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Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 1 of 16
ATTACHMENT C
IS46/PS33 Lightning Protection System
October 2009
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 2 of 16
TABLE OF CONTENTS:
1. Summary .............................................................................................................. 3
2. Terminology ......................................................................................................... 3
3. LPS description .................................................................................................... 3
3.1 Array elements ............................................................................................ 3
3.1.1 Air termination system .......................................................................... 3
3.1.2 Down-conductors .................................................................................. 3
3.1.3 Earth-termination system ...................................................................... 3
3.1.4 Equipotential Bonding ........................................................................... 4
3.1.5 Surge Protective Devices ....................................................................... 5
3.2 Central Recording Facility ......................................................................... 5
3.2.1 Air termination system .......................................................................... 5
3.2.2 Down-conductors .................................................................................. 5
3.2.3 Earth-termination system ...................................................................... 5
3.2.4 Bonding system ...................................................................................... 5
3.2.5 Surge Protective Devices ....................................................................... 6
4. Figures .................................................................................................................. 7
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 3 of 16
1. Summary
The document describes the Lightning Protection System (LPS) at the IS46/PS33 co-
located IMS arrays in Zalesovo, Russian Federation, as it is in October 2009.
The document is prepared based on the results of the station visit carried out during
the period 15-22 October 2009.
2. Terminology
CRF – Central Recording Facility;
SPD – Surge Protective Device;
Station – IS46 infrasound and PS33 seismic co-located IMS arrays;
3. LPS description
3.1 Array elements
The LPS consists of the following sub-systems, described in details below:
Air termination system;
Down-conductors;
Earth-termination system;
Equipotential bonding;
Surge protective devices.
3.1.1 Air termination system
The air termination system consists of lightning attractors, installed on the top of each
communication tower.
The lightning attractors are 2-sectional, 3-m high pipes, with 48/27 mm O.D. and wall
thickness of 3.25/2.5 mm. The lightning attractors are made of bare construction steel
and painted. The pipe is welded to the tower (Figure 1).
3.1.2 Down-conductors
The down-conductors are installed on the last pole of the 10 kV power line, one per
pole. They connect the mounting profiles of 10 kV surge protective devices and step-
down transformer with the earth termination system. However, the conductors are not
installed at a number of array elements, e.g. at A1, B1 and B2. The conductors are
made of 8-mm diameter solid round construction steel (cross-section 50 mm2). At H1
and A0/A0B the down-conductors are fixed to the earth-termination system at the
bottom of the pole by welding and by clamp-type connectors.
3.1.3 Earth-termination system
The existing earth-termination system consists of two parts:
1. A combination of vertical and horizontal earth electrodes, connected to the
communication towers, as shown in Figure 5. At the array elements the earth-
termination system is made of bare construction steel as follows:
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 4 of 16
At elements H4 and B4: 7 vertical electrodes of 3 m long each; right-angle
profile with dimensions 35x4 mm. Those electrodes are connected to
horizontal electrodes buried at 20 to 30 cm depth. The horizontal electrodes
are made of solid, round construction steel bars with a diameter of 10 mm.
They have a total length of approximately 24 m, arranged in a form of a
triangle.
At the rest of the elements: 7 vertical electrodes of unknown length (probably
less than 3 m), made of solid, round 18-mm diameter construction steel. They
are connected to horizontal electrodes buried at 20 to 30 cm depth. The
horizontal electrodes are made of metal strap with dimensions of 40x4 mm,
with total length of approximately 24 m, arranged in a form of a triangle.
.
In addition, each communication tower has 4 or 8 (depending on the tower height)
guy-wires anchors, also serving as ground electrodes.
The components of the grounding system show clear signs of corrosion at a depth of
approximately 30 - 40 cm. This depth corresponds to the boundary between the two
superficial ground layers (upper soil layer and loam layer below). The measured
thickness of one of the vertical electrodes at H4 is 4 mm on the top, and 3 mm at the
depth of 40 cm. The grounding system was installed in 2004, thus the corrosion rate
can be roughly estimated to be 0.2 mm per year.
2. Metal equipment vaults
At array elements H4 and B4 the equipment vaults and the communication towers are
not connected to each other. A the rest of the array elements both installations are
connected by a 20x4 mm bare steel strap laid 20 cm below the ground.
3. Other
The fences of the array elements are not connected to the grounding system.
The earthing rods at the last poles of the power transmission lines are not connected to
the earth termination system of the array elements, except at element H2.
The pipe arrays at the infrasound array elements are not electrically connected to the
earth termination system. The pipes of the pipe arrays are painted and cannot
contribute much to the improvement of the earth termination system.
3.1.4 Equipotential Bonding
At the array elements all the chassis of the equipment installed inside the equipment
vaults is connected to the metal walls of the vault. The chassis of the modems,
installed at the communication towers, is connected to the tower ant then to the earth
termination system at the tower. The PE wire of 20 VAC input cable is also connected
to the walls of the vaults.
The 10 kV power line is a two-phase line without PEN conductor. The PEN
conductors of the 220 VAC and 20 VAC systems are not connected.
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 5 of 16
3.1.5 Surge Protective Devices
Surge protective devices:
10 kV line: According to the station’s documentation, the 10 kV part of the power
system should be protected by combined SPDs type RVO (spark gap and varistor),
installed at the beginning of the line and at each last pole. However, at the Station
these devices are installed only at the beginning of the line and at the array elements
H1, H4/B4, A0/A0B.
220 VAC part: According to the station’s documentation, this part should be protected
by a varistor-type OPS1-C/2 devices (Class C SPD according to VDE0675 or Class 2
SPD as defined in IEC 61643), installed between phase and PE conductor. However,
the SPDs are incorrectly installed between the PE conductors of the 220 and 20 VAC
systems. In addition, the installed SPDs are rated for maximum continuous operating
voltage Uc of 320 V, which is incorrect for this type of installation. In summary, the
220 VAC part of the system is not protected.
20 VAC part: Not protected.
DC part: Not protected.
Ethernet link to the modem: Protected by the Huber&Suhner Data Line Protector
mod. 3414.99.0001. Note: the 24 VDC power line to the modem is not protected.
GPS cable: Protected by Polyphaser DGXZ+06NFNF-A surge arrestors.
Cables to meteorological sensors (H1 infrasound element only): Not protected.
3.2 Central Recording Facility
3.2.1 Air termination system
The existing air-termination system at the CRF consists of a 47-m high
communication tower, located 16 m away from the building. There are also two 8-m
reinforced concrete poles located approximately 6 m away from the building on two
opposite sides, which can be used at a later stage as bases of additional lightning
attractors.
3.2.2 Down-conductors
No down-conductors are installed on the tower.
3.2.3 Earth-termination system
The earth-termination system includes the building’s ground loop, the concrete bases
of the communication tower with one earthing rod (50x5 mm, right-angle profile,
length unknown), the anchors of the 6 guy-wires, and finally, the two satellite dishes
The building is not interconnected to the bases of the tower and the satellite dishes.
3.2.4 Bonding system
All conductive and continuous pipe systems and shields and the PEN conductors of
all incoming power cables, running to the CRF building are connected together and to
the protective ground of the building. All incoming power supply cables are shielded
and laid underground. The shield of the signal cable to the radio modem is not
connected to the ground. This cable runs inside an above-ground plastic conduit. The
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 6 of 16
outgoing 220 VAC lines (2 wires, L and N) to satellite dishes are not shielded, but
laid underground in a metal pipe. However, the metal pipe is not connected to the
local ground of the satellite dishes.
The telephone line is not protected.
List of incoming and outgoing cables and pipe systems:
1. 3-phase 0.4 kV line from TP 2 for building’s installation, 4 wires & shield.
2. 3-phase 0.4 kV line from TP 4 for building’s installation, 4 wires & shield.
3. 3-phase 0.4 kV line from diesel generator for building’s installation 4 wires &
shield.
4. 3-phase 0.4 kV line from TP 2 for heater, 4 wires & shield.
5. 3-phase 0.4 kV line from TP 4 for heater, 4 wires & shield.
6. 3-phase 0.4 kV line from diesel generator for heater, 4 wires & shield.
7. 3-phase 0.4 kV line from diesel generator for heater, back-up, not connected, 4
wires & shield.
8. 1-phase 230 V line to communication tower light, 2 wires, no shield.
9. 1-phase 230 V line to the satellite antenna 1, 2 wires, no shield.
10. 1-phase 230 V line to the satellite antenna 2, 2 wires, no shield.
11. PoE line to the station’s modem, Cat5 cable.
12. Cat5E cable to RN station.
13. Coaxial cable RK11 (RG8 type) to the satellite antenna 1, F=3650-4200 MHz.
14. Coaxial cable RK11 (RG8 type) to the satellite antenna 1, F=5975-6525 MHz.
15. Coaxial cable RK11 (RG8 type) to the satellite antenna 2, F=3650-4200 MHz.
16. Coaxial cable RK11 (RG8 type) to the satellite antenna 2, F=5975-6525 MHz.
17. Telephone line to RN building (twisted pair).
18. Water pipe.
19. Sewage pipe.
3.2.5 Surge Protective Devices
The building does not have any SPDs.
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 7 of 16
4. Figures
Figure 1. Lightning attractor at the top of a communication tower.
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 8 of 16
Figure 2. Down-conductor at a 10 kV power line pole.
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 9 of 16
Figure 3. Layout of communication tower earth termination system.
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 10 of 16
Figure 4. Bonding strap 20x4 mm between equipment vault and communication
tower.
Figure 5. Connection of earth termination system to the communication tower (H4
array elemnt).
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 11 of 16
Figure 6. Part of the earth termination system at H4 array element, a grounding rod
and horizontal conductor. Signs of corrosion are clearly visible at the boundary
between the upper soil layer and yellow loam layer below.
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 12 of 16
Figure 7. Part of the earth termination system at H2 array element, a grounding rod
and horizontal conductor.
Figure 8. Guy wire’s anchor of a communication tower.
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 13 of 16
Figure 9. Installations at a last pole of 10 kV line, including surge protection devices
type RVO-10, fuses and 10/0.2 kV transformer.
Figure 10. 220/20 VAC
transformer and surge
protection device type
OPS1-C/2.
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 14 of 16
Figure 11. View of the CRF building, communication tower, satellite dishes and
concrete pole for lightning attractor.
Figure 12. Grounding bar at the entrance of power cables in the CRF. Connection of
PEN conductors and cable’s shields.
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 15 of 16
Figure 13. Equipotential
bonding inside CRF
building: water pipe, sewage
pipe and heating system.
Attachment C. Existing Lightning Protection System
Terms of Reference – Power supply and Lightning protection system – PS33/IS46.
04/02/2010 Page 16 of 16
Figure 14. Grounding bar in the equipment room.
Figure 15. Base of the
CRF communication
tower, grounding rod
and plastic conduits.