Amp, gauge, duty cycle recommendations

[Spintab]

Yeah you may be right. I need to really get it all in an excel doc and crunch the numbers. The money I'd save though, is more from the parts I already have. If I reduced the system to two outlets then made one for the lower element in the kettle then switched the hlt and upper bk element at the other outlet, I'm pretty much already wired past the outlets. I just need to add some code to the arduino. I'd need two more 2000w elements, nuts from bargain fittings, and the extension cords to them, one breaker, one gfi outlet, etc. Like I said though, I've still got numbers to crunch. I'll let you know what I come up with.

As far as pwm, that's all pids do already. Pulse width modulation is just turning the load on and off for a percentage of the latch time. Generally latch times are pretty fast, in the kHz, but even 2 seconds is still technically pwm. What makes it cheaper is that you could put together a pwm circuit for about 10 bucks using a 555 chip and a pot. Anything large is run this way. 240 volt 30 amp rheostats are fairly non existent.

 

[Lost]

As far as pwm, that's all pids do already. Pulse width modulation is just turning the load on and off for a percentage of the latch time. Generally latch times are pretty fast, in the kHz, but even 2 seconds is still technically pwm. What makes it cheaper is that you could put together a pwm circuit for about 10 bucks using a 555 chip and a pot. Anything large is run this way. 240 volt 30 amp rheostats are fairly non existent.

That is pretty much my understanding as well. The pid, though, incorporates a temp sensor and intelligently adjusts the pulse width to obtain and maintain the set temp.

 

[EFaden]

That is pretty much my understanding as well. The pid, though, incorporates a temp sensor and intelligently adjusts the pulse width to obtain and maintain the set temp.

Actually depends on the pid output. Output styles include relays, pwm for a ssr, voltage, and current. They do this so you can use them for many applications. The major use around here is to drive a relay or ssr, thus the pwm output is used.

 

[cwi]

As far as pwm, that's all pids do already. Pulse width modulation is just turning the load on and off for a percentage of the latch time. Generally latch times are pretty fast, in the kHz, but even 2 seconds is still technically pwm. What makes it cheaper is that you could put together a pwm circuit for about 10 bucks using a 555 chip and a pot. Anything large is run this way. 240 volt 30 amp rheostats are fairly non existent.

It is hard to tell what your knowledge level is, but building your own PWM circuit, especially if your own custom spec'd waveform deviates drastically from common parameters, is a little sketchy. I am only mentioning this since you had to had to ask about 240v flavors, but even with some EE knowledge, the US electrical system and codes are a little mysterious.

You say you are already using an Arduino and want to use an SSR (eventually). The PID routines and designs for PWM boards/outputs to use with an SSR are already available for Arduino, as well as manual control modes. Why not use one of those, and the available support on the Arduino (Brewtroller) forums?

 

[Walker]

1: Building the controller myself I can use just about any cycle length I want. I think most PID's use a 60hz cycle but I don't see that being necessary and rough on the SSR. I was thinking more like a second or so. So 50% would be .5sec on .5sec off.

I thought I had responded to this in my earlier post, but apparently I didn't.

Most PIDs actually only use an 0.5 Hz cycle. 1 timing cycle ever 2 seconds. Not 60 cycles every second.

 

[Spintab]

It is hard to tell what your knowledge level is, but building your own PWM circuit, especially if your own custom spec'd waveform deviates drastically from common parameters, is a little sketchy. I am only mentioning this since you had to had to ask about 240v flavors, but even with some EE knowledge, the US electrical system and codes are a little mysterious.

My knowledge of anything 12volts dc and lower is pretty high. Anything in that range is a simple hot/gnd setup so having 4 wires, two of which being hot is a little new. Plus we're talking about pretty major amounts of current. I'm just making sure I'm within code. I have an Arduino in a telescope mount that runs a self built circuit to control stepper motors and point to precise points in the sky and follow them. That controlled by a lcd, pot, and PS2 joystick. I think I can handle a 555 circuit especially if all it's doing it turning a relay/SSR on and off. I don't see a self assembled PWM circuit being sketchy unless you don't know what you're doing or are too lazy to do any sort of testing on it. We're talking on and off, nothing more complicated than that for what we're using here. I don't really see PWM having common parameters per say unless you're syncing it to some sort of clock for sending data places. That or you get into the 60hz range, then you're fighting against the frequency that the AC is cycling at. I'm certainly not pushing into those ranges at all.

You say you are already using an Arduino and want to use an SSR (eventually). The PID routines and designs for PWM boards/outputs to use with an SSR are already available for Arduino, as well as manual control modes. Why not use one of those, and the available support on the Arduino (Brewtroller) forums?

I program for a living. I'd rather write it myself and solder it myself.

 

[cwi]

I think I can handle a 555 circuit especially if all it's doing it turning a relay/SSR on and off. I don't see a self assembled PWM circuit being sketchy unless you don't know what you're doing or are too lazy to do any sort of testing on it. We're talking on and off, nothing more complicated than that for what we're using here.

30 amps is good bit of current, and 240v is nothing to sneeze at. I was just giving a warning about using switching rates and waveforms far outside what tried and true PIDs/PWMs use for this type of system. Your wording about doubting existing waveforms as being suitable was concerning. There are numerous effects when dealing with that much current/voltage/power that prevent nice, pretty, digital behavior.

I program for a living. I'd rather write it myself and solder it myself.

I never said you shouldn't, or couldn't, build it yourself, and even referenced that the designs were available. Even if you want to design or code it yourself, there is no shame in reviewing prior art. After all, I assume you will be using Ohm's law without deriving the effects and equations yourself. Standing on the shoulders of giants, and all that, you know.

 

[cwi]

I thought I had responded to this in my earlier post, but apparently I didn't.

Most PIDs actually only use an 0.5 Hz cycle. 1 timing cycle ever 2 seconds. Not 60 cycles every second.

This is why reviewing and verifying known applications of what you are trying to design is important. Getting the facts from a known source, or several, is critical if you are going to build your own PWM driver to mimic a PID. There are all kinds of PWM out there, from DC with <.1 Hz to HF AC with > 20Khz. The information that is important is that which applies to the situation at hand.

 

[Spintab]

I think most PID's use a 60hz cycle but I don't see that being necessary and rough on the SSR. I was thinking more like a second or so. So 50% would be .5sec on .5sec off.

My own gut instinct and design was pretty close to what they actually use. I was thinking more of the art a DC motor PWM might use in my assumption.

I don't intend on reinventing the wheel, just making my own version, with a few tweaks to make it more round than round

 

[cwi]

My own gut instinct and design was pretty close to what they actually use. I was thinking more of the art a DC motor PWM might use in my assumption.

I don't intend on reinventing the wheel, just making my own version, with a few tweaks to make it more round than round

It is a whole lot easier have seen a few good wheels first, and improve on those. That is all I was saying. Relying on your gut for high power electronics has greater consequences than a few laps around the block on a square wheel.

 

[EarthBound]

Perhaps it might help you to better understand wire ratings if you did a little more research instead. Take a look at this wire chart:
Wire Chart
Please note that #8 copper wire is capable of carrying 50 or 55A depending on the wire's insulation.
Oh - and the information is from NEC.

Thank you for posting this. It does depend on the insulation.

I just have a trivial question, though. I have 8 gauge wire with insulation (THHN) that can handle 55 amperes, according to NEC. Is it okay for me to consistently run 55 amperes through it? I don't plan on doing so - just wondering.

 

[P-J]

Thank you for posting this. It does depend on the insulation.

I just have a trivial question, though. I have 8 gauge wire with insulation (THHN) that can handle 55 amperes, according to NEC. Is it okay for me to consistently run 55 amperes through it? I don't plan on doing so - just wondering.

You are Welcome..
Yes it is A-Ok to run it that way. No problem at all.

 

[wyzazz]

Perhaps it might help you to better understand wire ratings if you did a little more research instead. Take a look at this wire chart:
Wire Chart
Please note that #8 copper wire is capable of carrying 50 or 55A depending on the wire's insulation.
Oh - and the information is from NEC.

Thanks for that, I stand corrected...

 

[Walker]

It is this kind of stuff why I review prior art if it is available. There are all kinds of PWM out there, from DC with <.1 Hz to HF AC with > 20Khz. The information that is important is that which applies to the situation at hand.

Read it again. I said PIDs, not PWMs.

The PIDs out there that are commonly used for brewing will not allow you to specify a output period of less than 2 seconds. So when you are using a PID like that in manual mode for PWM functionality, you can go no faster than 0.5Hz. You are permitted to slow down from there, but 0.5Hz is the max.

 

[cwi]

Read it again. I said PIDs, not PWMs.

The PIDs out there that are commonly used for brewing will not allow you to specify a output period of less than 2 seconds. So when you are using a PID like that in manual mode for PWM functionality, you can go no faster than 0.5Hz. You are permitted to slow down from there, but 0.5Hz is the max.

I was essentially agreeing with you, and commenting that the factual info you provided regarding PIDs and their typical cycle times is exactly the type of info the OP needs to review for his design.

I did muddle it up with the info on the varied nature of PWM stuff available out there, but only because that is what the OP is planning on using.

Edit: I tried to clean up the previous post to make that clear, but it's late so it may be worse. The main point was to get some facts before playing around with 50 amp SSRs.

There was earlier talk of PIDs and higher freqs. Cleanly switching that much power that fast with a typical high current SSR raises my warning flags enough to check before trying that. If one would even respond that fast, I would guess that driving the SSR close the the line freq would require accounting for phase harmonics/alignment issues, but I don't really care enough to find out.

 

[Spintab]

For the record I never once said I would use a cycle time any faster than 1Hz. I did make the mistake of thinking PID's used a much quicker cycle but in my own words said that would be rough on the SSR. I did suggest that PWM is PWM be it at a kHz cycle or .5Hz cycle.

That being said, cwi, why don't you actually give us some useful information and tell us about your brewery. I can tell you're dying to tell us all how smart you are.

 

[cwi]

For the record I never once said I would use a cycle time any faster than 1Hz. I did make the mistake of thinking PID's used a much quicker cycle but in my own words said that would be rough on the SSR. I did suggest that PWM is PWM be it at a kHz cycle or .5Hz cycle.

That being said, cwi, why don't you actually give us some useful information and tell us about your brewery. I can tell you're dying to tell us all how smart you are.

I did give you useful information: Go find out some facts and review some proven designs, instead of designing high power electronics to chat room specs.

Here is a common sig in electric related threads:
Warning:
If you get advice on an electric brewing rig, you need to take it to a licensed electrician or two to have it looked over.
This stuff can kill you. When it comes right down to it, we're just some dudes on the internet.
I have seem some TERRIBLE advice on here in the past few months. I may even be guilty of bad advice myself.

I use gas, and am only considering electric for an HLT and HEX. A standard temp controller tied to an SSR is good enough for that, but if I want PID and proportional output, I will just buy one for ~$50.

 

[Walker]

I was essentially agreeing with you, and commenting that the factual info you provided regarding PIDs and their typical cycle times is exactly the type of info the OP needs to review for his design.

I did muddle it up with the info on the varied nature of PWM stuff available out there, but only because that is what the OP is planning on using.

Edit: I tried to clean up the previous post to make that clear, but it's late so it may be worse. The main point was to get some facts before playing around with 50 amp SSRs.

Got'cha. the edited post is definitely clearer.

 

[Walker]

Here is a common sig in electric related threads:
Warning:
If you get advice on an electric brewing rig, you need to take it to a licensed electrician or two to have it looked over.
This stuff can kill you. When it comes right down to it, we're just some dudes on the internet.
I have seem some TERRIBLE advice on here in the past few months. I may even be guilty of bad advice myself.

LOL. That was my sig that I removed quite some time ago. Are other people actually using it?

 

[sjwelna]

Perhaps it might help you to better understand wire ratings if you did a little more research instead. Take a look at this wire chart:
Wire Chart
Please note that #8 copper wire is capable of carrying 50 or 55A depending on the wire's insulation.
Oh - and the information is from NEC.

Great table. My comments were for THHN copper. I agree that the gauge wires are capable of carrying higher amperage, however I don't know any electrical inspector that would let you put a 25A breaker on a circuit with 14/2.

-Steve

 

[cwi]

LOL. That was my sig that I removed quite some time ago. Are other people actually using it?

I thought that was yours, but didn't see it in your current posts. I just searched for it with keywords, and it came up so at least one guy is currently using it. I remember when I first noticed it, and there was some scary advice being given. Guys were even removing their correct advice to divorce themselves from the situation.

 

[EarthBound]

that being said, cwi, why don't you actually give us some useful information and tell us about your brewery. I can tell you're dying to tell us all how smart you are.

+1 lmao!

 

[cwi]

+1 lmao!

I really don't see what is so funny about recommending someone get some facts instead of relying on internet chat rooms for electrical advice, but I guess you must:

Thank you for posting this. It does depend on the insulation.

I just have a trivial question, though. I have 8 gauge wire with insulation (THHN) that can handle 55 amperes, according to NEC. Is it okay for me to consistently run 55 amperes through it? I don't plan on doing so - just wondering.

Why not just pick your favorite answer from one of several conflicting ones already posted.

 

[Lost]

I really don't see what is so funny about recommending someone get some facts instead of relying on internet chat rooms for electrical advice, but I guess you must:



Why not just pick your favorite answer from one of several conflicting ones already posted.

cwi, I mean this in the absolute nicest way so take this advice as constructive criticism and not as a personal attack. Your attitude here doesn't appear to be winning you any friends. You seem to be smart and well informed but your posts are typically formatted in such a way as to showcase your intellect while subtly mocking others. You are the living, breathing definition of smarmy. I think you mean well and often give out very good advice but it gets overlooked or discounted because of the manner in which you deliver it.

Back to the original question of wire gauge and ampacity, there are going to be different answers because there is no hard rule about what gauge is correct. The NEC has it's rules and various other wiring books and guides have theirs. It will depend on the application. I would certainly err on the side of caution if the wiring were inside my walls and I ran the risk of burning down the house. I'm far less concerned when the length is very short, the wire is run through the air, and the wire is run singly (i.e. chasis wiring). It's all about comfort level.

I think there are a lot of risks in electric brewing but honestly, undersized wire catching fire in the event of a short is very low on my list. Others may disagree and they should plan their build accordingly. I think everyone here has suggested that each person should do their own homework and do what they are comfortable with.

 

[cwi]

You are the living, breathing definition of smarmy.

It has usually been referred to as snarky, but smarmy probably fits also.

I would say the guy deserved it after going to the trouble of posting a 'lmao' in response to someone else's equally smarmy comment directed at me. I usually only get smarmy after the other side already has.

I think everyone here has suggested that each person should do their own homework and do what they are comfortable with.

This did not happen, and was the reason why I posted. Somebody posted saying that it was perfectly OK to drive the SSR at whatever freq one wants, even after others said not to. I just suggested getting some factual info.

 

[Spintab]

cwi, I mean this in the absolute nicest way so take this advice as constructive criticism and not as a personal attack. Your attitude here doesn't appear to be winning you any friends. You seem to be smart and well informed but your posts are typically formatted in such a way as to showcase your intellect while subtly mocking others. You are the living, breathing definition of smarmy. I think you mean well and often give out very good advice but it gets overlooked or discounted because of the manner in which you deliver it.

Thank you Lost. I wasn't sure if I was being over sensitive about the attitude. It comes across as patronizing when what we really want is a piece of the smarts. I get smarmy when my ability is questioned in a patronizing manner especially when it's not backed by solid evidence of actually being wrong. I don't feel I was the first to smarm but if I was then I apologize. I've already dropped the idea of going electric any time soon anyway due to budget limits.

I don't expect direct answers coming here asking for advice. Sometimes you get them and they're from someone qualified to give them and bingo. Sometimes people clue you in on what you need to do homework on. Other times you're just looking for someone who has also assigned themselves with the same homework you've assigned yourself. Perhaps they've found links to legitimate sources of info, and maybe you've found some they haven't. In the end you've both saved each other time and Googling. I mean what if you started a thread about typical malts in an amber and the first response was to go do your homework as opposed to a link to a clone of a commercial amber? You could also get a response that it contains 80% roasted barley. At that point it's up to the OP to choose their own fate by directly using that advice or cross referencing it against another source.

Can we just go back to making beer now?

 

[cwi]

I get smarmy when my ability is questioned in a patronizing manner especially when it's not backed by solid evidence of actually being wrong.

I qualified my questioning of your knowledge level, and that it may not be the case. It was more related to your ability to screen all the conflicting info that had already been presented. I never posted any specs or system advice other than the existence of other forums, which I listed, that are more focused on this topic.

I mean what if you started a thread about typical malts in an amber and the first response was to go do your homework as opposed to a link to a clone of a commercial amber? You could also get a response that it contains 80% roasted barley. At that point it's up to the OP to choose their own fate by directly using that advice or cross referencing it against another source.

That is why my initial advice was to try the arduino and brewtroller boards which are populated with people more focused on electronics than beer. I don't see how that was equivalent to me telling you to go do your own research.

Keep in mind this was after conflicting posts regarding SSR driver freqs, PID behavior, wiring specs, etc. I was only suggesting another source of info and input that may be a better choice for cross referencing, as you say. It appeared to me that you had already received the 80% roasted barley advice. 2% and 40% as well.

I don't feel I was the first to smarm but if I was then I apologize.

Like identifying porn, classifying smarm is something only a jury of peers could determine, or maybe a governmental agency. Less fun than id'ing porn, though.

 

[Walker]

Like identifying porn, classifying smarm is something only a jury of peers could determine, or maybe a governmental agency. Less fun than id'ing porn, though.

Ok, I like you again now.