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Old 10-16-2019, 12:21 PM
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Thermocouple extension wire

I need some help / information about using thermocouple extension wire. I'm converting an old Arrow Springs AF99 annealing - fusing kiln from analog control to digital. I'll be using it for a pickup kiln in the production of paperweights. I've wired up a box with a PID controller and SSR. Given the space available in my studio I'd like to position the controller about 6-9 feet away from the kiln. I confirmed with Craig at Arrow Springs that the kiln used a type K thermocouple. I purchased type K thermocouple extension wire and wired up a plug to mate it to the thermocouple itself. Strange thing is that now the kiln won't go above 750F (measured by my non-contact thermometer) even when the controller is set to 950F and reads 950F. It stopped at the same 750F when the controller was set to 850F. I've had this kiln up to 1200F on the analog control so that's not the issue.

Any ideas, observations, thoughts or questions are welcome. Insults accepted as warranted by the facts.

Thanks in advance!
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Old 10-16-2019, 12:30 PM
Rick Kellner Rick Kellner is offline
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Have you delved into the parameters and settings in the controller?

I had one I hadn't used in about five years, and went to put it into service for a different application. Couldn't figure out what why it wouldn't go above about 965f. Then I poked around in the settings, and realized that I had previously programmed in some overtemp safety settings, to not exceed that temperature level.

A few quick parameter changes later, and I was able to ramp it up to higher temps.
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Old 10-16-2019, 12:32 PM
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Quote:
Originally Posted by Rick Kellner View Post
Have you delved into the parameters and settings in the controller?

I had one I hadn't used in about five years, and went to put it into service for a different application. Couldn't figure out what why it wouldn't go above about 965f. Then I poked around in the settings, and realized that I had previously programmed in some overtemp safety settings, to not exceed that temperature level.

A few quick parameter changes later, and I was able to ramp it up to higher temps.
Did that. It arrived with a max temp setting of 400F. Set it to 1050.
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Old 10-16-2019, 12:40 PM
Rick Kellner Rick Kellner is offline
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How did you terminate your extension wire? Raw wire, or with spade terminals, etc? They make special versions of the appropriate alumel and other alloys for various thermocouple types, but I still can't imagine this level of variance in temperature detection from a wonky terminal of the wrong metal.

Is your extension wire solid, or stranded? Have you verified a secure connection to controller terminals, and to the TC itself?

Somehow this still strikes me as a possible controller related issue...
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Old 10-16-2019, 12:44 PM
Rick Kellner Rick Kellner is offline
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The color coding on the thermocouple wire + and - is sort of counter intuitive. Any possibility of the polarity of the device not being wired correctly?
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Old 10-16-2019, 12:48 PM
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Quote:
Originally Posted by Rick Kellner View Post
The color coding on the thermocouple wire + and - is sort of counter intuitive. Any possibility of the polarity of the device not being wired correctly?
Had it reversed on first assembly. But that just makes it read negative numbers, not stop the heating process.
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Old 10-16-2019, 03:16 PM
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Quote:
Originally Posted by Rick Kellner View Post
How did you terminate your extension wire? Raw wire, or with spade terminals, etc? They make special versions of the appropriate alumel and other alloys for various thermocouple types, but I still can't imagine this level of variance in temperature detection from a wonky terminal of the wrong metal.

Is your extension wire solid, or stranded? Have you verified a secure connection to controller terminals, and to the TC itself?

Somehow this still strikes me as a possible controller related issue...
Extension wire is solid wire. Thermocouple is connected to the extension wire with a male/female thermocouple connector for type K wire (it's yellow). Connection to the PID is bare wire.

Connections are tight.
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