SMA Solar Technology AG
4 Product Description
Operating Manual
MC-BOX-12-3-20-BE-en-10
11
4 Product Description
4.1 Multicluster Box
The Multicluster Box is an SMA multicluster technology device for off-grid systems, battery-backup systems and systems
for increased self-consumption. The Multicluster Box is a main AC distribution board to which you can connect up to four
clusters. Each three-phase cluster is made up of three DC-side, parallel-switched Sunny Island 6.0H / 8.0H inverters with
software release 3.5 or higher. Functions of the Multicluster Box include:
• Main AC distribution board for Sunny Island inverters, one generator, one load and one PV system
• Load shedding
• Automatic bypass and reverse current monitoring for the generator
• Active anti-islanding
Figure 3: Multicluster Box with cabinet door open
Position Designation
Explanation
A
Protective cover
Prevent inadvertent contact with live components during
operation and thus protect from electric shocks. When the
Multicluster Box is in operation, the protective covers must
always be mounted.
B
Protective cover
C
Residual-current device
Protects against electric shock and is always used in addition to
existing protective measures such as insulation or protective
grounding. As soon as a dangerous touch voltage occurs, the
residual-current device disconnects the loads at all poles.
This is achieved by means of a summation current transformer in
the residual-current device which detects the electric currents in
the conductors
L1
,
L2
,
L3
and
N
. In the normal operating state,
the sum of these currents equals zero. Under fault conditions a
differential current is formed which trips the residual-current
device.
D
Circuit breakers
To protect the power cables of the Sunny Island inverters
