[TowerTalk] OT: Generators and UPS's

Richard M. Gillingham rmoodyg at bellsouth.net
Thu Aug 24 22:15:04 EDT 2006

I have several of the APC units too.  The only time they've cycled/failed 
for me is when the batteries were about done in and wouldn't hold a charge.. 
After replacing the batteries, they behaved.  I get 3 to 5 years out of a 
battery.  Depends if it's been completely discharged a few times or not.

Good luck
Gil, W1RG
----- Original Message ----- 
From: "Doug Rehman" <rehman at surveil.com>
To: <towertalk at contesting.com>
Sent: Thursday, August 24, 2006 9:55 PM
Subject: [TowerTalk] OT: Generators and UPS's

>I realize this is off topic, but I can't find an answer elsewhere and
> TowerTalk has the best technical resources I can think of. (OK, I guess I
> can tie it to towers, because the generator will run the tower winch in 
> the
> event of a power failure and the computer in the shack has a UPS and will
> eventually control the rotator...)
> I have a generator with an automatic transfer switch. In the event of grid
> failure, I have more than enough capacity to run the house, shack, and
> office (all co-located). I have numerous computers in my office; each has 
> a
> line conditioner (primarily useful for over/under voltage events) and a 
> plugged into the line conditioner.
> Yesterday, the grid went down for about an hour. The generator came on 
> after
> about 30 seconds; the UPS's carried the computers during this interval. 
> Some
> of the UPS's began to switch on and off. The generator was running at 
> around
> 40% average load; the voltage fluctuation couldn't have been very much, as
> the line conditioners were not reacting at all. While I didn't monitor the
> frequency, in the past I haven't seen it change much.
> I always set the UPS's for maximum tolerance of noise and voltage. The UPS
> on my primary computer was one of the ones cycling on and off. It was
> reporting noise as the reason. That UPS, along with all of the others that
> were cycling, died after around 15 minutes.
> Interestingly, the three UPS's that weren't cycling were Belden 
> 350VA/500VA
> models that I would consider cheaper units. The more expensive APC units 
> and
> some cheaper Conext units all cycled and failed.
> The generator is well grounded and connected to the single point ground 
> with
> 2" copper strap.
> It is pretty certain that the cycling culprit is noise and I doubt I could
> clean the line sufficiently to make the sensitive UPS's behave- especially
> since the line conditioners have noise filters in them already. (There are 
> a
> lot of posts similar to this in the Usenet, but I couldn't find any
> solutions.)
> I need to replace about 7 or 8 UPS's, from 500VA to 1500VA. Has anyone 
> been
> down this road before and found a reliable UPS model and/or brand for use
> with a generator?
> Tnx,
> Doug
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