[wellylug] ups

Jim Cheetham jim at gonzul.net
Mon Mar 31 08:51:57 NZDT 2008


On Sun, Mar 30, 2008 at 10:25 PM, David Antliff <david.antliff at gmail.com> wrote:
>  I have a strange observation - every hour, on the hour, both UPSes go
>  into a semi-random switching state where they switch on and off mains
>  power every few seconds for about a minute. The APC one has a
>  'sensitivity control' so I made it less sensitive and it stopped doing
>  it. The Dynamix one doesn't seem to have this control so I have to put
>  up with lots of audible switching clicks every hour. Quite annoying. I
>  believe it's the ripple control causing this and I'd love to know if I
>  can legally block this somehow... (I have gas hot water). Maybe some
>  sort of filter on the UPS AC input?

The ripple control was responsible for causing similar shut down
problems on a windfarm recently built near Queenstown (don't remember
the name, sorry), and they just built a couple of filter blocks to
take it out :-)

Given that the ripple signal is imposed for commercial reasons (i.e.
to allow load management by the power company) and that the power
companies know who is on a load managed contract, blocking it from a
non-load-managed location should be just fine.

A quick google didn't reveal any precise info on how to filter the
ripple out (I'll guess it's not trivially the same as an output
smoothing filter from a transformer), but it is possible and I can't
see any legal objection, unless your electricity supply is contracted
on the expectation that you will be receiving the ripple ... :-)

-jim




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