Electric Temp Controller 120/240

[grupe]

CYA stuff here: this post is what I have learned and for educational value only. Electricity is dangerous.  If you harm yourself, don't contact me. Blah Blah Blah

I know there are other post on this topic, but I thought my build could help.

Notes: I added a 90mm fan that blows on the SSR as the box was getting hot during an 8 hour smoke. Don't have pics right now, but can add them if anyone wants to see them.

Requirements:

1. Be able to control the temp on my 120v smoker

2. Be able to control the temp on my 240v smoker which is still being built

3. Be able to control the temp on my keg/conical cleaner (yes I brew beer as well)

4. Be able to control a 120v output with a 240v input

5. Be able to control 30 amps (Around 7000 watts)

6. Aux plug for fan, cold smoker, conical pump, etc. Ended up using it for a DC adapter since I ordered the wrong PID. Will fix later.

Wire:

1. All of the wire going to the relay, SSR and plugs is 10 awg

2. All of the wire but the SSR control wire is 14 awg

3. Don't be cheep. Buy the right wire.

This post is a combination of stuff I have learned from the forums and from talking to certified electricians.

-First thing I did was ordered the parts that were cheaper online. List is included below. Most of this stuff is going to be shipped from China which will take awhile so plan ahead.

-Second thing I did was checked to see if it would fit in an 8x8x4 enclosure using a taped together cardboard box. The PVC version you can get at lowes, menards, home depot etc. Don't try to find them online as all of the big box stores searches suck, but they have them.

-Third - I glued the input plugs to PVC which is threaded so that I can close off these plugs when not in use. My controller will be around water and the way I wired it will have one of the lead on the opposite input hot at all times. You could fix this by adding more relays, but less than $5 of PVC and plugs fixes it easier. ** Safety first people **

-Forth - Once I got the box and the plugs, I drilled out the holes in the PVC enclosure and started the wiring. The image of the wiring diagram can be enlarged.

Picture of the cardboard mockup:

1.jpg

• grupe
• Nov 30, 2012

Picture of me gluing the plugs into place:

2.jpg

• grupe
• Nov 30, 2012

Layout of the parts inside the box pre-wiring:

3.jpg

• grupe
• Nov 30, 2012

Post wiring:

4.jpg

• grupe
• Nov 30, 2012

The plugs covering the power inputs:

7.jpg

• grupe
• Nov 30, 2012

Cover closed and all is well:

5.jpg

• grupe
• Nov 30, 2012

Wiring Diagram:

6.jpg

• grupe
• Nov 30, 2012

Online Parts List:

-PID. Make sure it is 120 vac that has DC output and will support F as well as C. I would also suggest getting one with a "k" type sensor. I got the wrong one so do your research. If the picture show a NO/NC SSR control, you are looking at the wrong one. Get it off eBay.

-SSR: Search eBay for a "50a ssr". Make sure to get one with a heat sink

-240V plugs: Do a search on eBay for L14-30

-Open Face Relay. I use 40amp one. You can get them here: http://www.automationdirect.com/adc...n-Style,_40A_(AD-PR40_Series)/AD-PR40-2C-120A

-Thermal Couple connector (female): Search eBay for: "3 Pin XLR Female Plug Socket"

-Thermal Couple connector (male): Search eBay for: "XLR 3Pin Male Panel"

Offline stuff

-120V male plug: Lowes, etc

-Box: Lowes, etc

-120 and 240 female plugs: Lowes, etc

-Wire: Lowes, etc

-PVC to close inputs: Lowes, etc

-Other wiring stuff: Lowes, ect

Let me know if I skipped anything in the notes above and I will provide more info.

-Graham

 

[tjohnson]

Hey Graham

Looks Great!

What are you using it for?

Large Smoker?

TJ

 

[grupe]

TJ,

I am in the process of building a fridge smoker for making sausage, but I use it for a few different things.

-Graham

 

[tjohnson]

How about a price list for parts

Approximate would be OK.

Auber makes some PID Controllers, but they don't seem to hold up at higher amps

Some guys were having issues with them

THX!

 

[grupe]

SSR: $11.45
Relay: $20
XLR Plugs: $8
Box: $24
Light: $7
Switches: 2 X $7
PID w/ Thermalcoupe: $37
240 plugs: $7 a peice

Wire for inside the box would be a few dollars

The 10-4 cord is around $1.68 a foot. Guess you can figure out how much you need.

PIDs aren't really designed to switch large AMP loads. That is why the have SSR outputs as SSRs can switch large AMP loads.

-Graham

 

[sound1]

I like the idea of the multi-use control..A couple questions if I could.

1) On your main power relay, you are showing the output on the NC contacts. Wouldn't this disconnect your power when you energize the control coil?

2) What is the advantage of the SSR. I see that folks like to use them but wouldn't a simple relay/contactor work and reduce the heat sink/fan requirement? PID issues?  

 

[grupe]

@Sound1.

1. You are right. I should have showed the NO contacts. I lost my first drawing so had to re-draw it for the post. I noticed another error as well and will update the drawing later.

2. SSRs have the ability to switch on and off several times a second and not burn up. A normal coil relay really shouldn't be turned off and on more than once in 4 seconds or it will greatly reduce its life expectancy. You can program most PIDs to only cycle every X seconds, but I like the idea of being able to control the temp within +-.2 degrees by using the SSR.

-Graham

 

[sound1]

OK and THX, I'm understanding a bit better now. With  the short cycle you can "partially" heat the element without the rapid clicking, almost a buzz of a contactor.  I don't know if a type k would react that fast but I do like the quiet thing.

BTW, so much equipment and appliances only switch one leg, hence the "service only by qualified personnel". I like the safety thing with your design, when the switch is off, it's totally off.

With all the little projects I want to try, I see one of these in my future. So many little critters around here seem interested in what I'm doing (and really want to help), I think twist-lock outlets my be prudent.

Nicely done, and thanks for sharing!!

 

[grupe]

Getting shocked just takes all the fun out of a project. Not to mention it could damage you. :(

 

[grupe]

Here is an update image of the wiring diagram.

I update the NC to NO contacts on the coil relay. I also forget that all of the power needs to come off the right positive leg since when connected to 120v, this will be the only live leg. The left positive leg is only used when input voltage is 240 and is only used when outputting 240.

10.jpg

• grupe
• Nov 30, 2012