My network UPSs (APC Smart 1000) are unhappy with the quality of energy while on Inverter emergency battery power - attaching video, it gets instantly fixed when grid is connected - (it is making this loud noise while compensating)
I have Fox KH10.5
When you are running on EPS, have you got a Neutral to Earth bond being made and is your Earth on a local rod ? - if not you will have floating Neutral and/or possibly floating Earth.
Have a look at these 2 posts,
viewtopic.php?t=139
Particularly the last post on this thread viewtopic.php?t=52
Have a look at these 2 posts,
viewtopic.php?t=139
Particularly the last post on this thread viewtopic.php?t=52