Help me scrutinize my control panel wiring diagram

Working on building a NG fired brutus 10 type system and am just getting around to working on a wiring diagram for my control panel. The system will have three Honeywell VR8200 valves, two controlled by Auber SYL-2362 PID's. The boil kettle will be controlled via a switch on the control panel (no need for a PID there).
I've also implemented P-J's e-stop and two alarm switches for the PID's that will control a 24VAC flashing buzzer.

My main questions are:
-Do I have fuses where I need them, and should I put one on the gas valves?
-Am I running the wiring efficiently enough by running some stuff in parallel?
-Do I actually have these PID's wired correctly for PID relay control, with J2 as my temp alarm?
-Should I use that many terminal blocks, or does anyone have any better ideas?

Thanks in advance!

Maybe have a fuse at least on the hot primary line to the transformer and optionally on the output. Usually industrial panels I've seen, the 'neutral' on the transformer output is also grounded to prevent the secondary voltages from floating with respect to ground.

For the e-stop maybe just using the main power switch would be better? The way it is the button relies on the GFCI being functional to trip, which yes it should be, but in a situation where the e-stop is needed you don't want to find out the GFCI is failing to trip for some reason.

Thanks for the response porcupine!

Question regarding the transformer neutral to ground. I plan on grounding the enclosure, is it safe to assume that the transformer being grounded as it's mounted to the backplate that's also grounded, is sufficient enough to stop floating voltages? Or is the neutral and chassis of the transformer isolated?
I was going off of Kal's plans, amongst others and thus far haven't seen any mention of grounding the secondary neutral. Googling it gives me plenty of results on home and commercial transformer wiring where they do this, but I'm not finding much in terms of lower voltage control panel transformers. I'm curious how much of an issue it would really be...

I agree on the e-stop\GFCI issue, however I think the true function of an e-stop is to kill all power throughout the system. P-J found a pretty good solution for this with his GFCI usage. However, I will also have the main power switch there should the GFCI fail to trip from the e-stop.

As for fuses, any thoughts on what size\type of fuses I should use for the transformer lines?

Fuse size for the transformer would depend on two things, the VA rating of the xfmr and the xfmr impedance. Basically at the minimum a short circuit on the secondary side needs to blow the primary fuse, and ideally if the xfmr is overloaded it should blow as well. Sometimes people fuse both the primary and secondary.

I'm not sure if any CPT's control power transformers have any leads of the output grounded to the chassis. I would guess probably not. Where I work we always show grounding one of the power leads out of the CPT but often see it missing in the panels when they are built.

An e-stop ideally needs to shut down all powered equipment. However normally e-stops are hardwired so that they do not depend on any part of the control system functioning properly. I would consider the GFCI part of the control system in this case. I believe on a GFCI a neutral to ground short is supposed to trip it as well.

@porcupine I agree with your feelings on P-J's GFCI E-Stop configuration that seems to be ubiquitous on this forum. This has always bothered me. Though it is clever, it intuitively seems dangerous, especially considering all the potential points of failure. At the moment, I can't quote any specific NEC code that would prohibit this. A ground conductor shouldn't be considered a current carrying conductor.

And, in general, E-Stops should open a circuit--not close a circuit. If you are really set on tripping the breaker it should be done with a shunt trip breaker that is specifically designed for this purpose and doesn't require grounding the hot conductor.

As an alternative, you could use a simple contactor (appropriately rated) to switch your incoming power and a normally-closed Mushroom pushbutton to drive the contactor coil.

FastTalker said:

As an alternative, you could use a simple contactor (appropriately rated) to switch your incoming power and a normally-closed Mushroom pushbutton to drive the contactor coil.

Click to expand...

I have though about this, but as I am renting the house I'm in currently, I didn't want to install a permanent housing for the contactor. I do agree though that this would be the proper way to go and will likely do that once I'm in a home I own again.

@porcupine, I'm on my phone currently, so I don't have reference to the exact transformer I purchased. As soon as I get on my computer though I'll see if I can find the full specs of it so we can figure out the fuse sizes.

Good points all around. Normally if I'm using a breaker with 'side pockets' that support shunt trips, I'd use a undervoltage release rather than a shunt trip for any critical application, so that the 'fail safe' is to trip the breaker. The downside is that on a power outage the breaker trips as well. Or I've seen normally closed maintained pushbuttons that when you press it stays pressed in, and you twist the button then to release it again. I'm sure Allen Bradley has these though just putting the AB logo on something seems to increase the price about $70.

Here's the transformer I bought for the control panel. It's a 75VA transformer, not certain of what the impedance is on it though.
http://www.pexsupply.com/Honeywell-AT175A1008-Foot-mounted-120-208-240-Vac-Transformer-w-9-in-Lead-Wires-75VA-11016000-p

For that I might run a .75A or 1 amp slo blo fuse on the primary side. 75VA/120V = 0.625A on the primary side, then I think you're allowed to go up to 125% of that in the overcurrent device, which would be .78A or so. It's just without any fuse on that transformer if it has a fault or the secondary is overloaded the xfmr could get very very hot.

Sounds good. I'll go pick some up. Thanks again for the advice and taking the time to look it over!
Hopefully I'll be able to get to building this thing within the next month. My time is of high demand these days with a 1yr old daughter!

Next up - I need to bring my brain back into my high school days and see if I can still remember how to weld!

porcupine73 said:

...
Or I've seen normally closed maintained pushbuttons that when you press it stays pressed in, and you twist the button then to release it again. I'm sure Allen Bradley has these though just putting the AB logo on something seems to increase the price about $70.

Click to expand...

Yeah. This is the type of button I'm referring to--a real E-Stop button. Pulled-out the contacts are made and pushed-in the contacts open.

Krazy,
Any progress with the system? I know kids do make demands but just wondered if you had made any headway and got your welding done. Thats a tough skill to pick up and run with after a long lay off so be carefull and do non critical welds first to get back into practice so you don't get leaks. Water + Leaks+ Electricity= Bad Day....
Wheelchair Bob

Not much in terms of the stand, I spent a little time learning Sketchup though, I just need to measure everything out and get a plan and material list going so I can pay a visit to the local metal supplier.

I did punch all the holes in my control panel enclosure and get all the electronics mounted,but haven't found the time to wire it all up yet. All of my kettles are complete also, with jay bird false bottoms in the MLT and BK and all stainless pickup tubes, recirc ports and cam locks.

However, I start a new job Monday that's about an hour closer to my house than my current one. So I'm hoping that once things smooth out there, I'll be able to make some headway finally with the extra time that I'll have back.

Thanks for checking in though! I'll do my best to update everyone on my progress when I make some.

KD,
Cool deal on the closer job. It will save you a ton on fuel too. i just went to home dialysis from in-clinic and it saves me around 150 a month just in gas. Plus I get three extra days a week to putter in my shop and cobble my system together. Gotta loveit...
Wheelchair Bob

Krazydave,

I have a question for you. In looking at your schematic you show that you are powering the Auber controllers w/24vac. Question I have is that according to Auber, the input voltage needs to be between 85v and 460v ac/dc, so how does your controllers work?? Did you do something different than what you showed in your schematic?

Thanks,
tommyg_17543

tommyg_17543 said:

Krazydave,

I have a question for you. In looking at your schematic you show that you are powering the Auber controllers w/24vac. Question I have is that according to Auber, the input voltage needs to be between 85v and 460v ac/dc, so how does your controllers work?? Did you do something different than what you showed in your schematic?

Thanks,
tommyg_17543

Click to expand...

Egads! It seems you are correct! Fortunately I haven't wired anything yet though, so it's an easy change. I'll update the diagram above soon to reflect the changes.

Thanks for catching that!

okay, the wiring diagram has been updated. I now have 120VAC going to the Aubers.

Cool! I didn't see a pic attached to your post though?? Also, what are you using for a panel/enclosure?

Thanks,
tg

I updated the pic on the main page with the corrected version.
For my panel, I'm using a 12x12x6 box that I picked up at the local scrap yard for $10.
However, I'm also on the lookout for something larger as it's certainly a tight fit in that box. Still plenty do-able though.

Thanks!

By the way, if you or anyone else wants a higher res version to print or anything, just let me know.

Yeah, if you could send a high res pic, that would be great! Do you have a materials list for this? Also, I found a few 120v and 24v lamps that you might like. Here are links:

http://www.ebay.com/itm/ALPINETECH-...500?pt=LH_DefaultDomain_0&hash=item336d02ce34

http://www.ebay.com/itm/ALPINETECH-...218?pt=LH_DefaultDomain_0&hash=item4ab4742fe2

Thanks,
tg

Here's a link to a PDF version of the schematic.
http://www.0wnj00.com/picstemp/ForumImages/v2.pdf

I also went with these lamps for a cleaner look. These are the same as you see at http://www.theelectricbrewery.com.
http://www.ebay.com/itm/NEW-22mm-COMPACT-LED-PILOT-LIGHT-24V-AC-OR-DC-/390108211841?pt=LH_DefaultDomain_0&hash=item5ad442ea81

Crap, I just realized that I left my 24v buzzer on the 120v leg for that Aubers now. Looks like I need to update it yet again!

ok, main image has been updated and here's an updated PDF as well.
http://www.0wnj00.com/picstemp/ForumImages/v3.pdf

So here's a very early pic of the control panel with all the gadgets in temporarily. It'll be painted first, then I'll get started on the wiring.

Wow looks nice. I would say definitely invest in lamicoid nameplates, those add a very professional touch.

I' been poking around in this topic and I see lots of diagrams that, in common with this one, rely on 'fooling' the GFCI outlet into thinking there is leakage as a means of obtaining an emergency stop function. I see that someone else has voiced the same concerns. What happens if the fuse is missing, dislodged or burned. GFCI's are supposed to be tested monthly to be sure that they work. How many of us do that? This scheme is devilish clever but too klugey (derved from the German word meaning 'clever') for me.

I can suggest 2 ways of doing this and there are obviously others. In both implementations you would have a normally open pushbutton in series with a normally closed pushbutton in series with the coil of a relay the string connected across the 24 VAC control transformer secondary. A normally open pair of the relay's contacts is connected across the normally open push button. If you push that button momentarily the relay coil is energized, the contacts close and thus the relay is 'latched' on and stays on until you push the normally closed pushbutton. This breaks the circuit and the relay is unlatched.

There are now two things you can do with the other contacts on the relay. You can wire a normally closed contact between the high side of the 24 volt circuit and the common wire that goes to the switches in the controller or you can wire a normally open contact in that position. If you do the former (NC contact) the systems behaves as it does now. Nothing happens until you push the NO pushbutton, which would be labeled "Stop" at which time the relay latches on and the control voltage path to the gas solenoids is latched open. Things stay this way until the NC pushbutton (labeled 'Reset') is pushed or the main power is recycled.

This works but is subject to the same criticism. What happens if the relay fails?

With the NO contacts is series with the control contacts the NO pushbutton is labeled 'Start' and must be pushed in order to energize the relay and latch the gas control loop closed. The loop stays closed until the NC pushbutton, now labeled 'Stop' is depressed or the power is recycled.

I prefer this arrangement because failure of the relay effects you at startup - not during an attempted emergency stop. Further more, the extra step of pushing Start to 'turn on the gas' might be a good feature to have. Finally, if you put the NO contacts in series with the common solenoid return lead (or used a separate NO contact for each) you could run the system to see when the controllers are asking for heat (by watching the lamps) without actually producing heat. This might be useful for diagnostics.

Right it has been discussed, will the forcing leakage to the GFCI work most of the time yes. But it really shouldn't be called an emergency stop or e-stop. That term in industrial automation has a certain meaning and typical requirements that the leaking the GFCI would never be used to achieve.

In industrial applications an e-stop is normally completely hardwired and made to be as failsafe as possible. Normally that means using something like an undervoltage release in a pocket on the breaker and normally closed switches wired in series to all the e-stops. That way, if a wire breaks or comes loose, or anything happens like that, it will still interrupt the circuit and drop the undervoltage release on the breaker. The control system is never used to implement an e-stop, and I would say the GFCI has circuitry in it that must be functional for the leakage method to work, so it would be part of the control system.

Finally a little progress. All painted up and ready to start wiring.

And the inside. Got some work to do!

krazydave said:

Finally a little progress. All painted up and ready to start wiring.

Click to expand...

Cool. Get some labels and you'll be set.

Let the wiring begin! I had to alter from the wiring diagram slightly as I discovered that I somehow ordered a 120v buzzer instead of a 24v. I'll update the diagram on the first page as soon as I find my Visio license and get it reinstalled on my computer.

Lights up! She's about as wired as I can get her until I get the stand started and get conduit run.
I should also mention that my diagram had the relays backwards in the means that my alarms were on J2 and my valves on J1 instead of the opposite as they should be for the way I'm using the Auber's.
The diagram on the main page of this thread has been updated with all of the changes.

I should also mention that for now I'm forgoing the whole E-stop through GFI routine until I decide on a better plan for it. For now the E-stop switch is just the first in the series, then the power switch. I left the diagram reflecting the GFI E-stop though, for now at least.

What size is that enclosure?

12x12x6