Need hepl with PID operation

[herc1354]

I'm on the home stretch of completing my single tier brew rig, I'm using an Auber SWA 2441 and can't for the life of me wrap my head around the set up. I've read the instructions and still am having comprehension issues. I'm using the PID to control temps in the HLT through a Honeywell LP gas valve. Last night I applied power to the system for the first time, the PID fired off the burner with no problems, but I'm stuck...I guess what I need is some basic guidance/instruction on how to use a PID.

I'm very mechanically inclined which makes this even more frustrating I know this is not rocket science.

 

[tyzippers]

Well, congrats on making the jump to automation! In order for the PID to work correctly, you need something to provide feedback in the form of temperature in this case. So you need to attach a temperature monitoring device to the PID if you haven't already. This will tell the PID when to stop your burner. After that, make sure you have the settings in your PID set properly, e.g. Temperature probe type, heating vs cooling, etc. Don't worry about the P, I, and D settings just yet. Those can be taken care of using auto tune. So once you have your PID set up according to the instruction sheet, fill up your HLT with the amount of water that you will use in your normal brew day. PIDs work the best when you use the same vine of water every time. The results will be more repeatable that way and there will be much less overshoot. So, now that there's water in the HLT and you're certain that your probe is returning the proper temperature (also referred to as the Process Value, or PV) now you can adjust your set point, also referred to as the SP, and run your auto tune according to the manual.

Now this was all off the top of my head and I am not directly familiar with your specific PID, I use an Auber PID as well, but a different one. So I may have been a little general and missed a few things. Don't hesitate to ask if you have any more questions!

 

[herc1354]

Well, congrats on making the jump to automation! In order for the PID to work correctly, you need something to provide feedback in the form of temperature in this case. So you need to attach a temperature monitoring device to the PID if you haven't already. This will tell the PID when to stop your burner. After that, make sure you have the settings in your PID set properly, e.g. Temperature probe type, heating vs cooling, etc. Don't worry about the P, I, and D settings just yet. Those can be taken care of using auto tune. So once you have your PID set up according to the instruction sheet, fill up your HLT with the amount of water that you will use in your normal brew day. PIDs work the best when you use the same vine of water every time. The results will be more repeatable that way and there will be much less overshoot. So, now that there's water in the HLT and you're certain that your probe is returning the proper temperature (also referred to as the Process Value, or PV) now you can adjust your set point, also referred to as the SP, and run your auto tune according to the manual.

Now this was all off the top of my head and I am not directly familiar with your specific PID, I use an Auber PID as well, but a different one. So I may have been a little general and missed a few things. Don't hesitate to ask if you have any more questions!

Thanks!

I think I've read the instructions 12 times, every time I understand it more. I understand PV as temperature indicated and SV as the set temperature...and that is about it for now. I'm going to go out and play some more on this PID, fix some leaks and try and wrap my head around this PID operation. The PID I purchased has an alarm feature, that is why I chose it over the ones others have used.

 

[tyzippers]

Sure! I'm an electromechanical engineer by day and a brewer by weekend! I design control systems for vacuum heat treat furnaces which utilizes PIDs frequently. As a homebrewer, PIDs are not easy to understand because it uses crazy calculus to control the output based on your PV. The explanation would just confuse further probably, mostly because I'm not that good at explaining the inner operations of a PID! But suffice it to say that that crazy calculus equation is used along with the Proportional (gain), Integral (time), and Derivative (time delay) values to hit your SP right on the money with out overshooting it! After using auto tune, you simply adjust your SP where you want it and the PID does the rest! That part is simple and really all you need to understand for what we're doing as homebrewers! I see your model has a timer and a couple alarm outputs as well. Those could be quite useful! Again, if you need help, just ask!

 

[herc1354]

Sure! I'm an electromechanical engineer by day and a brewer by weekend! I design control systems for vacuum heat treat furnaces which utilizes PIDs frequently. As a homebrewer, PIDs are not easy to understand because it uses crazy calculus to control the output based on your PV. The explanation would just confuse further probably, mostly because I'm not that good at explaining the inner operations of a PID! But suffice it to say that that crazy calculus equation is used along with the Proportional (gain), Integral (time), and Derivative (time delay) values to hit your SP right on the money with out overshooting it! After using auto tune, you simply adjust your SP where you want it and the PID does the rest! That part is simple and really all you need to understand for what we're doing as homebrewers! I see your model has a timer and a couple alarm outputs as well. Those could be quite useful! Again, if you need help, just ask!

Again thanks, I just wish these controllers were a bit more simple to operate, I'm sure once I've figured it out it will be a snap. I was hoping to be able to hook it up and set a desired temps true via a very easy to understand set of instructions and let it go, way too many confusing parameters is what has me stumped

 

[herc1354]

So apparently SV is displayed as SP. I kept looking for SV so I could set the target temp but could not find it but I did see SP, when I set SP to a temp higher then what the sensor was reading it kicked in, when I set it below what the sensor was reading is shut off. Right now I have the PID in manual on/off mode, P=0. I'm going to call Auber on Monday, perhaps they can confirm that either the instructions are wrong or the PID was programmed incorrectly.

 

[tyzippers]

Remember. SP is your set point. It is your target temperature that you are trying to attain. That is the number that YOU change. For example, if you are sparging at 170F, you change your SP to 170F and the PID will kick on as you described and hear the water until the PV (which is the actual temperature of the water) starts to get close to your SP (your goal). Once your water temp gets close to your SP, the PID will start to reduce the amount of energy going into your water. I'm not sure how a gas set up is controlled, but in my electric setup, my SSR will start to be controlled by PWM (pulse width modulation) to reduce the amount of time the element is on to reduce the output of the element. The closer the PV gets to the SP the output should start to get smaller and smaller so you don't overshoot your SP. So your PID is operating properly. Make sense?

 

[herc1354]

Remember. SP is your set point. It is your target temperature that you are trying to attain. That is the number that YOU change. For example, if you are sparging at 170F, you change your SP to 170F and the PID will kick on as you described and hear the water until the PV (which is the actual temperature of the water) starts to get close to your SP (your goal). Once your water temp gets close to your SP, the PID will start to reduce the amount of energy going into your water. I'm not sure how a gas set up is controlled, but in my electric setup, my SSR will start to be controlled by PWM (pulse width modulation) to reduce the amount of time the element is on to reduce the output of the element. The closer the PV gets to the SP the output should start to get smaller and smaller so you don't overshoot your SP. So your PID is operating properly. Make sense?

Yeah I understand what SP is but the instruction kept telling me to look for SV. In a gas system the PID needs to be set up in on\off mode as a gas valve is either on or off, it can't be modulated to turn down the gas. My plan was to set the PID to turn on and off when the temps are 2-3degres within the my set value,