PID Thermocouple Issue

How much drift in degrees are you seeing. different than what was posted earlier? Is the reading steady over like 15 seconds?

The drift over 15 seconds can be 2-3 degrees.

At my last test with the general purpose TC Ieft it in the ice water for several hours with the PID on. At the time I left it the water temp was still 32.5 and the TC was fluctuating between 25 and 1. When I came back several hours later the water temp was 65 and the TC was at -13.
 
Nice oven. I don't see any electrical noise issues. Did you build that oven? I want one that is like 5 to 6 foot long and internal width and height can be 5" x 5" or so. Just want to treat long rods like 5/16" diameter.

With output signal disconnected. and T/C in stable temperature environment you should see like +/- 1 degree range. ( rounding on digital signal ) With output disconnected, don't care about PID and what it is doing. you basicly just got a temp meter.

Do you have a sketch of schematic? I like that you twisted the wire pairs together.

I'll try and get a picture of my internals so you can see what ugly wiring looks like. Been spoiled over the years with amazing techs.
 
The drift over 15 seconds can be 2-3 degrees.

At my last test with the general purpose TC Ieft it in the ice water for several hours with the PID on. At the time I left it the water temp was still 32.5 and the TC was fluctuating between 25 and 1. When I came back several hours later the water temp was 65 and the TC was at -13.
So the water temp went up and TC was reading a colder temp?
Switch the wires around and see what happens.
 
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Nice oven. I don't see any electrical noise issues. Did you build that oven? I want one that is like 5 to 6 foot long and internal width and height can be 5" x 5" or so. Just want to treat long rods like 5/16" diameter.

With output signal disconnected. and T/C in stable temperature environment you should see like +/- 1 degree range. ( rounding on digital signal ) With output disconnected, don't care about PID and what it is doing. you basicly just got a temp meter.

Do you have a sketch of schematic? I like that you twisted the wire pairs together.

I'll try and get a picture of my internals so you can see what ugly wiring looks like. Been spoiled over the years with amazing techs.
Yes I have been building the oven a little at a time over the last several months.

I don't have a sketch of the wiring.

Sent from my SM-G955U using Tapatalk
 
So the water temp went up and TC was reading a older temp?
Switch the wires around and see what happens.
Hi ddicky the polarity is correct. Already checked that.

Sent from my SM-G955U using Tapatalk
 
Hi Doodle, re-read my last post. I did swap out the kiln style K type thermocouple for a general purpose K type thermocouple. The only change was the general purpose TC stabilized (i.e. to the central drift point) a lot quicker. I have since tried another K type thermocouple out of my smoker with the same results.

Do you still have an offset programmed in to the controller?

When you substituted the other TC's, did you connect them direct to the control terminals 4,5 ?

Do you know if your shop humidity is above 40% ? I am considering static discharge damage to controller.
 
Do you still have an offset programmed in to the controller?

When you substituted the other TC's, did you connect them direct to the control terminals 4,5 ?

Do you know if your shop humidity is above 40% ? I am considering static discharge damage to controller.

No offset.

Yes the substitute TC was wired directly to the PID.

No the humidity is not that high. I've never had a static issue here especially in the summer months.

I'm going to contact the vendor tomorrow and see what they have to say.
 
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3 different T/C's on the tube furnace . Pretty ugly wiring job. Swapped out controller for a smaller one and addition got it looking worse that bad.

Output is off and temperature changes 0.1 F as I watched it for a bit.

ColdCube and fan in there along with a power contactor and transformer. I built it with what I had to keep price down. Should be a breaker in there out of view. For layout, an example of how not to do it.
 
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My little oven. got for next to nothing but controls were trash. The toggle switch turns the output off. This one has an SSR in it along with a really old Watlow PID controller. note the temp off set by around 5 F or so. I think this one required a cold junction reference and I didn't do it. Got a replacement Automation Direct controller to install to match other oven and not got around to it.
 
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