Project - PID on Lee Pro 4 20 furnace

[el34]

Frozone, you are 150% correct. This week I finally made time to replace the banana plugs with the proper TC connectors Thanks again...you definitely know your PID's.

Frozone does know his stuff.

A tc works by the principle that dissimilar metals connected to each other at a small point generate a very small voltage at that point (bead), and the voltage, expressed in millionths of a volt, is temperature dependent. Introducing connections made with a different type of metal along the way to the final destination (PID terminals) will likewise create voltages that conflict with what the tc bead generates. There's your banana plugs.

I had a similar experience-
http://castboolits.gunloads.com/show...ler-lie-to-you

[bpratl]

K-type TC confusion. Online data says that the color codes for K-type TC wire is that the white wire with red tracer is the negative wire and the white wire with the blue tracer is the Positive lead. Does this mean that the red wire goes to the - on the yellow panel connector and the blue wire to the + side or doesn't it matter? I know that if I reverse them on the PID you get bogus reading. It just does not seem right that the RED lead should go to the - on the panel connector. Please explain what is the best and proper way of using the yellow connectors as I am using three different pots with one PID.

[el34]

For type K, the blue marking is positive and the red is negative. There are several types of thermocouple, all (most?) use red to indicate the - side, the other color indicates the + side and what type it is.

http://www.omega.com/techref/colorcodes.html

Yeah, there's something unnatural of making red negative. Same in AC wiring where black is the hot one

[Frozone]

For type K, the blue marking is positive and the red is negative. ....

Other way around likely. BUT:
It depends on the country of origin. There are no international standards.

red+/blue- is one color code and is used on things from China ; yellow+/red- is another common one (USA code).

Same in AC wiring where black is the hot one

Well in Australia the colors are brown / blue / green. Easy way to remember what's hot is "If you touch brown, you're in the ground".

It makes sense in a way.
USA - "Black = widows weeds"

[bpratl]

Does the polarity on the yellow K-type TC panel connect matter as long as the correct polarity is on the PID?
My PID is working great and calibrates right on; but I'm curious and would like to know what is the proper way to wire the panel connector or can I ignore the + & - designators?

[Frozone]

Yes, it's made of the same metals as the wire that goes to it. That way it doesn't effect voltage.
No, you should Not ignore the polarity.

[bpratl]

Yes, it's made of the same metals as the wire that goes to it. That way it doesn't effect voltage.
No, you should Not ignore the polarity.

Thanks for clearing this up. In further checking I found that that wider male pin, on the yellow connector is magnetic as well as the blue tracer TC wire and the narrow pin and the red wire are not. I will double check to insure that my three TC cables are the same length and have the same polarity. Maybe I am a little anal; but the learning has been most interesting.

[Frozone]

It has to do with the way a Thermocouple works.

Any two differing metals in contact produce a dielectric voltage, the same as iron in sea water.
The exact voltage produced by the junction is dependent on the junction temperature.

A K type TC is made of 2 differing metals - chromel (90% nickel and 10% chromium) and alumel (95% nickel, 2% manganese, 2% aluminium and 1% silicon).

The 'positive' side is the chromel, but the voltages produced at the junctions are algebraically additive.
In other words a combo of C(hromel) and A(lumel) then a junction of A and C cancel each other out (assuming Both junctions are at exactly the same temp).
Add a third C/A junction and you get the voltage of the third junction as the reading.
That is why the reversed wiring in your controller didn't produce an error.
The junctions cancel each other out.
BUT, if the device gets warmer inside as it operates, the 2 junctions will no longer be at the same temp and you will start to see a 'drift' in calibration.

That is also why you can use a normal pinch type screw to join 2 sections of the same type of wire, the screw remains at a uniform temp.
The wire to screw voltage going in is exactly opposite the screw to wire voltage going out, for a net change of zero.

[el34]

I checked my K type that came with a connector attached, the white/red is indeed neg and the white/blue is ***. Looks Chinese by the packaging. The chart in the link of ANSI standards shows red is neg for all the types that have a red lead. But what the hey.

[kayak1]

I picked up some K panel connectors, and probe connectors. I was wondering where one can purchase K type wire to hook from the pid to the panel mount.

[Frozone]

just cut a piece off the TCs wire and use that.

[Frozone]

.... The chart in the link of ANSI standards shows red is neg for all the types that have a red lead. But what the hey.

Well since "ANSI standards" are USA ONLY, they likely wouldn't have Chinese codes. A(merican) N(ational) S(tandards) I(nstitute)

Have you considered that the thing may have been wired wrong from the factory?

As I said there are no true 'standards' in color code for K type TCs.

Here is a link to slightly more international chart.
Notice that 'most' ( the US being the Only exception) K type RED wires are positive.

[el34]

Well since "ANSI standards" are USA ONLY, they likely wouldn't have Chinese codes. A(merican) N(ational) S(tandards) I(nstitute)
Notice that 'most' ( the US being the Only exception) K type RED wires are positive.

I have 2 thermocouples, boh wired as I described, the one in use works.

The chart you found is good, I noticed all TC's aimed at the US markets use red neg while red *** is a standard for Germany and Japan. I guess it's a crapshoot.

Over and out.

[Frozone]

....The chart you found is good, I noticed all TC's aimed at the US markets use red neg while red *** is a standard for Germany and Japan......

Not 'AIMED' at but manufactured in or for.

If the TC was made by or for a US brand name (Omega for example) it will likely have ANSI colors no matter where it's made.
But, If you import from Brittan using a British wholesaler you get British codes.
Japan sends TCs with their colors.
IIRC Taiwan uses red/green.



how about a test?

Take the plug off and wire it up to your PID directly. double check what wire is really ***. BTW the neg wire is magnetic.
The connector could be on reversed and as long as it was reversed both plug and jack you might not notice much error.

Just curious,really, every China TC I've seen to date has red *** and blue neg.
Not that that matters China does what China wants.

[el34]

how about a test?

Take the plug off and wire it up to your PID directly. double check what wire is really ***.
The connector could be on reversed and as long as it was reversed both plug and jack you might not notice much error.

Just curious, every china TC I'v seen has red *** and blue neg

That's a good idea but I currently don't have enough interest left to dig back into my controller enclosure. When I first got my parts I hooked it all up on my kitchen counter as a sanity test. The TC's plug pins conveniently fit under the PID terminal screws and I went by the + and - markings on the plug. I put water in the pot and confirmed correct operation at 200F. That's pretty conclusive to me, there were no other TC connections involved.

Absolutely no doubt you've seen many TCs, the validity of my reports is only based on my 2 Chinese units, bought together, and a few J-types that I've dealt with at work.

[deoje]

I just finished my PID Box. I ended up putting it into an ammo box. I plan on putting together at least one more to use on my smoker.

Below are some really bad cell phone pictures. I'll probably post better picture later. These are the only ones I have with me at the time.

[el34]

I just finished my PID Box. I ended up putting it into an ammo box.

There's something fundamentally cool about that.
Is your SSR heatsinked to the box?

[deoje]

The SSR is attached to the heatsink and that is attached to the box. You can sort of see it in the last picture near the bottom of the photo.

[Beagle333]

Nice unit, deoje! I like it.

I don't care if mine ends up bigger than my Samsonite.
I want some room to work in there while building it, and I cast outdoors, so bench space is not even a consideration.

[Frozone]

I don't want to be picky but you have the 'clips' for the PID on backwards.
the 'loop' goes to the rear and the slotted part to the front.