Building a potentiometer controller

[Lonster]

I'm looking for a high quality, US made, 240v, 70-100 amp [SSVR...SSR VA...Solid State Voltage Regulator]....whatever they're called, for a 240v, 50a temp controller I want to build.
For the life of me, I cannot find one. The cheap chinese SSVR's dominate my searches, no matter how I word the search. I've found Otto22 and Carlo Gavazzi SSR's, but I can't find (or don't know enough to find) the proper SSVR that I need. The biggest Otto22 makes is 45 amp, so they're out. I plan to control two 5500w elements, one manually and one with a PID, but I don't want to use a lower amp SSR/SSVR. I want 70A minimum.

Please don't point me to Auberins, Finglai, Crydom, Omron, or websites that offer DIY build kits. I'm just looking for the correct USA made (or high quality made anywhere) relay that will allow me to manually control the temperature with a potentiometer.
I'll probably add an Auberins DSPR400 PID and the necessay components for it in the enclosure, but that's not what I'm looking for right now.

I have most of the parts needed to build a 50a or 70a controller - new NEMA 4/12 enclosures in several sizes, NIB 22mm and 30mm push button switches, start-stop buttons, indicator lights in all colors, potentiometers, etc. All are big dollar, industrial grade operators (Allen Bradley, Schneider, ABB, etc).
I also have 14/12/10/8/6 gauge stranded wire, 12/3, 12/4, 10/3, 10/4 AWG SOOW wire, and a slew of NIB, US made, high amp rated twist lock plugs and receptacles.
Please understand I'm not boasting, I'm just explaining what my hoarding has allowed me to collect. I want to buy parts that match the quality of what I have.

I able to build the controller, I just need help sourcing the parts that match the rest of the components.

 

[Broken Crow]

I hate to see a question like this languish unanswered. I was injured years ago (brain included) and the oscilliscope I regularly used for about 20 years became incomprehensible to me, so treat my answer with caution.. (at the very least it'll bump this thread back to the top and maybe someone competent will weigh in)
this:

I cannot find one.

I plan to control two 5500w elements, one manually and one with a PID, but I don't want to use a lower amp SSR/SSVR. I want 70A minimum.

Has me wondering if you're trying to use a single SSVR to control 2 elements.
In any event, SSVR's aren't hugely popular (one of the reasons being that they are notorious RFI emitters) and if you can't find a UL approved one in the range you want on mouser or digikey, then the cheap imports really are your only option.
I have a 40A 'TW Tade' SSVR I bought from amazon years ago for my BK and it's still performing just fine. You don't need near 70A to power an single 5500W element. Your wording makes me wonder if one of us is confused, so with respect, just to be clear: You are looking for an SSR to go with a PID and an SSVR to go with a pot, and not a single unit to wire both a pot and PID to?

 

[Bobby_M]

Why not just a standard SSR with a PWM driver? It's cleaner and the control is perfectly linear as opposed to SSVRs.

Assuming your strong insistence on U.S. made isn't driven by socio-political motives but that you're trying to match the quality/value of all the other stock piled components, I think it may be misplaced. There are high quality, reliable imported components and most of their longevity is going to be mostly determined by heat management (external heat sink with good thermal grease between).

I've been using Auber branded SSRs in my controllers for 10 years and haven't had a single one of them fail.

If you're powering a pair of 5500 watt elements for a total of 50 amps, my recommendation is to drive a pair of reasonably priced, import 40A SSRS driven by either a PWM (Auber DSPR-1) or just bite the bullet and get the Auber DSPR controller that you think you'll eventually want. It's already a superior PWM for power control even if you don't need temperature control now.

 

[khannon]

Check out https://stilldragon.com/diy-controller-kit.html They might have what you are looking for.

 

[Agent]

I work with industrial controls on a daily basis, and I feel you on using better/best components whenever possible.

That said, as always, @Bobby_M is on point. The US is not the king in chip manufacturing, and brand name imports are where its at. Not to mention redundancy usually ekes out overkill for utility.

My knuckle-dragger build is the SSVR and pot from the StillDragon kit @khannon linked, with a fan-cooled Xbox 360 heatsink and a 100% power bypass switch. So far that's lasted 10 years and better than a thousand gallons of beer.

 

[Broken Crow]

Check out https://stilldragon.com/diy-controller-kit.html They might have what you are looking for.

It's another import and they don't list the specs, but if you zoom in, it's a 40A SSVR; https://stilldragon.com/solid-state-relay.html A plus though is that @Agent just vouched for it... 10 years and still going sounds fine to me. My amazon cheapie has been going fine for 4 years, and though I did get a miniature fan, I never needed to install it.

My knuckle-dragger build

I really like that description! Has me wondering what it looks like... My own was experimental, so aesthetics weren't a consideration..only compactness and ergonomics. It's ugly, but works just fine:

I did however, decide to build a nicer looking but still simple one, and I got the Auber DSPR1 and their own UL approved regular SSR to go with it....Still haven't put it together yet...haven't needed to, since the cheapie is still going strong.

 

[sibelman]

redundancy usually ekes out overkill

Seems like a pair of devices would be a fine approach to powering/controlling two elements, and offers a much wider range of products.

 

[Bobby_M]

Non-linear control of an SSVR aside, I do like the idea of putting in that cheap ammeter because it's as close to knowing the actual wattage as you can get.

 

[Agent]

Man, I'm thinking "knuckle-dragger" may have oversold the build quality. One of the universal truths is that the more temporary you plan something to be, the more permanent it becomes.

(Don't build this at home kids)

Like @Broken Crow I have the parts to build something nicer, and more importantly, safe-ish. I just haven't prioritized it yet.

 

[Broken Crow]

Non-linear control of an SSVR aside, I do like the idea of putting in that cheap ammeter because it's as close to knowing the actual wattage as you can get.

It just a cheapie from amazon ali or ebay and I didn't expect it to be accurate so I tested it out with my Fluke, and when it reads 11.7A, it really is, but higher or lower it drifts by about 0.2A to 0.4A....What counts to me is that it's consistant and repeatable and so I don't have to lift my steam-condenser to check the boil.

Man, I'm thinking "knuckle-dragger" may have oversold the build quality. One of the universal truths is that the more temporary you plan something to be, the more permanent it becomes.

(Don't build this at home kids)
View attachment 842229Like @Broken Crow I have the parts to build something nicer, and more importantly, safe-ish. I just haven't prioritized it yet.

I love it!! I was gonna use a big square biscuit tin for the controller and a small cylindrical one for the element enclosure...I ended up using the steel sides of an old ATX case because it had the nice slotted vent strip, and a round outdoor spotlight junction box for the element. (For my next pots, I bought @Bobby_M 's hot-pods...way easier....you are braver than I!

 

[sibelman]

"knuckle-dragger"

something nicer, and more importantly, safe-ish

I tend to drag my knuckles to HomeDepot for galvanized boxes for items with 240VAC in 'em.

 

[khannon]

Man, I'm thinking "knuckle-dragger" may have oversold the build quality. One of the universal truths is that the more temporary you plan something to be, the more permanent it becomes.

(Don't build this at home kids)
View attachment 842229Like @Broken Crow I have the parts to build something nicer, and more importantly, safe-ish. I just haven't prioritized it yet.

Temporary is only until it works.. I think there might be a Red Green quote in there somewhere..

 

[Lonster]

Wow guys, thanks for being who you are, and for offering suggestions. After posting my question, the next day I thought I came off as a smug a-hole. I was embarassed to sign on and check for a response. I planned on deleting this post and starting over.

I'm very new to this, and to be honest, don't know a freaking thing. I've done a lot of reading, I formulated an idea of what I want to do with what knowledge I already have and from what I've read.
To clear up some questions - I want one relay that controls one element with a potentiometer. I shouldn't have mentioned a PID or second element, that's not the point of my question. As Bobby_M and others have said, a Auber SSR or equivalent has done well, and I've read that in many posts. I want something better...I'll explain why. FYI - a standard SSR with a PWM driver is something I don't know anything about. I'll have to research that.

Agent - a coffee can with 12 gauge romex coming out of it made me smile. I've done simular with less in my younger years.
sibelman - that wins the prize for the worst DIY controller I've ever seen. And between this forum and another popular forum, I've seen some awful, low budget controllers. Amazing. I wonder how many are connected to a main panel that's a newly installed Zinsco bought at a good price.

So, to explain more about what I want to build. I'd really like to use a Hoffman N12 console for this controller (I'll attach a pic). It's a 8x12 box that's 7" high on the tall end. I like this one because I can use it as a desktop. but I'll build it with the harness to the front panel long enought to allow me to turn the panel 180 degrees and mount it on the wall if I want to. The connections for the cords would be at the back of the panel if in a tabletop configuration, or on the bottom if it was wall mounted.
An exterior heat sink won't work if I want to have the option of flipping it one way or the other at will, the relay/heatsink has to be internal, and probably with a fan and a vent. I'm not against doing that, but my thought is, just like wire, an oversized part 'should' run cooler because the internal components are built for a higher amperage.
A >70a relay won't get as hot as a 45a relay when running at the same voltage. Paired with an oversized heatsink, it 'should' run cooler. But that's providing the relays internal components are truely built for the rated amperage. How can I be reasonally sure it is? I think it's safe to assume a $15-$40 chinese relay isn't going to be the right part. I can be resonably sure a USA made relay is.

Will that allow me to use the smaller N12 enclosure without a fan? I won't know until I try it. I know there are formulas, 1.2 degress per amp, or whatever it is.....but the real temp won't be known until I try it.

 

[Broken Crow]

Glad you came back! One other question; I notice that you mentioned the Auber DSPR 400 which is geared toward stills... Is this for a still, a beer-kettle, or dual-purpose system?
In any event, it sounds like you've read a lot of peoples mistakes with burnt out cheaply/poorly made systems...while there is cause to be cautious, there is also overkill. As it is, a 40A SSR is usually used because it has nearly twice the maximum capacity needed..I don't remember exactly, but I'm pretty sure the max draw on a 5500W element is about 22.6A or so. My own (ugly) unit that has the heatsink on the inside relies soley on convection, with some holes in the bottom of the case and vent slots in the top, and even when it's been running all out to get 13 gallons up to a boil and keep it there for an hour, I can still keep my hand pressed against the top and while my GF calls it 'hot' I call it 'warm and comfortable'. As long as you use the proper gauge wires and connectors that are properly rated and properly crimped, you won't have any problem with excessive heat....at least half the failures I've seen have been caused by either improper and/or badly crimped terminals and/or undersized wires.
If you haven't been to the Electric Brewery site, reading through the building guide would be very helpful..here's the index, just follow the links;
https://shop.theelectricbrewery.com/pages/building-your-brewery
Another truly great (and interactive) place to read up more is with this site...the very best advice you can get for a controller build being @doug293cz who has designed and helped countless users...just read through some of these posts and you'll probably find ALL the answers you could want and then some:
https://www.homebrewtalk.com/search/6908084/?q=schematic&c[users]=doug293cz&o=relevance
BTW: Never be embarassed by a post! Welcome to the fun!

 

[doug293cz]

Wow guys, thanks for being who you are, and for offering suggestions. After posting my question, the next day I thought I came off as a smug a-hole. I was embarassed to sign on and check for a response. I planned on deleting this post and starting over.

I'm very new to this, and to be honest, don't know a freaking thing. I've done a lot of reading, I formulated an idea of what I want to do with what knowledge I already have and from what I've read.
To clear up some questions - I want one relay that controls one element with a potentiometer. I shouldn't have mentioned a PID or second element, that's not the point of my question. As Bobby_M and others have said, a Auber SSR or equivalent has done well, and I've read that in many posts. I want something better...I'll explain why. FYI - a standard SSR with a PWM driver is something I don't know anything about. I'll have to research that.

Agent - a coffee can with 12 gauge romex coming out of it made me smile. I've done simular with less in my younger years.
sibelman - that wins the prize for the worst DIY controller I've ever seen. And between this forum and another popular forum, I've seen some awful, low budget controllers. Amazing. I wonder how many are connected to a main panel that's a newly installed Zinsco bought at a good price.

So, to explain more about what I want to build. I'd really like to use a Hoffman N12 console for this controller (I'll attach a pic). It's a 8x12 box that's 7" high on the tall end. I like this one because I can use it as a desktop. but I'll build it with the harness to the front panel long enought to allow me to turn the panel 180 degrees and mount it on the wall if I want to. The connections for the cords would be at the back of the panel if in a tabletop configuration, or on the bottom if it was wall mounted.
An exterior heat sink won't work if I want to have the option of flipping it one way or the other at will, the relay/heatsink has to be internal, and probably with a fan and a vent. I'm not against doing that, but my thought is, just like wire, an oversized part 'should' run cooler because the internal components are built for a higher amperage.
A >70a relay won't get as hot as a 45a relay when running at the same voltage. Paired with an oversized heatsink, it 'should' run cooler. But that's providing the relays internal components are truely built for the rated amperage. How can I be reasonally sure it is? I think it's safe to assume a $15-$40 chinese relay isn't going to be the right part. I can be resonably sure a USA made relay is.

Will that allow me to use the smaller N12 enclosure without a fan? I won't know until I try it. I know there are formulas, 1.2 degress per amp, or whatever it is.....but the real temp won't be known until I try it.

Since my name was brought up, I thought maybe I should make an appearance (I have been following, and the advice so far has been good.)

I can't visualize why being able to flip the orientation of the enclosure precludes an external heatsink. Can you maybe provide some sketches? Vent holes for air circulation with an internal fan provide an entry way for spilled/splashed liquids, which is always a risk when brewing (or with similar activity.) An external heatsink allows a mostly spill/splash proof build, and usually eliminates the need for a fan.

The amount of heat generated by an SSR is mostly driven by the current, not the voltage being switched. The main differences between a 40A and 80A SSR will be the area of the junction in the TRIAC switching element (a larger area will reduce the junction temp [the main driver of SSR failure]) by spreading the heat generated over a larger area, and better provision for heat removal from the SSR package. But even with a higher rated SSR, you still need an adequate heatsink, as dissipation of the heat into the atmosphere is often the limiting factor on heat removal from the SSR.

The heat generated in an SSR is determined by what's known as the forward voltage drop across the TRIAC junction times the current thru the TRIAC. The forward current drop is a weak, less than linear, function of the current, and is independent of the operating voltage.

For a single 5500W element (~23A max current) a 40A rated SSR is perfectly adequate. In fact a properly heatsinked (heatsunk?) 40A SSR would probably be more reliable than an 80A SSR with inadequate heatsinking.

It would be helpful for those trying to offer advice if you would fully describe your intended application, and how you envision the control panel operating, in order to be able to offer appropriate suggestions.

Brew on

 

[whoaru99]

...

 

[Broken Crow]

Vent holes for air circulation with an internal fan provide an entry way for spilled/splashed liquids, which is always a risk when brewing (or with similar activity.) An external heatsink allows a mostly spill/splash proof build, and usually eliminates the need for a fan.

Thanks for mentioning that!! I hate it when I forget to include safety advice online. I should have mentioned that while I chose to do it that way, I also included a very long cable and have never let it sit within splashing range. My RIMS and HLT controllers will be much closer and hence, fully splashproofed with open heatsinks.

 

[sibelman]

never let it sit within splashing range

properly heatsinked (heatsunk?)

These are important pieces of advice. Over-sizing electrical components can sometimes reduce risk of failure. Keeping them cool and out of harm's way can be more important.

It may not be possible to fully protect pumps from spills, but electrical stuff can be wall-mounted or otherwise kept above/away from liquids.

Best of luck with your no-doubt beautiful, bullet-proof build, @Lonster

 

[whoaru99]

I think everyone on the thread recognizes the importance of heatsinking in general.

But, just how much it matters is pretty interesting. An example 40A and 75A SSR I looked at from same brand and series showed free air ratings were just 6A and 7A respectively. Even with moderate heatsinking the 40A and 75A were little different in rated current. Not until a bigger or more efficient heat sink (0.5 C/W) was strapped to the 75A did it achieve full rating vs. the 40A with 0.9C/W sink. This is what doug alluded to in his earlier post.

 

[Bobby_M]

Explain what the controller is for, it's been quite cryptic.

 

[Lonster]

I have some (unexpected) things going on right now that's taking up a lot of my free time, I haven't been able to get back to this project. I probably won't have much time for this in the foreseeable future, but I want to touch base to let you know I haven't gone away.

I appreciate the responses, you guys have helped me understand a little more. I changed my mind on what I'm going to do.
I haven't been cryptic, I had one question - can someone point me to a quality built, high amperage SSVR. That's all I was looking for. The replies have led me to have some faith in an Auber built SSVR, so that's the way I'm going to go.
I'm building a controller that will allow me to manually regulate the AC current on one element with a potentiometer, and also control a second element on a seperate circuit with a PID. You can do the math why.

I detailed some of what I have on hand, I just need the specific parts I don't have. Yes, a DSPR1 would work very well, perfect for my needs. But I have a few industrial grade Allen Bradley potentiometers collecting dust, sitting next to a few dusty PEC tapered potentiometers. They're high quality, expensive parts. I want to use them. The common saying is buy once, cry once. I hoping to build once, cry once.

EDIT - I should have mentioned I now plan to go with a large external heatsink with 2 relays attached to it.

 

[doug293cz]

@Lonster , it is definitely not clear why you want to control two elements. If they are in separate vessels, then, it's obvious why the elements need to be controlled separately. But if they are in the same vessel, then there are controllers, like the 3 digit models of the Auber DSPRs, that can act like a PID or potentiometer (but with better linearity) depending on what stage of your process is active.

Brew on

 

[sibelman]

You can do the math why.

Mmph. 42.

 

[Lonster]

3 digit models of the Auber DSPRs, that can act like a PID or potentiometer (but with better linearity)

Let's say I have an XX gallon boiler with a 60" tower that consists of 8 seperate flutes, with bubble plates between each flute. Above that is a dephlegmator. I want to bring it to a certain temp with two elements, then shut one element off and manually control the heat with one element for the rest of the brewing process. And I want to do it with what I have.
Your advise is for me to cast the $300 potentiometers I have aside and spend money on Auber DSPRs so I have better linearity?

I'm not trying to be a jerk. I've tried to ask the questions I need answered, but it seems with every bit of info I give, curiosity is raised and more infomation is needed. The more info I offer, the more suggestions telling me I need to go in a different direction. I want to use what I have, not spend more money on something that could work marginally better. I'm getting very frustrated by all of this.

 

[Bobby_M]

Well don't get so hot and bothered. It's not like they're $1000 potentiometers which is what all the cool kids have these days. This kind of crap has come up in other threads. People get so wrapped up in the sunk cost fallacy that it clouds their judgement on what they really need.

There's no reason to shut one element off and modulate the remaining one. You can use both elements to achieve the desired set point temperature and then modulate both elements for power output. This is superior because the watt density is half as high (spreads out the power output over more surface area) and you'll get less fouling of the elements. This would still be true if you want to continue building with the use of an SSVR. If both elements are controlled by an SSVR, you really just need a temperature alarm to ring when you achieve operating temp and then turn the power down to whatever you wanted.

Maybe you care, maybe you don't (I'm leaning towards don't). The Auber DSPR-320 will allow you to set a temp target, then it will automatically switch over to power regulation mode at whatever output you pre-program (while it also alarms to let you know it's happening). You can also use the alarm relay output to trigger a cooling water solenoid at a certain temp.

If people volunteering their free time to help you with absolutely no expectations of a returned favor frustrates you, the "close tab" button is right up there. What is really frustrating is when people come in here with a question, they don't like the answers and then they act like they had the answer the whole time.

 

[doug293cz]

Let's say I have an XX gallon boiler with a 60" tower that consists of 8 seperate flutes, with bubble plates between each flute. Above that is a dephlegmator. I want to bring it to a certain temp with two elements, then shut one element off and manually control the heat with one element for the rest of the brewing process. And I want to do it with what I have.
Your advise is for me to cast the $300 potentiometers I have aside and spend money on Auber DSPRs so I have better linearity?

I'm not trying to be a jerk. I've tried to ask the questions I need answered, but it seems with every bit of info I give, curiosity is raised and more infomation is needed. The more info I offer, the more suggestions telling me I need to go in a different direction. I want to use what I have, not spend more money on something that could work marginally better. I'm getting very frustrated by all of this.

OK, have fun.

Brew on