is46/ps33 lightning protection system improvement · 2010-05-14 · attachment c. existing...

Attachment C. Existing Lightning Protection System

Terms of Reference – Power supply and Lightning protection system – PS33/IS46.

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ATTACHMENT C

IS46/PS33 Lightning Protection System

October 2009



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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



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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:



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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.



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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



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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.




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.



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4. Figures

Figure 1. Lightning attractor at the top of a communication tower.



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Figure 2. Down-conductor at a 10 kV power line pole.



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Figure 3. Layout of communication tower earth termination system.



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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).



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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.



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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.



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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.



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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.



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Figure 13. Equipotential

bonding inside CRF

building: water pipe, sewage

pipe and heating system.



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Figure 14. Grounding bar in the equipment room.

Figure 15. Base of the

CRF communication

tower, grounding rod

and plastic conduits.

is46/ps33 lightning protection system improvement · 2010-05-14 · attachment c. existing...

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