SMA SI 4548-US - Manual (Page 129)

SMA America, LLC 14 Connecting External Sources
Operating Manual SI4548-6048-US-BE-en-20 129
Generator Failure
If a generator failure is detected (failure on the master phase), the generator is disconnected
immediately and a stop signal occurs on generator. The system enters the minimum stop time (Lock).
Generator Phase Failure
The failure of a line conductor (e.g. broken fuse) on a slave device is treated as a line conductor
failure. The slave device then disconnects this line conductor. If the line conductor is detected as being
available again, it is reconnected after the warm-up time "234.12 GnWarmTm" has elapsed.
The line conductor failure on the master device is treated as a generator failure (see above).
Slave Device Failure
You can influence the behavior of the cluster upon failure of a slave device (see Section 12.9
"Behavior in the Event of a Failure in a Three-Phase System", page 106).
14.2 Utility grid
The Sunny Island supports the operation of battery-backup systems. Here, a distinction is made
between two main states: either a utility grid and stand-alone grid are connected or a utility grid and
stand-alone grid are disconnected. The operating mode of the Sunny Island is derived from this. If the
stand-alone grid is disconnected, the Sunny Island alone is responsible for powering this stand-alone
grid. If the utility grid is connected to the stand-alone grid, the stand-alone grid is powered from the
utility grid. Voltage and frequency in the stand-alone grid are identical with the utility grid.
14.2.1 Limits of the Voltage Range and Frequency Range
In order to operate on the utility grid, very strict limits (for voltage and frequency) must generally be
maintained. These strict limits are not sensible for generator operation. The limits are therefore set
separately for grid operation and the generator limits are not used.
Reverse power
Observe the reverse power which the Sunny Island can generate. The generator must provide
this protection; observe the information of the generator manufacturers.
RS485 communication between the Sunny Island and PV inverters
If a battery-backup system is connected to the Sunny Island, the RS485 communication between
the Sunny Island and the PV inverters is necessary (see Section 6.5.1 "Connection of the
Interface for External Communication", page 62).
Operating mode "Grid Charge"
Under specific conditions, the system can also temporarily feed energy from the stand-alone
grid into the utility grid in the operating mode GridCharge (parameter "232.08 GdMod").