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Voltage Controller

PostPosted: Wed Mar 19, 2014 4:40 pm
by OzKev
There has been a few questions about voltage controllers, so here is what I use.

This is a information topic so you can easily explain to your electrician what you need them to build. Do not wire this yourself

We use a SSR (Solid State Relay) that accepts a resistance to control the output voltage. It will vary from 0 volts to 240volts (240v being the given input voltage, or 110v for some countries). It must have a capacity equal or greater than the load it will be used for, in this case we are using a 25va for a maximum of a 10amp load. - $8 ebay
A pot (Potentiometer) that matches the SSR, both in resistance and in current (watts). - $5 ebay
* Using a pot with a higher resistance value means the voltage will cut to zero at a higher setting.
* Using a pot with a lower resistance value means the voltage may not be able to achieve a zero value.
* The pot must meet or exceed the watts specified on the SSR. In this case 2w.
* In this build the SSR requires a 500k ohm 2w pot, my electrician had a 560k ohm 2w and I hit zero voltage at around 1/3 on the dial.
Enclosure to put it in. - available form Jaycar.
Heat sink - Jaycar for a neat external style.
Thermal paste. - ebay, Jaycar
Cables / plus. - almost anywhere.
{optional} Voltage gauge to show the output voltage. - I get these from Uxcell.com

I'll let the picture do most the talking

The front - including optional voltage gauge.
Image

Inside
Image

Back - note you can see the screw that mounts the SSR onto the heat sink.
http://i988.photobucket.com/albums/af3/ ... f42898.jpg


Some notes
[*]The back of the enclosure is cut away so the SSR sits directly on the heatsink.
[*]Some versions do not attach an earth lead to the pot, I prefer to be safe and have an earth point. Most decent pots will have a hook up point, you can see this pot has a dedicated pin for it.
[*]The internal wiring does not have wires for the volt gauge in the photo. The gauges Active is hooked to SSR terminal 2, and the Neutral is wired to the Neutral joiner.

Re: Voltage Controller

PostPosted: Sat Mar 22, 2014 10:15 pm
by APR
Hi OzKev, I take it the 2 earth screws on the SSR module are also the screws which attach the module to the heat sink so the heat sink is also earthed? Is this correct?

Re: Voltage Controller

PostPosted: Sat Mar 22, 2014 10:23 pm
by Linny
Careful of the 500kohm jaycar pots ... they have a tendancy to fail regularly . ive seen 2 fail in 10 builds ,,, not very good odds but on a positive they usually carbon up which means they fail in the off position

Re: Voltage Controller

PostPosted: Sat Mar 22, 2014 11:53 pm
by ekul
Have i shown you these bad boys kev? http://www.ebay.com.au/itm/AC-220V-3800 ... 0999016048 Worked fine for me until I realised that just one 200W element was better (easier) than one element + another one turned down most of the way.

Re: Voltage Controller

PostPosted: Sun Mar 23, 2014 8:20 am
by OzKev
APR wrote:Hi OzKev, I take it the 2 earth screws on the SSR module are also the screws which attach the module to the heat sink so the heat sink is also earthed? Is this correct?


Yep sure are. I like to ensure everything is earthed. You can touch the heat sink on the outside so it must be earthed. One screw provides the earth from the supply, the other side provides the earth up to the pot. The heat sink touched the SSR so it too has the earth contact.


Linny wrote:Careful of the 500kohm jaycar pots ... they have a tendancy to fail regularly . ive seen 2 fail in 10 builds ,,, not very good odds but on a positive they usually carbon up which means they fail in the off position


These ones were sourced from ebay. Also in the original post I talk about the pot's resistance. The one in use is actually a 680k ohm one.


ekul wrote:Have i shown you these bad boys kev? http://www.ebay.com.au/itm/AC-220V-3800 ... 0999016048 Worked fine for me until I realised that just one 200W element was better (easier) than one element + another one turned down most of the way.


Yep seen your one, and I also have one. Not sure why, it works on my Uxcell element (2,000w), my house kettle and my brew area fan. It will not works on the 2,200w element I use in the boiler. Even though we both use the same element and your one works? From memory you have your one wired via the neutral, maybe I should try that next time. It's probably more a Chinese ebay quality issue. So if I got another it may work.

Re: Voltage Controller

PostPosted: Sun Mar 23, 2014 9:47 am
by ekul
yeah, i'm not sure which way i had mine wired up but an electrician mate told me it was the opposite way to normal. And it was working on the 2200W keg king element until both elements blew up a mates place and he replaced them with the uxcell ones.

Re: Voltage Controller

PostPosted: Wed May 14, 2014 10:37 am
by TheMechwarrior
Thanks OzKev,

Could you run the 40A SSR with 2 x 15A parallel inputs to drive 2 x 3600W parallel elements? Using the same design?

This is the one MuleKicker built for me in 2010:
I was hoping to "simply" upgrade the SSR.
Image

Cheers,

Mech.

Re: Voltage Controller

PostPosted: Wed May 14, 2014 11:24 am
by OzKev
TheMechwarrior wrote:Thanks OzKev,

Could you run the 40A SSR with 2 x 15A parallel inputs to drive 2 x 3600W parallel elements? Using the same design?

This is the one MuleKicker built for me in 2010:
I was hoping to "simply" upgrade the SSR.
Image

Cheers,

Mech.



I'm not a sparky, so you would need to confirm this theory with the person who would do the wiring. I do not think it would work. 15amp circuits are generally on their own dedicated circuit, so when you cross two separate feeds it would cause the RCD to trip due to imbalance on each circuit.

I think you have two choices,

Build 2 separate setups as above, but within 1 enclosure. The SSRs and pots are cheap, and you are going to need to run a second set of cables in and out of it. You will have 2 pots to manually adjust every time. I would probably build two separate controllers and velcro then together as 1 unit. Then later if you want a single controller for another reason you have it ready. So in your case you would just build another unit the same as you have.

Use a pid, most have a manual mode where you can adjust the output %. Then you just hook 2 SSRs into the one pid. Then keep your existing controller aside.

Myself I would just build the second controller the same as you have.

Re: Voltage Controller

PostPosted: Thu May 15, 2014 11:56 pm
by davecuds
Another good write up Kev,
im looking to upgrade my controller box, currently have a 25 ssr running a single 3500w element.
My shed has 25a and 32a circuits that i would like to make use of :)

Im a bit of a dunce when it comes to electrical stuff. I wired up my current controller but that was directly ripped off someone elses design.

What pot is good for SSR40?
or i have 2 x 25a ssrs lying around, but they will be underated for 32a correct?

I have a sparky mate so ill rig up what i can and run it by him.

Re: Voltage Controller

PostPosted: Fri May 16, 2014 12:23 am
by davecuds
btw where do you get your pots from. i tried a while back to get a 2w 250k for my PSR25 and i remember that being really difficult. Just having a quick look now and they dont seem to exist.

Re: Voltage Controller

PostPosted: Fri May 16, 2014 12:27 am
by APR
davecuds wrote:... i have 2 x 25a ssrs lying around, but they will be underated for 32a correct?


No. It is not the maximum ampage capability of the circuit you plug the SSR into. It is the maximum current drawn by the element (or other electrical device) you hang off the SSR that is relevant.

An element that will draw 25 amp at 240 volt will be a 6,000 watt element. (25 times 240 = 6,000)

Due to the fact that the SSR will be operating for hours at a time when it is operating a still boiler, I personally would not hang a 6,000 watt element off it. I would be inclined to limit the element wattage to 4,800 watt or less. Also, you need to have the SSR on a good heatsink using a thermal grease between the SSR and heatsink, and I would be inclined to have a fan blowing across the heatsink.

On your 32 amp circuit you can run 2 x 25amp SSR's each handling a 3,600 watt element which means each SSR is pulling 15 amp. (15 x 240=3,600)

Re: Voltage Controller

PostPosted: Fri May 16, 2014 1:00 am
by APR
davecuds wrote:btw where do you get your pots from. i tried a while back to get a 2w 250k for my PSR25 and i remember that being really difficult. Just having a quick look now and they dont seem to exist.


You can use this....

http://www.uxcell.com/wth1181a-220k-ohm ... 66523.html

While it is 220K ohm it will work OK. What you will find is that you may not be able to turn the element fully off with a 220K ohm pot. You will have to either switch off power to the controller/place an on/off switch on the controller box, if you want to fully turn down the heat from the element.

Note: with uxcell.com any second and subsequent items on the same order get a $3 discount, so a second pot will be discounted $3. Pricing is $US unless you change the currency toward the top on the RH side of the Home page. If you look long and hard enough you may find a 250K okm 2W pot, but I wouldn't bet on it.

For those requiring the 500K ohm 2W pot.... I got this far...

http://www.uxcell.com/wth118-470k-ohm-w ... 71748.html

Re: Voltage Controller

PostPosted: Fri May 16, 2014 1:33 am
by davecuds
Cheers APR.
I may just run one element on the PSR25 and the other simply on a switch, on/off. Just for boil up.
Yeah i was eyeing off that 220K ohm, looks like the go.

Re: Voltage Controller

PostPosted: Fri May 23, 2014 10:39 pm
by ENTITY77
Just wanted to verify that this design would function fine with a T500 boiler?

Won't need it with the refux head but at some point I would like to either make or acquire a pot still head and control over the element will be a must.

Re: Voltage Controller

PostPosted: Fri May 23, 2014 11:09 pm
by APR
ENTITY77 wrote:Just wanted to verify that this design would function fine with a T500 boiler?

It will.

Won't need it with the refux head but at some point I would like to either make or acquire a pot still head and control over the element will be a must.


My experience is that the pot still we made to go on the T500 type boiler will take all that the boiler can throw at it. We have around 1 metre of water jacket over 1" copper.

I also have a 2" Boka and it certainly benefits from using a power controller. I have a couple of power controllers including an SSR40, and am happy with this unit...
http://www.ebay.com.au/itm/271355766269

I have had one unit stop working with a solder joint overheating and becoming open circuit. I assume this occurred because the joint was "dry" from manufacture and therefore of high resistance. I resoldered the joint and the unit is working OK again.

viewtopic.php?f=60&t=5597&start=20#p100839

I believe a power controller definitely needs a volt metre for reference.

Re: Voltage Controller

PostPosted: Fri May 23, 2014 11:15 pm
by MacStill
ENTITY77 wrote:Just wanted to verify that this design would function fine with a T500 boiler?

Won't need it with the refux head but at some point I would like to either make or acquire a pot still head and control over the element will be a must.



you should consider this :handgestures-thumbupleft:

Re: Voltage Controller

PostPosted: Sat May 24, 2014 12:00 am
by SBB
The link Macs posted up would be a better way to go re the pot still part.
Its a bargain at that price and as it comes apart it can be posted for a few dollars more. You wouldn't build one cheaper without a lot of scrounging around for cheap copper , solder , flux and other bits n pieces.
The other thing is that its much easier to make good cuts with a larger boiler charge than a small one when using a pot still. Its not impossible with T500 boiler but it could be a struggle.

Re: Voltage Controller

PostPosted: Mon Nov 22, 2021 7:17 pm
by Jayson_Black
MacStill wrote:
ENTITY77 wrote:Just wanted to verify that this design would function fine with a T500 boiler?

Won't need it with the refux head but at some point I would like to either make or acquire a pot still head and control over the element will be a must.



you should consider this :handgestures-thumbupleft:


Err. every time I try to view "You should consider this" Forum asks me to log in, when I am already logged in. Glitch maybe?

GLA :D

Re: Voltage Controller

PostPosted: Mon Nov 22, 2021 7:47 pm
by The Stig
Jayson_Black wrote:
MacStill wrote:
ENTITY77 wrote:Just wanted to verify that this design would function fine with a T500 boiler?

Won't need it with the refux head but at some point I would like to either make or acquire a pot still head and control over the element will be a must.



you should consider this :handgestures-thumbupleft:


Err. every time I try to view "You should consider this" Forum asks me to log in, when I am already logged in. Glitch maybe?

GLA :D

Try now , I fixed the broken link.
But it’s a link to something that doesn’t exist any longer, was a for sale add that’s been moved out of sight after the sale