Understanding dirty power from the grid

[Rafagus]

I have 2 EG4 3K, configured for 220, inverters. Recently our grid provider browned out a large area and folks are reporting damaged appliances. My system takes in grid power and outputs solar power, if there is enough, to my critical loads panel. If there is not enough solar it sends grid power to my critical loads panel. If the grid goes down it also sends solar for as long as it can.

My question is, what happens if the inverter receives this "dirty" brown out power from the power grid?

Thanks!

 

[Mattb4]

You would likely get an AC in fault and transfer to inverter. Pretty much what you would expect from a UPS. It is not uncommon for it to act this way when generators are not providing power within specs for voltage and frequency.

 

[Shimmy]

There are a lot of different kinds of "dirty" power, but generally an inverter has a minimum and maximum acceptable voltage and a delay, both of which could either be fixed or adjustable. Once power is outside that voltage range it should be isolated by the inverter.

That said, the time delay or the voltage threshold might be too loose to avoid damaging equipment. Making the threshold tighter could cause you to need to manually reset the unit often after normal conditions resume.

(Other power quality issues include brief interruptions, brief sags, brief overvoltages, longer overvoltages, and voltage surges and transients. "brief" is usually up to a few seconds, and a transient is a few microseconds whereas a surge is a few milliseconds.)