Any problems with Skutt APM elements purchased after July 2022?

[Lilith Rockett]

Has anyone had problems with their APM elements purchased after the supply chain shortage and being available again in July 2022? I use zone control and my center elements do not seem to be able to keep up, so the kiln continually stalls out, usually without an error code. Even in single zone the center section of my 1231 pk fires cooler than the top and bottom.  I've replaced every part of the kiln and the problem still exists, so I am left only with the elements as the problem. The kiln worked fine for a decade, until this last element change. As I said, everything has been changed except the elements. Has anyone experienced anything like this? Any anomalies at all after an element change, whether single zone or zone control?  I have spent 18 months troubleshooting this problem, and this is the last thing I can change. 

[Min]

Hi Lilith and welcome to the forum.

Have you measured the resistance of the element(s) to see how much they have degraded since new? Any chance you measured the resistance of all the elements before you installed them?Do you have specs on APM elements for the 1231PK when new? 

 

 

[PeterH]

What is your kiln make/model.

Are the element resistances consistent with those  in the kiln diagram.

... oops if it is a KM-1231PK the wiring diagram doesn't have resistances on it.
https://skutt.com/images/KM1231PK-1PH-and-3PH.pdf

This gives the resistances of the (normal?) elements
https://www.armadilloclay.com/uploads/5/1/2/8/51288343/element_resistence.pdf
... but only gives 6 figures, while I believe that the KM-1231PK has 7 elements.

https://community.ceramicartsdaily.org/topic/23960-a-few-questions-about-replacing-elements/?do=findComment&comment=194119
I order Skutt elements almost weekly. With modern kilns, the top/bottom elements are one for the top and one for the bottom. Always, for 27" and shorter kilns. The center elements make up the rest, whether that's 2, 3, or 4. The only exception are the KM1231PK models, which have 7 elements- 2 T/B, 2 intermediate, and 3 center.

[neilestrick]

Sounds like maybe the elements aren't in the proper locations in the kiln. Like Peter said, there are 3 different elements in that kiln, and if they're in the wrong positions the kiln won't fire evenly. Check the element resistance of each section of the kiln. I don't know if your kiln is 240V or 208V so here's both:

1231PK 208V  Top 6.7  Mid 8.5  Bottom 6.7

1231PK 240V  Top 8.9  Mid 11.3  Bottom 8.9

If the resistance measurements in your kiln are not correct, then you've either got the wrong elements or the right elements but in the wrong place. Depending on the condition of the elements, you may be able to pull them out and put them in the correct locations. That would definitely be preferable to buying a new set, given the price of APMs. If you find they are in the wrong locations, you should be able to determine which go where based on the resistance readings of the individual elements.

[Bill Kielb]

7 hours ago, neilestrick said:

1231PK 208V  Top 6.7  Mid 8.5  Bottom 6.7

1231PK 240V  Top 8.9  Mid 11.3  Bottom 8.9

This is interesting in the design of top and bottom elements  are prox 6400 watts and the center is prox 5000 watts (as expected, most loss at top and bottom and they assist the center) but the experience is the center is not firing as hot.  I wonder if the zones are out of sequence with the thermocouples, board connections or even the relay wiring. In addition to resistance I think I would make sure the zone sequencing is absolutely correct.  IE zone 1 tc = zone 1 = zone 1 relay and elements. Cross firing (or a really really bad center element)  is a potential reason that would explain the center to be cooler. Very odd! Positionally it would be hard to mix these up and get the current result.

Edited December 10, 2023 by Bill Kielb

[neilestrick]

1 hour ago, Bill Kielb said:

This is interesting in the design of top and bottom elements  are prox 6400 watts and the center is prox 5000 watts (as expected, most loss at top and bottom and they assist the center) but the experience is the center is not firing as hot.  I wonder if the zones are out of sequence with the thermocouples, board connections or even the relay wiring. In addition to resistance I think I would make sure the zone sequencing is absolutely correct.  IE zone 1 tc = zone 1 = zone 1 relay and elements. Cross firing (or a really really bad center element)  is a potential reason that would explain the center to be cooler. Very odd! Positionally it would be hard to mix these up and get the current result.

If the zones were not connected to the correct thermocouples it would error out right near the beginning of the firing.

I totally had that backwards in my head, thought the center was firing hot! My bad.

I'd still check the resistance, though and make sure you've got the correct elements. Also make sure a center element hasn't burned out.

[Lilith Rockett]

On 12/10/2023 at 3:21 PM, neilestrick said:

If the zones were not connected to the correct thermocouples it would error out right near the beginning of the firing.

I totally had that backwards in my head, thought the center was firing hot! My bad.

I'd still check the resistance, though and make sure you've got the correct elements. Also make sure a center element hasn't burned out.

On 12/9/2023 at 12:20 PM, Min said:

Hi Lilith and welcome to the forum.

Have you measured the resistance of the element(s) to see how much they have degraded since new? Any chance you measured the resistance of all the elements before you installed them?Do you have specs on APM elements for the 1231PK when new? 

 

 

 

[Lilith Rockett]

Thanks for your responses. I have a Skutt 1231 PK single phase, 240v, with type S thermocouples and APM elements.  In single zone it will complete a firing, but it is a half cone difference, cooler in mid section, and fires too hot. (I know I can do an offset.)  In zone control it is inconsistent and mostly stalls without an error code. It will fire to anywhere from 1530 -2050, stay for an unlimited time and never get any hotter, with up to an 80 degree difference between T2 and the top and bottom. The output for T2 locks on at 100 very early in the firing, sometimes around 300, and stays there the entire time without making much difference. T2 lags from 20-80 degrees. It has been looked over by 2 difference techs and Jim Skutt and I sent the logs to the engineer, and no one knows why this is happening.  It all looks fine. The kiln worked fine for a decade and then this started after the last element change. Almost every part of the kiln has been changed out, and now finally I even have a whole new box on it to try to eliminate the issue.  Sadly it made no difference. The only thing that hasn't changed is T3, but it has been tested in all positions , and the same thing happens, so it mustn't be that. The only thing I can think of is that there is some anomaly in the alloy that the elements are made of. They are from the batch that came after the supply chain shortage. The resistance is normal, so no one has believed it could be a problem. That is why I am reaching out here to see if anyone has heard of anything like this. There is a second 1231 PK right next to it running fine, so it is also not the building. Is there anything I might be overlooking? It has also had 3 controllers, and I download the logs from every firing to try to find the anomalies and see if I can detect how they are triggered. I hope someone out there can help! Thanks!

[Bill Kielb]

I think it’s possible the zoning might not match which would act very strange unless in single zone. So can we be absolutely certain  the relays are wired in zone sequence? High voltage (element) wiring to the relays but also the relay control wiring to the controller. I have on occasion seen these switched after a rebuild. Just switching 2 could create an issue. Also I do not see a type S option for thermocouples, so maybe so but worth checking.. If you have K and it’s programmed for S or even vice versa, this would lead to very odd firings. It’s super important all these match, meaning the software programming and if a jumper is present they all match the actual  type. What color are the extension leads that attach to the control board? Type S most often black and red, type k most often yellow and red. Can you post a picture of the thermocouples and maybe several context photos of the kiln open with the wiring going to the control and elements. Maybe more eyes on it will spot the issue. Finally, what do the elements measure in ohms as exact as you can measure. A different alloy will very likely show up in this measurement but the measurement needs to be reasonably accurate and confirmed.

Edited December 12, 2023 by Bill Kielb

[Jeff Longtin]

Good Morning Lilith.

To answer your question: Yes, I've been there before. For nine years I worked at a pottery shop with 18 1231PK's. Ten were dedicated glaze and eight were dedicated bisque. As a majority of the crew were inexperienced young people it fell to me to figure out "why the kiln isn't working".

We had one glaze kiln like yours. Changed out the elements, changed out the touchpad, maybe replaced a relay or two. Replaced the thermocouples. Seemingly everything. (At Perry's suggestion.) 

For some reason could not get that kiln to glaze temps regularly. We moved it over to the bisque kilns but even then it continued to fire inconsistently. (But as a bisque kiln the inconsistencies weren't as dire.) 

It sounds like you know what you're doing but I'll mention the simple things that were often a cause for problems at the pottery shop:  when you have a 1227 sitting next to a 1231 its easy for employees to mix up the elements sequence. We'd shoot for 28-22-28 amp sequence. If the amps ever went over 28 I knew someone probably put a "Top/Bottom" element where "Intermediate" should go. 

The crew liked to pack the glaze kilns tightly. Sometimes I'd see a pot, or a kiln shelf, resting against the thermocouple.

Because the kilns were packed tightly sometimes bits a glaze would pop off and land on an element. At high temp these bits would burn through the element and cause a failure. Sometimes folks would replace elements without removing the glaze bit. (Which usually melts into the element groove.) I would have people carve out the melted glaze so that nothing would interfere with the element when it got hot.

These are just a few thoughts to get you thinking in a different direction. Sometimes a kiln problem is really obvious and sometimes not.

Good Luck!

 

 

[neilestrick]

9 hours ago, Lilith Rockett said:

Almost every part of the kiln has been changed out, and now finally I even have a whole new box on it to try to eliminate the issue.  Sadly it made no difference.

Including a new controller and relays?

Have you put a meter on the elements while the kiln is firing to verify that they're getting power? Checked voltage and amperage draw of the middle section under power?

S and K type thermocouples being wrong should result in much bigger issues than this. Thermocouples being connect to the wrong sections should result in a pretty quick error, as the sections will heat much too quickly.

[PeterH]

Rightly lots of talk about measuring resistances, voltages and currents with a meter, but doesn't this kiln have current sensing technology?

https://skutt.com/products-page/ceramic-kilns/km-1231pk/

What does this say about the power going into each section at full blast?

And I suspect that it should be pretty easy to eyeball that the current sensors are reading from the right elements.

[Bill Kielb]

6 hours ago, PeterH said:

And I suspect that it should be pretty easy to eyeball that the current sensors are reading from the right elements.

Yep - I think any readings and even pictures would help here.

[neilestrick]

@Lilith Rockett Have you had the service wiring checked out? I had a customer once where everything on the kiln checked out just fine- element resistance was dead on, thermocouples and relays were new, etc, but it kept erroring out at higher temps. Turns out the outlet and power cord were heating up and affect the draw once the kiln had been running for several hours and getting up to higher temps. Also, that kiln was kinda buggy from the beginning and really burned up relays fast, so we isolated the controller from the main power with its own 120 volt plug, and that fixed the bugginess.

[PeterH]

On 12/12/2023 at 6:34 AM, Lilith Rockett said:

The kiln worked fine for a decade and then this started after the last element change.

>I use zone control and my center elements do not seem to be able to keep up, so the kiln continually stalls out, usually without an error code.
>Even in single zone the center section of my 1231 pk fires cooler than the top and bottom. 

The single-zone result is surprising, as presumably the different element resistances in the top/bottom & centre sections are designed to avoid/reduce temperature differences between sections.  [Presumably with caveats about extreme differences in the loading of the sections.]

So checking that the various sections are drawing their design power when the kiln is running "flat-out"  seems a good first step. The current sensing technology provides a per-section current  measurement, and an eyeball check can confirm that the current-sensing loops are indeed round the wires going to the appropriate elements.

What currents do you get for the three sections?

Edited December 13, 2023 by PeterH

[Lilith Rockett]

On 12/12/2023 at 4:46 AM, Jeff Longtin said:

Good Morning Lilith.

To answer your question: Yes, I've been there before. For nine years I worked at a pottery shop with 18 1231PK's. Ten were dedicated glaze and eight were dedicated bisque. As a majority of the crew were inexperienced young people it fell to me to figure out "why the kiln isn't working".

We had one glaze kiln like yours. Changed out the elements, changed out the touchpad, maybe replaced a relay or two. Replaced the thermocouples. Seemingly everything. (At Perry's suggestion.) 

For some reason could not get that kiln to glaze temps regularly. We moved it over to the bisque kilns but even then it continued to fire inconsistently. (But as a bisque kiln the inconsistencies weren't as dire.) 

It sounds like you know what you're doing but I'll mention the simple things that were often a cause for problems at the pottery shop:  when you have a 1227 sitting next to a 1231 its easy for employees to mix up the elements sequence. We'd shoot for 28-22-28 amp sequence. If the amps ever went over 28 I knew someone probably put a "Top/Bottom" element where "Intermediate" should go. 

The crew liked to pack the glaze kilns tightly. Sometimes I'd see a pot, or a kiln shelf, resting against the thermocouple.

Because the kilns were packed tightly sometimes bits a glaze would pop off and land on an element. At high temp these bits would burn through the element and cause a failure. Sometimes folks would replace elements without removing the glaze bit. (Which usually melts into the element groove.) I would have people carve out the melted glaze so that nothing would interfere with the element when it got hot.

These are just a few thoughts to get you thinking in a different direction. Sometimes a kiln problem is really obvious and sometimes not.

Good Luck!

 

 

I've been working with Perry on this for 18 months now. I have changed out the controller 2x, changed out the relays, the thermocouples, the thermocouple wires inside the box and outside, the terminal strip, and now finally I have a brand new box on the kiln, essentially making it a new kiln, with the new bus bars and wires and solid state relays. I kept the touchpad controller so I can download the logs to analyze. The wiring from the box to the wall is new as well. the elements appear to be fine. I run manual diagnostics each firing to be sure. I tested the voltage while the kiln was firing every 15 minutes for a while to be sure I caught everything. (that was a little scary) Perry finds it hard to believe it could be the elements, but we may change out the center elements next to see if that does the trick. It is truly mysterious. We assumed the new box would solve the problem. No one can figure out the problem. Bartlett continues to think it's a thermocouple, but the unchanged T3 has been moved to each position with the same problem occurring.  I do not usually get an error code, The kiln usually just starts lagging at T2 and eventually the kiln stays at some temp (usually 1500-2000) that it can't get past for hours until I shut it down. It will stall on both bisque or glaze firings. Also the outs at T2 go to 100 very early, around 300-400 and stay there for the duration. So even with the center section giving full 240v the whole time it does not keep up with the top and bottom. Everything is clean. The load is a consistent simulated load of kiln furniture every time. The cones are placed about 4 inches from the thermocouples and nothing else is interfering with them. Both Jim Skutt and Perry Peterson have gone over the kiln for hours and found nothing. That is why I am out here crowdsourcing, in case this anomaly has appeared somewhere else. There really is little else to change beside the elements, even if it seems impossible that they are the problem. It is a very confusing and frustrating situation. 

Any thoughts?  and Thanks for thinking through this with me!

[Bill Kielb]

2 hours ago, Lilith Rockett said:

Any thoughts?  and Thanks for thinking through this with me!

Without pictures, real measurements, response to all that’s been asked above, I think this will be difficult to solve.

[PeterH]

4 hours ago, Lilith Rockett said:

There really is little else to change beside the elements, even if it seems impossible that they are the problem.

If the only fault is the elements -- and they are run at the correct voltage -- surely they must be drawing the wrong currents. That's all an element does, turn electricity into heat.

So using current-sensing to measure the per-section currents when at full blast gives an end-to-end test of the elements. (Providing that the current sensing is wired correctly.)

If the elements -- when fully powered -- are meeting the design specification for power output, then it looks like their duty-cycles aren't correct for at least part of the firing.  

PS Question for the experts.  Do the solid-state relays switch at a sufficiently high frequency for the current sensing to accurately measure the time-averaged current?

[Bill Kielb]

6 hours ago, PeterH said:

PS Question for the experts.  Do the solid-state relays switch at a sufficiently high frequency for the current sensing to accurately measure the time-averaged current

Yes I believe they will be just fine. They are zero crossing so the fastest they can be commanded off or on will need to wait for zero crossing. I think the default for typical heating  controllers would be approximately 200 milliseconds  ( so 2 seconds, something on that order). The default typical fastest for kiln relays (if my memory serves) approximately 10 seconds.  Measuring the amperage of a resistance load by ct ought to be fine especially at maximum output.  I think your idea is fine and reveals the heated resistance as well,  I am a sequential troubleshooter so any data with integrity  is helpful to me. Not everyone troubleshoots in the same way though.

aTo your other point about duty cycles, yes …….. and the controller generally is set to compensate or even things out using the top or bottom element to help the middle. That the kiln actually stalls is very interesting to me. It has potentially symptoms of several faults, yet everything has tested good. My take, I need to know some real values, thermocouple type, wiring sequence ….. something is wrong but without real confirmation I cannot speculate.

Edited December 15, 2023 by Bill Kielb

[neilestrick]

8 hours ago, PeterH said:

PS Question for the experts.  Do the solid-state relays switch at a sufficiently high frequency for the current sensing to accurately measure the time-averaged current?

The controller cycles the SSR's twice per second (500ms). When I put a meter on mine it gives a fluttery reading.

@Lilith Rockett This is a long shot, but 3 times in the last 20 years I had kilns similar in size to yours have a very strange stalling problem. It turned out to be an electrical interference issue (there are a lot of magnetic fields and whatnot created by the elements and bricks), and the solution was to make sure the controller was directly grounded, not just through the transformer. It's an easy fix and worth trying if yours isn't already grounded that way. Take a look at the backside of your controller, there needs to be a wire that goes directly from the Center Tap terminal to the grounding stud. Not to the transformer or anywhere else first. You may need to get a terminal doubler so you can add another wire.

[Bill Kielb]

1 hour ago, neilestrick said:

The controller cycles the SSR's twice per second (500ms). When I put a meter on mine it gives a fluttery reading.

Good catch & bad math interesting, does this fire 30 cy on and 30 cy off at 100% output?

[neilestrick]

46 minutes ago, Bill Kielb said:

Good catch & bad math interesting, does this fire 30 cy on and 30 cy off at 100% output?

I think it just stays full on at 100%. I haven't really tested that, though. I just assumed there was no reason for it to cycle at 100%.

I should have said 'up to' 500ms. It's cool to listen to it cycle. If you get up close to the kiln you can hear it like a steady drumbeat hum.

[Lilith Rockett]

I apologize if I am not communicating properly here. I do not understand the + QUOTE box. Am I to respond there or here? I don't mean to make this more confusing than it already is. 

I have a Skutt KM-1231PK. 240v, single phase, cone 10, Type S thermocouples, APM elements.

After replacing almost everything, and having several techs look at it, I now have a brand new box on it and new bus bars. The same thing happened in the next test (zone control cone 9 med)-  it stalled at 2050 for 7+ hours. The t2 outs were at 100 from 400 degrees on and still could not keep up. There was up to an 80 degree difference between t2 and t1/t3, but no error code. The next test (not a test really but a single zone bisque I attempted) fired about 2 to 3 cones too hot. After that Perry gave me 2 more thermocouples and wires to change out t2 and t3. T3 was the only thing not yet changed. He thought it was a t2 problem, although that was a new thermocouple we had replaced before. Now absolutely everything on the kiln has been changed except for the elements. I am running another test now. I ran the manual diagnostics from the controller prior to starting. The amps are 28-23-28.

There are many things that people have mentioned or suggested as possible problems that are beyond my technical understanding of how things are working. I have a more general understanding of the way it works and am mechanically adept enough to change out all the parts and troubleshoot the problem. But currents and duty cycles are not something I am familiar with. I can tell you that everything is new now. And that it worked fine for a decade until that last element change. Since then it has not worked. It has boggled the minds of everyone at Skutt, which is why I am reaching out to a wider audience. Perry absolutely does not think it could be the elements, but if everything else has been changed, what else could it be?

 

On 12/15/2023 at 3:53 AM, PeterH said:

f the only fault is the elements -- and they are run at the correct voltage -- surely they must be drawing the wrong currents. That's all an element does, turn electricity into heat.

So using current-sensing to measure the per-section currents when at full blast gives an end-to-end test of the elements. (Providing that the current sensing is wired correctly.)

If the elements -- when fully powered -- are meeting the design specification for power output, then it looks like their duty-cycles aren't correct for at least part of the firing.  

I will take this to Perry tomorrow and see what he says.  Plus, I'll know by tomorrow if the kiln stalls tonight.  

I'm not sure what more information to give you. I am willing to do any other tests, but would need to be told what and how. I have not tested the amps during a firing. only the voltage.

[Bill Kielb]

3 hours ago, Lilith Rockett said:

I'm not sure what more information to give you. I am willing to do any other tests, but would need to be told what and how. I have not tested the amps during a firing. only the voltage.

For me I would initially be interested in the following:

• a context picture of your control board showing the connections to it , maybe from about two to three feet away so we can see the connections and the wires leading away
• a context picture of the element connections showing them and the wire that leads to the relays
• post the element resistance if you can measure them, if not can someone measure them for you so you can post here? So top elements measured resistance =______ ohms, middle section measured resistance = ____ ohms, bottom section measured resistance = ______ ohms.
• post a picture of the thermocouple itself and the wires leading to where it connects and tell us why you believe it is a type S

If you hit the little  + quote  below this message and post the items named above it will be a  direct response to this message

Edited December 19, 2023 by Bill Kielb

[PeterH]

3 hours ago, Lilith Rockett said:

Perry absolutely does not think it could be the elements, but if everything else has been changed, what else could it be?

I would take a very careful look at Neil's suggestion.

On 12/15/2023 at 8:40 PM, neilestrick said:

This is a long shot, but 3 times in the last 20 years I had kilns similar in size to yours have a very strange stalling problem. It turned out to be an electrical interference issue (there are a lot of magnetic fields and whatnot created by the elements and bricks), and the solution was to make sure the controller was directly grounded, not just through the transformer. It's an easy fix and worth trying if yours isn't already grounded that way. Take a look at the backside of your controller, there needs to be a wire that goes directly from the Center Tap terminal to the grounding stud. Not to the transformer or anywhere else first. You may need to get a terminal doubler so you can add another wire.

A very plausible cause of baffling problems, and you can check if it's causing your problems with a very simple wiring change.

As Neil says it's a long shot, but if electrical interference is the cause it's going to be practically impossible  to identify by normal diagnostic procedures.

To me trying his suggested fix is a no-brainer, the cost/potential-benefit is so one-sided.

... but I'd continue exploring other options in case it doesn't work out.