UPS Problems With Generator-Supplied A/C

[Anonymous user]

Hello. I have been using model ES-550 for some time and recently have noticed that when I am running my generator to supply power during black outs, they refuse to use A/C power. They report being on battery and beeping. Not sure if this has always been the case or not.

In looking at the event log from PowerChute 3, I see something like the following:

APC Event Decoder by SCCI
Generated	2018-12-22-04:02:33
Event #	Month	Day	Year	Hour	Minute	Seconds	Event Code	Event Description
130	12	20	2018	10	31	47	173	Battery backup transferred to battery power due to under voltage.
131	12	20	2018	10	31	51	61455	Battery backup transferred to AC utility power.
132	12	20	2018	10	45	2	61453	Battery backup transferred to battery power due to electrical noise.
133	12	20	2018	10	45	6	61455	Battery backup transferred to AC utility power.
134	12	20	2018	10	55	12	174	Battery backup transferred to battery power due to blackout.

There may have been an under voltage when on the generator. But I do have set the ES-550/PowerChute to have both Low Sensitivity AND a voltage range of 92 to 139. So that is one reason I think that under voltage may not be the issue.

Another reason to doubt that under voltage is the issue is because immediately after the utility power came back on, I checked the voltage with my Kill-A-Watt meter and the utility A/C was under voltage at 109-110 for some time but the UPS did not complain/beep.

So I am thinking that under voltage - while likely the case - is perhaps NOT my issue. Looking at the log above I have to then wonder about the "noise" - whatever that means.

I read elsewhere on this forum that if the power frequency is off by +- 5%, the UPS will not use it. Is this true of the ES-550 and other models? Could this be the "noise" issue? I did not know/think to check this with my Kill-A-Watt but will do so next time. If this is the issue, what can I do? What I was reading elsewhere here said this was nothing I could tune or change regarding the frequency sensitivity. But I am not sure if this is true of all APC UPS models or not.

I understand that the frequency of power from the generator is a function of its running speed and that this should be 3600 RPM to yield 60 cycle power. I have not tried a way to test the RPM speed on the generator but maybe I can somehow. My auto dwell-tach won't likely work as it supports 4,6, and 8 cylinder engines and the generator has but 1. I can not find any way to control this in the generator or engine manual. So I am figuring that I will have to adapt via the UPS and not the generator.

Any suggestions on what to do here, other models of UPS that may work well enough under these conditions, etc?

Thanks and happy holidays from Seattle, WA USA!