# Designing a 24v control panel with relays and contactors.



## mattsilkwood (Sep 21, 2008)

The first step is figure out how you want it to work and draw it out. 

You can get SSRs that will handle that load but they wont be cheap.


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## RIVETER (Sep 26, 2009)

For all that you will need, look on line in the Grainger catalogue, including the solid state relays. What is the emergency stop for, in case the revenuers show up?


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## John Valdes (May 17, 2007)

Like mattsilwood said you must draw this control panel before you even consider what parts you will need, cut your first piece of wire or tap your first hole. Without a drawing you are just asking for headaches and a crappy looking panel since you will be troubleshooting it before you get it to work. Right now, get paper, pencil and ruler and start the schematic. *Make it work on paper first!*

If you have not purchased the relays yet, have you considered a small PLC? You can eliminate relays and timers with a very inexpensive controller. They make them today with a small touch pad for simple programming. So no special software or HIM is required.

Solid state relays are an excellent choice for heating elements. When working with heating or cooling there will be many actions. The SSR's are great for this purpose. 

If you want 24 volt control just get a control transformer to reduce your input voltage and fuse it correctly.

Why don't you post your drawing and we can critique it? 

Welcome to the forum!

Ps.........Once the panel is complete you can dry run it before you put it in service.


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## randomkiller (Sep 28, 2007)

Wow sounds like a state of the art meth lab.


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## wildleg (Apr 12, 2009)

i hope the scram button also energizes an emergency beacon and warning horn that repeats the message " Warning, Beer machine is off ! Warning Beer machine is off !!"


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## EasyEast (Apr 29, 2010)

Once I have something on paper, I'll upload the design. The PlC idea sounds like a great idea. Wildleg I like your idea about about the horn that has the the warning message going off.


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## mattsilkwood (Sep 21, 2008)

The plc isn't necessary in this case IMO. You could streamline the design with a plc but you will still need relays of some sort for your outputs.


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## John Valdes (May 17, 2007)

mattsilkwood said:


> The plc isn't necessary in this case IMO. You could streamline the design with a plc but you will still need relays of some sort for your outputs.


The PLC will replace the relays and timers if used. Small PLC outputs require no relays. The PLC will drive most reasonably sized contactors or SSR's.

I agree in some cases a PLC is over kill. I would look at the pricing for both and make a monetary decision.
If he only needs a few miniature relays and a SSR or two he may be better of going standard relay logic.
I like PLC's, and since they have become more affordable, I use them exclusively in control panels. Siemens makes several small PLC modules with just a few I/O. I saw one the other day with 12/12/? for around $200.00.


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## EasyEast (Apr 29, 2010)

I have decided to use relays and SSR I found some cube relays and sockets for a great price. The 2 SSR are a bit pricey but, will be well worth it. i also decided to make the control panel 120v instead of 24v. I will only have 8 buttons. One button will turn on the system and one will shut the system down. Can I do that off one relay to kill the whole system? Please advise.


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## John Valdes (May 17, 2007)

Wheres your drawing? 
Hint. No relay needed for shutdown and restart. Or, you can use a relay. Your options are endless!
No one is going to design this for you. Get a drawing started. Slacker.


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