I used to have a APC UPS, it worked fine for quite a few years but suddenly stopped working. I heard good things about Eaton, and bought one, but it has been a disaster to be honest. I use it on a fileserver, and the capacity should be good, but when i tried the new one from Eaton it cut power during startup, and restarted the machine several times, maybe some peak power thing, but the APC what 650VA, and the new one is 850VA and the APC worked fine. For some reason it caused some data loss, which is certainly a big drawback when preventing data loss is the main reason for having it in the first place. I had a power failure, and the Eaton seems to have handled shutting down the machine, but after the failure it trips the circuit when it is plugged in. Does anyone have some other UPS to recommend? As of know the UPSes has caused more power outages than just not having one.
First part:. Different UPSs have different behavior. Some are more sensitive to disturbances, whether caused by line or load.
Second part, the UPS being connected to utility has no effect on the inrush to the server. It all depends on where in the AC sine wave the energy starts flowing. Ever plug something into an extension cord with a clear receptacle? Sometimes there is a sizable blue arc, sometimes small, sometimes none. All about where in the cycle the connection is made.