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Franklin France Saint-Elme® lightning conductor
With piezoelectric exciter device
Complies wih NFC 17-102 standard Franklin - France / CEA patent
Franklin France presents you the Saint-Elme® lightning conductor. It results from the research work conducted with the French Atomic Energy Commission, and is the
efficient, inexpensive and clean protection solution, using piezo – electric ceramics to
transform the wind energy into electric energy.
Principle
A rod – type lightning conductor, connected to earth, efficiently works by altering, at its level,
the equipotentials which match the structures of the building it protects. The emergence of
the lightning conductor is an important factor in increasing the local electric field. The
principle of the piezoelectric lightning conductor designed by Franklin France relies on
several factors : the reinforcement of the local electric field and the early creation of a
preferential discharge channel.
Description
The SAINT-ELME® piezoelectric lightning conductor is mainly composed of the
following :
1. Capture head
Profiled, inalterable and good conductor, structured to generate a forced air circulation at its tip and in its prolongation (VENTURI system : air intakes and peripheral ejectors).
2. Support pole
Of treated copper (or stainless steel according to models) which upper part has one or more
stainless steel ion emitter points, inserted in an insulating sleeve and subjected to the
potential supplied by the piezo–electric ceramic.
The emitter points are protected from direct impact by lightning and from the weather by the
capture head which, like the support pole, is permanently connected to the earth potential.
3. Transducer (piezoelectric stimulator)
Built into the lower part of the pole and consisting of piezoelectric ceramics stressed in an
insulating container, combined with a simple, perfectly reliable and mechanical stimulation system (CEA and FRANKLIN patents). A high – voltage cable running inside the pole
connects the stimulator to the emitter point(s). The voltage created by the
ceramic is applied to the emitter point through the high voltage cable. |
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Opration
Piezoelectric Stimulation
The basic principle of the Saint-Elme® lightning conductor is to
increase the number of free charges (ionized particles and electrons) in the air surrounding the lightning conductor and to create, within a cloud–ground electric field, a channel of high relative conductivity
constituting a preferential path for lightning.
Free charges are created by the corona effect by applying on the Saint-Elme® lightning conductor’s ionized point(s) the voltage supplied by cells of piezo–electric ceramics (lead zirco–titanate); their feature is to produce a very high voltage by simply modifying the applied pressure. The Saint-Elme® lightning conductor is therefore equipped with a
mechanical device that transforms the stress resulting from the wind action on the lightning
conductor into a pressure stress on the piezo–electric cells.
The voltage therefore produced is applied, through the high voltage cable that runs inside
the lightning conductor’s support pole, onto the ionized point(s) to create, by corona effect,
free charges. Then, these charges are expulsed, by the venturi system, from the lightning
conductor’s head, profiled on purpose (forced air circulation). When they are outside the
head, these charges are submitted to the cloud–ground electrical field. The charges
polarized like the cloud are repelled towards the ground, the channel of charges that forms
in prolongation of the lightning conductor is then exclusively composed of charges from the
opposite pole to the cloud’s electric pole (it takes into account the discharges’s pole :
(positive or negative).
Reduction of the excitation time of the CORONA effect
Any artificial increase in the ionic density of the air surrounding an electrode favours a
lowering of the breakdown potential.
Therefore, by favouring :
- The increase of the local electric field,
- The presence of a seed electron at the capture point (electron that is rare in the atmosphere and necessary for the excitation process),
- The creation of a rising ionized air channel in the prolongation of the lightning conductor, it will lead to the shortening of the excitation lag, and to favourably
influence the initial conditions of the triggering of the corona effect.
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Protection Specifications
Protection offered by Saint - Elme® lightning conductors
(NFC 17-102)
Preferential capture
The ability to promote excitation at lower values of the
electrostatic field (hence earlier) enhances the capture probability of lightning conductors. This capacity gives them
greater efficiency in the role of “preferential capture points”
compared to any other point of the building they protect.
Therefore these lightning conductors offer superior guarantees
during low intensity discharges (2 to 5 KA) compared with simple
rod type lightning conductors, which can only intercept them over short distances (D = 10 I 2/3, where D is in meters, I in KA). |
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Larger zone of protection
The zones of protection of lightning conductors are obtained theoratically by plotting the electrogeometric model, but
are comparable in practice, for low heights, to a cone of revolution which apex is the tip of the lightning conductor.
French standard NFC 17 100 describes the calculation method applicable to Franklin and meshed cages rods.
French standard NFC 17 102 deals with early streamer emission (ESE) lightning conductors, and takes into account the
levels of protection Np of varying severity (I to III), to be determined previously by an assessment of the lightning risk
for each project.
It defines the installation rules and the radii of protection Rp (m) depending on the average excitation advance ∆ L (m) of the lightning conductors and the excitation distance D (m), considered according to the degree of
severity : D (I) = 20 m, D (II) = 45 m, D (III) = 60 m.
The table hereunder gives the Rp (m) values for the three levels of protection Np depending on the actual height h(m)
of the lightning conductor in relation to the different planes considered.
Rp (m) |
SE6 ∆ L = 15 m |
SE9 ∆ L = 30m |
SE12 ∆ L = 45 m |
SE15 ∆ L = 60 m |
h(m) \ Np |
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2 |
13 |
18 |
40 |
19 |
25 |
28 |
25 |
32 |
36 |
31 |
39 |
43 |
4 |
25 |
36 |
41 |
38 |
51 |
57 |
51 |
65 |
72 |
63 |
78 |
85 |
6 |
32 |
46 |
52 |
48 |
64 |
72 |
63 |
81 |
90 |
79 |
97 |
107 |
8 |
33 |
47 |
54 |
49 |
56 |
73 |
64 |
82 |
91 |
79 |
98 |
108 |
10 |
34 |
49 |
56 |
49 |
66 |
75 |
64 |
83 |
92 |
79 |
99 |
109 |
20 |
35 |
55 |
63 |
50 |
71 |
81 |
65 |
86 |
97 |
80 |
102 |
113 |
30 |
35 |
58 |
69 |
50 |
73 |
85 |
65 |
89 |
101 |
80 |
104 |
116 |
60 |
35 |
60 |
75 |
50 |
75 |
90 |
65 |
90 |
105 |
80 |
105 |
120 |
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Applications
Lightning is a natural, universal and permanent phenomenon. It occurs daily and strongly in tropical areas.
Lightning causes considerable damages and expenses to a country’s economy, it also represents a significant and
constant threat for the population. Every year some people are killed, mainly while being in open–areas.
Industries
Refineries, pump stations |
Open–air installations
Stadiums, golfs, amusement parks |
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Telecomunications
Hertzian relays, antennas |
Buildings
Warehouses, churches, monuments |
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Saint-Elme®
range
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Tyoe |
Standard |
Corrosive
atmosphere |
Church |
Church |
Historical
monument |
Aladin |
Model |
2 m chromium
plate copper |
2 m stainless
steel |
1,5 m chromium
plate copper |
1,5 m chromium
plated copper |
2 m polished
copper |
2,4 m chromium
plated copper |
SE 6 |
reference |
reference |
reference |
reference |
reference |
reference |
AFB0006SE |
AFB1006SE |
AFB2006SE |
AFB3006SE |
AFB0016SE |
AFB4006SE |
SE 9 |
AFB0009SE |
AFB1009SE |
AFB2009SE |
AFB3009SE |
AFB0019SE |
AFB4009SE |
SE 12 |
AFB0012SE |
AFB1012SE |
- |
- |
AFB0112SE |
AFB4012SE |
SE 15 |
AFB0015SE |
AFB1015SE |
- |
- |
AFB0115SE |
AFB4015SE |
Saint-Elme® kits equipped with impact controllers (Discharge Counters)
Tyoe |
Standard |
Corrosive
atmosphere |
Church |
Church |
Historical
monument |
|
Model |
2 m chromium
plate copper |
2 m stainless
steel |
1,5 m chromium
plate copper |
1,5 m chromium
plated copper |
2 m polished
copper |
Kit SE 6 |
reference |
reference |
reference |
reference |
reference |
AFB0706SE |
AFB1706SE |
AFB2706SE |
AFB3706SE |
AFB4706SE |
Kit SE 9 |
AFB0709SE |
AFB1709SE |
AFB2709SE |
AFB3709SE |
AFB4709SE |
Kit SE 12 |
AFB0712SE |
AFB1712SE |
- |
- |
- |
Kit SE 15 |
AFB0715SE |
AFB1715SE |
- |
- |
- |
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