Re: Switching Silvias pump with SSR - snubber?
Dont know a lot about PIDs and their capabilities but using one of the PID buttons as a 25 second timer seems the most sensible to me and run the output of the timer to a switch / relay / SSR in parallel with the brew switch. Then the brew switch can be used as it normally is in full manual mode or for an override for extending the 25sec shot, and presumably the PID has a button you could cancel the 25sec timer if you need to.
My ignorant $0.02
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Re: Switching Silvias pump with SSR - snubber?
I copied Pauls original idea and have mine wired so that BOTH the brew switch AND the timer have to be on for the pump to run.Originally posted by robusto link=1174749485/0#5 date=1174950934Jim, can the PID timer be overridden by the normal brew switch or other handy means? Therell be plenty of times when 25 seconds isnt enough, particularly if the grind is too fine.
In that configuration, getting a longer shot (say 30 seconds) would require starting the timer again at the end of 25 seconds, then flipping the brew switch off when the timer reaches the 20 second mark of the second run. Not very convenient.
Im sure theres also a way to wire it so the EITHER the brew switch OR the timer can make the pump run. Then you could extend the brew time by just flipping the brew switch sometime near the end of the 25 second timer. But you could never stop a shot short of 25 seconds.
A third way, using the original wiring scheme, would be to just set your shot time to 30 seconds, then manually stop when it looked "done" by turning off the brew switch.
Jim
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Re: Switching Silvias pump with SSR - snubber?
Jim, can the PID timer be overridden by the normal brew switch or other handy means? Therell be plenty of times when 25 seconds isnt enough, particularly if the grind is too fine.
-Robusto
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Re: Switching Silvias pump with SSR - snubber?
Thanks for this, Mal. I felt pretty good about the internal varistors ability to handle the pump, too. FWIW, I havent noticed any problems with the D2425 I have on my bench machine as it happily operates the 25 second timer for my test shots.
Cheers,
Jim
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Re: Switching Silvias pump with SSR - snubber?
Hi again Jim,
Just had a look at the specs for these and in my opinion either unit will be entirely satisfactory for the job intended. I guess if you had additional concerns that needed allaying, then you could always connect a suitable MOV (Metal Oxide Varistor) across the pump coil leads to ensure that rapidly rising spikes from the coil were clamped well before the dv/dt rating of the SSRs was reached. Very economical and secure method to ensure protection.
Hope this helps out,
Cheers,
Mal.
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Re: Switching Silvias pump with SSR - snubber?
Hi, Mal -
Many thanks for helping out here.
Am considering the Crydom Series 1, more specifically the D2410 or D2425 (they seem to have the same snubber specs).
http://www.crydom.com//userResources/productFamilies/24/crydom_S1.pdf
Jim
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Re: Switching Silvias pump with SSR - snubber?
Gday Jim,
I think you should be ok.... Perhaps if you can tell us which Crydom unit you are considering I can have a glance at the spec sheet and get back to you.
Cheers mate,
Mal.
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Switching Silvias pump with SSR - snubber?
With a creative CS member leading the charge, several folks (including me) are using the timer output on their PID controller to automatically control shot timing on a Silvia.
Although I am disappointed at not being clever enough to think of this myself :-[, it really is a simple and handy variation on the PID theme.
My question to you sparkys out there is this: is there enough of an inductive load in Silvias Ulka vibe pump to overtax the SSRs built-in snubber? The Crydom specs say the internal snubber can handle a dv/dt of 500V/usec at 220V, but I dont know how this compares to the demand placed on it by switching the pump.
Thanks in advance for any thoughts/suggestions.
Jim
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