SMA SC 500CP-US - Manual (Page 25)

SMA America, LLC 3 Product Description
Installation Manual SCCP-US-IA-US_en-41 25
3.5 External Fast Stop
The external fast stop is to be used if the inverter is to be disconnected via an external signal in accordance with IEEE
1547 (e.g. External Islanding Detection). The inverter is delivered with a fast stop input. It is possible to connect an
external switch to this fast stop input. The external fast stop disconnects the inverter from the utility grid within 100 ms.
The options for configuring the external fast stop are displayed in the following table.
The models SC 850CP-US inverter and SC 900CP-US inverter are only provided with transfer trip functionality to meet
unintentional islanding requirements. An external signal is required from the utility (EPS) to utilize this feature.
3.6 Islanding Detection
Stand-alone grids form when the following conditions occur simultaneously:
• The medium-voltage grid fails.
• The inverter feeds in an amount x of power. There is an electrical load on the same branch of the grid with a load
equal to that of power x.
There are two methods for islanding detection:
• Active Islanding Detection*
• External Islanding Detection
Active Islanding Detection
The inverter detects the formation of stand-alone grids during a grid failure and disconnects the inverter from the utility
grid.
This function is set via the parameter EnaAID and cannot be active at the same time as the "FRT" function.
External Islanding Detection
In the event of a grid failure, the formation of stand-alone grids is detected at the farm level. If a stand-alone grid is formed,
a signal is transmitted to the fast stop input of the inverter.
If the signal appears at the fast stop input of the inverter while the inverter is in the "MPP load operation" operating state,
the inverter switches to the operating state "Shutdown". Once shutdown is complete, the AC contactor and the DC
switching device open automatically and the inverter switches to the operating state "Stop".
For external islanding detection, a suitable cable must be connected to the inverter fast stop input during installation.
Option Description
The external fast stop is
deactivated.
The terminals of the active fast stop are bridged ex works. The fast stop function is
thus deactivated.
The external fast stop is
operated via an external 24 V
supply.
An external latching switch (break contact) is connected to the inverter terminals via
an external 24 V voltage supply. If the external switch is inactive, the switch relay is
energized and the inverter feeds into the grid. If the external switch is activated, the
relay is de-energized and the fast stop is tripped. The inverter is stopped and no
longer feeds energy into the grid.
Voltage ranges for the relay:
24 V to 30 V: The inverter is in operation.
0 V to 4 V: The inverter is not in operation.
Tripping the fast stop function
The fast stop function should only be tripped in the event of immediate danger. Tripping the fast stop will not rapidly
discharge the capacitors. If the inverter is to be switched off and correctly shut down via an external signal, use the
input of the remote shutdown function.
* Not with some models of the SC 850CP-US inverter and the SC 900CP-US inverter