R3&A Limited
Does Surge Protection = Surge Protection?
The answer is NO!
In the world of surge protection we differentiate between impacts
of high energy currents with an energy content up to 10 MJ/Ohm
caused by a direct lightning strike and low energy transients just
caused by electrical and magnetic effects, so called indirect
effects of lightning, similar like an antenna of a radio.
By international consensus such a direct lightning current could
be described/simulated with a so called 10/350 us current pulse
compared to a 8/20 us current pulse, just to simulate the indirect
effects of lightning. The major difference of these pulses is the
duration of the current flow, which is in case of the 10/350 us
pulse more than 15 times longer than the low energy pulse.
Consequently, it’s obvious that a surge arrester, with the purpose
to protect against direct impacts, should be tested against the
10/350 us pulse and not only with the low energy 8/20 us pulse,
like it is most common in North America. The consequence of this
mismatch could be in the best case the loss of the surge
protector and the protected equipment and in the worst case the
destruction of the whole installation, which most likely will happen
by using the above mentioned cord line protector only.
DEHN, in the market since 1910, is offering a wide range of surge
protection products for power applications and also for any kind
of instrumentation and control circuits. In consequence to what
has been mentioned above, DEHN’s offer includes devices rated
for these high energy 10/350 us current pulses and for the low
energy impact of induces voltages simulated by the 8/20 us pulse.
An example of such a “lightning current”
arrester is our DEHNbloc Maxi 320. This device
is based on a triggered crow bar, but designed
to avoid the former disadvantage of a high let
through voltage and short circuit current issue.
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An example: Do you think a cord line
surge protector is able to protect your
electrical installation against a direct
lightning flash into your property?
Hopefully not!
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