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Re: UPS and generator interaction?

  • From: Scott McGrath
  • Date: Mon Mar 29 14:08:49 2004

Brian,

The way the generators usually are set up is an transfer switch at the
input of the UPS.  When commercial power is lost the ATS signals the
Genset to start and once the input voltage stablizes the UPS shuts down.
This scenario assumes the use of a line interactive UPS which includes the
UPS you describe.   In the case of a online the UPS "sees" that
line power has been restored.

When power is restored the ATS switches back to commercial power and
signals the generator to shut down.   The ATS usually "exercises" the
generator as well on a set schedule as well.

My advice is to contact a local electrician who specializes in generator
installations as local codes define what you are allowed to do.

BTW APC has an environmental monitor card with relay outputs which can
be used to start a compatible generator.  once again you need to talk to
your local electrician.

                            Scott C. McGrath

On Mon, 29 Mar 2004, Brian (nanog-list) wrote:

>
> Does anyone know of a way to get a UPS to trigger a generator to start, and
> to switch over to the generator power automatically or does this type of
> thing just not exist?
>
> Right now we've got a APC Symmetra UPS at 12kva, with no generator.  The UPS
> keeps us running for about 45 minutes, which just isn't enough time.  I
> called APC, but they didn't seem to have any type of automatic solution.
> Their method is to hook it up to a switch, and manually change the feed to
> the UPS from the building power to the generator power and back, but it sure
> would be nice to have something more automated (to save me from running like
> a madman when the UPS page wakes me up at 4am).
>
> I'd be very grateful to hear of any solutions that you guys have come up
> with in this arena.  Also, any recommendations for generators?  I'm not
> looking for something huge, just something that can be mounted on a roof.
> If I have to pour diesel into it every couple hours, that's fine too.
>
> Thanks in advance,
> Brian
>