4 Product Description
SMA America, LLC
16
CU600-1000US-IA-en-10
Installation Manual
4.3 DC Switch-Disconnector
The Connection Unit is equipped with a DC switch-disconnector. The DC switch-disconnector enables
disconnection of the inverter from the PV array. The disconnection takes place at all poles.
Figure 4: DC switch-disconnector of the Connection Unit
When the DC switch-disconnector is switched
OFF
,
it can be protected against restarting with a
padlock via one of the three openings.
4.4 String Fuses
String fuses are used to protect wiring and equipment from excessive currents that can cause damage,
heating, or in extreme cases, even fire.
If the string fuses are designed too small, they may open too early and cause interference. If the string
fuses are designed too large, they do not provide the required protection as they open too late.
In PV systems, the minimum and maximum size of the string fuse is determined by the electrical nominal
sizes of the PV module as well as by UL and
National Electrical Code
®
requirements. Contact the
manufacturer of the PV modules in order to obtain the corresponding nominal sizes of the string fuses.
The maximum nominal size for string fuses in the Connection Unit is 20 A.
Item
Designation
A
Switch position
ON
B
Switch position
OFF
Opening for padlock to protect against restarting
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