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Number of down conductors of the external lightning protection system
Class of LPS and < 4 ≥ 4
max. lightning current Values for the voltage-switching type 1 SPDs or type 1 combined SPDs (parallel connection)
(10/350 µs)
I SPD1 = I SPD2 I SPD3 = I SPD1 + I SPD2 = I total I SPD1 = I SPD2 I SPD3 = I SPD1 + I SPD2 = I total
I imp I imp I imp I imp
I or unknown 200 kA 25 50 12.5 25
II 150 kA 18.5 37.5 9 18
III and IV 100 kA 12.5 25 6.25 12.5
Table 9.18.2 Selection of the minimum discharge capacity of voltage-switching type 1 SPDs (spark gaps) or type 1 combined SPDs (parallel
connection of varistors and spark gaps); according to CENELEC CLC/TS 50539-12 (Table A.2)

Original 1. Activation 2. Arc 3. Electrical
state of the extinction isolation
disconnector

SCI
SCI
SCI
SCI SCI SCI SCI
SCI
Figure 9.18.7 Switching phases of the three-step d.c. switching
device integrated in DEHNguard M YPV SCI … (FM)
Figure 9.18.6 DEHNcombo YPV SCI type 1 combined arrester for
protecting photovoltaic systems from surges and
partial lightning currents

Type 1 d.c. arrester for use in PV systems:
Multipole type 1 + type 2 combined d.c. arrester,
DEHNcombo YPV SCI (FM)
With their integrated SCI technology, DEHNcombo YPV SCI
(FM) combined arresters (Figure 9.18.6) fulfil the above
mentioned requirements. In addition to the proven fault-re-
sistant Y circuit, DEHNcombo YPV SCI (FM) features a three-
step d.c. switching device (SCI technology). This d.c. switching
device consists of a combined disconnection and short-cir-
cuiting device with Thermo Dynamic Control and a fuse in the Figure 9.18.8 DEHNlimit PV 1000 V2 spark-gap-based type 1
bypass path. This circuit (Figure 9.18.7) safely disconnects combined arrester
the arrester from the generator voltage in case of an overload
and reliably extinguishes d.c. arcs. Thus, DEHNcombo YPV SCI
(FM) allows to protect PV generators up to 1000 A without (FM) is available for voltages U CPV of 600 V, 1000 V and 1500 V
additional backup fuse. This arrester combines a lightning and has a width of only 4 modules. Therefore, DEHNcombo
current arrester and a surge arrester in a single device, thus YPV SCI (FM) is the ideal type 1 combined arrester for use in
ensuring efficient protection of terminal equipment. With its photovoltaic power supply systems.
discharge capacity I total of 12.5 kA (10/350 µs), it can be flex- Voltage-switching spark-gap-based type 1 SPDs, for example
ibly used for the highest classes of LPS. DEHNcombo YPV SCI DEHNlimit PV 1000 V2 (Figure 9.18.8), are another power-

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