UPS Alarms

[Live2learn]

I am about to do a load transfer on a UPS and I noticed a "Static Switch Unable" alarm on an old Emerson UPS. I believe we also get alarms on the newer Liebert UPS ("Not OK to Transfer"). I would like to understand why this is happening. When the generators that support the Emerson & Liebert UPSs are tested via ATS, we get the "Input Fail" and "Battery Discharge" alarms - which is normal.

 

[Boof87]

Is the static switch unable alarm present whilst the input is supplied by the generator and not the mains. if this is the case it will have to do with the variance of the frequency output of the generator being out of tolerance with the settings on the unit. if it occurs whilst on mains supply check the potential between the inverter output and bypass supply if this is greater then 15 VAC generally the static switch will not sync with the inverter

 

[Live2learn]

Just checked it. It was the frequency variance. Thanks

 

[powerjunx]

agree..it's frequency variation at the time when small generator reacts with the load..i guess this is stand by emergency generator?!


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