SMA Solar Technology AG
3 Product Description
User Manual
SCCP-JP-BA-A4-en-12
21
3.6 External Fast Stop
The Sunny Central is equipped ex works with a fast stop input. You have the option of connecting an external switch to
this fast stop input which is activated via a 24 V signal.
The external fast stop disconnects the Sunny Central from the utility grid in less than 100 ms.
The Sunny Central is delivered ex works with open terminals. The following options are available for configuring the
external fast stop:
•
The external fast stop is deactivated:
The terminals of the active fast stop are bridged. The fast stop function is thus deactivated. You will need to bridge
the terminals if required.
•
The external fast stop is operated via an internal 24 V supply:
An external latching switch (break contact) is connected to the Sunny Central terminals via the internal supply
voltage in the Sunny Central. When the switch is closed, the all-or-nothing relay is activated and the Sunny Central
feeds into the grid. If the fast stop is tripped, the switch opens and the relay is deactivated. The Sunny Central is
stopped and no longer feeds energy into the grid.
•
The external fast stop is operated with external 24 V supply:
An external latching switch (break contact) is connected to the Sunny Central terminals via an external 24 V voltage
supply. When the switch is closed, the all-or-nothing relay is activated and the Sunny Central feeds into the grid.
If the fast stop is tripped, the switch opens and the relay is deactivated. The Sunny Central is stopped and no longer
feeds energy into the grid.
3.7 Ground-Fault Monitoring and Insulation Monitoring
The different types of insulation and ground-fault monitoring are described in this section. The type of Sunny Central
insulation and ground-fault monitoring depends on the order option.
3.7.1 Mode of Operation
The insulation and ground-fault monitoring ensure system protection. The type of monitoring depends on whether the
PV array is grounded or not.
In Grounded PV Arrays
The ground-fault monitoring is implemented by means of a residual-current monitoring device. If a ground fault occurs,
the residual currents are detected and interrupted.
•
Ground fault on the ungrounded terminal
If a ground fault occurs on the ungrounded terminal of the PV array, the normally ungrounded terminal of the
PV array is grounded non-specifically by the ground fault and a residual current flows to the grounded terminal.
This residual current flows through the ground-fault monitoring device, e.g. the GFDI, and triggers it.
Tripping the fast stop
The fast stop should only be tripped in the event of imminent danger. The tripping of the fast stop does not entail fast
discharge of the capacitors. If you wish to use an external signal to switch the Sunny Central off in a controlled
manner, you should use the input of the remote shutdown function.
