- Error code
- MSD-Vac
- Category
- Internal device fault
- Manufacturer
- SMA
1What the error means
The MSD-Vac message appears on older SMA Sunny Boy inverters. It indicates an internal measurement comparison fault: the inverter's two independent grid monitoring units measure different AC voltage values. For safety reasons, the inverter does not connect to the grid while this deviation persists. The exact cause is identified through diagnosis in the workshop.
2Possible causes
- Deviation in the internal AC voltage measuring circuit
- Fault on the inverter's control board
- Severe fluctuations or distortion of the grid voltage
- Loose or oxidised connection on the AC cable
3What to do
- Disconnect the AC side and the DC side, wait a few minutes and reconnect them.
- Check the AC fuses and the AC cable connection at the inverter and in the distribution board.
- If the fault persists, the inverter needs to be checked in the workshop.
4Repair by Aineas
You send the inverter to our lab in Thessaloniki. We diagnose it, inform you of the fault and the cost, and the repair starts only after you approve it. Every inverter is tested under simulated operating conditions before delivery.