Skystream Owner’s Manual
3-CMLT-1054 Rev O XCO 1191
Pg. 52
Select Model and Number of Lightning Current Arrestor(s)
Select the appropriate model and quantity of the Type 1 lightning current arrestor(s) required from
Table 6
. The selection method is described below:
The lightning arrestor peak current rating is the peak current carrying capability of each pole or contact
of the arrestor. It is generally assumed that the total current the surge arrestor will end up carrying
(cumulatively, in all its phases), is about 50% of the total lightning discharge current. Say, if there is
100kA of peak discharge current due to lightning, 50kA will flow through ground, and the other 50kA will
be divided between L1, L2 and N, thus requiring the surge arrestor to be rated for ~16kA per phase.
This concept of lightning current division is described in
Reference (3)
listed at the end of the lightning
protection description.
Lightning and surge protection is intended to be placed between each phase (hot line) conductor and
ground, and possibly between ground and neutral, if the distance between the neutral and ground bond
is significant. Therefore the voltage rating of the SPD is to be based on phase (hot line) to neutral
values (since neutral and ground are connected at the main service panel, and hence normally
at the same potential).
The following table shows example lightning current arrestor recommendations (single pole versions
with spark-gap technology).
Note:
Lightning Current Arrestors from DEHN Inc. have been cited here, however, comparable
arrestors from other companies may be utilized.
Table 6 - Type 1 Lightning Current Arrestor Recommendations: One Pole Versions (spark-gap
technology)
Efficiency
Lightning
Protection Level
(LPL )
Peak Lightning
Current Discharge/
Sinking Capability
120/240V split 1-ph and
120/208V system
(L1, L2, N, G)
230V, 1-ph system
(L, N, G)
E > 0.980
LPL with added
measures
200kA
DEHNbloc Maxi 150 (DB
M 1 150), AT LEAST one
each L1-G, L2-G, N-G
DB M 1 255, AT
LEAST one each
between L-G, N-G
0.95 < E < = 0.98
LPL 1
200kA
DB M 1 150, one each
between L1-G, L2-G, N-G
DB M 1 255, one each
between L-G, N-G
0.90 < E < = 0.95
LPL 2
150kA
DB M 1 150, one each
between L1-G, L2-G (N-G
optional)
DB M 1 255, one each
between L-G, N-G
0.80 < E < = 0.90
LPL 3
100kA
DB M 1 150, one each
between L1-G, L2-G
DB M 1 255, one
between L-G (N-G
optional)
0 < E < = 0.80
LPL 4
100kA
DB M 1 150, one each
between L1-G, L2-G
DB M 1 255, one
between L-G (N-G
optional)
Notes: Above specified arrestors are manufactured by DEHN Inc.
Part number & price for above models are:
DEHNblock Maxi 150 (DB M 1 150), part#, 961 110, limp = 35kA, list price $289.00 as of Sep 2013
DEHNblock Maxi 255 (DB M 1 255), part#, 961 120, limp = 50kA, list price $300.00 as of Sep 2013
The arrestors shown above are manufactured by DEHN Inc. and may be obtained in the USA by ordering from:
DEHN Inc., 851 S. Kings Hwy., Fort Pierce, FL 34945
Local Phone: 772.460.9315 | Toll-free Phone: 877.927.6510 | Fax: 772.460.9316 Email:
References:
1)
IEC 61400-24, IEC 61400-2.
2)
DEHN Lightning Protection Guide
3)
Characteristics of Direct Strike Lightning Events and Risk Assessment,
Dr.
–Ing Peter Hasse, Managing Director, DEHN, PEG 2001 Meeting,
Las Vegas, March 27-29, 2001.
4)
National Electric Code, 2005 Handbook, National Fire Protection Association (USA).
