Nfc 17-102 Pdf Free Download

This paper is devoted to a detailed presentation of all aspects involved in a novel experimental technique to prove the effectiveness of an early streamer emission air terminal (ESEAT) versus a traditional Franklin rod in a laboratory. Firstly, a theoretical basis for the equivalent-circuit analysis of an ESEAT model is presented. It is shown that the dynamic electric field intensity on the active ESE rod is higher (theoretically even twice as high) than the static field intensity of the conventional Franklin lightning rod. Then, an experimental test using a method and associated with an electrostatic simulation demonstrates the effectiveness of an ESEAT (Pix3-60 from Piorteh Company) versus a conventional Franklin rod in the SIAME laboratory of the University of Pau in France. This method consists in locating both the ESE terminal and the Franklin rod together in the same configuration in accordance with the French Standard NFC 17-102 (09/2011). During the tests, all discharges were recorded on the ESEAT manufactured by Piorteh Company when its rod was active. This experimental test could be used on any kind of lightning protection device.

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IEEE Transactions on Dielectrics and Electrical Insulation Vol. 22, No. 2; April 2015 789

DOI 10.1109/TDEI.2014.004629

Experimental Demonstration of the Effectiveness of an Early

Streamer Emission Air Terminal Versus a Franklin Rod

L. Pecastaing, T. Reess, A. De Ferron, S. Souakri

Laboratoire SIAME, Equipe Génie Electrique,

Université de Pau et des Pays de l'Adour,

Hélioparc Pau-Pyrénées, 2 av Angot 64053 Pau cedex 9, France

E. Smycz

Piorteh and Orw-Els companies, 53 rue Berthe, 75018 Paris, France

A. Skopec and C. Stec

Institute of the Fundamentals of Electrotechnics and Electrotechnology

Wroclaw University of Technology, Wybrzeze Wyspianskiego

27, 53-370, Wroclaw, Poland

ABSTRACT

This paper is devoted to a detailed presentation of all aspects involved in a novel

experimental technique to prove the effectiveness of an early streamer emission air

terminal (ESEAT) versus a traditional Franklin rod in a laboratory. Firstly, a

theoretical basis for the equivalent-circuit analysis of an ESEAT model is presented. It

is shown that the dynamic electric field intensity on the active ESE rod is higher

(theoretically even twice as high) than the static field intensity of the conventional

Franklin lightning rod. Then, an experimental test using a method and associated with

an electrostatic simulation demonstrates the effectiveness of an ESEAT (Pix3-60 from

Piorteh Company) versus a conventional Franklin rod in the SIAME laboratory of the

University of Pau in France. This method consists in locating both the ESE terminal

and the Franklin rod together in the same configuration in accordance with the French

Standard NFC 17-102 (09/2011). During the tests, all discharges were recorded on the

ESEAT manufactured by Piorteh Company when its rod was active. This experimental

test could be used on any kind of lightning protection device.

Index Terms - Lightning protection, early streamer emission, electrical discharge,

effectiveness evaluation, active rods.

1 INTRODUCTION

THE investigation of atmospheric discharges belongs to

the most complex challenges of science and technology,

requiring a broad interdisciplinary approach. This is due to the

fact that an extremely large number of factors in a cause and

effect relationship are involved in the generation and

development of atmospheric electricity phenomena,

particularly the accumulation of an electric charge and the

various forms of its discharge. It is only known that the

lightning protection devices are studied and for the last decade

or so increasingly employed.

The effectiveness of the standard Franklin rod, used in

lightning protection, is known to depend on the development

of a corona effect near its tip as the result of high electric

fields developed in a lightning storm [1]. With the approach of

a downward leader, the resulting rapid field enhancement

increases corona activity. When electrical conditions are

fulfilled, one of the streamer filaments which constitute the

corona may undergo sufficient heating to develop into a highly

conductive, arc-like 'upward leader' which can then propagate

for a considerable distance in a comparatively low electric

field. It may thus progress towards the downward leader. The

downward and upward leader will meet thus forming one new

leader bridging the gap and allow the subsequent high-current

discharge to pass down the conducting path so formed.

A simple passive Franklin rod, on the roof of a large

building, may not give full protection against a strike to the

building itself, since upward corona may be initiated at parts

of the structure more favorably placed in relation to the

downward leader. A much better efficiency can be expected

however from an 'active' rod, for which a corona effect is

initiated at an early time during the downward progress of the

lightning.

Manuscript received on 3 March 2014, in final form 4 November 2014,

accepted 13 November 2014.

790 L. Pecastaing et al.: Experimental Demonstration of the Effectiveness of an Early Streamer Emission Air Terminal

This principle forms the basis of the so-called early

streamer emission devices which have been developed in

recent years. The success of such a device depends on the

timing of the corona initiation in relation to the downward

leader approach and the rapidity with which the leaders can

attach compared with the time that would have been taken

with passive rods. During the lightning in negative polarity,

the propagation of a negative downward leader systematically

leads to the development of a positive upward leader [2]. The

development of this upward leader is conditioned by the

electric field increase induced by the downward leader near an

asperity (e.g. lightning protection device). In the case of an

ESEAT, the positive corona or upward leader is initiated by

the active lightning protection device regardless of the

position of the downward leader. The breakdown time is

therefore decreased.

Three types of lightning protection systems are in common

use today: conventional systems, Charge Transfer Systems,

and systems based on Early Streamer Emission air terminals

(ESEAT) [3].The purpose of a lightning protection system

(LPS) is to prevent or greatly reduce damage from a direct or

nearby lightning strike to the protected facility. A

conventional LPS is designed to prevent damage by providing

a number of preferential strike receptors (air terminals) with

low impedance paths to conduct the large lightning current

harmlessly to the ground. ESEAT are claimed to have a much

larger zone of protection than conventional lightning air

terminals, resulting in an LPS with significantly fewer air

terminals and down conductors than a conventional one.

Studies have shown that taking into account the upward leader

increases the radius of the protection sphere in the

electrogeometric model [4].

There are a few types of ESEAT working on a different

principle [5]:

- The air ionization at the tip is produced by piezoelectric

element using the wind energy,

- The air ionization is caused by electrical impulses

delivered by a generator. The electrical field of downward

leader charges a capacitor which supplies the generator,

- The high voltage impulse is induced by the

electromagnetic impulse in a coil. The product presented in

this paper (Pix3-60 manufactured by Piorteh Company) is

based upon this principle. Here a theoretical basis of active rod

is presented at first and then an experimental test using a novel

method and associating with an electrostatic simulation

demonstrates its effectiveness versus a conventional Franklin

rod in a laboratory.

2 TEST TECHNIQUES OF LIGHTNING

PROTECTION SYSTEMS

Because of the considerable danger to life and property

arising from lightning discharges, lightning protection

improvement constitutes an important technical and economic

issue. Since 100% lightning protection is technically and

economically impossible, it is essential to seek and use

protective devices substantially increasing its effectiveness.

Active ESEAT meet such requirements. Nevertheless the

current opinions about active rods are often controversial and

contradictory [5-9]. Various experiments are presented in

laboratory or in nature under operating conditions. The

effectiveness of ESEAT is clearly demonstrated in laboratory

conditions. However, under natural conditions, their

effectiveness is difficult to prove and is not unanimous.

In order to discuss the LPS technology, it is necessary to

have a basic understanding of the phenomenology of the

lightning process. More detailed discussion can be found in

standard references on lightning (e.g., [10]). The electric fields

on the ground under a thunderstorm are typically 5 to 20 kV/m

[3]. The field at the tip of an exposed lightning conductor

terminal can thus be expected to be much higher. These

conditions can be simulated in the laboratory by application of

a DC voltage to a large object suspended above a conductor.

The subsequent descent of the leader is simulated by the

super-imposition of an impulse voltage to the gap, with fall

time approximating to that of the field produced by an

approaching leader.

A critical test requires not only measurement of the

respective probabilities of striking to active and passive rods,

but also information on the time during the impulse at which

the strike occurs.

The classical method to test an ESEAT in a laboratory is to

use the French Standard NFC 17-102 (09/2011) [11] which

describes the testing condition and evaluation criteria for

ESEAT. Electrical, mechanical, environmental as well as

electromagnetic compatibility requirements are fully explained

in the standard. The effectiveness of the ESEAT is assessed by

way of comparing, in a high voltage laboratory, the emission

time of the ascending tracer, which it emits with the one a

reference single rod air terminal (SRAT) emits. To achieve

this, the SRAT and the ESEAT are assessed one after the other

under the same electrical and geometrical conditions during

laboratory tests that simulate natural discharge capturing start-

up conditions (ascending positive tracer). The natural wave

that exists before a lightning strike has consequences on the

forming conditions of the corona and the pre-existing space-

charge. It is therefore necessary to simulate it by applying a

direct current that creates electric fields between the plate and

the ground ranging between 20 kV/m and 25 kV/m. The

impulse field may be simulated by a switching impulse whith

fall time ranging between 100 μ s to 1000 μ s. The waveform

slope when the upward leader initiates should be between

2.108 and 2.109 V/m/s. The impulse field is preferably

simulated with a 250/2500 µs shaped operational wave as per

CEI 60060-1.

The chosen criterion in the standard for assessing the

effectiveness of ESEAT is its ability to repeatedly emit an

ascending tracer before SRAT placed under the same

conditions. For each usable impact on the SRAT and on the

ESEAT, one measures the value of the emission time of the

upward leader. Based on the measurements of the ascending

tracer's emission times taken from SRAT and ESEAT, the

average emission times TmoySRAT and TmoyESEAT are calculated.

IEEE Transactions on Dielectrics and Electrical Insulation Vol. 22, No. 2; April 2015 791

The standard deviations of the two distributions are also

calculated (σ SRAT and σ ESEAT ).

While using the reference wave shape (fall time = 650 µs),

one deduces the emission times related to the reference curve

Tmoy'SRAT and T moy'ESEAT used for calculating the early streamer

emission Δ T(μ s) = Tmoy'SRAT – Tmoy'ESEAT .

The tested lightning conductor of an ESEAT is in

accordance with the French Standard if both of the following

conditions are met:

Tmoy'ESEAT < Tmoy'SRAT and σ ESEAT <0.8.σ SRAT .

ΔT shall range between 10 µs and 60 µs. It is assumed that

the earlier streamer "elongates" the height of ESEAT and by

this manner the attractive area of active devices increases by

the distance of Δ L.

Other experiments are available in open literature which

enable us to prove the effectiveness of the ESE terminals in

laboratory. As an example, it is possible to directly test the

ESE terminal in comparison with a traditional Franklin rod. If

the geometrical configuration is the same, then the discharges

must be systematically initiated on the ESE terminal. These

conditions were satisfied in experiments performed by

Bouquegneau [6] in which the numbers of strikes were

measured, out of two groups of 100 shocks, to an active and a

passive rod mounted l.00 m and 2.00 m apart and

symmetrically placed in relation to an upper rod electrode

suspended vertically above the mid-point of the line joining

the bases of the two rods. An impulse voltage (1.2/50 µs) was

applied to the upper rod. The active rod was excited by a

steady 25 kV voltage applied from a separate supply; active

corona is assumed to have been set up. The results showed no

significant difference between the rates of striking with regard

to the active and passive rods. The tests, however, could not

be regarded as conclusive, since the impulse voltage to the

upper rod was too fast to simulate the effects of the leader

descent and no preceding steady electric field was provided.

Generally, similar tests on commercial devices have been

carried out more recently by Grzybowski et al [7] with similar

results.

Finally, we can find some data in literature where ESEAT

are tested outside under operating conditions. Some

publications may show failures in ESEAT functioning [3, 5, 9,

12]. As an example, many cases of ESEAT and radioactive

terminal failures in Malaysia were recorded in recent years

[5]. The failures in Kuala Lumpur were often detected on

buildings higher than 60 m. In another field study, Hartono

[12] has documented many instances of lightning strikes to

structures in Malaysia and Singapore, which bypassed ESEAT

installed on them, and struck parts with the structures within

the zones of protection claimed for the terminals.

The aim of this present paper is to give a novel method to

prove the effectiveness of ESEAT versus a traditional Franklin

rod in a laboratory with a direct comparison of these two

devices. Unlike previous work [6-7], the geometrical and

electrical configurations are identical to that of the French

Standard. Before experimental tests, a theoretical analysis of

an active rod is presented.

3 THEORETICAL ANALYSIS OF AN ACTIVE

ROD

3.1 THEORETICAL BASIS OF THE MODEL UNDER

CONSIDERATION

As far as the theoretical aspect is concerned, the first

stage can be correctly described by the quasi-electrostatic

field equations while the development of the main stage

phenomena requires an electrodynamic description. Due to

the existence of the first stage one can formulate a

relatively simple mathematical model on the basis of which

various active ESEAT designs can be sought.

In this part, a model being a modification of the

conventional solution is considered. The modification

consists in the magnetic assistance of discharge

development. The theoretical analysis presented below

shows that it is possible to enhance lightning protection

effectiveness. Franklin's idea of lightning protection is still

preserved and under the same conditions the probability of

lightning stroke occurrence and localization may increase.

It is shown that the principal physical mechanism

producing an active rod action is the possibility of a

spontaneous initiation (once the spark gap is triggered) of a

transient state inducing (due to the character of voltage

oscillation – a change of the voltage sign). The electric

field intensity induced in an active rod is twice as powerful

as the steady-state field generated when a conventional,

non-active lightning rod is used [13]. This fact basically

constitutes the main physical premise for the higher

effectiveness of active rods.

The equivalent circuit diagram under consideration

(Figure 1) represents our active rod design.

The following quantities are specified in the equivalent

circuit diagram:

Ca : an active rod partial capacitance connected with the

charge accumulated on the cloud's surface,

C0 : an active rod partial capacitance connected with the

charge accumulated on the earth's surface,

Ci : the design capacitance of the rod's spark gap,

L, R: the inductance of the rod's internal coil, the total

resistance of the rod and the earth electrode,

Ua : the cloud's atmospheric charge voltage relative to the

earth,

u: the voltage between the rod's surface and the earth's

surface,

i: transient-state current generated by the shorting of a

spark gap with capacitance Ci ,

Q: the total charge accumulated on the rod's surface,

E0 : the intensity of the external induction field.

C: the rod's total capacitance C=Ca +C0 with neglected

spark gap capacitance Ci <<C as much smaller,

u0 : the rod's voltage relative to the earth prior to spark

gap shorting in the static state.

792 L. Pecastaing et al.: Experimental Demonstration of the Effectiveness of an Early Streamer Emission Air Terminal

cloud

earth

t=0

Figure 1. Equivalent circuit diagram of active rod.

3.2 FORMULATION AND SOLUTION OF INITIAL

EQUATIONS

First the static state of charge with initial conditions i=0,

u=u0 Q=0 for t<0 prior to spark gap shorting was analyzed.

Assuming a zero initial charge, from the total charge

conservation law one gets the following equation:

000  u)CC(C)Uu( iaa (1)

Hence:

CCC

u





0 (2)

Where:

C - is the rod's total capacitance C=Ca +C0 with neglected

spark gap capacitance Ci <<C as much smaller,

u0 - the rod's voltage relative to the earth prior to spark gap

shorting in the static state.

After spark gap shorting at t 0 a transient state occurs,

which is defined by the charge and voltage balance equations:



aa dtiuC)Uu(C

00 (3)

Lu  (4)

The following relation is derived from equation (3) after

differentiation:

Ci  (5)

from which after substitution into equation (4) one gets this

differential equation:

 u

LC (6)

with initial conditions u(0)=u0 , i(0)=0

After substituting u=Aept the characteristic equation:

2 RCpLCp (7)

has complex roots p=-





when

and the solution of equation (6) has this oscillatory form















cos

tcos

eutsintcoseuu tt 













 

00 (8)

with the following auxiliary denotations successively

introduced:

attenuation coefficient





oscillation pulsation 2



 LC

phase angle







arctg 

For the conventional rod in which L=0, u=u0 exp(-t/RC)



0 there is a direct connection of the rod with the earth and

voltage u is permanently equal to zero.

From the solution for voltage one can determine the

waveform of the charge accumulated on the rod's surface.

From the balance equation:

uCUCuC)Uu(CQ aaaa 

0 (10)

taking into account (2) and (8) one gets the relation













 







cos

tcos

eUCQ t

aa 1 (11)









cos

tcos

Qt 

 

(12)

where Q0 =-Ca Ua stands for the charge accumulated in the

steady state, which is equal to the charge of the conventional

rod (at u=0).

It is apparent that the right side of equation (12) assumes the

highest value for



tm=



, which may be expressed by the

formula:





























 e

cos

tcos

emaxk t

m11 (13)

Hence at



 0, km



One can also check through direct calculations whether the

derivative of function (12) is equal to zero:



01 





















cos

tcos

dt (14)

when





, which validates formula (13).

Expressing the exponent in formula (13) by parameters R,

L, C, one gets the relation:

2









(15)

IEEE Transactions on Dielectrics and Electrical Insulation Vol. 22, No. 2; April 2015 793

where quality factor kQ and characteristic resistance



are

defined by the formulas:

 (16)





(17)

Figure 2 shows a diagram of peak value km (expressed by

formula (13)) as a function of system quality factor, calculated

for a range of 0.5< kQ <100.

020 40 60 80 100

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

Figure 2. Peak value km versus quality factor kQ .

In practice, the system quality factor is higher than 15 and

so the peak value of active rod charge is nearly twice as high

as that of the charge of the conventional Franklin rod with the

same C0 and Ca .

3.3 DETERMINATION OF FIELD DISTRIBUTION

In order to qualitatively evaluate the discharge phenomenon,

a more detailed analysis of the field distribution is needed. For

this purpose a spherical rod with radius r0 , was selected and

placed in a uniform primary field with intensity E0 . The other

adopted symbols are shown in Figure 3.

In the initial situation, corresponding to the initial state, the

conducting sphere is insulated and its initial charge is equal to

zero: Q(0)=0.

According to the known theory [13], under the assumptions

made the sought field potential distribution can be determined

as a superposition of the external field and the point dipole

field and it is expressed by the formula:

000

cos

cos ;

Vr E constrr







   

(18)

where: p- the electric moment of the point dipole, 0 - the

permittivity of free space.

The potential on the surface of the sphere with r=r0 is

expressed by the formula:

00 0 3

cos

cos 4

V r E const





 

(19).

Figure 3. Rod in form of conducting sphere in external field E0 .

Assuming dipole moment:

4Erp



 (20)

one gets sphere surface equipotentiality V0 =const.

Fixing the potential in point A on the earth's surface, equal

to zero VA =0 for r=h,  = in formula (18) one gets:

0)(4

)(

)(0 V

Eh 







(21)

and taking into account (20) one determines sphere

potential V0 .

00 1hE

hEV 











 (22)

where the approximation can be used at r0 <<h.

Taking the above relations (18, 20, 22) into account one

gets for r r0 the potential expressed by the formula:

(cos)(1)

Vhr E V



(23)

The highest field intensity in this state occurs in points M,

N on the sphere's surface and it can be calculated as the

derivative of potential (23)

,0 00

3 cos , ( , 0), ( , )

EEMrrNrr

   



(24)

Under the assumption that the sphere's surface is not

neutral, but charged with charge Q the distributions of

potential and field intensity in points M and N are expressed

by the respective relations:

(cos)(1) ( )

Vhr E V

rrh



 

(25)

EEM



 (26)

EEN



 (27)

It follows from the above formulas that at negative charge

Q<0 and E0 >0 field intensity reaches a higher absolute value

in the upper point M than in the lower point N. The value of

charge Q which will flow to and accumulate on the surface of

the sphere depends on the potential induction on the former.

794 L. Pecastaing et al.: Experimental Demonstration of the Effectiveness of an Early Streamer Emission Air Terminal

Let us consider two cases:

a) According to solution (8), for the active rod in a transient

state the potential of the sphere's surface may assume an

instantaneous value (change polarization) reverse to the static-

state potential relative to the earth: V= -V0 .

b) In the case of the conventional rod, the sphere surface

potential for the direct connection with the earth assumes the

value of zero: V=0.

Hence from equations (23) and (22 in case a) the charge is

expressed by the formula:

 

018

42 h

hrE

VQa  



(28)

and in case b)

 

014

hrE

VQb  



(29)

The peak values of field intensity on the surface of the

active rod and on that of the conventional rod are expressed by

the respective formulas:

0123

EE a

Ma 



























(30)

013

EE b

Mb 



























(31)

The degree of field intensity concentration (relative to the

primary induction field value) on the surface of the active rod

and on that of the conventional rod can be calculated from the

respective formulas:

)

(

kma

123  (32)

)

(

kmb

13  (33)

In a more general case (as regards the shape of the rod's surface),

it follows from the problem linearity that field intensity in point M

of maximum concentration consists of two components: a

component proportional to primary field intensity E0 and a

component proportional to the largest charge accumulated on the

rod's surface Q=km .Q0 (formulas (12) and (13))

Hence ultimately the concentration coefficient (32), (33)

assumes this form:

EmE

Ekkk

k (34)

Where:

kE1 =



E represents the static-state field concentration

coefficient when the rod is disconnected (insulated) from the

earth (Q=0),

kE2 =C a .a.



Q represents the steady-state field concentration

coefficient when the rod is permanently connected to the earth

(u=0 ),

km stands for the transient-state peak value coefficient

expressed by formula (13).

Assuming approximately r0 =0.1 m, h =10 m one calculates

concentration coefficients kEa =205, kEb =104 from (32) and

(33). The nearly twice higher field concentration in the case of

the active rod is a factor increasing its operating effectiveness.

Assuming air strength Ew =30 kV/cm one gets external field

E0 =30/205 15 kV/m, which may cause the development of a

full discharge. At cloud altitude a =0.5 km, the cloud voltage

relative to the earth triggers discharge Ua =E0 .a =7.5 MV.

In the case of the spherical rod the concentration

coefficients (34) amount to kE1 =3, kE2 =101, km =2, kE =205.

The above coefficient values depend on the geometric shape

of the rod and may be much higher at a smaller radius of

curvature of the rod's surface.

The theoretical analysis carried out in this paper shows

that the active rod is more effective than the conventional

Franklin lightning rod. Physically, the achieved effect of

increased field intensity concentration (km



2) stems from

the reversal of the voltage sign during transient-state

oscillations. As a result, the rod's potential becomes lower

than the earth's potential whereby the active rod is

overcharged with a nearly twice as large charge as that of

the conventional rod. The induction element plays a

significant role in the development of this phenomenon. In

energy terms, higher instantaneous electric field energy

results from the addition of the magnetic field energy

accumulated in the induction element. The increase in field

concentration causes increased air ionization in the

neighborhoods of the rod, creating conditions conducive to

the formation of a streamer and consequently, to total

discharge. On the basis of the physical premises active rods

can increase lightning protection effectiveness.

4 EXPERIMENTAL SET -UP AND PROTOCOL

4.1 HV SET-UP

The experiments were carried out with two ESEAT

manufactured by the Piorteh Company at the High Voltage

laboratory of the University of Pau in France. The cloud was

simulated by a L=2.35 m diameter metal plate, to which the

high negative voltages were applied, suspended above the air

terminations to be tested, which were mounted on the

laboratory floor (Figure 4).

The distance between the metal plate and the grounded

laboratory floor is H=2.20 m. The air gap length between the

plate and the lightning protection system is d=1.10 m. Then

the distance between the two ESEAT is fixed to d1 =1.00 m

(see part 4.2).

During the tests, a negative DC voltage of -49.5 kV was

applied to the high voltage electrode. This value is necessary

to simulate the natural atmospheric electric field that exists

before a lightning strike by applying a direct current that

creates an electric field between the metal plate and the

ground of 22.5 kV/m. The air gap was triggered with the help

of a conventional Marx generator of maximum peak voltage 1

MV and 350 µs fall-time. Thus the metal plate is energized by

the apparatuses presented in Figure 5.

These geometrical and electrical arrangements are

completely in accordance with the experimental set-up and

conditions specified in the latest French Standard NFC 17-102

(09/2011) prevailing at the time of testing.

IEEE Transactions on Dielectrics and Electrical Insulation Vol. 22, No. 2; April 2015 795

Figure 4. Dimensions of the experimental set-up.

Figure. 5. Apparatuses used in the experiment.

1: Grounded plate

2: High voltage DC power supply (-100 kV)

3: Marx generator

4: Resistance in series with the generator: 70 k

5: Adjustment waveform capacitor: 666 pF, 700 kV

6: Insulation gap: insulate up to 60 kV the Marx generator from the

continuous voltage (-49.5 kV)

7: Metal plate

8: ESEAT under test

9: Capacitive divider (40 pF, 1MV, ratio 1/24.6)

10: North Star commercial probe (1/1000)

11: Load resistor (100 M )

12: Security gap (set-up: 60 kV)

13: 1nF capacitor (integrating circuit of the impulse)

In all the experiments, initiation of corona at the

terminations was detected by photomultiplier observation of

the light emission. Time to breakdown, between plate and rod,

was found from the potential divider observation of the

collapse of voltage across the gap.

The measurement of the voltage delivered by the Marx

generator is achieved by means of a capacitive voltage divider

(40 pF, 1 MV) and a commercial North Star voltage probe.

The acquisition of electrical signals such as the waveform

and the voltage signal output from the photomultiplier is

performed with the use of a Tektronix 3054 digital

oscilloscope (500 MHz/5 GS.s-1).

Meteorological conditions during the tests were recorded as

follows:

Temperature: 20 °C < T < 22 °C

Humidity: 46% <  < 52%

Pressure: 0.1 MPa (1019 mbar)

It can be assumed that the climatic conditions in the

laboratory were nearly the same during the tests.

The first tests were carried out in accordance with French

Standard NF C 17-102. The conclusion is that the upward

leader initiation advance time of the PiX3-60 is superior to

60 µs. Besides the experimental results obtained satisfy the

following conditions:

• Tmoy'ESEAT < Tmoy'SRAT

• Tmoy'ESEAT - Tmoy'SRAT > 10 µs

• σESEAT <0.8 σ SRAT

The PiX3-60 early streamer emission air terminal appeared

to be intact and in good condition after the test as only very

minor stains were observed on its main and auxiliary

electrodes.

4.2 SRAT AND ESEAT RELATIVE LOCATION

Before experiments on both devices are undertaken, it is

important to find the laboratory locations for which the two

ESEAT are placed in the same electromagnetic environment.

The electric devices of big size (Marx generator, capacitor or

capacitive divider in Figure 5) must not influence the

electromagnetic field distribution in the vicinity of the two

ESEAT. That is why electrostatic simulations are needed.

They are aimed at determining the minimal distance d1

between the two ESEAT and so at finding the best

configuration for the location of them. CST EM Studio 3-D

electrostatic solver [14] includes solver modules ideally suited

to the analysis of static and low frequency devices.

Experimental conditions as outlined above were simulated,

with Figure 6 presenting 2-D and 3-D views of the electric

field distribution for negative polarity. The applied voltage is

-500 kV and the distance d1 between the two ESEAT is

1.00 m.

Figure 7 shows the electric field distribution along the

vertical central axis from the tip to the cloud of the

arrangement. The tip of the rod corresponds to the origin d=0

m while the plate is located at d=1.10 m. The result with a

single ESEAT located above the cloud is also given in order to

compare the electric field distribution. The results show that

the electric field generated in the immediate vicinity of the rod

is very strong i.e., approximately 35 kV/cm. Thereafter, it

decreases exponentially towards the metal plate, where it is

only 4 kV/cm. Most importantly is the comparison between

the electric field distributions provided by the three curves.

The results are quite similar. That is why we can conclude that

the electromagnetic environment, due to all the apparatuses

does not modify the future experimental results. This result is

valid from a distance d1 =0.80 m. But during the tests, the

distance d1 is always chosen to be 1.00 m.

Figure 8 presents also the horizontal electric field

distribution between the two tips of the ESEAT spaced by a

1.00 m distance. The origin d=0 m corresponds to the tip of

the rod of the ESEAT1 while d=1.00 m corresponds to the tip

of the other ESEAT2. A good symmetry is observed along this

horizontal axis between the two ESAT when they are spaced

by a 1.00 m distance.

796 L. Pecastaing et al.: Experimental Demonstration of the Effectiveness of an Early Streamer Emission Air Terminal

(a)

(b)

Figure 6. Electric field distribution obtained with CST software in negative

polarity for an applied voltage of -500 kV and a distance d1 =1 m

(a) 3-D view and (b) 2-D representation.

Figure 7. Electric field distribution for a single ESEAT and for two ESEAT

located at a distance d1 =1.00 m (V= -500 kV).

Figure 8 presents also the horizontal electric field

distribution between the two tips of the ESEAT spaced by a

1.00 m distance. The origin d=0 m corresponds to the tip of

the rod of the ESEAT1 while d=1.00 m corresponds to the tip

of the other ESEAT2. A good symmetry is observed along this

horizontal axis between the two ESAT when they are spaced

by a 1.00 m distance.

4.3 EXPERIMENTAL PROROCOL

For each configuration, the first 30 usable impacts were

recorded. The delay between two impacts was 2 minutes.

Figure 8. Horizontal electric field distribution between the two ESEAT

spaced by a 1.00 m distance.

The first step of the tests consisted in finding an

experimental configuration in which the strikes are observed,

almost alternately on one or the other of the two ESEAT

positioned under the metal plate. The first 30 shocks were

used to determine the U50 voltage through the "up and down"

method. The following 30 shocks are done for a voltage

slightly above this value. Two ESEAT (PIX3-60

manufactured by the Piorteh Company) are tested and they are

previously shorted to make them inactive. We estimate that

this is the best solution to form the Franklin terminals from

ESEAT after grounding the tips of ESEAT. Such procedure

ensured that the shape of ESEAT and Franklin terminals was

identical. We note the number of the shock, the voltage value

at the breakdown time of the gap (Ub ), and the time of

breakdown (Tb ) which elapsed between the application of the

voltage waveform and the dielectric breakdown. Finally, we

note especially the ESEAT on which the discharge was

initiated.

In a second step, the ESEAT1 is activated while ESEAT2

remains shorted. We note, again, for a series of 30 shocks, the

number of the shock, the voltage value at the time of dielectric

breakdown of the gap (Ub ), the time of breakdown (Tb ) as

elapsed between the application of wave voltage and dielectric

breakdown and of course always the ESEAT on which

discharge was initiated. The average value of Tb obtained

when the lightning protection system was inactive is then

compared to that obtained when the lightning ESEAT1 is

active.

5 EXPERIMENTAL TESTS AND RESULTS

During the first experiments the two ESEAT are shorted

(Figure 10). They can be considered as inactive and equivalent

to a traditional Franklin rod. In this configuration, the U50

voltage is 479.1 kV with an average time to breakdown of

285 µs. During experiments, initiation of corona at the

terminations was detected by photomultiplier observation of

the light emission. Figure 9 pres ents the electrical activity near

the tip of an ESEAT when an impulse voltage is applied.

There is no breakdown here but we can note that the corona

initiation is effective during the first 300 µs and it promotes

the breakdown when the electric field reaches its maximum

amplitude.

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1

E Abs  (kV/cm)

d (m)

IEEE Transactions on Dielectrics and Electrical Insulation Vol. 22, No. 2; April 2015 797

Figure 9. Initiation of corona near the ESEAT terminations detected by means

of a photomultiplier (CH1: voltage waveform with 1 V=18 kV and CH2:

signal output from the photomultiplier).

Then, with a slight increase of the voltage delivered by the Marx

generator, test results show a complete homogeneous distribution

of breakdowns: 15 breakdowns were recorded on each ESEAT

unit. The average breakdown voltage is 490.9 kV with an average

time to breakdown of 299 µs and a standard deviation of 62 µs.

Figure 10. ESEAT1 and ESEAT2 are shorted during the first experiment

(adhesive thin sheets of copper are used on both devices).

When the ESEAT1 is activated while ESEAT2 remains

shorted (Figure 11), the breakdown distribution is completely

changed: all discharges (30 shocks) are now initiated from the

active lightning rod i.e. the ESEAT1.

We also note that the average time to breakdown in this

case (241 μ s) is below the average time to breakdown when

both ESEAT are inactive (299 μ s). In addition, the standard

deviation for the active ESEAT2 (43 µs) is less than 80% of

the deviation obtained when both ESEAT are inactive.

Figure 11. ESEAT1 is active and ESEAT2 is shorted during the second

experiment (thin adhesive sheets of copper are used only on one device).

Similar results were obtained by reversing the two EEAT

(the ESEAT1 becomes active and the ESEAT2 inactive).

This novel experimental technique demonstrates clearly the

effectiveness of the Pix3-60 ESEAT manufactured by Piorteh

Company in the High Voltage laboratory of the University of

Pau.

6 CONCLUSIONS

In this paper, the theoretical analysis carried out shows

that the active rod is more effective than the conventional

Franklin lightning rod. The peak value of active rod charge is

almost twice as high as that of the charge of the conventional

Franklin rod and the induction element plays a significant

role in the development of this phenomenon.

A novel method of experimental test evaluation in the

High Voltage laboratory of the University of Pau in France

confirms the theoretical conclusions. Unlike the NFC 17-102

French Standard (09/2011), where the tests are carried out

alternately on an inactive device and then on an ESEAT, our

method is to test both devices simultaneously. In our

experimental configuration, all discharges are observed on

the active device.

In order to fully evaluate the protection effectiveness, real-

scale tests need to be carried out. As an example, the

photograph presented in Figure 12 points out the

effectiveness of the lightning protection devices

manufactured by Piorteh Company in nature during a storm

at the Millau Viaduct in France (August 6, 2013). On this

picture, the effectiveness of ESEAT from Piorteh Company

is clearly visible.

798 L. Pecastaing et al.: Experimental Demonstration of the Effectiveness of an Early Streamer Emission Air Terminal

Figure 12 . Photograph of lighning strikes on Piorteh's ESEAT protecting the

Millau Viaduct in France (06/08/2013).

REFERENCES

[1] N.L, Allen, K.J. Cornick, D.C. Faircloth and C.M. Kouzis, "Tests of the

early streamer emission principle for protection against lightning", IEE

Proc. Sci. Measurement and Technology, DOI:10.1049/ip-

smt:19982209, 1998.

[2] V. Rakov and A. Martin, Lightning: Physics and Effects , Cambridge

University Press, ISBN 978052035415, 2003.

[3] W. Rison, "Experimental validation of conventional and non-

conventional lightning protection systems", IEEE Power Engineering

Society General Meeting, Vol. 4, DOI:10.1109/PES.2003.1270959

ISBN: 0-7803-7989-6, 2003.

[4] S. A. Amar and G. Berger, "A modified version of the rolling sphere

method ", IEEE Trans. Dielectr. Electr. Insul., Vol. 16, No. 3, pp. 718-

725, 2009.

[5] K.L. Chrzan and Z.A. Hartono, "Inefficacy of radioactive terminals and

early streamer emission terminals", XIIIth International Sympos. High

Voltage Engineering, ISBN 90-77017-79-8, p. 86, 2003.

[6] C. Bouquegneau, "Laboratory tests on some radioactive and corona

lightning rods", 18th Int'l. Conf. Lightning protection, Munich,

Germany, pp. 37-45, 1985.

[7] S. Grzybowski, A.L. Libby, J.R. Gumley and S.J. Gumley,

"Comparative testing of ionizing and non-ionizing air terminals", 10th

Int'l. Sympos. High voltage engineering, Montreal, Vol. 5, pp. 331-334,

1997.

[8] Z. Flisowski and P. Korycki, "Advertised and actual effectiveness of

lightning rods with early streamer emission (ESE)", Przeglą d

Elektrotechniczny, No. 11, 282, 1998 (in Polish).

[9] Z.A. Hartono, I. Robiah and M. Darveniza, "A database of lightning

damage caused by bypasses of air terminals on buildings in Kuala

Lumpur, Malaysia", 6th Int'l. Sympos. Lightning Protection, Santos,

Brazil, pp. 211-216, 2001.

[10] M. Uman, The Lightning Discharge , Academic Press, Chapter 3,

Orlando, 1987.

[11] French Standard NFC 17-102. "Protection against lightning. Early

streamer emission air terminals", 2011.

[12] Z. Hartono and I. Robiah, "The Collection Surface Concept as a Reliable

Method for Predicting the Lightning Strike Location", 25

Int'l. Conf.

Lightning Protection, pp. 328-333, 2000.

[13] P. Moon and D. E. Spencer, Field Theory for Engineers ,

Princeton, Toronto, London, New York, 1961.

[14] Computer Simulation Technology (CST), https://www.cst.com/, last

time accessed in November 2013

Laurent Pécastaing received the Ph.D. degree and the

Research Directorship Habilitation in electrical

engineering from the Université de Pau et des Pays de

l'Adour, Pau, France, in 2001 and 2010, respectively.

He is currently a Lecturer with the Laboratoire SIAME,

Université de Pau et des Pays de l'Adour. His research

interests are focused on high-power microwave (HPM)

sources, compact pulsed power devices, including

pulse-forming lines or Marx generators, and ultrafast

transient probes.

Antoine Silvestre de Ferron was born in Tarbes,

France, in 1977. He received the Ph.D. degree in

electrical engineering from the Université de Pau et des

Pays de l'Adour (UPPA), Pau, France, in 2006. From

2006 to 2008, he was a Researcher with the Atomic

Energy Comission (CEA), Le Barp, France – a French-

government-funded technological research organization.

He is currently an Engineer with the Laboratoire

SIAME, UPPA.

His research interests include high pulsed power generation for military and

civil applications and combined high-voltage transient probes.

Thierry Reess was born in Pau, France, in 1968. He

received the M.Sc. degree in plasma physics from the

University of Toulouse, France, in 1992 and the Ph.D.

degree in electrical engineering from the University of

Pau, France, in 1996. He is currently a lecturer with the

Electrical Engineering team of the SIAME laboratory,

University of Pau, France. His research interests include

high power devices and electrical discharges in gases

and liquids.

... ESEATS manufacturers test their devices in high voltage laboratories with the switching impulses 250/2500 µs in accordance with NF C 17-102 [9], or with composite voltages consisting of high DC voltage and superimposed switching impulse voltage as in [12]. Such a test has proven better protection efficiency of the ESEATS over the standard Franklin rods [12], [13]. However, many leading physicists stated that laboratory tests of the ESEATS suggested in [9] cannot be used to prove their efficiency in natural conditions [11], [13], [14]. ...

Mladen Banjanin
Svetozar Banjanin

This paper analyses and compares the conventional lightning protection systems proposed in IEC 62305 to the lightning protection systems based on the application of early streamer emission lightning rods proposed in NF C 17-102. Comparison between the two approaches to the lightning protection of structures was presented, both from a technical and economic point of view. Some inconsistencies in the conventional air termination system design methods are pointed out. The critical attitude of the scientific community regarding the declared protection characteristics of the early streamer emission lightning rods is discussed

... Based on this consideration, many new types of lightning air terminals have been proposed. It has been claimed that these can emit upward streamers or upward leaders earlier than Franklin rods can [5][6][7], giving these devices much greater areas of protection and therefore better protection performance. ...

Different types of lightning air terminals have been designed over the years. The concern about the effect of different types of air terminals, especially the early streamer emission (ESE) type, remains controversial. This paper describes the discharge characteristics of different types of air terminals, two of which are quite similar to the ESE type dynasphere, and concludes that the tested non-standard air terminals have discharge characteristics similar to those of Franklin rods and that their lightning protection performance should be similar.

Matija Varga

This research paper in its first part focuses on the theoretical concepts of "innovation", "innovation Management", and "ICT innovation management". The second part of the paper aims to follow results of the survey (research methodology) in determining whether the innovation is of interest to the participants of the survey. It questions whether ICT innovations are the key for economic development of the country, or if the interviewees own their (patented) ICT innovative product. It questions where the interviewees find motivation for creation of ICT innovation and if the managers consider opening vacancies for ICT innovation development. It questions whether they are familiar with the Strategy of Innovation Incentives in the Republic of Croatia, in the period 2014-2020, or whether the interviewees believe it was real and achieved. Did the interviewees know that the Republic of Croatia was behind Slovenia, Hungary and Bulgaria according to the Index of Innovation, and if they agree with the statement that innovations are the source of real competitive advantage of individual business, and one of the most efficient ways for sustainable prosperity. Are the SMEs (small and medium enterprises) the cornerstones for development of modern economy?

Krystian Leonard Chrzan

The Two basic constructions of Early Streamer Emission terminals were shown: terminals with enhanced ionization and terminals with internal coil. The simplified theoretical background of these lightning terminals was explained. The paper shows the difficulties related to testing active lightning terminals in a laboratory. The limitations of applied conditions recommended in the NF C 17-102 standard were discussed: (a) electrode arrangement plate-rod, (b) very short 1 m distance between them, (c) switching impulse with DC voltage bias. With the help of the air breakdown theory it was shown that the protection zone of the Early Streamer Emission terminals practically cannot be greater than the protection zone of classical Franklin terminals.

The paper [1] reports on comparative experiments on a triggered-gap electrode used as an early streamer emission air terminal, with some equivalent circuit analysis of the triggering circuit and simplified electric field calculations.

The paper reviews about research of radioactive lightning rods carried out 30 years ago and about new measurements of early streamer emission terminals. Lightning damage on over 100 buildings equipped with ESE terminals in Malaysia and on one family house in Poland is reported. The main measure criterion was the breakdown voltage of the air gap consisted of the high voltage electrode (rod or plate) and a grounded radioactive or ESE terminal. These careful measurements show that the air gaps with ESE terminals have the same breakdown voltages as the air gaps with standard rods. Therefore the big protection zone of ESE terminals as claimed by their manufactures seem to be impossible.

William Rison

Three types of lightning protection systems are in common use today: conventional systems, charge transfer systems, and systems based on early streamer emission air terminals. There is a wealth of empirical data validating the effectiveness of conventional lightning protection systems installed in accordance with recognized standards. Field studies of charge transfer systems show that they do not prevent lightning strikes as has been claimed. Studies of early streamer emission air terminals show that their performance in the field is similar to that of conventional sharp-pointed air terminals, and they do not have a greatly enhanced zone of protection as has been claimed.

Parry Moon

Scitation is the online home of leading journals and conference proceedings from AIP Publishing and AIP Member Societies

Sonia Ait-Amar
Gerard Berger

The calculation of the striking distance can estimate the probability of lightning strike on a structure and thereby evaluate the effectiveness of a lightning protection system (LPS). The dimensioning and the positioning of air-termination on structures is often performed with the Rolling Sphere Method (RSM). RSM originated from the electric power transmission industry and is based on the well-known Electrogeometric Model (EGM). The EGM relates striking distance to the prospective peak stroke current. To apply this technique, an imaginary sphere is rolled over the structure. All surface contact points are deemed to require protection, whilst the unaffected volumes are deemed to be protected. The main drawback of this method is that it disregards the upward leadersiquest development and assumes the same probability for attachment to the ground, to a structure, and to a LPS. The proposed model is based on physical phenomena leading to the formation and the development of positive upward leader in the field produced by the negative downward leader charge distribution and by some other competing upward leaders. Its purpose is to develop a 3-D numerical model in order to improve the interception efficiency of the Lightning Protection System.

N.L. Allen
K.J. Cornick
Daniel Charles Faircloth
C.M. Kouzis

Experiments are described which are designed to test two devices based on the `early streamer emission' (ESE) principle, for lightning protection, against the traditional Franklin rod. In all three cases, the device was subjected to a steady negative electric field from a sphere, simulating the field beneath a thundercloud, prior to application of a superimposed negative impulse field, simulating the field due to the downward leader. The first device consisted of a vertical rod to which a subsidiary 1/50 μs positive impulse voltage, variable up to 40 kV peak, could be applied with varying delays from the start of the negative impulse field. Energising of the rod was thus independent of the applied negative field. The second device was a commercial product, energising of which was controlled by its own power supply. Sparkover voltages in the sphere/device gaps and times to breakdown were measured. It is shown that the ESE devices showed a small advantage, in time to breakdown, over the Franklin rod

Experimental Demonstration of the Effectiveness of an Early Streamer Emission Air Terminal Figure 12. Photograph of lighning strikes on Piorteh's ESEAT protecting the Millau Viaduct in France

L Pecastaing

L. Pecastaing et al.: Experimental Demonstration of the Effectiveness of an Early Streamer Emission Air Terminal Figure 12. Photograph of lighning strikes on Piorteh's ESEAT protecting the Millau Viaduct in France (06/08/2013).

Laboratory tests on some radioactive and corona lightning rods

C Bouquegneau

C. Bouquegneau, "Laboratory tests on some radioactive and corona lightning rods", 18th Int'l. Conf. Lightning protection, Munich, Germany, pp. 37-45, 1985.

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