Inverters does not show a fault, but shows a status or state which says "Wait AC" or "Wait DC".
If the inverter is showing a status of "Wait AC", consider checking your grid voltage and frequency parameters. If there is no fault code associated, this generally suggests that the inverter is being restricted by "OpMin" or "OpMax" parameters. These define the voltages that the inverter needs to see from the AC grid in order to switch states from "Wait" to "Operation".
This function can be changed permanently for your plant, or by individual devices when needed. We highly recommend reviewing the SMA manuals to fully understand the functions prior to making any changes.
- VCtl.OpMinNom / VCtl.OpMaxNom - These define the AC grid range that the inverter must be in for a defined time, before the inverter can change from a wait/stop status to operation. If the AC voltage is out of this range, the inverter will NOT issue a fault and the timer will continue to reset.
- VCtl.OpMinNomRecon / VCtl.OpMaxNomRecon - Similar to the former, these define the AC grid range that the inverter must be in for a defined time, before the inverter can change from a wait/stop status to operation AFTER a power loss. If the AC voltage is out of this range, the inverter will NOT issue a fault and the timer will continue to reset.
To change the behavior, try the following steps:
- Check your AC voltage to determine how high/low it is.
- This will determine whether you need to adjust the minimum values or the maximum values
- Calculate the p.u. value and determine an acceptable level
- For example: If the grid voltage is at 580Vac when I need the inverter to reconnect, and the inverter nominal voltage is 550Vac. I would change choose 1.07 p.u. which equates to 588.5Vac which is safely above the current level.
- Stop the inverter - remote or local - and navigate the parameter page. Filter for VCtl.OpMin or VCtl.OpMax
- It is important to do a sanity check here to confirm your problem. Check your current settings and calculate what the minimum / maximum thresholds are. For example: if it's set to 1.05, I can calculate 550 Vac nominal multiplied by 1.05 to understand that the current setting requires the voltage to be below 577.5Vac for a defined period of time before changing to operation.
- Change the value to the value which you determined to be acceptable.
- Save the changes and attempt to reconnect your inverter.
We genuinely hope this article was helpful. Now, help us stay sharp! Please share any notes you have so that we can keep supplying you with the most up-to-date information. Thanks and stay safe!