SMA SC 500HE-20 - Manual (Page 27)

SMA Solar Technology AG 3 Product Description
Operating Manual SCxxxHE-20-BE-BEN111210 27
If, after approx. 5 minutes, one of the failures "3501 ‒ insulation failure", "3504 ‒ insulation failure
ignored" or "3601 ‒ Warning insulation failure" is displayed, the insulation is defective. In this case,
an electrically qualified person must check and, if necessary, repair the insulation and confirm the
failure.
3.5.7 Remote GFDI and Insulation Monitoring
The "Remote GFDI and Insulation Monitoring" order option enables automatic error correction and
allows you to temporarily disable the grounding connection of the PV array and then check the
insulation with the integrated insulation monitoring device.
When the GFDI is closed, the PV field is grounded and the insulation resistance cannot be determined.
If the remote GFDI trips, a temporary error is assumed and a motor will close the GFDI after a delay.
The triggered remote GFDI can be closed without an external starting command. The inverter can
switch back to feed-in operation after a delay.
In the default setting, the Sunny Central software will attempt to start the GFDI up to 3 times per day.
If the GFDI is triggered on consecutive days, the software assumes a permanent insulation error and
shuts down the inverter permanently. In this case an electrically qualified person needs to check and,
if necessary, repair the insulation and then confirm the error.
If the remote GFDI is open, the grounding connection is disabled and the insulation monitoring device
can continuously measure the insulation resistance. In the "MPP load operation" operating state, the
insulation resistance of the entire system will be detected, from the PV modules to the medium-voltage
transformer. If the inverter is the "Grid monitoring" operating state, only the insulation resistance from
the PV modules to the inverter will be detected.
Insulation monitoring should be performed in the "MPP load operation" operating state so that all
sections of the PV plant are included in the insulation measurement.
The parameter for insulation monitoring allows you to configure how an error message in the
insulation monitoring device will affect the operating behavior of the Sunny Central:
• If the parameter "IsoErrIgn" is set to Off, the measuring circuit generates a fault message and
the inverter switches off when the ALARM1 value falls below a specific threshold. LED1 turns on.
• If the parameter "IsoErrIgn" is set to On, the error message from the measuring circuit is ignored
when the ALARM1 value falls below a specific threshold. The inverter continues to feed power
into the grid and generates the error message "3504 ‒ insulation failure ignored".
Insulation Monitoring
To disable the grounding connection of the PV array, the "RemMntSvc" parameter must be set to On.
This allows a motor to open the remote GFDI.
If the remote GFDI is opened via the "RemMntSvc" parameter, the insulation monitoring device will
start measuring after the delay defined by the "IsoMeasDly" parameter. This allows the insulation
monitoring device to determine the insulation resistance without interrupting the feed-in operation. If
an insulation failure occurs, it will be considered at the end of the delay.