4 Product Overview
SMA Solar Technology AG
Operating manual
27
SI44M-80H-13-BE-en-15
Possible function or
output
Explanation
Display of operating
states and warning
messages
Control of a battery-
room fan
The multifunction relay is activated when the charging current causes the battery to emit
gasses. A connected battery room fan is switched on for at least one hour (see Sec-
tion 6.5.15, page 52).
Control of an elec-
trolyte pump
Depending on the nominal energy throughput, the multifunction relay is activated at least
once a day (see Section 6.5.16, page 53).
Use of excess energy In off-grid systems with lead-acid batteries, a multifunction relay is activated during the con-
stant voltage phase. It thus controls additional loads that can put any excess energy to good
use (see Section 6.5.17, page 53).
4.7
Information on Battery-Backup Systems
Wiring and connection of automatic transfer switches for single-phase or three-phase battery-
backup systems
• Do not bridge the neutral conductors of connections
X1
to
X5
in the automatic transfer switch. If the neutral
conductor connections are bridged, residual-current devices could trip accidentally.
• Label the equipment and devices of the automatic transfer switch in accordance with the schematic diagrams.
This will facilitate installation, commissioning and assistance in case servicing is required.
Connection of automatic transfer switches for single-phase battery-backup systems
In single-phase battery-backup systems, only the line conductor of the Sunny Island that is connected to the circuit
breaker
F1
of the automatic transfer switch is monitored for grid failure. If terminal
AC2 Gen/Grid L
is connected
to another line conductor, the battery-backup system is not able to synchronize with the utility grid following a grid
failure.
• With single-phase battery-backup systems, connect circuit breaker
F1
and terminal
AC2 Gen/Grid L
of the
Sunny Island to the same line conductor, e.g. to L1 (for a single-phase battery-backup system with an all-pole
disconnection function).
• Connect the PV inverter and the Sunny Island to the same line conductor if possible. This way, in the event of
grid failure, the PV inverters are supplied with voltage directly and then can feed in even if phase coupling is
deactivated.
