APC UPS Smart 1400 goes to battery even if voltage is 120vac from generator

[w2jo_apc]

This was originally posted on APC forums on 6/2/2013

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I have two UPS Smart 1400 systems.  One supports a server and various modems, switches and routers in an equipment room.  The other supports only a PC and RAID tower. Both UPS systems are only required to deliver about 250 watts or less to their loads.   Both suffer from the following problem.

If the Utility AC Power fails, after about 2 minutes, the building's diesel generator comes on line.  The voltage is always from about 118 to 122vac RMS from the generator and the frequency between 59 and 61hz.  Usually the frequency is about 59.4hz on backup power but it does vary with shifting load.  The problem is that both units repeatedly go on and off line when operated on the emergency power.  I am wondering why this might be?  You can hear the relay in both UPS units going on-off-on-off- at intervals of a few seconds. 

I am wondering if this might be related to the FREQUENCY being low or high?  Or perhaps the problem is the generator's AC Output Waveform?  The waveform looks like a slightly compressed sine wave with two short spikes of about 10% on the rising part of the waveform.  The spikes do not seem to ever exceed the peak voltage of the waveform.

The power supplies of all the equipment are switchers and, as such, could not care less about the AC Power Frequency within reason.

Suggestions?  Are there ADJUSTMENTS in the UPS units to control this problem's sensitivity?

All thoughts and suggestions are welcome.  Thanks!

Joe

[nael_apc]

This was originally posted on APC forums on 6/3/2013

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Hi

change sensitivity for ups to low this problem because output power from generator not pure

thanks

[BillP]

This reply was originally posted by Angela on APC forums on 6/3/2013

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yes, check out article ID FA158891 in our knowledge base (http://www.apc.com/site/support/index.cfm/faq/) - you'll want to change the sensitivity,

assuming these are the older beige Smart UPS, you can do this with a network management card if installed, powerchute if connected via USB or serial, or even better, by the LED/push button on the back of the UPS. if it is brightly lit, sensitivity is high, dimmer is medium, off is low.

[w2jo_apc · Accepted solution]

Golly... 

MANY Thanks for your answer!  Probably that would have solved my problem!!!!

There is likely a WORLD Record here!  I asked my question in 2013 and never heard from you.

Then..  Now in 2021 I get my answer.. That is Great!

However, the old UPS equipment has long been in the scrap heap and my new Toshiba UPS gear is working just fine!

Have a nice day!

Joe