cadenrank

ErrD, at least in this kiln, is difference between thermocouple and target temp of +50 degrees for at least 18 seconds. And correct, only one tc. Temp when a program is started, just rises, but stops when the kiln stops. (presumably the idea of the safety relay)

This kiln of a friends has still continued to have issues. A new relay was put in, and the kiln worked normally for three firings, before presenting with the same errors. Skutt had looked over connections, and recommended replaced all of the wires. That was done, and the relay was replaced again. The result is now a kiln that when a program is running, fires max output and errors out with ERRD in a short span of time. Skutt said that it had to be the SSR (which is also new within the last month or two). I had some new measurements taken, and saw relatively similar results: The transformer is outputting 30 volts AC. 15 from each leg to the center tap. (FD5-24) Still outputting 16.5 VDC from the controller to both relays switching appropriately when running and off. The SSR also still switches on and off appropriately on the output side to ground, still seeing 42 volts to ground on the output leg of the SSR when the relay is open. 120 when it's closed. And at the time that it was being tested with me, I could not find a source of constant output flow at all. Wiring is visibly correct from my knowledge and based on the diagram and Skutt's input too. I have some other things I want to test and look at, time was short when we did these tests. But was interested to see the responses relative to the transformer output and the development of the situation. This friend already bought a new L&L kiln to replace this one, but wants to get it back working.

Is this attributed to increase in resistance in the wires? Corrosion/oxidation? That eventually causes heat to build up in the relay? and is this the wiring that provides power from the terminal block for the relays to do the switching? Or the feeder wires to elements? Or are you referring to the low voltage control wires?

Thanks! Not great with percentage math, but wouldn't it be more like 37% increase in voltage? If rated for 12, being 16.5? Either way. That was also my reason of testing it, but it is something that I told her to keep in mind in case a similar situation happens prematurely either way. I can't attest to if the reading was accurate, there was nothing that I knew of around her that had a confirmed DC voltage to test affirmatively. But, did confirm with known AC voltage. And it was a brand new meter. (for what that information is worth) Just based on my knowledge of transformers, SSR's, and mechanical relays (grouping these three since they all share the same piece of metal that's acting as a heat sink in this kiln), as well as being inside of a kiln control box, seems like heat would be in abundance in this control box.

In case anyone was curious of the outcome, she called Skutt today, which had her repeat some of the tests (including the vDC test on the mechanical relay's control side, meaning the Skutt tech also would have seen the 16.5vDC and didn't say anything relative to it) and conclusion was that the mechanical relay was defective, and they're sending a replacement.

I had told her that we should at least check the voltages at the transformer when she replaces the relay while she has the kiln apart. The resistance of the feeders (didn't test any of the small wires that distribute power in the control box though.) were all within expected limits as well if that means anything, but I mentioned it to her regardless. It's always nice to have a list so that if in a month or two (or any premature time of another premature relay failure) we have a direction to go.

Just to confirm on this point, does the 47v from output to ground when in the off-state seem to be something that would be acceptable or otherwise expected? (electrically speaking) or does the output to ground test not accurately depict the off state voltage? We will check at the transformer, and then double check at the board again and see what the results are.

The transformer is a FD5-24. It says 250Vac on the front. So to understand, the measurements, between the two outer posts should be 24vAC, and from any of the outer posts to the center post should be 12vAC? If they weren't within that range of 10%, would that imply the transformer is bad? If they are within that range, but control voltage at the relays is still 16.5vDC, what would that imply? A controller issue? I figured that was the case, but wasn't sure if those values meant anything without a load/with it not working properly as it was.

I will bring up this point with her. The SSR's control side is labeled 3-34VDC, and I thought the specs for the Deltrol relay said up to 24VDC on the switching side, but the specs for that weren't exactly clear. We sort of did a test as you're describing. I didn't record the numerical values of it though. With the relay closed from the controller, we checked for (audible) continuity between all variations of the input and output pins in case it was wired incorrectly somehow, and none of the variations we tried across the relay caused the meter to beep when the relay had audibly clicked on, and a program was running. I'm not sure what the meter's range is for when it provides the beep or not, but I can probably find it out. Testing the leads against each other provided the audible beep, but again, no combination of input to output pin caused the meter to beep. (meter's manual says: • Continuity Check: Audible signal <50Ω) We know that both of the inputs to the mechanical relay have 240v when the SSR is closed. But only 10.1vAC at the output pins. And we know that when the SSR was open, there was 100v across the input pins on the mechanical relay, nothing on the outputs. We sort of did this test originally, I forgot that this SSR was only switching one leg, so took the initial measurement across the output pins with the relay closed and got 0 - 0.1 vAC. For what that information may be worth. The mechanical relay was still in the circuit during that test, as well as the issue still present. It wasn't tested in the off cycle this way. Only tested the SSR in the off cycle between output and ground (output to ground when off was 47vAC, when closed was 120vAC) and input and ground. (Input to ground when it was off or on was 120vAC). I appreciate everyone's input! I've passed it along to her that the consensus seems to be with me that the mechanical relay is probably the fault, and also passed along all of the other information provided about possible causes.

Would an aging wiring harness theoretically increase in resistance? Or is there a numerical way to test that value? Visibly there were no signs of discoloration on the wires or at connectors and resistance through the element and TC terminal block and feeders was perfect to what I predicted (skutt doesn't provide the resistance data for this kiln like their other kilns for some reason. They spec at 4000w. So at 240v, am basing my estimate on the resistance of the whole element loop at 14.4) and measurement through the feeders and the whole element loop and the connection block was 14.4 on the dot. I brought that up to her though. I noted that if she replaces it and it fails again prematurely probably needs to look into what's causing it to fail prematurely. Nothing visibly or from the various tests appeared to indicate any other issues. So, you're thinking that 47v to ground when the relay was not closed could be coming from the failed mechanical relay? I knew 47v didn't make any sense to be there in that condition, but didn't seem like it would be causation to this issue

And just talked with her, confirmed that prior to this year, in the 3 years she's had it she hasn't needed to do any repair related stuff on it.

I will pass that information along to her. Thank you! I'm unsure how long before this started happening prior to this time. However, I know she said she moved in January, and it had been working normally up until a month or so ago, and she had said she had the kiln for about 3 years prior to the move. Then the elements and everything were replaced when the issue presented itself, then both relays. The relays have only been installed for 1 month or 8 firings she said. And the past month of firings had been normal until she messaged me today, where it had failed to ERR1 again, and then upon trying to restart, didn't gain any temp at all. It is the same small size control box. Louvers on top and bottom. There is a form of heat sink, it's mostly just a large metal piece that has a 1 inch air gap behind it that spans the whole area there though, not dedicated to the SSR. The safety relay, SSR, terminal block, and transformer are all mounted to this sheet of metal.

Other than the voltage only dropping out to 47vAC from the SSR switched leg, the controlled side of the equation seemed to be working as I'd expect. And when control was telling the SSR to close, the voltage at the inputs on the mechanical safety relay were good. Just nothing (10.1v) on the outputs.

When the program was off, but the kiln was still powered, I believe the output of the SSR still had 47vAC to ground. (This was the only way I could think to test it since it only switches one leg of the 240v on the SSR.). I'd have to go back and look for certain, but I believe when the SSR was deenergized (0.4 or less vDC from the controller) but the kiln was still powered, there was 100vAC across the inputs of the mechanical relay. It wasn't tested from each leg of the inputs to ground, but I'd assume one was 47v, and the other 120v. Which went to 240v when the SSR was switched closed when the program was running. I thought this part was odd. It's the clear Deltrol relay as the 'safety' mechanical relay. It's a Deltrol 20850-81. The SSR is a Crydon CSW2475. I always imagined that clicking would mean that the contacts were closing, but I suppose that doesn't mean that the contacts are able to carry current appropriately.

This is a modified version of the wiring diagram that shows the voltage measurements taken with a program running and where they were taken relative to the original wiring diagram attached to my first post.

I have been helping a friend with doing some testing on her Skutt GlazeTech kiln. To give some back story, the kiln originally started throwing an ERR1 code, she's replaced elements and thermocouple, and that didn't solve it, Skutt told her that it was more than likely the mechanical relay, and she replaced it. ERR1 continued. Skutt said they didn't think it would be the case, but told her to replace the solid state relay as well. She did, and it was running fine for a few weeks, and now once again has failed with ERR1. The kiln will not rise in temperature at all anymore, and eventually ERR1's all programs given to it within 20 minutes or so without any increase in temp. It was tested at the elements, and resistance was as expected. Voltage between the two terminals that lead to the elements was 10.1vAC. Opened it up further, and did some tests inside. Incoming voltage was 243vAC. With a program running, the control wires from the controller to the SSR were 16.5vDC, and the control wires from the controller to the mechanical 'safety' relay was also 16.5vDC. When the program was running (and TC still attached) voltage at the middle (input) terminals of the mechanical relay were 240v, and the output was 10.1vAC. Voltage (with program running) at the SSR, between the output side and ground was 120v when the relay was active, and 47v when the relay was open. When there was no program running, the output side of the SSR and ground was also 47v. I thought this was odd, but no less odd than the 10.1vAC out of the mechanical relay to the elements. My conclusion from testing was that the mechanical 'safety' relay has failed. The relay clicks, but there is no continuity between any of the input and output pins when the control side is energized, and the output side is 10.1vAC when it's energized. So here's what still doesn't have me 100% on the diagnosis. The mechanical safety relay clicks still when the controller energizes it. And receives the 240v input, but only gives 10.1v across it on the outputs. The other part is that this relay is only a month old with 8 firings on it. The other part is that I'm unsure if that 47v on the SSR when it's deenergized by the controller is normal. Skutt's documentation in this field is poor. At this point I'm 95% certain the mechanical relay is at fault for the failure to provide power to the elements and the current Err1 code, but would like some reviews of the data collected, from you folks and see if you agree with that diagnoses and what you think about the other anomalies that were recorded. Below is the wiring diagram for reference. 12.700-GlazeTech-1ph.pdf

Ahhhh, so it's mechanical. The load side is just powering the timer, not actually having anything to do with disengaging the sitter contacts. I knew something had to be missing from the equation I was trying to figure out. Thank you guys!

This question is not relative to an actual problem that I'm having, just something that I'm curious about from an electrical standpoint that I don't see any information about online, and I don't have a timer on my sitter kiln to do tests. I've noticed that the timers on kiln sitters only have the two wires coming off of them, and they're attached to the 'load' side of the kiln sitter terminals, usually just underneath the feeder wires to the switches on the same terminal. My question is, how does this actually interrupt the connection between the line and the load at the sitter? What is happening when the timer reaches zero that prevents the connection at the sitter terminals? I'm sure I'm missing something, and like I said, my older kiln doesn't have a timer, and my other kiln is digital so I don't have any ways to curiously test around and find out actually what's happening, so to settle my curiosity and expand my kiln electrical knowledge, I thought I'd ask here lol.

Thank you!

Hey all! I've been waiting for a replacement bottom slab for one of my older kilns for a few months now and it finally showed up and is in place. The kiln had been fired last week, but the new bottom slab hasn't been fired yet, and I'm wondering if there's any reason or need to fire the kiln without it loaded first? If I fire it normally it's first firing on the new bottom slab would be a fully loaded slow bisque to 04. I don't think it would make much of a difference if it was loaded or not, but would like to make sure the bottom slab lasts as long as physically possible lol. Thanks in advance!

I opted to solder direct from the 31856 to the GPIO pins, and haven't had any issues to loosing the thermocouple readout. I really only opted to do this because I'm comfortable with a soldering iron, and I didn't think about buying the pins and such to make pin to pin connections, mostly because as I mentioned, I only intend to use this for monitoring for now, and I was trying to keep it as cheap as possible. I think I used 22gauge stranded wire, twisted it tight, stuck it through and soldered.

Disregard this. After a checking again, they were both matching each other this time, and then when I gave the kiln some power to heat it up, they both got up to about the same point as well. I did learn that the connectors I bought fit backwards or normally into my pyrometer, so I'll have to keep an eye on the negatives and positives when I plug into my pyrometer.

Alright so, follow up: I did this, and the pyrometer is reading 64 degrees F, and the pi is reading 34 (which is what it read prior to adding the connectors, and is more likely closer to the actual temperature. I never used the pyrometer originally when I installed it because I knew what the temperature of my garage was, and the pi was matching it, so I'm not for certain if it always had this difference or not. This pyrometer also has given me funky readings in the past, so I'll try again later and see what it reads. I figured if there would be any issues or differences it would be on the pi's end, since it had to go from male connector, to female, and then to the max 31856, where the pyrometer is just going from the thermocouple, to the male connector, to the pyrometer.

I direct this at @Bill Kielb because I think I've seen him comment about it before, but anyone else is welcome to answer too if they know: Would it be not a good idea if instead of connecting the thermocouple wires directly to the 31856 board (photo for reference), could I instead connect a female type K connector to the max 31856, and a male type K connector to the thermocouple wires and make a junction that way? Or would it make any kind of difference? again, this is just being used to monitor temperature remotely, there's no control happening. The only reason I want to do this is just in case of any issues, I can still use my pyrometer as I normally would just by unplugging it at the connector and then plugging the male end into the pyrometer. I already bought the connectors from Amazon, but wanted to make sure that this wouldn't cause any issues in regards to temperature reading before I did it. connector imaged below:

Things worked well once I got it figured out on the pi, and am successfully monitoring temperature from the thermocouple now, and it performed as expected during my last firing. I don't know that I have the confidence in it just yet to actually set it up to control (this really wasn't my intention anyways, but still cool to have the option), but I'm very satisfied with the ability to see the thermocouple values remotely, and to be able to graph them out if I wanted. Anyone have any other ideas/schedules or anything like that that would make this work even better just in regards to monitoring temperature?