Paragon FTL mystery

[Art By Iggy]

Hello all, 

I have an older Paragon TNF-82 with Sentry 2.0 controller.  I have been having issues for sometime reaching proper temperature and get an "FTL" code at around 1960 degrees.  After replacing elements, relays, still the same issue.  I thought that amps received from the power source could be an issue, so I replaced the old wiring, tightened connections and was able to get the kiln to 1984 degrees, but still not as hot as it should get.  I have another larger kiln that works fine from the same fuse box on a different circuit.  I have had the same issue with this Paragon kiln at multiple locations so I am skeptical about it being related to the power source itself.  I am perplexed at what the situation could be as I have gone through with multimeter and have also successfully worked on other kilns, diagnosing and fixing.  I am looking for suggestions, please.

[neilestrick]

Hi @Art By Iggy. Welcome to the forum!

Have you double checked the voltage of your electrical service?

What firing schedule are you using?

Have you replaced the thermocouple?

What size wiring did you run, and what size breaker is it on?

Are the power cord and plug in good condition? Does the plug get hot when firing?

[Art By Iggy]

Neil,

I have double voltage and it is 240V …I have another larger kiln working fine on the same service.  I have a custom slow fire schedule and it’s programmed to move at 140 degrees/hr.  I have not replaced the thermocouple .  The kiln is on a 40amp breaker and only needs 30 amps, I am not certain of the wire size but its the same as what is running to the larger kiln that fires to temp,  The kiln is wired directly into the box so no plug to look at.  How would thermocouple affect this situation?  

Thanks for your assistance, much appreciated!

 

[neilestrick]

20 hours ago, Art By Iggy said:

How would thermocouple affect this situation?  

Every decision the controller makes is based on information from the thermocouple. If it's not reading correctly then the firing can't progress normally. I would change it, it's cheap and easy.

Typically when kilns stall out at 1850-1950 degrees it's because an element is out or a relay has died or is sticking. I know you said you replaced the relays, but did you replace the wiring in the control box? If the power wires going into and out of the relays are worn then they can cause a relay to overheat and stick or fail. I've seen brand new relays die on their first firing due to the wiring.

[Art By Iggy]

Neil, 

I replaced the thermocouple today.  I have replaced the wires in the control box as they were pretty worn.  I will fire this kiln in a day or so and report back what the outcome is.  Thanks for lending your expertise to this situation, so much appreciation.

Iggy

[Bill Kielb]

On 3/3/2023 at 2:19 PM, Art By Iggy said:

After replacing elements, relays, still the same issue.  I thought that amps received from the power source could be an issue, so I replaced the old wiring, tightened connections and was able to get the kiln to 1984 degrees, but still not as hot as it should get.

Suggestion: if everything is in order for the next test fire, your FTL or firing too long error implies that the kiln was not able to make 27 degrees per hour rate which implies not enough thermal power. So if everything is in order and you can measure actual voltage AND amperage while it is running that will reveal if in fact it has the power designed. Excess voltage drop will show up when a circuit is loaded up and the amperage will tell just how much power the kiln is able to deliver.  Really good data to know but best known while operating.

It would be good to check the deviation temperature set TeDe - pg. 24, default is 100f. Thermocouple is set to match type: R,S,K… also record the total time taken. It typically will be approximately 8 - 12 hours.

and your final segment or last 200f of the firing is 100-108 f per hour to match the Orton cone chart. Many kilns, just make this rate at very top temperatures when new, so 140f for the last segment (last 200f) aligns more with a fast firing schedule than slow.

The last 200f is where the major reactions occur or there is enough energy for the flux, silica and alumina to melt. The last 200f - 250f is really the most important part from a predictable heatwork respect.

All those measurements should tell the story

Edited March 5, 2023 by Bill Kielb

[Art By Iggy]

Thank you Bill and Neil,

I ran the kiln again after replacing the thermocouple and slowing down the last segment of the program.  Deviation is set to default. It still only got to 1983 degrees.  When I checked the voltage it was 240V at all the elements.  I did notice that the amps dropped from 15 to about 12 once the firing was underway.  Not sure if this is normal.  This kiln was the only equipment running at the time.  I do not think it’s a problem with the power supply from the panel as I have another larger kiln that can operate fully with the same power source.  Any further ideas would be helpful and thanks for your time and expertise.

Iggy

[Bill Kielb]

At 12 amps@ 240 volts thats 2880 watts. Not likely  you can get very far with that amount of power. Is this kiln built for China paints and lowfire work? Can you post a picture of the equipment tag so we know just what this ought to be?

Just looking quickly at these models, even the tnf 82-2 is 30 amps, 7200 watts so it would need to be on a 40 amp breaker and appropriate wire. That would give it a total element resistance of about 8 ohms. Not sure the model I picked is yours though. Equipment tag ought to provide clarity.

 

Edited March 17, 2023 by Bill Kielb

[PeterH]

TNF-82 spec https://shop.clay-planet.com/Paragon-TNF-82.aspx
Wiring for TNF-82 https://eadn-wc04-7751283.nxedge.io/wp-content/uploads/wtnf82.pdf

I find it hard to see how it's only pulling 12 to 15A at full power. [With 240V measured across the elements and all elements conducting/glowing.]
 

R=1/2*(10+6)=8
V/R=240/8=30

[Dick White]

A completely off the wall idea - you are using a custom ramp-hold program. The controller memory can hold several custom ramp-hold programs. What happens if you program the same schedule into a different user number? Maybe there is a bad bit on the memory chip that is causing havoc? But using a different spot in the memory chip, the error will not occur? Or what happens when you do a plain cone-fire to cone 6 at medium speed? Does that drive the kiln past this 1975+/- error point? Just some more crazy ideas for a crazy issue that doesn't make logical sense...

[Bill Kielb]

Maybe 15 amps per element set? That would make more sense, then truly measuring 12 amps each that would indicate the elements heated - have risen from 16 ohms to 20 ohms per set. Accurate measurements would be key here as this is not enough power and points to worn elements. Bad contacts, bad connections still in play as well. I would start with an accurate measurement of cold elements. Each set should be 16 ohms. At 17.6 ohms they are considered worn so a decent meter is important.

[Art By Iggy]

Okay, the image below is of a Cone 04 that was in the kiln on the last firing.  The digital display said it fired to 1983 degrees but this cone seems to be hotter than that.  I did not have another guide cone other than a cone 5 in the kiln and that cone did not move at all.  I guess i should order some other pyrometric cones and test further.  I am thinking that the pyrometer needs to be calibrated or the offset adjusted, which i am unfamiliar with.  Any suggestions are welcome and thanks

[Art By Iggy]

I will post an image of the equipment tag and the other specs as well as measure and repost the electrical diagnostics.

thanks!!very helpful indeed

[Bill Kielb]

14 minutes ago, Art By Iggy said:

Okay, the image below is of a Cone 04 that was in the kiln on the last firing

Cone 04 Would generally be achieved by firing to 1945 and for the last 200 degrees of the firing, fired at a rate of 108 degrees per hour per the Orton chart. Now if the kiln failed to go 108 degrees per hour or at least reasonably close to that speed in the final 200 degrees then heatwork accumulates with time fired.

One of the tricks often used is to fire to a lower cone with a hold to get to the next cone without increasing temperature. So firing to cone 5 with a twenty minute hold often gets  6 cone to drop. The 20 minutes of additional time added to the heatwork and melted the cone 6 cone.

since you were firing at a very slow rate and likely for quite some time, your cone reflects that and likely is showing you that it fired beyond 04.

When elements wear out sufficiently and as it takes more time to fire, usually things begin to overfire due to accumulated heatwork or the extra time spent in the firing.

[Art By Iggy]

Bill, 

in response to your post, your specs on the TNF-82 are the same as the kiln i have-2300 degrees top temp and 30 AMP.  I have a 40 AMP breaker and am measuring 15 amps per Element set.

[neilestrick]

@Art By Iggy If it's only pulling 15 amps instead of 30 then half the kiln isn't working, that means you either have a dead relay or a dead element (wired in series, if one goes out they both do). Have you tested the elements for continuity? Have you confirmed that the relays are working? If you're not comfortable doing live tests inside the control box, then put a little piece of paper on each element and start the kiln and see if they smolder.

Where are you measuring the amperage draw- from the circuit box or in the kiln control box?

[Art By Iggy]

I will measure the OHMS and report the resistance  to see if  the elements are worn,  Last time i checked they were within range.  Very helpful and I SO appreciate your knowledge.  Thank you

 

[Bill Kielb]

26 minutes ago, Art By Iggy said:

Bill, 

in response to your post, your specs on the TNF-82 are the same as the kiln i have-2300 degrees top temp and 30 AMP.  I have a 40 AMP breaker and am measuring 15 amps per Element set.

If that spec is right, this kiln is specified for China paint and lowfire use so it may not make for many cone 6 firings before the elements need replacing. Neil is spot on though, you measured 15 amps for EACH element set or the kiln is drawing a solid 30 amps on each leg? Also, when heated, does it drop to 12 amps per element set as measured before?

 

 

Edited March 18, 2023 by Bill Kielb

[Art By Iggy]

Okay, 

After some time with the multi meter here is my report:

Element Resistance: Top-11.1. Ohms Middle-5.9 ohms Middle 5.9 ohms and Bottom 12.0 ohms

Amps (measured in kiln control box): 27.2 and 27.4  going into relay.  13.1 and 13 coming out of relay. Per element: Top-12.8 , Middle 13.1, Middle 13.2 and Bottom 12.5

Volts (per element)  : top 158.4, middle 82.5, middle 79.4, bottom 162.3

The elements were new in 2021 and even when new only got to 2050 degrees once.  

How can this kiln be rated to 2300 degrees and  not be able to consistently get to 2000 or hotter?

Of course i could get another kiln but I am reluctant as I feel like I would like to understand what I am failing to see on this one. 

Again, many thanks for all thought and input.

My next step will be to run a cone fire program and not a custom program as someone on the thread had mentioned.

 

Iggy

[neilestrick]

The top and bottom elements should be at 10 ohms, so they're 10% and 20% off. That could definitely account for the problem.

[Bill Kielb]

I agree with Neil, lots of your measurements add up perfectly but the amperage doesn’t lie. So at 27.4 amps best case at 240 volts solid - it is 6576 watts. This kiln needs 7200 watts to just make cone 6 a hand full of times in new condition. So, the only conclusion can be: while hot, the element resistance goes up a bunch leaving not enough power to make temp.  I added a drawing below detailing where I would make measurements. The key - 30 amps going back to the panel. You don’t have it, you have 10% less, you won’t make temperature that way. 2021 is a bit of time, all firings wear the elements a bit, especially the high temperatures, so the elements ought to be worn by now.

As far as ratings go, I wish they designed kilns with more spare power but maybe think of it as you have a car, absolute best case, the engine at its very highest RPM can just get you to 140 MPH. Top speed is officially 140 MPH! How many times do you think you can do that without damaging the engine? It’s just not designed for sustained service there.

 

Edited March 23, 2023 by Bill Kielb

[Art By Iggy]

Gentlemen, 

I cannot praise and thank you enough for helping my overall understanding of the entire electrical operations and details of this kiln, wonderfully helpful!!! Very interesting to see how the math comes into play on all these numbers and readings.

 

 Is there a reason that the other Skutt I have reaches higher temps more consistently then this Paragon?  More life left on the elements? 

The Paragon kiln I use primarily for bisque and I have a longer soak at 200 degrees- I imagine that this is putting extra wear on the elements and making it difficult to reach higher temps when I decide to do so.

Both have a max temp of 2300 but I have had no trouble getting the Skutt to temp.  I attached the specs on it:  

This has been very educational 

[neilestrick]

Element life should be similar between the two, but if the Paragon elements are worn then it can't get to temp. The Skutt elements are probably still in good condition. The soak at the low end will have little effect on element life.