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mvanwie

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I have been contemplating my e-build for a while and I thought about the possibility of DC-powered panel. Basically, AC to the heaters, pumps, etc. will still be switched by SSR's, but everything else in the panel would be run off low voltage. Basically, the idea is to use an old PC power supply to switch line voltage to 12VDC and use the output to feed the PID's, control switches, indicator lights, alarms, etc.

1) Is there any difference in using a DC powered PID, e.g. Auber SYL-2363B (accuracy-wise, reliability, etc.)?

2) What are the con's of powering a e-brew panel with DC voltage?
 
mvanwie said:
1) Is there any difference in using a DC powered PID, e.g. Auber SYL-2363B (accuracy-wise, reliability, etc.)?
Click to expand...
No differences. Internally, the PID runs everything off 12VDC anyway. When you connect higher voltage than this, it drops it down. When you connect AC, it recitifies it and makes it DC.

mvanwie said:
2) What are the con's of powering a e-brew panel with DC voltage?
Click to expand...

I don't think there are any con's other the possible the availability of components like fuses, switches, contactors, etc.

But I don't think there are any pro's to doing this, more imporantly. If you are concerned about the risk of electric shock, then you just need to make sure you limit the current going to the controls on the front of the panel. The PIDs need less than 300 mA of current, so if you put a tiny fuse on the line that feeds power up to the face of your panel, you can control everything with low current devices.

DC is not any safer than AC when you get down to the basics of it. And it's not voltage that is important, but AMPS. You can kill yourself with a 12VDC car battery, because that thing has the capacity to send a LOT of amps through you.
 
walker said:
no differences. Internally, the pid runs everything off 12vdc anyway. When you connect higher voltage than this, it drops it down. When you connect ac, it recitifies it and makes it dc.



I don't think there are any con's other the possible the availability of components like fuses, switches, contactors, etc.

But i don't think there are any pro's to doing this, more imporantly. If you are concerned about the risk of electric shock, then you just need to make sure you limit the current going to the controls on the front of the panel. The pids need less than 300 ma of current, so if you put a tiny fuse on the line that feeds power up to the face of your panel, you can control everything with low current devices.

Dc is not any safer than ac when you get down to the basics of it. And it's not voltage that is important, but amps. You can kill yourself with a 12vdc car battery, because that thing has the capacity to send a lot of amps through you.
Click to expand...

+1...
 
52pickup said:
How would one go about that?
Click to expand...

Yeah... I guess you couldn't, could you? Human body is too resistive to let many amps through. I'll withdraw that statement.

But, sligtly irrelevant. My point was it's not an AC vs DC thing here. DC is just as dangerous as AC. It's abount current. 12V or 24V is safer than 120V or 240V. Either way, the tiny little fuses to protect components and limit current to the panel door is a good way to alleviate a lot of concerns.
 
I agree with Walker, I don't see any benefit. I don't think the DC parts would be any harder to find, such as switches, contactors .. etc. There are two drawbacks I can think of. 1) the room in your panel the PSU takes up and 2) Computer PSUs are flaky, and I don't know how they would do near moisture.
 
I was just thinking about this some more as I was digging around for an old wall wart to power some fans....

My initial thought was whether you could use as 12V wall wort for this. They are much smaller, less noisy, and more reliable than a PC power supply. So, I looked up the Auber PID power supply requirements to see if 12V was enough to run the PID.

It's not. And neither is 24V, so the PC power supply isn't going to cut it. The Auber PIDs require a minimum of 85V to operate according to the website.
 
Walker said:
I was just thinking about this some more as I was digging around for an old wall wart to power some fans....

My initial thought was whether you could use as 12V wall wort for this. They are much smaller, less noisy, and more reliable than a PC power supply. So, I looked up the Auber PID power supply requirements to see if 12V was enough to run the PID.

It's not. And neither is 24V, so the PC power supply isn't going to cut it. The Auber PIDs require a minimum of 85V to operate according to the website.
Click to expand...

The other downside I see is that at some point you would need to run a bunch of wires or some sort of control system (muxed or whatever) from the 24V control panel to a sub-panel or control box with all of the 120V and 240V stuff in it. It adds a lot of complexity to the system. I'd be curious to see your electrical diagrams if you do go this route though. :)
 
I was considering doing a 12v control system on the eBIAB I am starting, mostly because I am more familiar/comfortable w/ 12v DC systems. But, after looking around I decided the gains just weren't worth the extra steps required to make it happen. All of my switching circuits will be fused 120v circuits.
 
I was sort of "forced" to go a similar route. I got freebie 24v contactors and Watlow 24v PIDs. So I had to get a 24v power supply. It takes up a ton of room in the panel. It works great, but it's one more item that can fail later. If I had to buy from scratch, I would get all 120v control components and eliminate the ps.
 
Walker said:
No differences. Internally, the PID runs everything off 12VDC anyway. When you connect higher voltage than this, it drops it down. When you connect AC, it recitifies it and makes it DC.



I don't think there are any con's other the possible the availability of components like fuses, switches, contactors, etc.

But I don't think there are any pro's to doing this, more imporantly. If you are concerned about the risk of electric shock, then you just need to make sure you limit the current going to the controls on the front of the panel. The PIDs need less than 300 mA of current, so if you put a tiny fuse on the line that feeds power up to the face of your panel, you can control everything with low current devices.

DC is not any safer than AC when you get down to the basics of it. And it's not voltage that is important, but AMPS. You can kill yourself with a 12VDC car battery, because that thing has the capacity to send a LOT of amps through you.
Click to expand...

While it's true that it's current that kills you, it's only part of the story.

300mA is more than enough to stop the heart (which is incidently why a 12v could actually kill) BUT here's the difference and why low voltage is safer to work around:

Skin resistance. Skin typically toss out about 1-4kohms of resistance.

V=IR, and higher voltages result in higher currents. 12v to skin results in a miniscule amount of current. 220V results in a not minscule amount. That's why GFCI's are designed to trip off around 5mA of stray current.

A 300mA fuse probably won't pop if it's going through you, but depending on where it goes (worst is a way that sends it through your heart) it could be dangerous.

as for how 12v could kill? if the voltage was put in subcutaneous...it'll conduct through the blood, which is much more conductive.
 
Auber makes a DC PID SYL-2362B which can be powered by 12-30 VDC. Would that one work?
Click to expand...
would a device rated for 12v run on 12volts? im pretty sure it would.... ;)

The Auber PIDs require a minimum of 85V to operate according to the website.
[/uqote]
those are A/C. the voltage transformer on the thing will run on any AC input from 85 to 200-something volts. the internal electronic bits still run on 12v DC though. they make a model that runs on strait 12v DC too. it just has a voltage regulator instead of a transformer too.
Click to expand...
 
audger said:
would a device rated for 12v run on 12volts? im pretty sure it would.... ;)

The Auber PIDs require a minimum of 85V to operate according to the website.
Click to expand...
those are A/C. the voltage transformer on the thing will run on any AC input from 85 to 200-something volts. the internal electronic bits still run on 12v DC though. they make a model that runs on strait 12v DC too. it just has a voltage regulator instead of a transformer too.
Click to expand...
Yup. I didn't see that DC one down there on the page. My bad.
 
a bennifit of DC current... components are cheap! fuses, switches, fuse holders, lights, ect... go to the automotive section it is a lot cheaper than $25 for a 120V bus bar plus fuse holders you can get them combined like this...

Amazon.com: Bussmann BP/15600-06-20 Quick Connect Fuse Block: Automotive

not to mention cheaper wire and connectors.

edit: bennifit of low voltage DC current
 
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