Tests in laboratory
PREVECTRON® : Effectiveness Assessment in Laboratory
Indelec HV Lab is dedicated to conduct tests in accordance with the NF C 17-102 standard and conduct tests on new products in the framework of the framework of the Resarch & Development ongoing programs.
Layout of the laboratory (Fig. 1)
The high voltage laboratory used to assess the PREVECTRON®, contained the following equipment :
- A direct current generator (G1) designed to simulate the ambient atmospheric field during a storm
- A surge generator (G2) allowing induced rapid stimulation of the pre-strike electric field.
These two generators fed a plate positioned above the air terminal being tested.
Fig 1
Technical parameters used
- Dimensions :
- H = height of the plate from
he ground = 2,0 m
- h = height of the plate above
the tip of the air terminal = 1 m
- D = diameter of the plate = 3m
- Electrical :
- direct current (supplied by G1) : 25 kV/m.
- G2 waveform :
- rise time 250 µs
- peak voltage 1 MV
EDF H.V. Laboratory «Les RENARDIERES»
H.V. Laboratory
Salle de contrôle
Description of the test
The PREVECTRON® air terminal and the single rod used as a reference are positioned one after the other so as to be at the same vertical distance beneath the plate. The G2 wave generator increases the electric field between the upper plate and the ground. This impulse field superposes upon the permanent field of the D.C. generator G1. (Fig. 2a).
With this set-up a breakdown is produced between the tip and the plate. This breakdown short-circuits the generator leading to the wave form’s returning abruptly to zero.
With the single rod, this breakdown is produced in a high «ESRLC» field (Fig. 2b). With a PREVECTRON® lightning conductor however, the breakdown is produced earlier and in a less-intense field (Eeselc). The time gained allows the lightning conductor’s effectiveness to be accurately measured (Fig. 2c). A minimum of 100 shocks were induced on each lightning rod.
Test report Keri - Korea
Fig. 2(a)
Fig. 2(b)
Fig. 2(c)
Results
(to French standard NF C 17 - 102)
The gross value of the gain in triggering time, as measured in the laboratory, is interpreted in accordance with the French national standard, NF C 17 - 102 (Annex C) so as to correlate with a predetermined reference wave form (650 µs).
These standardised ΔT values are obtained after a great number of tests. However, given the statistical nature of the data, we considered it necessary to further weight the figures by 35% before using them to calculate the protection radii, thereby allowing an additional safety margin. The effectiveness of each PREVECTRON® air terminal is therefore significantly improved. The weighted values for ΔT are give in table 1 below.
Wuhan High Voltage Research Institute
Table 1
| Prevectron®2 |
ΔT (µs) |
| S6.60 |
60 |
| S4.50 |
50 |
| S3.40
|
40 |
| TS 3.40 |
40 |
| TS 2.25 |
25 |
Table 2
| Prevetron®2 |
ΔL (m) |
| S6.60 |
60 |
| S4.50 |
50 |
| S3.40 |
40 |
| TS 3.40 |
40 |
| TS 2.25 |
25 |
Shock on a PREVECTRON®
By applying the formula DL(m)=v(m/µs).DT(µs) where v is the velocity of the upward leader (1m/µs), the upward leader length gain for the PREVECTRON® air terminal can be calculated. This figure (tab. 2) can then be used to determine the protection radius
Rapport available on demand.
IEMN (CNRS) test report