--- In "Jim George" <> wrote:
>
> > I've googled myself silly with RC snubbers, MOVs and so on. My
> > application is not life-safety, but it has the potential for
> > economic (and emotional) loss - it's to control a breeding box. I
> > need to maintain a fairly well defined environment in terms of UV
> > lighting and temperature.
> >
> > Anything I can do to improve the reliability and longevity of the
> > relays is a plus. Since the relays on the TS-RELAY look sealed and
> > non-socketed, I have no way to check for sparks and no way to
> > replace a burned out relay.... Each relay would control a load
> > around 1.5 A @ 120VAC, some resistive (the heaters) and some with
> > fluorescent lighting. The heaters turn on and off every few
minutes
> > for 12 hours a day; say 100 cycles/day. The fluorescent lights
turn
> > on once a 12 hour cycle. It is possible that one of the relays may
> > also run a small fan, although that's not currently the plan.
> >
> > A clutch of eggs is worth around $500 alive, and and nothing
> > dead. :-) A few pennies on the proper protection for the relays is
> > definitely worth it. I can't find any way to size the proper
> > protection, other than "Watch for sparks and fiddle with the RC
> > values until the sparks go away." What are people doing to protect
> > against burned contacts?
>
> Would you be able to use solid-state relays? Their drive
requirements
> are quite small, so the DIO port on the TS boards should be able to
> drive them directly. You can also buy chassis-mount relays one at a
> time, the exact number you need. This also neatly avoids the issue
> with arcing across contacts.
>
> Search for the Crydom CC1000-ND this is just one example of an SSR
you
> can get. Various load ratings are available, this one can switch
> It also has AC zero-crossing switching, so the EMI will be
> low (may help protecting the TS7250). I found it by searching for
all
> SSRs on Digikey with DC control inputs that operate down to 3V
(which
> is what the TS7250 can put out on its DIO port).
>
> PS, interesting application :-)
Heh. It's a hobby. I'm toying with setting up a webcam on the
breeding box, and showing the eggs 'live'. Maybe I can sell'em
before they hatch. :-) I have an IR webcam coming, and even with
the limited framerate I can get from the TS-72xx USB port, the lack
of action won't be a problem - the eggs take 60 days to hatch.
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