Brochure/Catalogue

Test criteria
Test criteria
The classication is based on the experience that
“B arresters” can become overloaded in extreme situations,
and also on more recent investigations into lightning
discharges. This resulted in the standardised 10/350 µs
current curves for the testing of “Type I” arresters. The test
parameters lie between 12,5 and 25 kA I
peak
or I
imp.
The term “10/350 µs” means that the surge current reaches
90 % of its maximum value after 10 µs and then decays
to half that value after 350 µs. The area beneath this curve
corresponds to the current energy used in the test. As in the
past, “Type II” arresters (formerly “C arresters”) are tested
with the 8/20 µs current curve. The rated discharge current
for our arresters: for a 2-pole feed up to 75 kA; for a 4-pole
feed up to 100 kA. “Type III” arresters (formerly “D arresters”)
are used for protecting equipment. These are tested with a
2 W hybrid surge current generator delivering a maximum
charging voltage of 0.1 to max. 20 kV,
Classication Test values Application
formerly VDE IEC 0675 37A
Coarse
protection
B-
arrester
Type I I
IMP
= 25 kA
10/350 μs curve
Protection against direct
lightning strike (incoming
(supply, main distribution
board, etc.)
Medium
protection
C-
arrester
Type II single pole
I
N
= 20 kA
8/20 μs curve
3 or 4-pole
I
N
= 100 kA
8/20 μs curve
Protection for permanent
installations (electricity
distribution etc.)
Fine
protection
D-
arrester
Type III U
oc
= 20 kV max.
I
s
= 10 kA max.
hybrid generator
Protection for devices
(sockets etc.)
Voltage in %
100
90
50
10
0
Test pulse 8 / 20 µs
0
t in µs
8
20
52
515
Voltage in %
100
90
50
10
0
Test pulse 10 / 350 µs
10
350
t in µs
0
50 100 150 200 250 300 350
Voltage in %
100
90
50
10
0
0
Test pulse 1.2 / 50 µs
t in µs
1.2
10
20 30
40
50
50
Simulated surge pulse 8/20 μs
Simulated lightning impulse 10/350 μs
t
US
20 200 350 600 800 1000
20 kA
40 kA
50 kA
60 kA
80 kA
100 kA
2
1 2
Wave form
[μs]
10/350 8/20
5100
50 0.1
2.5 – 10
6
0.4 – 10
3
DIN V VDE V
0185-1
DIN V VDE
0432 T.2
I
max
[kA]
Q [As]
W/R [J/Ω]
Norm
1
Relationship between 10/350 μs and 8/20 μs
which during a short-circuit supplies between 0.05 and
10 kA, 8/20 µs.
W
The basics of lightning and surge protection
W.312028840000