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PIDs

post #1 of 15
Thread Starter 
Is there a sticky thread on PIDs? I've read so many posts that I'm very confused about how they work and what applications they are best suited for. It seems that BFEs and WSMs are prime candidates, and in that application they are installed to control fans (IIUC). I'm thinking that my 1200 W MES 40 could benefit from a PID and SSR and thermocouple, but I haven't read much about using them on the MES.

I've been searching and finding threads all over the place - some relevant and others not so much. I hate to Beating_A_Dead_Horse_by_livius.gif but I'd like to learn more and maybe try my luck at putting one to work on my MES. As I understand it, the PID is a bit of an intelligent controller that uses algorithms to 'learn' how what it is controlling performs then uses that information to send signals to the SSR (solid state relay) to pass current or not pass current based on the status of the PID. The thermocouple is the sensing device that provides the feedback loop to the PID which would be wired to the PID and the probe would reside inside the MES. I have trouble understanding how my MES would get its current. Would it be plugged into a 120V AC circuit or wired to the SSR - and not plugged into a 120 VAC source - allowing the PID to control the MES' heating element switching. Does the SSR have to be connected to the MES wiring so that low voltage signalling controls when the element has power with the MES getting its power from the 120 VAC mains, or does the MES actually get its power thru the SSR? It seems that the latter would not be feasible. If the MES power comes from the mains, then the SSR has to be wired into the MES circuits meaning that one must know and understand the MES wiring that controls the heating element.

From reading the MasterBuilt website I learned that my unit has a 1200 heating element. What, if any, bearing does that have on the specs for the PID and the SSR? Do they have to be rated specifically to cover 1200 watts? Is there some other controlling rating, such as the voltage and amperage used by the MES to control the heating element power switch?

I did a bit of looking online after reading posts here. Amazon Prime has a MYPIN TA4 PID unit with heat sensor probe for $26.99 and a FOTEK SSR 40DA unit rated -3 to 32 VDC for $5.29. Add a little bit of wire and the lugs to make the connections, and Bob's yer uncle, no? That is considerably less than the $175 for the Auber plug-n-play unit. I realize that others have said that he TA4 is not of the highest quality, but buying from Amazon means I can return it (as opposed to eBay).

What am I missing?


In closing, I think this subject of using PIDs to control temps in our smokers - be they charcoal or electric - has enough interest to have a sticky thread somewhere to make it easier to find and read the information. The search functions aren't quite discreet enough to winnow out all the chaff.

TIA
post #2 of 15
To use a PID in your MES.. you would have to make the MES's controls/wiring obsolete... everything would be controlled with the PID... The PID will control the SSR with low voltage.. the SSR will control the 110V heat element... What you would have to do is wire the heat element directly to the SSR and then supply the SSR with 110V from a separate outlet.. The MES's wiring/controls will be bypassed and not used at all.... I have one on my 30 with a 1500w element... It will get hot enough to burn down,,LOL... Hope this helps you understand ... I think it's way better than the OEM controls...
post #3 of 15
Thread Starter 
Thanks, Keith!
post #4 of 15
Thread Starter 
Does this diagram get the general configuration and voltages and power sources right?

post #5 of 15
yea.. that's pretty much it.. the only thing I don't see is the white (common) wire going straight from MAIN to the heating element .... I have a better diagram... just need to find it...
post #6 of 15
Thread Starter 
Thanks, Keith!

I wasn't really trying to show wiring as much as current flow whether 120 AC or 12 VDC.

If I buy a PID that will handle the 120 AC input and will output the 12 VDC, and buy an SSR that will take the 120 VAC and pass it through as the PID tells it to, are there any other specs I should be concerned about, say amperage limits?
post #7 of 15
get a 25 amp SSR... that will cover all your needs ...

was gonna post the link to the SSR I bought at Auberin... but the website is down for updating...
post #8 of 15
Dward has a good thread here with diagram showing PID wiring. I have it saved but can't access it from this device.
post #9 of 15
Thread Starter 
More questions on making a PID/SSR controller for my MES.

I have this metal box. It looks like it needs to be a PID controller box.



After looking at devices on Amazon and getting their dimensions, I drew mock-ups of the PID controller, SSR, a power outlet and cover, an ON/OFF switch that lights when 'on/in' an led and a plug for a thermal coupler probe. You might have to enlarge the pic a bit to read the labels.

I plan to mount the SSR on a heat sink and attach it to the bottom of the box. The box has a secure lid and clasp. At the right rear you can see a hole for the power cable to enter the box. If this concept is valid, I will draw in wiring and post an update later.

Here are some questions:
1) Is it feasible to use the SSR to control when the power outlet gets current flow? I plan to break the tabs on the outlet and wire it so that the rear side outlet is 'hot' when the unit is switched on and the front side outlet to have current only when the SSR passes it thru to it. If this will work, I should not have to modify anything in the MES, right?

2) All probes I've seen on Amazon and eBay have ends with connectors on them, presumably for connecting to the PID. I would prefer to have the probe have an end that I can just plug into the probe socket rather than having the probe always hanging out of the box. Is it possible to modify the probes with spade connectors so that the wires connect to a straight plug in? If so, what do I need to buy and how do I go about making the mod to the probe wiring?

3) I have a surplus, small computer fan. Would it be overkill to drill and mount one in the box and put an air input hole or 2 on the opposite side? I have no idea how much heat the SSR might generate for the 1200 Watt heating element and don't know how to find out; so I'm seeking the opinions of those more electronics literate than I am.

4) If you have any comments or suggestions, please send them my way?

rh
post #10 of 15

I've been looking into this a bit myself. I am always financially strapped and yet , after looking it over, there's no way I'd build my own. I've worked in and around electronics for 30+ yrs.

At some point you are going to want to be able to program your PID to do steps. (run at X temp for 2 hrs, then X+ 10* for 1 hr then x+20* for another hr ect) Those PID's start around $70 on fleabay. Then you need the SSR and other bits, it adds up quick. The Auber unit is currently $135 and will do all that. Pretty simple plug and play set up. You're not likely to save n

much if any building your own.

 If all you want or all you want for now is simple run at X temp until I say otherwise, by all means build your own. You can save big bucks that way.

post #11 of 15

If you do not modify the MES the computer in the MES will give you problem. In that SSR turns on and off every few seconds. Every time the computers power drops out of its operating range the MES will reset to the off condition turning off the heater.

 

In the bottom box there are 4 high voltage wires connect the 2 from the AC cord to the 2 for the heater circuit connect them and you are good.

 

Adding connectors to a thermocouple circuit can be a problem because the way a thermocouple works. A thermocouple is 2 pieces of dissimilar wire twisted together when heated this generates a very tiny voltage .01 volts it take very little to block the circuit. Not that it cannot work just that it is not worth the risk.

 

https://en.wikipedia.org/wiki/Thermocouple

 

 

 

 

Walta

post #12 of 15

Or you can be lazy like me and buy a pellet grill with a PID.

post #13 of 15
Thread Starter 
Thanks, Walt!

I forgot about the electronic switching in the MES.
post #14 of 15
Quote:
Originally Posted by rabbithutch View Post

More questions on making a PID/SSR controller for my MES.

I have this metal box. It looks like it needs to be a PID controller box.



After looking at devices on Amazon and getting their dimensions, I drew mock-ups of the PID controller, SSR, a power outlet and cover, an ON/OFF switch that lights when 'on/in' an led and a plug for a thermal coupler probe. You might have to enlarge the pic a bit to read the labels.

I plan to mount the SSR on a heat sink and attach it to the bottom of the box. The box has a secure lid and clasp. At the right rear you can see a hole for the power cable to enter the box. If this concept is valid, I will draw in wiring and post an update later... I would mount the heat sink on the outside of the box...

Here are some questions:
1) Is it feasible to use the SSR to control when the power outlet gets current flow? I plan to break the tabs on the outlet and wire it so that the rear side outlet is 'hot' when the unit is switched on and the front side outlet to have current only when the SSR passes it thru to it. If this will work, I should not have to modify anything in the MES, right? Yes.. you can do this the way your thinking ... just make sure you plug the right plug into the right receptacle... You will have to wire the heating element with a male plug on it (If it doesn't come with one on it already...

2) All probes I've seen on Amazon and eBay have ends with connectors on them, presumably for connecting to the PID. I would prefer to have the probe have an end that I can just plug into the probe socket rather than having the probe always hanging out of the box. Is it possible to modify the probes with spade connectors so that the wires connect to a straight plug in? If so, what do I need to buy and how do I go about making the mod to the probe wiring? Yes.. you can get a receptacle for the TC that will mount in the box and then just plug in the TC... I believe I seen one on Auberins web site...

3) I have a surplus, small computer fan. Would it be overkill to drill and mount one in the box and put an air input hole or 2 on the opposite side? I have no idea how much heat the SSR might generate for the 1200 Watt heating element and don't know how to find out; so I'm seeking the opinions of those more electronics literate than I am.... I would try without the fan for now.. if you feel it's to warm in the box you can always mount the fan at a later date...

4) If you have any comments or suggestions, please send them my way?

rh

The LED light for the SSR you have on your box is not really needed as there is a light for it already on the PID ...
post #15 of 15
Thread Starter 
Thanks, Keith!

Great information.
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