SMA SC 500CP-US-10 600V - Manual (Page 34)

3 Product Description SMA America, LLC
34 SCCP-US-BE-US_en-52 Operating Manual
A measuring circuit and a relay with a change-over contact are integrated in the insulation monitoring device.
The insulation monitoring device is connected between the PV voltage and the PE protective conductor.
The contacts of the relay are routed to the customer connecting terminal plate and can be used by the customer to trip a
signal light or horn. The characteristics of the relay are indicated in the circuit diagram.
If the insulation resistance falls below the warning threshold specified in the RisoCtlWarn parameter, the measuring
circuit closes and the LED ALARM1 on the insulation monitoring device lights up. The error message 3601‒ Warning
insulation error is generated by the inverter. Simultaneously, the insulation monitoring device activates the relay with
changeover contact. This relay is installed in the inverter.
If the insulation resistance falls below the error threshold (1 kΩ), an insulation error has occurred and the LEDs ALARM1
and ALARM2 on the insulation monitoring device light up. In this case, the operating behavior of the inverter can be set
via parameters:
• If the parameter IsoErrIgn is set to Off, the measuring circuit issues a disturbance when the insulation resistance falls
below the error threshold, the inverter switches off and issues the error message 3501 - Insulation error. The LEDs
ALARM1 and ALARM2 are glowing.
• If the parameter IsoErrIgn is set to On, the error message from the measuring circuit is ignored when the insulation
resistance falls below the error threshold. The inverter continues to feed into the grid and generates the error message
3504 ‒ Insulation error ignored.
• If the parameter IsoErrIgn is set to Run and the insulation resistance falls below the error threshold, the error
message from the measuring circuit will only be ignored if the inverter is in feed-in operation. In feed-in operation,
the inverter continues to feed in and issues the error message 3504 ‒ Insulation error ignored. If the insulation
resistance falls below the error threshold in another operating state, the error is not ignored and the inverter does
not go into feed-in operation. The error message 3501 ‒ Insulation error appears on the touch display. The LEDs
ALARM1 and ALARM2 are glowing.
Type of insulation monitoring device used
The insulation monitoring device used is the A-ISOMETER iso-PV1685 device supplied by Bender GmbH & Co. KG.
3.6.4 Combined Insulation and Ground Fault Monitoring
3.6.4.1 GFDI and Insulation Monitoring
With the "GFDI and Insulation Monitoring" order option, it is possible to temporarily disable the PV array grounding and
to check the insulation via the integrated insulation monitoring device.
When the GFDI is closed, the PV array is grounded In this state, the insulation resistance cannot be determined.
If the GFDI is open, the grounding connection is disabled. In this state, the insulation monitoring device continuously
measures the insulation resistance. In the operating state "MPP load operation", the insulation resistance of the entire
system, from the PV modules to the medium-voltage transformer, will be measured. If the inverter is in the operating state
"Grid monitoring", only the insulation resistance of the PV modules up to the inverter will be measured.
Insulation monitoring should be performed in the operating state "MPP load operation" This ensures that all parts of the
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 inverter:
• If the parameter IsoErrIgn is set to Off, the measuring circuit issues a disturbance when the insulation resistance falls
below the error threshold, the inverter switches off and issues the error message 3501 - Insulation error. The LEDs
ALARM1 and ALARM2 are glowing.
• If the parameter IsoErrIgn is set to On, the error message from the measuring circuit is ignored when the insulation
resistance falls below the error threshold. The inverter continues to feed into the grid and generates the error message
3504 ‒ Insulation error ignored.
• If the parameter IsoErrIgn is set to Run and the insulation resistance falls below the error threshold, the error
message from the measuring circuit will only be ignored if the inverter is in feed-in operation. In feed-in operation,
the inverter continues to feed in and issues the error message 3504 ‒ Insulation error ignored. If the insulation