SMA SC 250U - Manual (Page 40)

6 Electrical connection SMA America, LLC
40 DISU_SCUS-IA-IUS111711 Installation Guide
6.4 Connecting AC cables to the Disconnect Unit
Refer to section 6.2 ”Cable requirements”, page 32 for general requirements for DC, AC and PE
connection of the Disconnect Unit.
6.4.1 Additional cable requirements for AC connection
• Use the screw terminals or cable lugs to connect the AC cables to the AC breakers (see section
6.4.5 ”Connecting AC cables to busbars”, page 51).
Maximum number of AC outputs
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The AC outputs are isolated from the enclosure and the system grounding. If required by section
250 of the National Electrical Code
®
, ANSI/NFPA 70, the installer is responsible for this
grounding.
Maximum number of AC outputs per phase for Sunny Central 250U/500U 2
Maximum number of AC outputs per phase for Sunny Central 500HE-US/CA and
Sunny Central CP 6
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External AC fuses
The Disconnect Unit for Sunny Central 500HE-US/CA and Sunny Central CP is provided with UL
listed circuit breaker on output rated 1,600 A for branch circuit protection.
The AC output of the Disconnect Unit with Sunny Central 250U/500U must be fused externally by
the installer.
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• Over-current protection for AC output circuit of the Disconnect Unit must be provided by others
when used with Sunny Central 250U/500U.
• To reduce the risk of fire, connect only to a circuit provided with over-current protection in
accordance with National Electrical Code
®
, ANSI/NFPA 70.
AC fuses Disconnect Unit with Sunny
Central 250U High speed US fuses (Class J), maximum 400 A each.
AC fuses Disconnect Unit with Sunny
Central 500U Class L fuses, maximum 800 A each.