Remote Shutdown; Automatic Shutdown Functions; Grid Management Shutdown; Transformer Protection - SMA SUNNY CENTRAL 500CP XT User Manual

SMA Solar Technology AG
The external fast stop must be connected in accordance with the circuit diagram. The external fast-stop function must
be connected via a shielded cable.
Tripping the fast stop
The fast stop should only be tripped in case of imminent danger. Tripping of the fast stop does not entail fast
discharge of the capacitors. If the inverter is to be switched off and properly shut down via an external signal, the
remote shutdown input is to be used.

10.2.1.2 Remote Shutdown

By means of remote shutdown, you can selectively shut down and switch off the inverter within approximately six
seconds, for example, from a control room. The function of the remote shutdown is similar to the stop function of the
key switch.
If the remote shutdown function is activated from the control room while the inverter is in the operating state "Grid
monitoring", a motor drive automatically shuts off the DC switchgear and the inverter switches to the operating state
"Stop".
If the remote shutdown unit is activated from the control room while the inverter is in the operating state "MPP load
operation", the Sunny Central switches to the operating state "Shutdown". Once shutdown is complete, the AC
disconnection unit and the DC switchgear are switched off automatically and the inverter switches to the operating
state "Stop".
The remote shutdown is designed as an open-circuit fail-safe function and must be connected to an external 24 V
supply voltage. If 24 V is present in the remote shutdown, the inverter continues to operate in the current operating
state. If the remote shutdown unit is tripped or if a wire-break occurs, 0 V is present in the remote shutdown unit and the
inverter switches from the current operating state to the operating state "Stop".
Use of the remote shutdown will only be possible if the parameter ExlStrStpEna is set to On.

10.2.2 Automatic Shutdown Functions

10.2.2.1 Grid Management Shutdown

If the utility grid becomes unstable, grid management requires that the inverter disconnects from the utility grid
immediately to avoid grid overload. In this event a corresponding Modbus signal will be transmitted by the grid
operator or the safety system at the point of interconnection. The inverter disconnects from the utility grid immediately
and displays error message 9013. After another signal from the grid operator or the safety system at the point of
interconnection, the error will be reset in the inverter.

10.2.2.2 Transformer Protection

A fully hermetic protector can be connected to the inverter. This fully hermetic protector is integrated in the MV
transformer. If a fault occurs in the MV transformer, the inverter immediately shuts down. The inverter has two terminals
with a grip range of 0.08 mm to 4 mm for connecting the transformer monitoring unit. To use the transformer
monitoring unit, an external supply voltage of 230 V ~ must be provided. The transformer monitoring unit must be
connected via a shielded cable. To deactivate this function, the associated parameter must be disabled.

10.2.2.3 Active Islanding Detection

The islanding detection function detects the formation of stand-alone grids and disconnects the inverter from the utility
grid.
Islanding can occur when at the time of utility grid failure, the load in the shut-down sub-grid is roughly equivalent to
the current feed-in power of the PV power plant.
With active islanding detection, the inverter continuously checks the stability of the utility grid. If the utility grid is intact,
this has no impact on the utility grid. Only if a stand-alone grid has formed will the inverter disconnect from the utility
grid.
To enable the active islanding detection function, contact us (see Section 13 "Contact", page 153).
User Manual
10 Function Description
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