SMA America, LLC
Connecting External Sources
Technical Description
SI5048U-TUS121440
123
The voltage and frequency limits are monitored in phases. At least the phase on the master device
must comply with the limits defined for connecting the generator. If the limits are not maintained, slave
devices, where applicable, connect or disconnect individually.
The Sunny Island burdens the generator at each phase with the current defined in the parameter
”234.03 GnCurNom” as a maximum. The power that is not directly used by the loads flows into the
battery for charging. At the same time, the limits for the AC charging current limit
(”210.02 InvChrgCurMax” parameter) on the Sunny Island and the DC charging current limit
(”222.01 BatChrgCurMax” parameter) are active.
Low values for this limit may be the reason why the defined generator current cannot be adjusted. If
the battery voltage reaches the charging voltage nominal value, it is also reduced (absorption phase,
see section 13.4 ”Charge Control” (page 107)).
If the ”234.15 GnCtlMod” parameter is set to CurFrq, the generator is also limited at frequencies
lower than the nominal frequency (”234.04 GnFrqNom” parameter). This function can be used if the
full generator output is not always available and you want to prevent the generator from being
overloaded. The default setting is only intended to control the nominal generator current.
If the current set using the ”234.03 GnCurNom” parameter is not sufficient for powering the loads,
the battery provides support (”real generator support”).
The Sunny Island provides all the required reactive power.
Generator Disconnection by the master
If the master device disconnects the generator, all slave devices are disconnected as well.
Generator Disconnection by a Slave
If a slave device is disconnected from a generator (and the master continues to be
connected to the generator), the slave device can reconnect once the voltage and
frequency are within the valid range again.
In this case a monitoring period is running. Only after the time for the
”234.12 GnWarmTm” parameter has expired and after voltage and frequency are
determined to be valid does reconnection take place.
Value for the ”234.03 GnCurNom” Parameter
A sensible value for the ”234.03 GnCurNom” parameter is approx. 80 % of the maximum
generator current for each phase.
