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Help for PID controller

 
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Badrabbit



Joined: 16 Mar 2010
Posts: 14

PostPosted: Tue Mar 16 10 11:00 pm    Post subject: Help for PID controller Reply with quote

I just found this forum and I'm hoping someone can help me with my rig.

I'm using an Auber PID to run an electric smoker. I have wired everything according to the schematics I was given but it doesn't see to be working correctly. When I power up, the burner gets hot but it does not stop once target temperature is reached. The "out" light on the PID goes out once it passes target but this has no effect on the burner.

I am assuming I have something wrong on the relay. This is the pin configuration on the relay i'm using. This diagram is drawn as if you are looking at the pins on the bottom.




Bottom Left: Negative SSR output on back of PID
Bottom Right: Positive SSR output on back of PID
Bottom Center: Burner
Top Right: Power

The other line from the burner is connected directly to the other side of the power. Everything is AC except the switching for the relay which is DC output from the PID.

TIA for any help given.
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GoCoogs
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Joined: 05 Jan 2010
Posts: 26
Location: Houston, TX

PostPosted: Tue Mar 16 10 11:06 pm    Post subject: Reply with quote

Do you have a part number on the relay, or a diagram of the internal wiring of the relay? Without this it's difficult to troubleshoot.

--Coogs
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Badrabbit



Joined: 16 Mar 2010
Posts: 14

PostPosted: Tue Mar 16 10 11:11 pm    Post subject: Reply with quote

GoCoogs wrote:
Do you have a part number on the relay, or a diagram of the internal wiring of the relay? Without this it's difficult to troubleshoot.

--Coogs


Here's the relay I am using. It may be the problem. I am repurposing all of this equipment from a thermal immersion circulator I had built for cooking "sous vide".

RELAY

Model number is 275-248. Any ideas on a better relay for this purpose would be appreciated.
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killswitch505
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Joined: 05 Apr 2009
Posts: 3921
Location: Hobbs, NM

PostPosted: Tue Mar 16 10 11:30 pm    Post subject: Reply with quote

man if you could take a picture of the pid, how its wired and part # i would gladly help
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Mrs. K.A.M. wrote:
Those are some of the best looking wieners I've ever seen Shocked
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Badrabbit



Joined: 16 Mar 2010
Posts: 14

PostPosted: Tue Mar 16 10 11:44 pm    Post subject: Reply with quote

killswitch505 wrote:
man if you could take a picture of the pid, how its wired and part # i would gladly help



The page for the exact model is listed at the link below. There is a link for the instruction manual at the bottom. I'll have to post pictures of the actual wiring tonight when I get home.

I have the relay hooked up to post 9 (negative) and post 10 (postive). Power runs into posts 1 and 2. The only other thing connected to the PID is the PT100 RTD which is connected to 7 and 8 with a jumper between 6 and 7.

http://www.auberins.com/index.php?main_page=product_info&cPath=1&products_id=14
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JimmieOhio
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Joined: 11 Mar 2008
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PostPosted: Wed Mar 17 10 12:05 am    Post subject: Reply with quote

What is the wattage of your burner? A 10 amp relay at 120 volts is only rated for 1200 watts (10 x 120). This is less than most hair dryers...

My guess is that you fried the contact closed by overloading it. Buy another one significantly higher rated than the burner.
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Badrabbit



Joined: 16 Mar 2010
Posts: 14

PostPosted: Wed Mar 17 10 12:20 am    Post subject: Reply with quote

JimmieOhio wrote:
What is the wattage of your burner? A 10 amp relay at 120 volts is only rated for 1200 watts (10 x 120). This is less than most hair dryers...

My guess is that you fried the contact closed by overloading it. Buy another one significantly higher rated than the burner.


That's possible. I'm not sure what the wattage in the burner is. Any suggestions on a replacement relay (preferably one with an easily accessible wiring diagram, I had to fly blind on the Radio Shack relay)?
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JimmieOhio
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PostPosted: Wed Mar 17 10 12:29 am    Post subject: Reply with quote

Badrabbit wrote:
JimmieOhio wrote:
What is the wattage of your burner? A 10 amp relay at 120 volts is only rated for 1200 watts (10 x 120). This is less than most hair dryers...

My guess is that you fried the contact closed by overloading it. Buy another one significantly higher rated than the burner.


That's possible. I'm not sure what the wattage in the burner is. Any suggestions on a replacement relay (preferably one with an easily accessible wiring diagram, I had to fly blind on the Radio Shack relay)?

Unfortunately, nothing can be correctly suggested until you let us know the wattage of the burner. You know what they say about "assume", don't you? Wink

If the burner is large, you may have a wire ampacity issue as well. When you find out the wattage of the burner, let us know the wire size you are using for the power part of the circuit.

The PID control portion including the relay coil can be lower in gauge, but the contact wiring to the burner is important to size large enough. The National Electric Code (NEC) and National Fire Protection Association (NFPA) are your friends. Fire, outside your firebox, is not. Shocked
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Jimmie Ohio
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killswitch505
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PostPosted: Wed Mar 17 10 12:38 am    Post subject: Reply with quote

man just looking at the cut sheet you might have a few problems 1 setup 2 wiring 3 a welded contact if its any of the three it should easy fix because what im seeing you can change the ssr out put or the j1 output in the programming if you burnt the contact
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JimmieOhio
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PostPosted: Wed Mar 17 10 12:48 am    Post subject: Reply with quote

Once you find out the burner wattage, I would suggest using a solid-state relay since this thing will be cycling on-and-off all day long. I found this on eBay:

http://cgi.ebay.com/Solid-state-relay-SSR-40A-24-480V-output-70-280V-AC-ctr_W0QQitemZ110505456258QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item19baa37282

Rated 40 amps and takes a 120 VAC input. I doubt this wouldn't be rated high enough to handle your burner.

Your schematic would be most helpful, though.
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Jimmie Ohio
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JimmieOhio
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PostPosted: Wed Mar 17 10 12:54 am    Post subject: Reply with quote

After reviewing your relay and your PID controller, there is another issue:

The PID controller can be set up to either relay contactor (mechanical relay) or SSR (solid state relay) output modes.

Your relay is mechanical, not solid state. Plus the SSR output control is only 8VDC. Did you configure the controller to match the relay?
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Jimmie Ohio
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"Never criticize a man until you have walked a mile in his shoes. Then, criticize him all you want since you're a mile away and you have HIS shoes."
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killswitch505
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PostPosted: Wed Mar 17 10 1:14 am    Post subject: Reply with quote

here is a site that i use a lot fast shipping and they should have a ssr for you. im going to build a power draft controller of my dad and a buddy this is the pid i'm using http://www.lightobject.com/0-999F-Fahrenheit-Temperature-Controller-P139.aspx
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Badrabbit



Joined: 16 Mar 2010
Posts: 14

PostPosted: Wed Mar 17 10 2:00 am    Post subject: Reply with quote

Thanks for all the help.

The wattage on the burner is only 1500 watts (it''s a pretty small unit).

All power carrying wires are 14 guage.

I have not changed the settings for the PID other than just setting up the RTD. I was going to autotune but quickly realized that the burner was not cycling on and off.

I went to Radio Shack at lunch and I know why it is staying on all the time. I have it wired to the post that is normally closed. Which also means that the PID is not affecting the relay at all. I originally had it wired to the other post (normally open) and the burner stayed off.

I also realized I have the 12A version and not the one I linked to (which I realize is still short of the wattage rating I need). I will get a higher rated relay.

Just for academics (as I'm obviously new to these types of projects), do I need to use the J1 outputs if I'm using a mechanical relay?
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JimmieOhio
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PostPosted: Wed Mar 17 10 2:16 am    Post subject: Reply with quote

Badrabbit wrote:
The wattage on the burner is only 1500 watts (it''s a pretty small unit).

Enough to fry the relay, though.

Badrabbit wrote:
All power carrying wires are 14 guage.

This is okay.

Badrabbit wrote:
I have not changed the settings for the PID other than just setting up the RTD. I was going to autotune but quickly realized that the burner was not cycling on and off.

You need to find out if the default output setting matches what you have.

Badrabbit wrote:
I went to Radio Shack at lunch and I know why it is staying on all the time. I have it wired to the post that is normally closed. Which also means that the PID is not affecting the relay at all. I originally had it wired to the other post (normally open) and the burner stayed off.

Even changing the wiring is still no good if the relay is under-sized. But I would get a solid-state relay for better cycling.
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Jimmie Ohio
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Badrabbit



Joined: 16 Mar 2010
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PostPosted: Wed Mar 17 10 2:30 am    Post subject: Reply with quote

Thanks JimmieOhio. I'll be sure to go with an SSR and to get one that can handle the power. Your words are also well heard with regards to safety.

I basically adjusted the plans for the immersion circulator (its heaters were only 800watts). I thought about the additonal power in the smoker so I adjusted the wire size but I failed to even think about the relay.
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GoCoogs
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Joined: 05 Jan 2010
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Location: Houston, TX

PostPosted: Wed Mar 17 10 2:56 am    Post subject: Reply with quote

I haven't used this particular PID controller before, but reviewing the instruction manual in your link, it seems when you get your new SSR you should still connect it to the SSR pins, but you will also need to ensure that the configuration menu variable "outy" is configured to either 2 or 3. If it is set to any other value, the SSR output will be disabled.

Basically, the J1 pins are supposed to serve as an alarm output (to ring a bell or something if your cooker overheats, for example). The exception would be if you are using a mechanical relay, in which case you need to set outy to either 1 or 4 (depending if you want on-off or PID control output to the relay).

So, for SSR, connect the SSR to the SSR pins and make sure that OUTY is set to 2 or 3.

--Coogs
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Badrabbit



Joined: 16 Mar 2010
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PostPosted: Wed Mar 17 10 3:02 am    Post subject: Reply with quote

GoCoogs wrote:
I haven't used this particular PID controller before, but reviewing the instruction manual in your link, it seems when you get your new SSR you should still connect it to the SSR pins, but you will also need to ensure that the configuration menu variable "outy" is configured to either 2 or 3. If it is set to any other value, the SSR output will be disabled.

Basically, the J1 pins are supposed to serve as an alarm output (to ring a bell or something if your cooker overheats, for example). The exception would be if you are using a mechanical relay, in which case you need to set outy to either 1 or 4 (depending if you want on-off or PID control output to the relay).

So, for SSR, connect the SSR to the SSR pins and make sure that OUTY is set to 2 or 3.

--Coogs


It's definitely set to 2. That was one of the first things I checked. Thanks for your help.
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