SMA GRID CONNECT BOX 12 - Manual (Page 11)

SMA Solar Technology AG 4 Product Description
Operating Manual GRID-BOX-12-3-20-BE-en-10 11
4 Product Description
4.1 Grid Connect Box
The Grid Connect Box is an automatic transfer switch which enables the safe operation of the utility grid and a generator
as energy sources of an SMA Multicluster System.
Figure 3: Grid Connect Box with cabinet door open
Position Designation Explanation
A Protective cover Prevents inadvertent contact with live components during
operation and thus protects from electric shocks. When the
Grid Connect Box is in operation, the protective cover must
always be mounted.
B Fuse holder 1 A Used as receptacles for cylindrical thermal fuses (1 A, tripping
characteristic gG). The thermal fuses protect the connected
conductors from excessive heat build-up due to overload or short
circuits.
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 switches the loads off 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.