Due to the amount of PM's I have been getting from people asking how to connect their PID I threw these instructions together. Hopefully they will help some people out...
A guy on eBay named Tibetwalk sells a PID, SSR, TC combo for dirt cheap (I am not affiliated with this guy in any way) its a set-620 I believe and the terminal numbers in my drawing for the PID/SSR are based on it, as seen HERE.
The control should be fed from a GFCI circuit and adding a timer would also be an excellent idea.
This control uses the PID’s alarm contact to control a 2 pole NO (normally open) relay or contactor as a highlimit control, not ideal but it will kill the heater if the SSR fails closed (SSR’s often fail in the closed position leaving the heater on indefinitely). The PID must be set up correctly to open the alarm contact once the highlimit setpoint is reached. The momentary contact “reset button” is to ensure the heater stays off once the temperature drops below the highlimit setpoint. It will need resetting every time the power is turned off or if the grid power “blips”, keep that in mind if your not getting any heat! This is also a good reason to add the “heater on” indicator light.
If a line voltage highlimit is used (like the red button part of a water heater stat) the top line in the drawing can be deleted and the line voltage highlimit can replace contact R1 ahead of the heater.
Good quality, hard usage cords (SOOW cabtire) and connectors should be used for the feeds as well as a steel electrical box (D boxes are great and cheap) to house the controls. Cover up the heater terminals and any other exposed terminals with a steel box, open electrical terminals KILL people! Also be sure to ground EVERYTHING together.
It’s VERY important to use a flow (flow for an inline heater) or float switch to ensure the heater cant be powered up when not covered in oil (potential for a tank fire or worse explosion!). A cheap low power cord (like telephone wire) can be safely used to feed to the flow/float switch due to the ultra low voltage used to trigger the SSR from the PID.
If you have never wired anything up using a ladder diagram dont sweat it, they are the easiest to read. Just start at the top left and wire it wire for wire until you reach the bottom of the ladder.
Be sure to install the control away from any potential methanol fumes and dont think you can seal the box up to prevent fumes from entering it as it will only make it more hazardous.
This circuit is very similar to my current control that can be seen here;
Here are the files;
PID SET-620 manual download
Thanks to www.murphysmachines.com for hosting them!
All comments questions and concerns are welcomed!
JonThis message has been edited. Last edited by: Jon Heron,
Excellent stuff there.
My brew-partner and I were discussing this just the other day.
I think our "next generation" reactor will be PLC controlled.
If you want to email me the files, I'll be happy to host them at my site.
The files have been uploaded and can be found here:
www.MurphysMachines.com/PID.htmlThis message has been edited. Last edited by: Murphy,
PM me your email and I will send them over...
Thought I'd chime in one more time just to point out a silly fact.
Of all the fancy stuff in that picture, IE: Digital controller, fancy buttons, fuses, disconnects, strain relief cord grips, etc etc, the most expensive part of the entire thing is the NEMA JIC box he has it all mounted in. Is that a hoffman box?
That box, with a back panel, is probably about $150 new. (I think ebay has them cheaper)
When I bought my first hoffman box, errr, 20 years ago?, I almost fell over when I found out how expensive they are.
Yep thats for sure! Hoffman box's are built about 15 minutes from where I live and they are not any cheaper here either! Try pricing out some custom made boxes from them... Makes your butt pucker!
The cords and connectors can be pricey too. I was able to salvage most of that stuff though, the box was from a surge suppressor that was taken out by lightning... Salvaging used stuff is the only way to go when your a cheap prick like me! LOL
You can get a D box with a hinged lid for a fraction of the price...
Great info Jon!Too bad your not getting royalties or a commission
Now your talking!
Freedom 55 here I come!
Should we now start calling you Saint Jon????(ala St. tilly)
Much appreciated Murphy!
Are you guys using the PID to control/maintain temperature during the reaction? If so, what temp do you aim for, and how long do you mix/react?
I know the answer will probably be "it depends", but I'm just looking for some guidance. Should the temp be maintained at 150 F throughout the mixing/reaction, or is there a better way?
With proper mixing, you aim for 128 degF for an hour. Proper mixing is very important.
Yes, the temperature should be maintained at 128 for the entire hour. That's why the PID controllers are better than the normal water heater thermostats. The PID maintains a tighter temperature control where the thermostats have more difference between the ON temp and the OFF temp.
Ok, I need a little advice on the PID described in the links in this thread. I have a 500gl insulated propane tank, running 250 gallon batches (the Murphy's Machine setup).
Here's my experience.
I set the desired temp (SV). The PID starts to apply current in a on-off staged fashion. It takes about 5 to 10 minutes before it is constantly on. When the oil hits the SV, it performs the same process in reverse - 5 to 10 minutes before it goes completely off.
Here are the issues:
If I set the SV to 130F, I end up at about 150F.
I tried setting the value to 118F so the overshoot would end me up at about 130F. Works fine as long as my starting temp (the PV) is low. If I put hot oil (100 to 110F) from my pre-dry, I don't hit the constant on state - it hits 118F to fast.
Additionally, if I do get the temp to 130 (the SV), and then introduce my methoxyide, the temp drops, and the PID starts it's staged process again, and I end up overshooting.
I tried using the auto-learning feature. No go. It expects the temp to go over and then below and then over, etc, so it can figure it out. My reactor never goes below (at least in the 4 hours I waited during a test), so the auto-learning never finished.
What I want (I think) is: when I turn on the unit, I want 100% current until the PV hits the SV. Then I want it to shut off instantly. If the PV drops below, then instant on. When it gets to the SV, instant off.
I've been told PID's can be configured this way. Problem is, I don't know if this PID will do this, and, if so, exactly how to configure it that way.
Anyone done this?
Turn all that fancy stuff off so the controller acts as nothing more than a fancy temp controller.
I believe this means setting your proportional settings to all zeros and your control to on/off operation rather than pulsed.
There is a setting that tells you how long to make the "pulses" and that should also be set to zero I believe. (or maybe 100%). Not completely sure.
Wish I could be more specific but all those controllers are a bit different in how the settings read.
To decrease the overshoot you can increase the SouF setting, see table 3 and note 7 in the manual. Thats what I would start with, set it at 1 and keep decreasing it if needed.
If you dont feel like playing with the settings you can just use the alarm outputs instead of the PID outputs to have just an on and off control. See table 1 and table 4 to set up the alarm contacts.
Ok, I use to think I was a smart enough fellow. You know, built my processor, replaced a couple engines in cars, things like that.
But this controller has shown me the truth - I'm an idiot!
Upon reading Jon's post, I thought I found my long sought for answer - just use the alarms! Of course.
Except I cannot figure out how they are suppose to be configured. For instance, for my last test, I set AH1 to 90 and AL1 to 100. The PV was 78 and my thermocouple was in suspended in a pot of water.
The alarm turned on. Ok, so I figured this meant it would turn off at 90. Nope. Ok, how about 100... Nope. At 110, I quit.
I did a bunch of other testing, and I couldn't figure it out.
So, if anyone knows how the alarms really work, could you enlighten me?
Or could someone recommend a controller that will turn on until it hits a temp, and then turn off. Simple.
Thanks. I think I'll go hide my head in shame now....
Your no idiot, that manual was written by one though!
Did you set the Outy (table 1) parameter?
I neglected to mention the alarm relays provide no output voltage to trigger the SSR... Perhaps thats your problem?
If you dont have an external power source to trigger your SSR you can use the PID like this;
Connect terminal 7 of the PID to the - terminal of your SSR
Jumper terminal 6 to terminal 13 on the PID
Connect terminal 14 to the + of your SSR
Then be sure Outy is set to 2.
Set AH2 to a temp below the coldest your oil ever gets to ensure the heat stays on. Set AL2 to your desired temp. Then be sure you set the PID SV to above your desired temp to ensure it supply's constant voltage to the alarm contact.
That should work!
Hopefully that helps and doesn't confuse ya even more!
Thanks. I had set outy to 0. I did notice no voltage on the jumpers. Ignored that just trying to get the alarm lights to turn on at the right time. Will try your suggestions in the next couple of days.
AL1= alarm setpoint
AH1= hysterisis of alarm (difference between turning off and turning on.
Assume for a minute AL set at 100 and AH set at 10 tow outcomes are possible depending on type of setup the controller uses.
1) unit will heat to 100 and shut off as the pv decreases to 90 unit will start to heat. This is negative bias.
2)unit will heat to 110 then shut down until pv equals 100. Positive bias.
play with the unit settings by usinh a cup of hot water and a cup of cold water to act as product, set sv to a value between the two, heat and cool and move your probe between them and room temp watch the output indicator and you will get the best understanding possible. With large volumes of fluid the product does not change in temp fast enough to validate PID control set the parameter to on/off instead of PID and you will be able to control pv to 1 degree hysterisis without a problem. Then set the alarm 15 degrees higher and use it as your safety with hysterisis of 100 degree so that if oil overheats it will be left to cool right down before starting again. This drop in temp apart from delaying processing will be noticable and make you investigate, kind of forced maintenance
You can not change the winds, but you can reset your sails.
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