Heating Element Control

[Filby]

Arghhhh! So got the 500k pot on. All kinda works except the voltage goes from 232v to 243v at full travel. What do I need to replace now???

[Bob421]

I think you need to measure amps instead of volts because of the way the chip cuts off the waveform. You will mostly get the same voltage across the range but the amps applied will vary.
Plus make sure you are testing it with a load.

[rad14701]

With my 120V controllers I measure voltage at the element terminals... With the last one I built I can regulate from ~105 volts down to under ~5 volts... Voltage starts at 32 volts... Not the same circuit, however...

[Bob421]

I guess after you get past 50 percent of the waveform cut off the voltage has to drop.
Mine cut the amps to zero but it was very jumpy in a certain range. I never have measured voltage. Now I have the psr25 setup in the box. Unless it gives up the smoke I don't see me going back.

[Filby]

How do you measure amps with a digital multimeter? Ive got the ability on mine for up to 10amps but I cant workout how to do it. On DC its easy as you put it in series but for AC??

Cheers,


Fil

[Filby]

Ahh got it sussed. Multimeter has to go into a specific mode for amps on AC.

So results are 6.6amps to 9.7amps.

What component is the one defining the range?

[FractionalDisMan]

Been reading this forum about power control. I have been using the Crydom MCPC Microprocessor based phase angle controller / SSR at work here for years. I remember seeing a SSR that could be controlled by a variable resister. I did some searching and found what I was looking for. Crydom makes a RPC Series SSR. Cost is in the range of $75 USD. A little high but very robust high quality and cost for the higher power handling in nothing.
• Proportional controller
• Ratings from 15A to 40A 120, 240 and 480 VAC
• 500k or 1M Ohm potentiometer control.



Search Crydom for RCP.
For someone looking for easy power control this might be something to look at.

Edit:adding pict of wiring

[rad14701]

FractionalDisMan, thanks for the information... This is basically the same as the PSR line of SSR's by United Automation, mentioned elsewhere in this topic... The PSR line is about $30 USD cheaper, however... Nice to know there are alternate sources just the same...

Stop by the Welcome Center and give us a proper introduction...

[Zzyzxx71]

OK finally got everything wired together, and I'm glad to say this damn thing works like a dream. No blue smoke, no funny stuff, boils 10 gallons in about 20 minutes with a 4500w element.

Parts are as follows.

Potentiometer
Mouser #: 785-380C1500K
Desc.: Potentiometers 500 K Ohms 10% 2W Solder Lug

Capacitor
Mouser #: 647-QXK2G104KTPTZH
Desc.: Polyester Film Capacitors 400volts 0.1uF

6.8k Resistor
Mouser #: 660-MO2CT631R682J
Desc.: Metal Oxide Resistors 2W 6.8K 5%

Diac
Mouser #: 511-DB3TG
Desc.: Thyristors - Diacs, Sidacs, SCRs & Triacs 32 Volt Trigger

Triac
Mouser #: 576-Q6040J7
Desc.: Thyristors - Diacs, Sidacs, SCRs & Triacs 600V 40A

Final Schematic used attached (again - apologies for the redundancy). I used a 50 amp dryer plug and tail, spliced in some 8/3 guage outdoor wire to the project box, then a female generate nema plug, male plug attached to the element. Worked like a charm on the first try.

Currently researching the proper cleaning runs, just running water now. This weekend is going to be fun.

Edit: Uploaded wrong schematic.

[rad14701]

Zzyzxx71, recheck that diagram because I think your triac connections are wrong at MT2 and Gate...

Glad to hear that the controller is working...

[maheel]

ok, just looking at this PSR using 240V AUD and have a question
http://australia.rs-online.com/web/0841924.html#header" onclick="window.open(this.href);return false;" rel="nofollow

here is the wiring diagram


do you just run one leg of the 240 into #1 then out to the element from #2

then between # 3 & #4 you have a 250k pot wired in

mount it on a heatsink in a box and your done ?
add a fan

estimate after all bits and pieces (box, wires and power point etc) $100 aud?

that seems too easy? what am i missing

[Bob421]

Almost seems like cheating.
But yes that is all that is required. Most will put a switch in there.
It is recommended to use a circuit breaker.
I want to put an ammeter in there but right now mine is basic.

[maheel]

Almost seems like cheating.
But yes that is all that is required. Most will put a switch in there.
It is recommended to use a circuit breaker.
I want to put an ammeter in there but right now mine is basic.

well i guess it's on the xmas list then.

i have a triac one "working" but one of these might be the the workhorse and the triac a backup / mini still set up ...

[Zzyzxx71]

Zzyzxx71, recheck that diagram because I think your triac connections are wrong at MT2 and Gate...

Glad to hear that the controller is working...

You're correct, uploaded wrong image. Above post/image has been corrected.

[Samohon]

Hey guy's... Not an electronics engineer at all, but I probably could wire either the Triac diagram or even easier the SSR hookup...
Bulding an electric driven boiler for indoors use....

Could I Use This...

Whats confusing me is the Control Voltage.... This one says 3 → 32Vdc...

Going back to my high-school theory DC came from a battery and AC was the main supply...

Maybe a dumb question, but does this need a 3 → 32Vdc battery to drive the SSR...

I understand about the pot, heatsink, wiring, ect... But what would be needed to get one of these going...

Thanks guy's...

[maheel]

Hey guy's... Not an electronics engineer at all, but I probably could wire either the Triac diagram or even easier the SSR hookup...
Bulding an electric driven boiler for indoors use....

Could I Use This...

Whats confusing me is the Control Voltage.... This one says 3 → 32Vdc...

you could but your going to need a PID and a few other bits like thermocouple etc as thats only a SSR not a phase angle / burst fire thingy.

it's just a fancy relay really and the PID would drive the "switch' (the SSR) with a DC voltage.

your better off with the triac or the other phase angle thing in my post page prior (or the one in UK further back in the thread, not sure name)

[Samohon]

Thanks maheel, I'll hunt down the gear for the Triac build... Later I can purchase the PSR-25 if I need to...

Look simple enough to put together, I'll keep yall posted...

[rad14701]

Samohon, maheel is correct... I think that is merely an On-Off relay, not a proportional controller... The 3V - 32V is simply the trigger voltage requirement, not a voltage range for proportional operation...

I am currently awaiting some components from Mouser for several 120V controller designs... I will also be etching my own printed circuit boards so I may be able to offer a couple different controllers, or components, in the near future... I'm hoping to be able to eventually expand these designs to work with 240V as well...

[Samohon]

Thanks Rad, I'm in no hurry so keep me posted man... Would have to be 240vac though, but guess you knew that already...

[nickelbacher]

This may be over-kill for this application, but heck, they are so cheap these days, for 50$ you get a PID controller and a 40 Amp SSR (Solid State Relay) and 20$ connectors, case and such and there you go, full control of temperature.


http://www.alibaba.com/product-gs/23022 ... oller.html" onclick="window.open(this.href);return false;" rel="nofollow


On Ebay these days, somebody is selling accurate temperature measuring devices, SSR, and PID controller for 50$ ! Just search for 'PT100' or CD101 and you'll find it.

Personally, for myself, my Ponu still is very easy to control, I just set cooling rate low, turn on, do heads switching at right temperature, then shut off automatically before getting to tails. At 72 DegC, alarm goes off (I want to switch heads to hearts at this temperature), at 82 DegC, unit shuts off.

For some of those other VM, LM stills out there, you may need another controller and other measuring devices to manage flow. You'd probably want to hook that stuff up to a computer to to program actions through process .... perhaps over-kill but fun for those inclined. (PS: the CD101 can do that stuff but you have to special order .. more $$$ to)

Cheers!

[rad14701]

nickelbacher, isn't this just another fancy On-Off thermostat, or is it truly programmable to increase and decrease the signal input to a phase angle controller...??? Remember, we need constant heat input without detectable fluctuations...

Perhaps MuleKicker will have some input here...

[MuleKicker]

I do see that it has a 4-20ma output. Im guessing this is used as a "percent output function" as programmed in the controller. which suits our purpose well, (that is how i have mine set up, works great) you need a special ssr that uses the 4-20ma signal to vary the phase angle output. I dont see a pdf on that site for features/programming instructions. Can you post setup/programming instructions nickelbacher ? That does seem to be a pretty cheap PID controller, strait from china none the less. Not neccessarily a bad thing, but can be hell to get any tech support if you need it.

[maheel]

nickelbacher, isn't this just another fancy On-Off thermostat, or is it truly programmable to increase and decrease the signal input to a phase angle controller...??? Remember, we need constant heat input without detectable fluctuations...

Perhaps MuleKicker will have some input here...

i thought the pids turned the SSR on / off that fast that it does not fluctuate that much

assuming you can dial in a very small deadband / range of like .1 degree C into the pid

i use some pids and it can change the decimal point in the range from .1 to .01 but i have never tried it to run a ssr as mine dont have voltage out....

like a PID on a coffee machine, dial in 93' and it sits there happy @ 93

[MuleKicker]

trust me, i have tried. These things chase temp. so it will cycle and use the dead band when it gets close to the temp you set it to. This wont work when stillin, cuz you aint after temp. you want smooth heat from start to end. and it dont switch that quick, still raises hell with my collumn. The 4-20ma output is the only way to go. plus i see, you have to order a minimum of 10 of these.

like a PID on a coffee machine, dial in 93' and it sits there happy @ 93

This is why. You dont still at 78.3 all the way through your run, the wash temp gradually rises as the alcohol depletes from it. you cant simply set your pid at 78.3 and have it cycle fast. and the pid wont cycle fast until the wash temp is right at set point.

[evilempire]

Sorry if I'm beating a dead horse. I have not read this entire thread but I haven't seen a pulse width modulator (PWM) mentioned in these forums at all yet. It is commonly used in home brewing to control heating elements. It is a cheap and easy circuit build using discrete components that can be purchased at any radio shack (although cheaper to order). You also need a SSR (solid state relay). The PWM has a digital output (on or off). By using a potentiometer (adjustable resister) you can change the amount of time the element is on. Half power would be on 1 second, off 1 second. Full power would be on 2 seconds, off 0 seconds. You get the idea. SSR and heatsink run around 15 on ebay and you could build the PWM circuit for about 10 bucks. There is plenty of info on this on the intertubes but if requested I can try to add plans here for those interested.

[rad14701]

evilempire, if PWM hasn't been mentioned in this topic I'm relatively sure it has elsewhere... If you can build a working PWM power controller then by all means, post a tutorial as well as pictures in an all new topic... This topic is long and disjointed... MuleKicker has extracted some of the good information here and created new topics... He also has designed and built a nice controller with lots of bells and whistles...

[Samohon]

+2 Rad... Count me in evilempire...

Oh yeah, and welcome to HD my friend... Your very welcome here...

[MuleKicker]

We have talked about PWM, maybe not in this topic. But, Phase angle control is PWM that is timed to the phase of the current. I have built PWM controllers with arduino. They work, but not as effectively as true phase angle control.

[rad14701]

We have talked about PWM, maybe not in this topic. But, Phase angle control is PWM that is timed to the phase of the current. I have built PWM controllers with arduino. They work, but not as effectively as true phase angle control.

Yeah, part of the issue with using an Arduino, or even a PWM using an LM555 and opto-coupled triac driver, is that the DC powered logic side is not in sync with the AC load side so timing issues can cause these to be less than efficient... True phase angle control that uses AC voltage only is more accurate and consistent... This is the main reason why I haven't tried building anything but simple phase angle controllers...


My parts order has arrived from Mouser and I have started experimenting with the assortment of components to refine several 120V controller designs... Once done with 120V I'm hoping to ramp them up to 240V... I've built one circuit based on the dual time constant schematic in most triac data sheets but it doesn't work as well as stated, which I had expected, so I will be swapping in components of different values to gain greater control range as well as eliminating annoying harmonics... I like using a circuit with a sensitive triac to drive the high power triac much better because the harmonics noise becomes a non-issue... Driving the high power triac directly will most likely require the addition of an inductor to smooth out the ripple harmonics... More to come...

[MuleKicker]

DC powered logic side is not in sync with the AC load side so timing issues can cause these to be less than efficient...

exactly. That is why phase angle control is the way to go. phase angle control is nothing more than timed PWM. No more expensive either.