SMA SUNNY MINI CENTRAL 6000TL - Checking the Functioning of the Varistors

SMA Solar Technology AG Failure Search
Installation Guide SMC6-8TL-IEN101040 69
The approximate position of the ground fault can be determined from the ratio of the measured
voltages between plus against ground potential and minus against ground potential.
Example:
The ground fault is between the second and third module in this case.
3. Repeat step 2 for each string.
☑ The ground fault check is finished.
9.3.2 Checking the Functioning of the Varistors
Varistors are wearing parts. Their functional efficiency diminishes with age or following repeated
responses as a result of overvoltages. It is therefore possible that one of the thermally monitored
varistors has lost its protective function.
Result Action
☑ You have found a ground fault. • The installer of the PV generator must remedy the
ground fault in the affected string before you may
reconnect the string to the inverter.
•Do not reconnect the faulty string.
• Restart the inverter as described in section
7.3”Closing the Inverter” (page55), but without
reconnecting the faulty string.
☑You have found no ground fault. It is likely that one of the thermally monitored varistors is
defective.
• Check the varistors as described in section
9.3.2”Checking the Functioning of the Varistors”
(page69).