PID 101 for HERM/RIM system

[Ollie_44]

Hi all, just after some ideas on how people practically build these things for their brew rigs. I'm a bit stumped to be honest. Im guessing that the following process are occurring

-Something to get temperature data (temp probe and thermometer)
-something to analysis temperature data and provide an output based on an algorithm/ within set framework (PID - solid state relay with programmed mash steps)
-something that converts the "output" data to a usable signal that modifies input temperature...

But how!! Lol

Working with standard 3v system and was going to use an electric element for heating source for HERM or RIM system.. 5 step mash would be ideal (dough in, protein rest, beta, alpha and then mash out)

Any advice would be much appreciated cheers

 

[sp0rk]

Have you read the HERMS or RIMS mega threads?

 

[Ollie_44]

Ok will check them out.. cheers

 

[Ollie_44]

Arr there are like thousands of post on that forum.. there is probably the ans to a lot of questions on there.. like what is the formula for the perimeter of an ellipse, why you can never fully empty a bottle of rum (seriously you think it's empty and two days later...) tehehe anyway...

Was thinking of working up a schematic and just filling the parts list off eBay/jaycar or something. Ie just give it a crack.. will let you know how I go, but open for suggestions in the meantime..

Ps Is there a way to filter the herms forum or do I have to struggle though the whole lot on an iPhone... people do that right

Cheers

 

[Camo6]

The Electric Brewery website is a good starting point. Gives you a breakdown of how to build one. Their forum has a section on 230V builds and they even sell kits if you're willing to shell out the clams.
That being said, if you're honestly stumped on how to build one, I'd be doing some research first.

 

[malt junkie]

Straight out and simple a PID setup such as The Electric brewery, just note ramp step Auber PIDs can be a learning curve to program, there are some decent threads in gear and equipment on these. You could use a "Brauduino"/"Ardbir" controller and they would do your mash steps automatically and fairly easy to program. There are other systems such as BCS, hell you could even snavle a Grainfather connect controller and wire that up to run your mash.

Things to consider

1. How automated do you want the rig, just the mash? or all three vessels? pumps and chilling too? valves? (long term)
2. How easy do you want the programming of each brew day
3. Do you want wireless conectivity?
4. Budget

Note a simple STC1000 will control mash and if you go to the trouble of having it flashed it can then do steps for you ( STC1000+) and the simplest cheapest option but not as accurate as a straight out PID.

To buy and build a fully loaded Electric brewery control panel or BCS system can set you back thousands, but the control is tight.

You do get what you pay for, a lot of guys start with an STC1000, while the slowly build up a better featured control panel.

Right now you got some research to do.

cheers

Mike

 

[Zorco]

That's a good point Ollie44 makes. A mega thread really isn't good for answering someone's question. There is an opportunity for AHB to have a brewing wiki I think.

Not sure how that would actually work,

 

[Adr_0]

Damn, wish AHB had the Wiki thing working.

PID just refers to the controller being proportional (P), which means that the output is anywhere from 0-100%. On-off control is a lot more simple, and switches an output on or off, rather than providing 0-100% variable output.

The ID part of PID are other factors in the calculation to determine the output. PID controllers measure the difference between a temperature measurement (eg 62°C) and a set point (eg 67°C). This error is then multiplied through the P, I and D factors and spits out an output.

Both PID controllers and on-off controllers have a setpoint. The key difference is that the on-off doesn't know how close it is to the set point, so it's fully on until it hits the set point - while the PID knows that the 'error' (difference between setpoint and measured temperature) is getting less and less, so winds the output back.

How does an Auber - or similar - do this? This 0-100% output signal is a timed pulse, so 20% output means it's on for 2s out of 10s, or 0.4s out of 2s. This pulse can be pretty quick, so steady-state relays (high current) are strongly recommended - they get very hot with all the cycling, but they are built for it.

An on-off is a lot more simple, and generally will have a traditional/electro-mechanical relay, as they'll be on for a few minutes, then off for a few minutes - so a lot less cycling, and a lot less wear.

PID controllers need tuning and understanding, but if properly tuned will not overshoot the set point like an on-off will. The steady state relay (SSR) can drive the element all day without issue.

 

[Adr_0]

To further clarify, the 0-100% pulsed output, when connected to an SSR and in series with your element (2400W, 3600W) will pulse for a certain time, meaning that the wort is effectively only getting 240, 500,1500W (Joules per second) to heat it up.

When you're close to your set point, or at the set point, the pulsing will be 2-10%, so only on for a blip, providing a couple of hundred watts.

When the element is on, it still draws full current - just that the net effect (on for 2s,off for 8s) is less heat energy into the wort.

 

[bradsbrew]

There is an opportunity for AHB to have a brewing wiki I think.

Not sure how that would actually work,

Damn, wish AHB had the Wiki thing working.

If someone was to make a how to in the wiki area http://aussiehomebrewer.com/forum/42-ahb-resources-wiki-topics/ . We could lock it and make a hyperlink in a discussion thread or just have the OP as the guide and discuss from there or Admin or a Mod could add a note and hyperlink to the OP of the HERMS thread??

Cheers Brad

Cheers

 

[Adr_0]

Unfortunately our looks like new topics can't be added there.

 

[bradsbrew]

Unfortunately our looks like new topics can't be added there.

How about now?

 

[Ollie_44]

Hi all, thanks for advice.. definitely going for an SSR type system for mash tun. Seems the most fit for purpose. Plus I would get cranky with overshots and end up buying one eventually. Reading the product lists at the moment to find something that suits my system. The more research I do the less complex really.

Cheers

 

[Ollie_44]

Hi all, thanks for advice.. definitely going for an SSR type system for mash tun. Seems the most fit for purpose. Plus I would get cranky with overshots and end up buying one eventually. Reading the product lists at the moment to find something that suits my system. The more research I do the less complex really.

Cheers

 

[Adr_0]

So I finally did that Wiki.....

http://aussiehomebrewer.com/topic/93924-ahb-wiki-pid-and-onoff-control-basics/?p=1431504

 

[Ollie_44]

Thanks, Adr_0 will be reading after work. Cheers