Active Lightning Protection. Results of tests on the NFC
17 102 standard and statistics of world use
Elec. Eng. Gokhan Akman
OOO Elektra & Forend Co.
Active lightning protection (results of tests on the
NFC 17 102 standard and statistics of world use)
• NEW EDITION OF ESE STANDARDS
•
•
After many years of application of ESE standards in Europe (the first
standard for ESE: NF C 17-102 standard, has been published in 1995) and
worldwide it has been decided to revise the three standards from France,
Spain and Portugal in a parallel procedure based on a Franco-Spanish
working group that has been followed carefully by Portugal. This NFC C 17102:2011 standard is now approved in France and at the time of writing the
paper, the Spanish standard UNE 21186:2011 has just passed the national
public enquiry and is going to be published approximately in two weeks, and
Portugal standard NP4426-2 is on the approval procedure.
There are many new things in the standard and most of them are coming
from IEC and EN 62305-3 standard. As a matter of fact, there is no reason
why a Lightning Protection System based on ESE should behave differently
from other systems. This paper will then concentrate on the new items and
especially those related to ESEs.
THE TECHNICAL CHANGES
• Standards from series IEC 62305 or EN 62305 (international or
European) are “installation” standards: they explain how to select,
install and control the Lightning Protection Systems. These LPS use
components (rods,conductors, earthing rods etc.) that need to be
compliant with “product” standards: series IEC 62561 or EN 50164.
•
On the reverse French standard NF C17-102:1995 as well as its
2009 version is mainly a “product” standard. However , in 1995
version tests were only related to efficiency tests able to determine
the efficiency of the ESE: ∆T. 2009 version has been introduced to
harmonize the requirements of 17-102 standard with those of IEC
62305. Nevertheless some requirements form 17-102 had to be
more severe than those of simple rods to guarantee good operation
of ESE.
• It has been decided in 2009 to launch a new version of standard 17102 because the 2009 version didn’t allow to homogenize fully
standards 17-102 and 62305, the 17-102 standard having kept the
1995 structure.
• There is no reason for simple rod (SR) installation rules to differ from
ESE installations rules, except for ESE particularities (protection
model, good earthing impedance to allow ESE to work properly,
etc.). Revision has started based on a request from CENELEC
(European Standard Committee).
What are the main principles that are included in
2011 version of the standard???
• First of all the tests of the “product” standard had to be more
complete. An ESE contains electrical components that are located
near the lightning impact: it is then rather logical that an ESE be
submitted to tests at least as severe as the component of any other
LPS.
• Selection of ESE should be based on a risk analysis as described in
IEC 62305-2
• Its installation should be compliant with IEC 62305-3 except when
more severe requirements are necessary.
What’s NEW???
•
Risk assessment is described in IEC 62305-2.
•
An ESE is only a component of a LPS: all components are important and
shall comply with IEC 62561 or EN 50164 standards.
•
∆T is limited at 60 μs whatever is the value obtained during tests.
•
The protective area is no more a simple cylinder but is a sphere.
This means that some areas protected according to 1995 version of
NF C 17-102 are no more protected especially for tall buildings.
•
Protection for tall buildings over 60 m is now included in the scope:
- protection of the last 20% of the structure (or any point higher than 120 m)
by ESE or any other appropriate mean
-In addition, at least 4 down-conductors, interconnected by a ring
conductor, shall be used, distributed along the perimeter and, if possible, at
each corner of the building.
What’s NEW???
•
Number of down-conductors:
Number of down conductors for a non-isolated LPS, each ESE shall be
connected to at least 2 down-conductors.
•
Earthing System:
-Earthing resistance shall be as low as possible and < 10 Ω.
ESE Using Map on World wide
Standards Worldwide
•
This page provides information on the main standards (and technical
régulations) in use worldwide.
Focus on the New Range of tests For the ESE Technology
•
Since very long time, the ESE Technology has been the target of an
important lobbying in favor of the said conventional lightning protection
system. The critics use to be the same:
•
The critics on the first version of the standard tests use to be the same. It
was said that they are too large in their definition
•
In order to answer those critics, the French committee has work on a new
version of the NFC 17-102 standard. This latest edition has been published
in 2011.
HIGH VOLTAGE LABORATORY TESTS ACCORDING TO
LIGHTNING PROTECTION STANDARDS
• High voltage laboratory research has been a powerful tool for
lightning research in the last decades although today it has been
somehow forgotten compared to other research activities such as
natural lightning measurements or theoretical modeling. On the
other hand, standard testing of lightning protection components can
only be performed at High Voltage laboratory facilities at present.
There is no standard test of lightning protection performance under
natural lightning conditions. The advantage of a laboratory is that
testing parameters such as applied voltage or current, ambient
conditions and geometrical configuration can be controlled.
• Besides, testing at a high voltage laboratory provides a statistically
significant amount of data. Obviously, natural lightning conditions
cannot be fully achieved at a high voltage laboratory but some
parameters can be fairly reproduced. Although lightning is a large
scale phenomenon, laboratory tests offer a good opportunity to test
and perform research about lightning protection. In this paper we will
present two main important laboratory testing arrangements and a
summary of the standards procedure. New trends and suggestions
for improved future tests of lightning protection components will be
discussed.
NFC 17 102 Testing Procedures
• GENERAL TESTS
• MECHANICAL TESTS
• ENVIRONMENTAL TESTS
• ELECTRICAL TESTS
• EARLY STREAMER EMISSION TESTS
GENERAL TESTS
• DOCUMENTARY INFORMATION AND
IDENTIFICATION Visual Inspection according to the
requirement of NFC 17.102 C2.1.2 (Name, logo and
mark etc)
• MARKING TESTS Marking tests carried by the use of
Hexane Aliphatic. The test is carried out by rubbing the
marking by hand for 15 s with a cotton rag dipped in
waterand for 15 s more with a cotton rag dipped in
hexane aliphatic.
MECHANICAL TESTS
•
Based on manufacturer’s data
• Section compliant to EN 50164-2
• Striking point with a section of 200 mm2
• If such conditions are achieved, it assures as a good
behavior and flow of the current through the ESE
ENVIRONMENTAL CONDITIONING
• SALT MIST TREATMENT Spray test according to
EN60068-52 standard
• HUMID SULPHUROUS ATMOSPHERE TREATMENT
Test in a humid sulphurous atmosphere according to the
EN ISO 6988 standard with seven cycles and a sulphur
dioxide concentration of 667 ppm (in volume). Each
cycle lasts 24 hours and includes an 8-hour heating
period at a temperature of 40°C ± 3°C in a saturated
humid environment followed by a 16-hour standing
period. After this standing period, the humid sulphide
atmosphere is restored.
CURRENT WITHSTANDING TESTS
• After environmental pre-conditioning and without the
sample being cleaned, the ESEAT is subjected to the
following tests.
• Iimp Impulse current test
• The Iimp test impulse is defined by Ipeak, Q and W/R. A
unipolar current impulse shall reach these parameters
within 10ms.
CURRENT WITHSTANDING TESTS
• The sample shall be subjected three times to a test current given in
below table. The time-slot between each test shall enable the
sample to cool down at room-temperature.
• Value of current Iimp
• Ipeak(kA)
• Q(A.s)
• W/R(kJ / Ω )
• 100
• 50
• 2 500
• Test endorsement The sample passes the test if the voltage /
current recordings and the visual inspection do not reveal any
indications of deterioration or perforation of the sample, except the
parts that drain off the lightning current where traces of emission
and superficial fusion can appear.
EARLY STREAMER EMISSION TESTS
• The reference standard for testing procedures is EN
61180-1. The ESEAT shall be installed and connected
electrically according to manufacturer instructions.
• During the tests, no maintenance or disassembly of the
ESEAT is authorised. It shall be seen that appropriate
testing techniques are necessary for crash tests and
measurements, in order to ensure that the correct test
values are recorded.
Experimental set up of SRAT single rod
air terminal
Dimensions of the test assembly
• The height of the air terminals (h) exceeds or equals 1m. The
difference of height between the two terminals shall be less than 1%
• The distance between the upper plate and the ground(h) shall
exceed 2m. The h/H ratio shall range between 0,25 and 0,5
• The smallest horizontal dimnesion of the upper plate is the distance
between plate and ground (H)
• The 28mm diameter rod, the air terminal support, rests on a square
support with a 0,2m side.
• The following figures represent the two test confifurations that
correspond respectively with the testing of the reference SRAT
(defined in up) and testing of the ESEAT.
SRAT vs. ESEAT
EXPERIMENT CONDITIONS
• The effectiveness of the ESEAT is measured by comparing it to
SRAT’s emission time of the ascending tracer in a high voltage
laboratory.
• 1) WAVE SIMULATION
• The natural wave that exists before a lightning strike has
consequences on the forming conditions of the corona and preexisting space-charge. It is therefore necessary to simulate it by
applying a direct current that creates an electric field between the
plate and the ground ranging between -20 kV/m and -25 kV/m.
• 2) IMPULSE FIELD SIMULATION
• The impulse field may be simulated by a switching impulse which
rise time ranging between 100 μs to 1000 μs. The waveform slope
when the upward initiates should be between 2.108 and 2.109 V/m/s.
A typical waveshape is 250/2500 as per IEC 60060-1 (only the
tolerance on the front is important).
• 3) QUANTITIES TO BE INSPECTED –
MEASUREMENT TO BE CARRIED OUT.
• ELECTRICAL PARAMETERS
• The electrical parameters to be inspected and recorded
are the shape and the magnitude of the voltages applied
(calibration of the ambient field, impulse voltage
wave,associated current) for the SRAT and the ESEAT
• The following should be adjusted to achieve this.
• The continous polarizing voltage
• The impulse wave that triggers the emission on the
single rod air terminal: the voltage to be applied is
determined using a simplified «up and down» procedure
so as to obtain the value U100 with a final precision of
1%
• GEOMETRICAL CONDITIONS
• Distance d shall be strictly the same (+/- 1mm) for each test
configuration; it is inspected before each configuration.
• CLIMATIC PARAMETERS
• The climatic conditions ( Pressure,temperature,relative humiditiy)
shall be recorded at the beginning and the middle of the tests of
each series and at the end of the tests for the test configuration. In
order for the test configurations of the SRAT and the ESEAT to be
considered identical ( same U100 voltage), the variations of the
climatic parameters shall comply with the values defined in the table
below. Otherwise, it is necessary to re-measure the U100 voltage
before the next configuration.
•
•
•
•
•
Variation of the climatic parameters during the tests
Parameter Variation for both test configurations
Pressure
+/- 2%
Temperature
+/- 10°C
Relative humidity
+/- 20%
• The values are recorded in the test report but do not lead to
corrections.
• NUMBER OF IMPACTS PER CONFIGURATION
• For each configuration, the first 50 usable impacts will be
recorded.(Example of a non-usable impact: pre-starting of the
generator) The standing time between two impacts shall equal 2
minutes. This value should be maintained throughout the tests.
ESE Statistics in world wide
• An empirical study of effectiveness has been done on the
European-made ESE lightning protection systems installed
worldwide in accordance with the national standards in force at
Europe for this type of LPS.
• For this aim, the following data have been taken into account:
• European statistics about the amount and years of service of ESE
manufactured in Europe.
• Medium size building world type and world Ng established.
• Number of lightning discharges that are expected to hit the
protected buildings and structures. Calculation has been made in
accordance with established risk analysis of IEC/EN 62305-2, as
well as ESE national standards.
• Number of tolerable bypasses for the different protection levels
under the above mentioned regulations.
ESE Statistics in world wide
• The International Lightning Protection Association (ILPA) gives
statistical data about the ESE Air Terminal that have been
manufactured, according to the national standards, in Europe, The
data are following.
• In 1986, which is the first year of available statistics, number of ESE
was 4088 when in 1996 it was already a cumulated number of
112412 units.
• In 2009 the cumulated number of installed units is 550 000.
• Total number of ESE units per years is now 4 652 000 . This means
that experience is very long and important.
ESE Statistics in world wide
• The study shows that during the equivalent accumulated experience
of 4,652,600 years of service of these 550,000 ESE LPS, 174,473
lightning discharges were expected on the protected facilities.
According to the available data, the assessment of incidents to the
referred premises is negligible: very small amount, insignificant
material damages and no personal injuries. It is very important to
highlight that the number of these rare incidents are much smaller
than an order of magnitude with respect to the most restrictive level
accepted by the rules outlined.
• Furthermore, this paper provides an interesting analysis of the
lightning protection areas of these ESEs when compared with the
protection areas obtained if they were considered just as mere
simple Franklin rods. The result of this comparison indicates that in
the latter case more than 165,000 lightning discharges would not
have been intercepted and therefore should have caused damage to
protected structures, hence thousands of claims. Obviously this is
not the case.
• In short the study describes 25 years of safe and effective ESE
lightning protection experience, demonstrated by the 4,5 million
accumulated service years of more than 550,000 units installed
worldwide, many of them installed in countries with the highest rate
of annual lightning storms. On the other hand ESE European
national standards have also shown to be safe, effective, practical
and useful.
• The authors would also like that this document lessens the shortage
of data and statistical studies about existing lightning protection
system installations and their effectiveness.
Thank You  for listen me!
BIBLIOGRAPHY
• New edition of ESE Standards Fernanda Cruz, Olivier Trousse, Ana
Mariblanca Sánchez (CTE81 Committee Chairman Portugal; UTE
France; AENOR Standardization Division Spain)
• AENOR . UNE 21186 Diciembre 2011 Proteccion contra el rayo:
Parrarayos con dispositivo de cebado
• Environmental tests – Salt mist treatment, IEC 60068-2-52,
December 1996
• NFC 17 102 Protection of structures and open areas against
lightning using early streamer emission air terminals 2011
• Effectiveness of Worldwide Existing ESE Lightning Protection
Systems Manufactured in Europe V.Pomar, S.Polo , S.Fauveaux
• Michael Troubat, Focus on the new range of tests for the Early
Streamer Emission air terminal technology.
• IPSOS: Satisfaction survey “Lightning Protection” Questionnaire
GIMELEC/INERIS/MEDD 2002
• Metallic covers – Test in the sulfur dioxide with general condensation
of the humidity, EN ISO 6988, April 1995