SMA Sunny Island 4548-US, Техническое описание

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14 Connecting External Sources SMA America, LLC
138 SI4548_6048-US-TB_en-13 Technical description
The Sunny Island has one AC external source connection labeled AC2 Grid/Generator. With only
one external connection, the DigIn input is used to distinguish between the generator or line voltage.
If the DigIn input detects an open electric circuit, the Sunny Island is operated with grid parameters
and can feed excess electric current into the utility grid. When the DigIn input has a closed electric
circuit the Sunny Island recognizes that a generator is available.
When using a generator, install a transfer switch which switches from grid to generator. This can be
an automatic transfer switch (ATS) or a manual transfer switch. An automatic transfer switch provides
an automatic changeover between generator and utility grid. In the event of a grid failure, no
intervention by the operator is necessary.
In order to switch the signal circuit via the DigIn input, a single pole break contact or a single pole
auxiliary relay with a 120 V coil is necessary. If there is no auxiliary relay present in the ATS, you must
install an external contactor with a 120 V or 240 V coil. The coil is supplied with voltage via the utility
grid.
Treat this electric circuit as a communication circuit, and do not run this in parallel to AC voltage and
current cables. Running this circuit parallel to AC voltage and current conductors may cause
interference in the signal and give the Sunny Island an incorrect signal. No voltage should be present
on the relay during a grid failure. For external relays, pull voltage from the grid side of the transfer
switch.
The auxiliary relay can be a part of the automatic transfer switch or a separate assembly.