At 08:03 AM 8/25/2006, WA3GIN @ Arlington County, VA wrote:
>Perhaps when not receiving a true sine wave from the generator you
>should reduce the load on the UPS to 50%
A standard (non-inverter style) puts out a very nice sinewave, albeit of
varying frequency as the engine speed changes. I have seen generators that
put out bad waveforms in weird load situations (enough magnetic flux to
saturate the iron, for instance, or if the current waveform is very peaky),
but by and large, the physics of how generators work (spinning magnet
inside a coil) inherently generates a clean sine wave.
I'd look to load characteristics, if it's not a governor control law issue
(voltage and/or frequency stability). In particular, high transient
currents can overload the generator in an instantaneous sense, without
noticeably affecting the average power output or voltage. You get a funky
sinewave with a little dip in the top.
>APC has the best answer for you on their web page...
APC sells a lot of different UPSes, line conditioners, inverters, etc, for
all sorts of applications. Unfortunately, their consumer/small office line
doesn't have very good descriptions of how they handle various types of
problems. Get into their professional/data center type products and you
get a lot more information (and assistance from them in specification of
the correct kind).. but you'll effectively pay for it.
For instance, there's not a heck of a lot of data on APCs website for
something like the BR500 (a very popular UPS for desktop computer sorts of
uses), although there is reams of stuff on their computer room and data
>Doug Rehman wrote:
> >Thanks to all for the replies.
> >I did leave out another link to TowerTalk: the generator powers the tower
> >lights when the grid is down...
> >To answer a few questions and make a few clarifications:
> >The line conditioners are true line conditioners; They are APC model Line-R
> >600. They do a great job during the occasional low voltage episode. About
> >once a week or so, they'll kick in and raise a low line voltage from the
> >I don't have a problem with the UPS's during normal operation from the grid,
> >only when off-grid and running on the back up generator.
> >One of the units that died from cycling during this week's grid outage is a
> >one week old APC 500 VA model, so I don't think the cycling is related to
> >the battery condition- just the noise from the generator as compared to the
> >I do have a whole house surge protector installed. It doesn't seem to do
> >anything for the generator's noise though.
> >There were some suggestions about replacing the UPS batteries with larger
> >ones (such as marine deep cycle). While it would greatly extend the runtime
> >of the UPS's, I only need the UPS's to run for the 30 seconds it takes for
> >the generator to come on line. The primary purpose for the generator is to
> >power everything during prolonged outages such as the 5 day one during the
> >2004 hurricane season. (I'm in Central Florida.)
> >After thinking about it a bit, the UPS's that were not cycling were all
> >lightly loaded. (The Belden on the phone system was one of the ones that
> >didn't cycle- I doubt the phone system, an NEC DS1000, draws more than an
> >amp or so. An APC 500 VA on the shack computer was another that didn't
> >cycle- the computer was turned off.)
> >Perhaps the solution lies in using over-sized UPS's?
> >TowerTalk mailing list
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