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-   -   Temp Fluctuations (http://talk.craftweb.com/showthread.php?t=12671)

Mark Rendulic 09-15-2020 11:34 AM

Temp Fluctuations
 
I am having some trouble with my Denver EF200 furnace. It has a Bartlett RTC-1000 control. The temperature readout drops 15 deg. F when the power to the elements comes on. It is very consistent.
I checked to see if the thermocouple extension wire was running close to a coil or high power line, but it is not.
Any ideas?

Thanks!

Art Freas 09-15-2020 12:00 PM

Is this a new behavior? Have you updated the firmware recently? Can you update it? I see this when I start a ramp down on my Bartlett genesis controller.

Shawn Everette 09-15-2020 12:19 PM

Is this a actual temp reduction, or just on the readout? I've had issues before with old elements at high temps sending out signal "interference" on GB sending units.

Mark Rendulic 09-15-2020 02:09 PM

I was having problems with the control not reading the thermocouple correctly. I was getting thermocouple errors so I sent the control back to Bartlett and they repaired it. (it was under warranty. Only 18 months old) While it was there they tested it, and returned it (2 weeks ago). While they had it, they deleted my programs and settings. I don't know where all of the settings were because Denver set them.
Anyway I have been watching it closely because of the previous problems so I do not know if this is a new "bonus" feature or if it has been there all of the time.
I'm thinking shielded thermocouple extension wire perhaps?

Shawn Everette 09-15-2020 02:32 PM

If there's power to the coil and it's "sensing" a temp drop that's not actually occurring, then it could be interference that shielding the wire could fix. If the coil is losing power and there's an actual drop then that won't do anything, then something is probably still wrong with the controller, but that could just possibly be changing a parameter that determines how fast it reacts to a temperature drop.

Mark Rendulic 09-15-2020 02:54 PM

The readout drops 15 deg. almost instantly when the power comes on. Then it rises instantly when the power shuts off. This can't be actual temperature. It has to be misreading the thermocouple.

Does anybody have a source for shielded thermocouple extension wire?

Shawn Everette 09-15-2020 04:54 PM

The stuff wet dog uses is supposed to be shielded. You using type R? Alternatively you can try flexible conduit.

Mark Rendulic 09-16-2020 08:52 AM

Yes it is an R Type.
It is in flex up to the control box, but it is not in flex inside the box. I think that is where it is picking up the noise as it passes by the mercury switches.

Shawn Everette 09-16-2020 11:18 AM

That'd do it. Like I said, wet dog has some type r shielded wire with a ground. Don't know where they get it, but they might sell you some. Omega looks like they have some, but they want to sell you the whole roll.

George Vidas 09-16-2020 11:43 AM

From what I'm hearing of the situation -- a short run inside the control panel is near some electromagnetic components -- I imagine that it would be a lot cheaper and easier to just slip shielding over the wire there, instead of replacing the whole run.

https://www.mcmaster.com/wire-shield...able-sleeving/

Shawn Everette 09-16-2020 12:07 PM

This. Hadn't seen that stuff before. Might have to try it on the kiln that's giving me issues.

The normal conduit would have probably been to stiff for a tight box.

Mark Rendulic 09-16-2020 12:14 PM

You are correct. Short run inside control box
I like that idea! I've never seen that!
Hmm. I'm going to try that first.
I like simple solutions to complex problems!

Richard Huntrods 09-16-2020 12:53 PM

As a quick diagnostic test, you could wrap tinfoil around the wires inside the controller -IF- you shut of the power first and can be certain the tinfoil would be nowhere near any source of live power (i.e. screw contacts for 120/220 v).

If the deviation is less with the tinfoil, then you would have some evidence that a proper shield on those wires would help/solve the problem. If there's no effect at all, then it might be something else.

Mark Rendulic 09-21-2020 12:04 PM

I purchased some extension wire from Wet Dog. It was actually less expensive than the copper shielding because Wet Dog did not have a minimum purchase. It's nice because it is 20ga shielded instead of 22ga unshielded which is what came with the furnace. Can't go wrong!
I will let you know if the problem goes away.

Mark Rendulic 09-29-2020 03:19 PM

The 20 ga thermocouple wire seems to have done the trick. I don't know if it was because of the heavier gage or something else, but the temp holds when the elements turn on and off now.
Thanks for the help!

Pete VanderLaan 09-29-2020 05:05 PM

I always loved Steve Smyers description of studio problems. He said "Then every thing breaks. You do this, you do that, you try everything for weeks and then the problem goes away by itself."

True dat.

Mark Rendulic 09-30-2020 04:12 PM

My philosophy:
What goes away by itself comes back by itself.

This rarely lets me down.

Pete VanderLaan 09-30-2020 05:10 PM

true dat, except for virginity.

Jordan Kube 10-06-2020 11:19 PM

Quote:

Originally Posted by Mark Rendulic (Post 148975)
My philosophy:
What goes away by itself comes back by itself.

This rarely lets me down.

This should be included in the dictionary definition of "Transient Electrical Problems" as a warning.


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