I have an off grid solar system. 2 inverters. all of a sudden power dropped. One of the inverters was wacked out, all kinds of weird readings. took it off line and everything is fine now. the bad inverter blew out every transformer in the house! I do have a log for the inverters and the good one showed a constant 240v. the bad one showed low voltages down to 210v. Low but not high. Any ideas what happened? maybe put some MOV’s on the transformers?

 

Maybe the frequency dropped very low. This would cause a very high primary current.

 

the bad inverter is being sent back to the factory. I hope they will tell me the truth what they find.

 

Certainly the power frequency and voltage supplying a transformer matter a great deal. A lower frequency will reduce the reactrance and raise the current, possibly quite a lot, while reducing the efficiency. THAT combination can certainly lead to transformer burnout.

 

There may also have been a HIGH voltage relative to the system ground, but not to the common. "Blew OUt" is not a very specific description of the failure mode. An excessively high voltage can overheat, but not instantly, but it could cause a winding to break from a much to high current. LIGHTNING STRIKES cause that sort of damage frequently.

 

It could be wise to add series fuses to the transformer positions that qwere damaged. OR even thermal fuses to avoid future damage.