA (8/20)
UP < 2,2 kV
PE
TYPE 1+2
PE
PE
PE
PE
3) switchboard can be equipped
L1 L2 L1 L2 L1 L2
PE
PI-k8 IT
UN = 230 V/ 50Hz
UC = 275 V/ 50Hz
Imax = 8 kA (8/20)
UP < 2,2 kV
3 x HS55
UC = 440 V
In = 50 kA (8/20)
UP < 2,5 kV
3 x PI-L xxx
UN = 500 V
IN = xxx A
PIII(M)-275/3+1
UC = 275 V
In = 20 kA (8/20)
UP < 1,3 kV
4-pole arrester
3-phases network TN-S, TT
Imax 50 kA
M - replaceable module
DS – remote monitoring
(optional)
TYPE 2
3 x HZ110
UC = 255 V
In = 50 kA (8/20)
UP < 2,5 kV
TYPE 1
3 x PI-L xxx
UN = 500 V
IN = xxx A
PIII(M)-275/3+1
UC = 275 V
In = 20 kA (8/20)
UP < 1,3 kV
4-pole arrester
3-phases network TN-S, TT
Imax 50 kA
M - replaceable module
DS – remote monitoring
(optional)
DECOUPLING
INDUCTOR
DECOUPLING
INDUCTOR
TYPE 2
DECOUPLING
INDUCTOR
2) switchboard can be equipped
L1 L2 L1 L2 L1 L2
PE
TYPE 3
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PE
PE
TYPE 3
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Low voltage limiter for railway application
HL120
HL120 is a low voltage limiter (LVL acc. to EN 50122-1 ed. 2) intended for the protection of non-live parts of metal structures in AC or DC
traction systems. It is used for the effective protection of people who might come into contact with these parts during a lightning stroke
or in the case a fault of traction lines. HL is installed directly on the protected construction structure (using two M12 bolts) so that if it is
activated it creates a conductive connection between this structure and the tracks. The principle of the HL construction is based on the
parallel connection of three non-linear elements (1 high power metal oxide varistor MOV plus 2 high-performance thyristors) built into a
stainless steel cover. If the HL is activated by lightning current or current from the contact of the protected metal structure with for example
a fallen trolley line, this current is instantly shorted to the track by the fast reaction of the MOV (the standardly given time of its reaction
is 25 nsec). The maximum value of this current’s amplitude may be 40kA (10/350). For the duration of activation of the MOV a voltage
protection level about 500V is formed on it. So that the heat released in the MOV does not damage its structure, a delay element is built
into the HL hardware which for approximately 1msec ignites both the built-in high performance thyristors, and this moment is derived
from the VPL on the varistor. According to the polarity of voltage on the MOV, the relevant thyristor from the built-in pair is activated
and it takes up current which to that time have been conducted by the activated MOV. Depending on the immediate current value of
the passing current, the voltage level on this thyristor can be in the range 1÷3V. If the arising activation current is significantly lower than
the maximum working current of the used thyristor, this process can last up to tens of seconds (for the HL120 this process is characterised
by the typical value 300A/60sec... reversibly), which corresponds to the charge passing through of 18000 Asec. A large power loss is on
the thyristor for the time of its activation, and so the construction of the HL sleeve is based on the principle of conducting the released
heat to its metal outer casing and then via this casing to the construction building structure. One important requirement of the HL is the
assumption of the creation of an internal short circuit in the case of the voltage, current or heat overloading of the built-in MOV, which is
met in the case of the HL internal construction described above.
Advantages - vandal resistant, weather proof, long lifetime
Type
HL 120
Nominal voltage Ur
50 VAC
Maximum withstand voltage Uw
60 VAC
Maximum spark voltage Us
120 VDC
Nominal short-term withstand current
10 kA / 0,01 sec
Reversible current Irev
300 A for 60 s
Long-term current impulse Lw without guaranteed reversibility
500 A for 1800 s
Technical data of built-in metal-oxide varistors acc. to
EN 61643-11 ed. 2 and EN 60099-4 ed. 2
Nominal discharge current In
40 kA (8/20 µs)
Surge impulse current Ihc
100 kA (4/10 µs)
Lightning impulse current Iimp
40 kA (10/350 µs)
Maximum operational voltage Uc
115 VAC
Varistor voltage Uv@ 1mA
180 VDC
Residual voltage Up at nominal discharge current In
500 V
Long current impulse
6 x 3 x 1500 A (2000 µs)
Operating conditions:
-25°C to + 55°C
Temperature
Tightening torque
16 Nm
Height above sea level
without restriction
Protection type
IP 67
Weight / rozměry
c. 4,65 kg /
Article number
114 mm, l = 95 mm
10 240
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Low voltage limiter for railway application
HGS150 RW
It is range of voltage limiters designed for overvoltage protection of personnel and equipment in DC and AC rail traction systems. It
is recommended to install this limiter between the current return path and non-electrified parts of structures laying adjacent to the
rails. Internal construction of HGS is based at application of high power gas-filled gas discharge tube (GDT), which is built in to stainless
steel box. In case of overvoltage, HGS150 RW generates a durable conductive path between the overloaded area and the railway’s
substation. This results in increased current loads that are sensed at the substation, tripping the safety switch and thus protecting
personnel and equipment. In addition, all overvoltages generated by lightning are effectively limited by Hakel’s internal construction of
HGS150 RW. All requirements given by EN 50122-1 and EN 61643-1/A11 relating to electrical safety earthing for this specific use are also
fulfiled.
Type
Examinations according to
DC Spark-Over Voltage 1)
HGS150 RW
EN 61643-11/A11, EN 50122-1
300 ÷ 500 V *
AC Spark-Over Voltage
Impulse Spark-Over Voltage at 5 kV/µs - for 99% of measured
values (wave 1,2/50 µs, 6 kV)
> 350 Vrms
< 1200 V
Max. Impulse Discharge Current Imax (8/20 µs)
Nominal Impulse Discharge Current In (8/20 µs)
200 kA
Max. Lightning Impulse Current Iimp (10/350 µs)
150 kA
100 kA
Charge
Specific Energy
Rated withstand current
Behaviour after substantial overloading
Insulation Resistance at 100 VDC
75 As
5500 kJ/Ω
up to 8 kArms / 100 msec (AC - mode)
up to 20kA / 30 msec (DC - mode)
internal short circuit inside HGS150 body
>1 GΩ
Capacitance at 1 MHz
Housing
Operating and Storage Temperature
Weight
Climatic Category (IEC 60068-1)
Article number
< 5 pF
IP66
- 40 ÷ + 90°C
1260 g
40/90/21
10 113
* The same product for 200-300V is possible to produce on the base of special demand (Art. 10 115)
1)
In ionised mode
Terms in accordance with ITU-T Rec. K-12, DIN 57845/VDE 0845 and EN 61643-11:2002
YY - Year of the Production
O - Non Radioactive
INSTRUCTION HANDBOOK
ELECTRONIC INTERLOCKING AND GRADE
CROSSING SIGNALLING SYSTEM PROTECTION
AGAINST EFFECTS OF THE LIGHTNING CURRENT
H-SPD-06-04-2015-ENG
Surge
Protection
Device
HAKEL spol. s r.o.
Bratri Stefanu 980
500 03 Hradec Kralove
Czech Republic
tel.: +420 494 942 300
fax: +420 494 942 303
e-mail: info@hakel.cz
www.hakel.com
Surge
Protection
Device
Insulation
Monitoring
Device