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RE: [new_distillers] Re: PID Controller

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  • Gavin Flett
    Once again,great info, thanks so much for the explanation To: new_distillers@yahoogroups.com From: bobg542492@aol.com Date: Fri, 23 Nov 2012 00:25:52 -0500
    Message 1 of 28 , Nov 23, 2012
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      Once again,great info, thanks so much for the explanation

      To: new_distillers@yahoogroups.com
      From: bobg542492@...
      Date: Fri, 23 Nov 2012 00:25:52 -0500
      Subject: Re: [new_distillers] Re: PID Controller

       

      I'm not an expert at beer brewing, but I doubt that the temperature has to be held absolutely steady e.g. to less than +/-0.1 deg C of the desired temperature.  I'm somewhat surprised that your previous, simple thermostatic controller wasn't acceptable.  I wouldn't think that the temperature wandering around within a few degrees of the desired temperature would make much of a difference to the biochemcial processes at work here, as long as the desired temperature was optimized for the enzymes, pH , etc.  However, if you want to minimize this "wandering around" and have the temperature come up to some point and stay there rock solid, then you want to use a PID controller, as you are doing.  There is no disputing this!  The only issue here is whether actually having the PID controller use an electromechanical contactor to cycle the AC power to your heater reduces the "wandering" down to an acceptable level.  If not, you need to have the PID controller operate a faster device in order to cycle the AC power faster -- and this device would be an SSR.
      -----Original Message-----
      From: Gavin Flett <gavin_flett@...>
      To: new_distillers <new_distillers@yahoogroups.com>
      Sent: Thu, Nov 22, 2012 4:20 pm
      Subject: RE: [new_distillers] Re: PID Controller

       
      Now that's what I have been searching for. a lamens description of what a PID and an SSR does. Thanks

      How do the beer brewers do this then, what kind of W heating element do they use? Is it multiple low wattage elements?


      To: new_distillers@yahoogroups.com
      From: self.adhesive@...
      Date: Thu, 22 Nov 2012 23:48:08 +0000
      Subject: [new_distillers] Re: PID Controller

       

      > Cool, great info. I am actually using it for a barley mash process. So if I understand correctly, an SSR performs the same functions as a PID, but better?

      No, they're completely different things. The PID is a logic "brain" that attempts according to the parameters you program in to shoot for a particular temperature. It determines how long the element is "on" or "off" and makes adjustments according to results.

      SSR stands for Solid State Relay. It's really just an electronic switch - it has no moving parts. It is the equivalent of the contactor but because the contactor has moving parts it is not capable of switching power off and on to the element frequently without destroying itself.

      Your PID itself is able to switch loads of up to 3 amps, but this is well short of 2000 Watts. Remember that Watts = Voltage x Amps. Re-arrange this formula to get W/V = A, and depending on what your voltage is this will tell you how many Amps capability you need.

      So you employ a contactor, or SSR, to do the heavy-duty switching because these are capable of handling many more amps.

      There is one thing to remember with a SSR, and that is if they fail they switch, as far as I understand, to full on and will not turn off. The SSR has its own connection to voltage mains. So, as with all setups like this, you should always supervise operation.

      Paul



    • laxt57@aol.com
      Hi Well, er, ah,mumble*%#** I hate to butt in. But you could use a solid state contactor Switch on and off lots without issue Jeri ... From: Bob Glicksman
      Message 2 of 28 , Nov 25, 2012
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        Hi
        Well, er, ah,mumble*%#** I hate to butt in.
        But you could use a solid state contactor
        Switch on and off lots without issue
        Jeri







        -----Original Message-----
        From: Bob Glicksman <bobg542492@...>
        To: new_distillers <new_distillers@yahoogroups.com>
        Sent: Thu, Nov 22, 2012 11:17 pm
        Subject: Re: [new_distillers] PID Controller






        No. You would use an SSR in lieu of a contactor.
      • Fredrick Lee
        Gavin, I own a 12HL (a little less than 300 gallons) brewery and we use a 6000W RIMS tube for our mash tun temp changes. Two things we have solved that have
        Message 3 of 28 , Nov 26, 2012
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          Gavin,
             I own a 12HL (a little less than 300 gallons) brewery and we use a 6000W RIMS tube for our mash tun temp changes. Two things we have solved that have made this possible. 

          1.) We realized not only did we need to know the temp of the grain bed (mash temp), we also needed to know the temp of our RIMS tube output (rims temp).  We were recirculating our wort out of the RIMS back into the mash tun near the top (I think some breweries call this the "vorlauf"). This freshly heated wort would remain at the top of the mash, and only slowly work it's way down until it was replaced by enough hot wort to reach the thermometer. Often overshooting your the mash temp and denaturing the enzymes that were responsible for starch conversion; depending when this occurs, we could end up with significantly less sugar to ferment.  We solved this problem by averaging the mash temp and the rims temp. Most PIDs cannot do this, so for a while we used pencil and paper with a manual thermometer on the mash tun and PID (with SSR) on the RIMS tube. After a bit of mucking around we discovered this problem on our 100liter (about 20 gals) system too. 

          2) we feel like everyone should take good care to have a gentle vorlauf, it will rebuild the grain bed to act as a filter for the husks and whatnot. Clear flowing wort ferments better and leaves less residue in your kettles and fermenters. Low splashing and avoiding wort from channeling through the grain bed will make things much better for in the boil and subsequently whirlpooling, chilling and fermenting. 


          On Nov 22, 2012, at 7:20 PM, Gavin Flett <gavin_flett@...> wrote:

           

          Now that's what I have been searching for. a lamens description of what a PID and an SSR does. Thanks

          How do the beer brewers do this then, what kind of W heating element do they use? Is it multiple low wattage elements?


          To: new_distillers@yahoogroups.com
          From: self.adhesive@...
          Date: Thu, 22 Nov 2012 23:48:08 +0000
          Subject: [new_distillers] Re: PID Controller

           

          > Cool, great info. I am actually using it for a barley mash process. So if I understand correctly, an SSR performs the same functions as a PID, but better?

          No, they're completely different things. The PID is a logic "brain" that attempts according to the parameters you program in to shoot for a particular temperature. It determines how long the element is "on" or "off" and makes adjustments according to results.

          SSR stands for Solid State Relay. It's really just an electronic switch - it has no moving parts. It is the equivalent of the contactor but because the contactor has moving parts it is not capable of switching power off and on to the element frequently without destroying itself.

          Your PID itself is able to switch loads of up to 3 amps, but this is well short of 2000 Watts. Remember that Watts = Voltage x Amps. Re-arrange this formula to get W/V = A, and depending on what your voltage is this will tell you how many Amps capability you need.

          So you employ a contactor, or SSR, to do the heavy-duty switching because these are capable of handling many more amps.

          There is one thing to remember with a SSR, and that is if they fail they switch, as far as I understand, to full on and will not turn off. The SSR has its own connection to voltage mains. So, as with all setups like this, you should always supervise operation.

          Paul


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