[Any problems with Skutt APM elements purchased after July 2022?]

9 hours ago, Bill Kielb said:

Thanks for the pictures, will just scan and see if I notice something, but they look pretty good. The sequence single zone anomaly and kiln stall could be tc related so that would be great if it works fine now. One thing I may have noticed in the picture goes to the wires that feed the kiln. I would expect this kiln to be on a 90 amp breaker and likely #3 wire run to it. It’s really hard to tell from the picture but the liquidtight flexible conduit appears to be 3/4” to which only one #3 wire would fit by code. I think it’s worth checking what size are these wires (are they under sized) , if undersized they could heat up significantly while running and potentially cause mysterious operation.  I think it’s worth checking the main feeds are #3 or greater, and the flexible conduit is at least one inch (needed to cool them) and any temperature measurement that can be made from the kiln to the breaker, including the breaker with a non contact thermometer while this kiln is in operation could reveal these are at issue. Hard to Judge from a picture though, but worth double checking I think.

Since this is a production kiln (pk), Skutt has designed this for 75c wire, so while a very obscure thing, it also has bearing on the rating of the wire and breaker terminals. If you can read the wiring labeling somewhere along the way it would be good to know it’s temperature rating as well a wire guage. 

I think the wiring is correct, correct gauge, also conduit and 100 amp circuit, all of it has been checked by Skutt techs, and the wiring from the box is how it comes from Skutt.  It has worked fine for a decade like this as well and there is another 1231 next to it with no problems. Also, no heat on the wire or circuit during firing.

The 3rd test is firing right now and is on target. The second test came out perfect like the first. It seems like it may be fixed, but still pretty mysterious as the thermocouples had already been changed and checked several times. But the goal is a functioning kiln, so I'll be happy with that. I'm bringing the replaced thermocouples and wires to Perry to have checked at Skutt. It will truly be baffling if they find nothing wrong with them. I'll just be happy to be able to fire work in the kiln rather than simulated loads and tests.  It's been an expensive and time consuming 18 months for both me and Skutt. Thanks for thinking through this with me.

[Any problems with Skutt APM elements purchased after July 2022?]

8 hours ago, neilestrick said:

@Lilith Rockett did you check for the grounding wire? It should go from the Center Tap terminal on the circuit board to a grounding stud in the control box.

Yes, grounded.

[Any problems with Skutt APM elements purchased after July 2022?]

17 hours ago, PeterH said:

Help, I'm having trouble understanding these figures.

Problem 1.
28+23+28=79Aamps, but the 240V kiln seems to be rated at 60amps.
https://www.sheffield-pottery.com/SKUTT-KM1231-3PK-240V-1PH-p/skkm12313pk.htm

... note that 79/sqrt(2)=55.9, so it might be interesting to know if the current sensor is reading RMS or not.

Problem 2
Currents of 28+23+28 indicate that the centre section has a higher resistance than the end sections.

But the ends seem to have 2x 8.9ohm elements in parallel, and the centre 3x 11.3 ohm elements in parallel.
https://skutt.com/images/KM1231PK-1PH-and-3PH.pdf
https://www.armadilloclay.com/uploads/5/1/2/8/51288343/element_resistence.pdf

So, ends should be 8.9/2=4.45ohms & the centre=11.3/3=3.76...ohms.
... where the  centre has a lower resistance than the ends
... and the currents are very high at 240*2/8.9=53.9amps, 240*3/11.3=63.7amps and 240*2/8.9=53.9amps compared to 28-23-28.

Perry has confirmed that the amps are as they should be. I have not tested the resistance yet. I know that the elements are in the proper places as they were installed by a tech and looked over by 2 more. I have been wondering if there was some sort of contamination in the center elements that is causing this problem, which has been somewhat intermittent while also being consistent as it is the same intermittent problem for 18 months. Often I will make an adjustment (replace a part, like the relays, or thermocouples) and the first test will be normal, then the second firing will finish but have an anomaly that is easy to miss, then the third firing stalls. Sounds cursed, I know, but there must be a reason we just haven't been able to nail down. 

But, as I mentioned in a prior response, after changing t2 and t3 and their wires last night, the kiln fired perfectly.  And now a second test is in progress and looks normal too, so far. T2 was a new thermocouple that was replaced with a different new one. T3 was not new but had functioned in each section with the same problem in the middle section. So it had been determined that it wasn't a problem. But now absolutely everything has been replaced at least once, so if it doesn't work it should be related to the elements and/or some sort of interference there, right?

[Any problems with Skutt APM elements purchased after July 2022?]

16 hours ago, neilestrick said:

@Lilith Rockett I would still like you to check the temperature of the power wires when the kiln is reaching its peak temp. I assume you have a disconnect box by the kiln? Open that up and see if the wires are hot in there. Also feel the whip everywhere from the kiln to the disconnect and see if it's getting hot. Also check your breaker and see if it's running hot.

I checked all of that and nothing is hot. Phew!

[Any problems with Skutt APM elements purchased after July 2022?]

16 hours ago, neilestrick said:

It's a 1231PK 240V1P, so 72 amps.  @Lilith Rockett Is your voltage right at 240 or is it running high? What size breaker is it on?

It is on a 100 amp circuit. Voltage is 240, not running high. I tested it throughout a firing once in each section.  There is another KM1231PK right next to it firing perfectly with none of these problems (on it's own circuit, obviously).  

[Any problems with Skutt APM elements purchased after July 2022?]

22 hours ago, Bill Kielb said:

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

I know they are type S, and I know the difference between type K and type S.  I replaced t2 and t3 last night with brand new (type s) thermocouples and wires even though t2 had already been replaced a few months ago. Now everything is new. The test I did last night looked perfectly normal, cones dead on. I am repeating the test because the problem has been intermittent, making things more confusing.  So far the temperatures are reading within a few degrees, so completely normal again. I'll check the logs tomorrow and if good likely start a third test, but I can test the resistance before starting the next test, just to know. There is another identical kiln right next to this one that has had none of these problems, although less identical now that the problem kiln has all new parts. 

[Any problems with Skutt APM elements purchased after July 2022?]

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.

[Any problems with Skutt APM elements purchased after July 2022?]

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!

[Any problems with Skutt APM elements purchased after July 2022?]

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!

[Any problems with Skutt APM elements purchased after July 2022?]

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? 

 

 

 

[Any problems with Skutt APM elements purchased after July 2022?]

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.