Event numbers 74 and 7401 indicate that at least one of the inverter’s thermally monitored varistors is defective.
Varistors protect the electronics against atmospherically coupled energy peaks. They trigger for example, when a lightning strikes in the neighborhood.
Varistors are wear parts. Their function decreases after repeated overloading.
Corrective measures:
If you are the system operator, please contact your installer.
| DANGER! The tasks described below may only be performed by electrically qualified persons: |
Check that the varistors are operating, as described in the service manual or installation manual:
If the varistor is defective, we recommend to replace all varistors immediately.
Replacement varistors and insertion tools can be ordered from SMA Service .
If a conductive connection at the areas described is present, please contact the SMA Service .
Please provide the following information:
| Device type and serial number of the Inverter | |
| Event number | |
| Installation date | |
| How have the varistors been checked? | |
| Is the inverter feeding power in? |