kiln PWM parameter for PID - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: June 30, 2024, 11:22:08 pm
content: So the kiln I have has a electromechanical controller that is basically a 20 second duty cycle thing.I.e. 25% means 5 seconds on 15 seconds off.With my reflow oven, the PID basically applies continuous power to the elements until they get near the set point, then it starts pulsing them to reduce over shoot.If I put a PID on it, do I need to maintain this duty cycle? The elements are embedded in some kind of ceramic.Naturally the PID will enable the SSR continuously until it gets near the setpoint (say its 900C for brazing), then it will start reducing it. However, this means the elements will get continual power for quite a while.The turning on and off means that they suffer more temperature changes, but on the other hand it means that there is more time for the heat to equalize or whatever inside of the oven.I was planning on equipping it with a CN9000 series OMEGA PID controller with a zero crossing SSR (derated 50%)

author: coppercone2
author_rank: Super Contributor
timestamp: July 01, 2024, 06:04:39 am
content: basically I think I need to find a manaul for a manual kiln.I wonder if the instructions tell you how to run the god damn thing. Like "limit power to 20% for 30 minutes before each use" or something. I feel like it probobly has some crap like thatanyone use muffle furnaces and know this from experience?I don't have a sense of the time constants in there. Can the wire overheat and burn out before the thermocouple responds if its getting floored?Or are they designed with the expectation that people will set it to 100% to get their lab work done faster? Then turn it down.How was this done in the 70's?

author: rogerggbr
author_rank: Contributor
timestamp: July 01, 2024, 07:34:16 am
content: Quote from: coppercone2 on July 01, 2024, 06:04:39 amTypical on/off controllers, whatever the method of control (P, PI, PID) will assume that continuous output is ok if far enough away from the set point and measured value moving slow enough. The ones we have on our ovens also have a high level controller, sometimes called a supervisor or similar, in case the main contacts get welded. I assume a modern solid state system can also fail short circuit so a high level trip/lockout may still be a good idea.

author: coppercone2
author_rank: Super Contributor
timestamp: July 01, 2024, 07:44:23 am
content: hmm so basically their designed to be OK at 100% so long its not near the limit?Is this still true for embedded element heaters, where its a tile with wires?Safety issue too, I made sure to get the smallest one, is only 9 amps. Not sure what kind of safety I can put on a SSR. Putting a contactor in there to act as safety is maybe possible but it might be getting cramped.The old one was busted so it looks like when you over heat this type, it just melts the element and you get a drop of molten metal inside of the furnace.I think with that controller I can wire output #2 to be an alarm if its connected to a normally closed latch open relay at a over temperature event. Then it should disconnect the heater lol

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 01, 2024, 09:19:09 am
content: There are (legal!) limits to on/off cycling times of big current consumers. It probably does not matter for a DIY smt oven, but for commercial designs you have to make sure you don't switch too often. The PWM frequency does not matter much as long as it is about 4x to 10x faster then the time constant of the oven itself. But of course it depends also on how accurate you need to track the temperature.For the rest. If the oven is cold and you want it to get hot, it takes a while to get "close" and in that time the integrator will wind up. The whole PID algorithm does not work properly in that case. And instead of generating a slow temperature rise that can be tracked by the oven and it's PID regulator, it's faster and simpler to just turn the oven on on full power until the temperature get close, and only then start the PID controller.You can also:1. Turn on the oven until it's hot.2. Turn off the oven completely, and track the overshoot.3. Subtract the overshoot temperature from the overshoot.4. In a second test run: Turn off the oven when this setpoint is reached.5. Start the PID algorithm at maximum temperature of the overshoot peak.When done correctly, the peak of this "overshoot", now coincides with the final temperature setpoint. You can even preload the integrator with a value that is close to steady state operation. A bit of guesswork is OK, as (when adjusted correctly) the PID algorithm will adjust for the rest.

author: coppercone2
author_rank: Super Contributor
timestamp: July 01, 2024, 01:53:00 pm
content: i was worried that the elements will get melted in the while its running at 100% power. The burried elements are very funny to me. the walls just start glowing redthe method you give looks like the method for manual PID tuning in the manual for the CN9100Athe PID has a thing where you can limit it maximum power to say 90% if you want. But it disables auto tune. They say its when the heater is too big. In this case its just unlike everything because the heater is encased totally in the wall, no element groovebecause my measurement shows me, at 80% power, I am at 1000 degrees of the 1100C limit. I assume if I ran it continuously at 100% power it would burn out.If there was say a big block of copper in there, the furnace would be OK trying to get to setpoint at 100%? Say I want to braze a fitting on a ... copper heat exchanger of some sort. And the setpoint was maybe 875. Or to braze some feet on a sizable copper heat sink. The main idea is to use less acetylene for dan gelbert style prototypingwould I ever wanna limit maximum power to elements under any load condition? I know to keep the load from the walls etc by some recommended ratio

author: coppercone2
author_rank: Super Contributor
timestamp: July 04, 2024, 03:33:57 am
content: Well so much for trying to run it without a PID lol. it burned out at 80% power. For some reason the temperature sky rocketed to 1300 + within the hour. Maybe the coating, because I used the same settings before and it would not go past 1100! it melted the thermocouple. It got totally glassed. :'(I think its because I was curing the coating on my little tray and it was too close to the walls.well that was a painful expense. I think I will just use a thin alumina sheet on the bottom to keep it cleanI had already bought the PID, otherwise I would have thrown it into the trash.I see why people use open element kilns, because they are cheap to fix. this one kicks you in the nuts on the 4th of julyI am gonna limit power on this thing too in the PID algorithmtldr : don't try to wing it with unrecommended oven loading parameters

author: coppercone2
author_rank: Super Contributor
timestamp: July 05, 2024, 04:26:42 am
content: alright I got a 25A Panasonic SSR from digikey to use with this and a cheaper heatsink on ebay (the skeleton ones but with a fairly thick back bone). The nice hs have 100mm foot print, I only have 100mm to spare totalThe thing is rated at 9A so I think it should be good enoughI made the front panel out of 12 gauge galvanized steel that I plasma cut. I am going to paint this with the flame proof paint like the rest of the kiln.I am going to make a heat shield that goes between the SSR and the kiln bottom out of this stainless steel high nickel content sheet I have (bearly bubbles in contact with H2SO4 and HCl mixture after a long time). its shiny, fairly easy to bend and corrosion resistant. I am going to make a L shape that get sandwiched between the front panel and PID about 1/2 an inch from the top of the kiln and 1/2 inch from top of the PID module.The only thing I don't like is that the PID module has fast-on tabs for the thermocouple wires. For screw terminals I usually get the proper lugs made out of the correct metal. I can't do that in this case and I need to use regular fast on connectors.It looks like the PID module has a tube socket on the back with a adapter into the fast-on blades, so I guess it won't be super accurate anyway even if I did get type K fast-on connectors.

author: coppercone2
author_rank: Super Contributor
timestamp: July 09, 2024, 01:14:12 am
content: for a heat shield, I can either make a sheet metal cut out that basically floats above all the electronics or basically a roof that covers everything with a gap.Does it work better for convection if its just a line of sight thing between the components and the hot bottom of the kiln or if its a entire layer?Or should it be a layer with preforations?They have a partial heat shield in there already over the gauge, it only covers a bit of it and extends 2 inches, but its only a few mm away from the kiln floor. I wanted to attach my heat shield to their partial heat shield so I don't have to manufacture another bracket.It seems that since the channel is narrow, perhaps just doing a line of sight thing would be cooler for the components then making essentially a whole layer that has ventilation on the edges?I.e. I was going to extend 1 plate over the PID and another plate over the SSR heat sink a few mm away from the top by extending the original shield with some aluminum strips, or I can cut a big square of aluminum and basically make a whole floor. I am worried that the hot air might bunch up in this tight space and it won't cool the PID and heat sink as much as just a vertical direct line of sight only thing from the floor.But using a whole sheet is appealing because there is two mounting bolts that got replaced with a ceramic terminal block. I could bolt a sheet to this and have it float under the kiln box floor by the distance of 1 or 2 nuts and some washers. I would only need to cut wires through for the element leads and the mounting holes. Then I can lose the stupid segment of heat shield the kiln came with.

author: Poroit
author_rank: Frequent Contributor
timestamp: July 09, 2024, 08:17:11 am
content: The gauge of thermocouple wire used and its position in the kiln will affect the response time.Overshooting to 1300°C with the controller set to 1100°C sounds like a parameter programming issue with the Omega Controller.I have successfully upgraded numerous kilns by fitting an SSR and a good quality controller with SSR output.What are the current and voltage ratings of your kiln?

author: coppercone2
author_rank: Super Contributor
timestamp: July 09, 2024, 08:17:35 pm
content: oh no it over shot and destroyed itself set to 85% on the mechanical timer regulator (85% duty cycle of 10 seconds).Because I swore before I left it at 80% and it was maybe 1000 after 2 hours. When I set it to like 86% the next day, 2 hours later it was 1300. Maybe there was still moisture that got baked out and it suddenly got more efficient. . I just wanted to cure a base plate I made. I guessed that it might get to 1050-1100. BUt I came back and the TC was reading 1300.its like 9A 120VACThe good part is I know how it fails if you let it go or it malfunctions, basically becomes totally inert. I was worried that the exterior walls might start glowing and it could be a molten sheet metal dripping fire hazard. It appears so long its put in a safe spot, it won't do anything crazy even if it totally malfunctions. For me, it seems like a really scary device. I feel alot less scared of it now that I saw it fail

author: Poroit
author_rank: Frequent Contributor
timestamp: July 10, 2024, 06:35:12 am
content: Sorry...I misread that as I thought you had installed the Omega Controller.I suggest you push on and install a PID Controller and SSR as it will greatly improve the performance of your furnace.I have been involved with the instrumentation in foundries who also use the brazing technique and they normally use a Ramp/ Soak controller for this application.Brands I have used are RKC, Shimaden, Fuji, Brainchild, Eurotherm etc.You need one that has the following features;Type K Thermocouple Input3-32V DC SSR OutputAuto TuningYour 25A Solid State Relay will be fine but must have the compatible 3-32 VDC Control Input.A couple of questions re your Muffle Furnace.Does it have a thermal fuse fitted?How hot does the existing controller enclosure get? Can you touch it with your hand?

author: coppercone2
author_rank: Super Contributor
timestamp: July 10, 2024, 08:21:39 am
content: nah it would burn you it got to like 100C. But I built everything so it floats off the perforated plate walls in the under body on brackets and it looks like every component will have a heat shield on it.I have no idea how to install a thermal fuse, it looks like it does not get hot enough to ignite things even if its on the verge of burning out after operating for a long time. I am paranoid about it so its only probobly going to be used on the steel welding table and that area is kept clean from scraps and trash because sparks cause firesI thought about making a secondary mesh shell around it eventually so its touch safeWHat is the point of a thermal fuse if the thing just burns out without anything happening as I have seen? It will probobly be unstable to try to fuse the chassis with heat because of air temperature changes. I could glue something to the bottom... but it looks like its safe even if you let it burn up. The elements did not even drip nichrome into the furnace body, when I took it out, it was all contained.. the elements fuse literary like a fuse (look exactly the same from the outside)I think I just need to live with the fact that if the element wants to burn out, it burns out (assuming there is some kind of malfunction with the SSR or controller).I could see if the elements were exposed coils some kind of dangerous condition could happen if they start drooping in the thing to short out and explode, but in this case its embedded in the manufacturers fire brick material, so they can't move at all... it just melts in side of the refractory and opens circuit. And its only 1 circuit, that is a single monolithic element, so it either works or does not work., if you have multiple elements the behavior might get funny if one burns out and the other one makes it drip or somethingAnd a thermocouple just measuring air in the enclosure where the PID would be is ~30C in a fairly hot weather (maybe 28C)I just thought the ceiling might irradiate the enclosure since its black, so it will get a aluminum umbrella

author: Whales
author_rank: Super Contributor
timestamp: July 10, 2024, 10:39:53 am
content: Sorry to hear you melted your element, that sounds expensive.The performance difference between your two runs might have been related to the gaps in the kiln and how well sealed they were, including the peephole.

author: coppercone2
author_rank: Super Contributor
timestamp: July 10, 2024, 08:34:53 pm
content: I did have some coatings in there, ITC296. Maybe its highly non linear where it really kicks into gear at 1000C reflecting alot of heat. Or it finally cured totallyagain, slightly sad, but now im fully confident its pretty damn safe, I was border line scared of it before I knew how exactly it fails. I thought the whole thing might start glowing red dripping molten metal and spewing sparks and smoke lol, my imagination was off by maybe 100kW of power. And its power cord was fine too, and the outlet was not really hot or anything like I thought it might be. Its a small price to pay for peace of mind IMO

author: coppercone2
author_rank: Super Contributor
timestamp: July 11, 2024, 04:24:55 am
content: this one does not have a door seal. It has a flange with a brick frame that the door goes inside of, like a labarnyth path.I see I can buy ceramic fiber rope material to make a gasket seal between the door brick and the bricks making the exterior heath frameHow much efficiency does it gain if I did that? These mods are getting a bit pricey. I did try to jam kao-wool and put ICT on all the gaps to seal it up as much as possible because things were getting a little loose in there, but the seal needs to be woven to maintain integrity, felt will make a mess thereThink it would be more then 20 watts saving?also, what glue would you recommend for the door seal adhering ceramic fiber material to fire brick material if its worth doing?I do see a red glow through it if its hot and closed around the ring like a light in closed room in a dark hallway deal. I assume it might be substantial if I can see it glowing through the gapALso I was thinking lol, if the front and back are coated with IR reflector, is the kiln not sort of a laser, with a aperture instead of a silvered mirror? A low q thermal laser? It makes me think of lasers. Its just too big

author: coppercone2
author_rank: Super Contributor
timestamp: July 11, 2024, 06:47:26 am
content: I think I found a case for using the thermal fuse. If your using this for chemistry I can see possibly a crucible full of molten metal rupturing and flooding the bottom of the kiln and turning it into a short circuit. Not sure what exactly would happen but maybe it would allow it to get hotter then normal. Then even if the monolithic heater fuses some where, the pool on the bottom might conduct electricity. I would expect it would blow the fuse unless you get very unlucky. if molten metal shunted the nichrome in some bad spot maybe it could cause trouble that could result in the chassis going bonkers. I would think it would trip the GFCI.Maybe I will glue that on. Not really something I can test, it seems like it would be one of those things you either got a contingency or it goes nuclearI wonder if this case of flooding the circuitry with molten metal is a concern for liquid metal reactors or a leaking ladle in a foundry. thats some mega bullshit. The circuit box is full of molten steel againI think what I can do is make a leaf spring that presses a thermal fuse into the bottom of the chassis using the old mounting studs for the nichrome wire that I replaced with a ceramic terminal block. It should fit between them and get pressed in by a M shaped spring thing for good thermal contactMaybe put that at 175C? It should never activate unless things have gone seriously foul.

author: Poroit
author_rank: Frequent Contributor
timestamp: July 11, 2024, 09:25:44 am
content: The furnace may have reached 1300°C because the thermocouple was already open circuit.If the thermocouple open circuits, the furnace keeps heating trying to reach to setpoint.A Thermal fuse looked like another thermocouple and was normally housed in a Ceramic sheath protruding into the workspace.They were made from a precious metal combination. It would burnt out at a higher temperature than the workspace rating, turn off the power and protect the furnace from thermal runaway.Modern Furnaces/Kilns don't use this method and use the thermocouple break feature of the PID Controller and a second contact output to turn off the power at higher temperatures.Some also have a second controller and thermocouple for this belt and braces approach.

author: coppercone2
author_rank: Super Contributor
timestamp: July 11, 2024, 11:37:35 am
content: no when i burned it it was just running at 85% of its duty cycle in 10 or 20 second period with a relay oscillator with no feedback. I thought I could get away with it. I really wanted to make a ceramic PCB on the 4th of july, and I needed to cure a little kiln tray in a hurryi was very enthusiastic about the project, because basically it was totally fine before running for a few hours at 80% the other day. its just non linear.you gotta totally watch it if you wanna go hot with out feed back control. not worth doingi previously had alot of failure with a microwave kiln attempt and I thought I could finally knock a trace out lol

author: coppercone2
author_rank: Super Contributor
timestamp: July 12, 2024, 09:03:49 pm
content: well I managed to crack the bottom protective plate, meaning either I spend 3 hours with a die grinder and saws trying to recut it, so i just fixed it with furnace cement. i hope that holds.I like the bait and switch tactics of laboratory materials suppliers too. its supposed to be america but it works like alibabano wonder R&D is being cut everywhere, when they keep getting robbed on their equipment budget for repairs

author: johansen
author_rank: Super Contributor
timestamp: July 12, 2024, 09:40:55 pm
content: can't really help you when you've not included any information on who made this kiln, or where you got the heating elements, what modifications you made, etc.

author: coppercone2
author_rank: Super Contributor
timestamp: July 12, 2024, 11:12:37 pm
content: i got plenty of help already

author: coppercone2
author_rank: Super Contributor
timestamp: July 19, 2024, 01:25:04 am
content: glad i started to dig into that old cable. I thought I could reuse it but it suffered from brittle insulator, which turns into maccaroni fragments. effectively, it was just separated by wool/fiberglass in the cord. Always check the cord out. IMO those rubber cords offer a false sense of security because its packed with soft stuff and rubber, so it feels good on the outside ,but if you look in there its often totally compromised

author: coppercone2
author_rank: Super Contributor
timestamp: July 23, 2024, 10:54:52 pm
content: Does anyone know what the error means in the CN9000AEE5 - Outside Time LimitIts when I try to run a autotune to 850C.https://assets.omega.com/manuals/M1191.pdfNot sure what its talking about exactlySomething with the integral? I think someone said something to me before about the I being problematic with kilns?

author: Poroit
author_rank: Frequent Contributor
timestamp: July 24, 2024, 05:21:41 am
content: EE5 means Auto Tune outside of time limits.What were your PID values after you ran the Auto Tune?

author: coppercone2
author_rank: Super Contributor
timestamp: July 24, 2024, 10:42:56 am
content: I don't know. Then I reset it and it gave me EE3 but it looks like everything is all good. It was flashing EE3 but the temperature was being measured and when I power cycled it, clearly the heater was OKhmm maybe I should check the SSR for a short, but I have a feeling its a bogus error.Is this possible because I have a very thin temporary thermocouple and its not like losing heat fast enough because the thick one that is like 16 awg wire will conduct heat out the wires and maybe vary the temperature a little bit?Previously I did the auto tune at like 350C. It completed OK. The next day I set it to 850C and did it again and its going on about the errors

author: Poroit
author_rank: Frequent Contributor
timestamp: July 25, 2024, 08:06:01 am
content: If your Controller Auto Tuned at 350°C then that proves that your SSR is functioning OK.EE3 is Loop Break Alarm so check your thermocouple.Thermocouple.How is your thin temporary thermocouple constructed?Has it shorted somewhere behind the Hot Junction?Controller Settings.What Operating Range have you selected?What Operating Mode have you selected?Are you also using Setpoint2?Output 1 Cycle Time?What are the existing PID settings?Sorry for all the controller questions but there are a few parameters that can screw up the controller operation if not set correctly

author: coppercone2
author_rank: Super Contributor
timestamp: July 25, 2024, 12:22:41 pm
content: I need to print the manual because I don't like running this device in the house.I replaced the thermocouple with the proper one.The temporary thermocouple was very thin, probobly 28 awg single strand wire, which I folded over and put into a 22-18 crimp. It seemed OK but its possible that connection was bad. Now the thermocouple should be good since its properly terminated.I can try to get this information,I just need to do one more disassembly because I wired the new one in backwards lolI kind of like the Chromalox PID better, because they try to communicate better through the display... but it was too big. This one is 100% cryptic codes, so I need the manual near me

author: johansen
author_rank: Super Contributor
timestamp: July 25, 2024, 04:12:18 pm
content: Quote from: coppercone2 on July 25, 2024, 12:22:41 pmIf you had provided any of that information previously otherwise i would have told you the thermocouple is non linear with temperature and that's why it ran out of time.you can weld your own thermocouples but crimping them together doesn't work beyond maybe.. soldering iron temperatures, and even then the corrosion is going to set in and the wires go open circuit.also the kiln ceramic insulation becomes slightly conductive the hotter it gets and you can have 60hz leakage affect the temperature.

author: coppercone2
author_rank: Super Contributor
timestamp: July 25, 2024, 08:45:49 pm
content: no their welded at the factory I mean the crimps to the machine, it needs to be crimped to fit on a 250 spade. I just removed the yellow connector and put crimps on instead.I know your not supposed to mess with the hot end. I have a spot welder for that part toofor the input of the thermocouple the C9000A PID literarly has 2 brass spades, the same as for AC power and the SSR.It did pass the yank test. Anyway thats gone nowfolding the wire into a over sized crimp on the hot end is mad noob haha. klingon wiringhttps://static.wikia.nocookie.net/memoryalpha/images/e/e4/Opti-cable.jpg/revision/latest/scale-to-width-down/301?cb=20121204030820&path-prefix=en

author: coppercone2
author_rank: Super Contributor
timestamp: July 26, 2024, 01:58:31 am
content: Well I don't get it. I got a good thermocouple in there and it reads EE3 again when it gets to like 500 degrees on Autotune.It still measures temperature. The heater still works.What the hell does this thing want.I read the section about the LBA.Is it possible that if its set to 2x the integration time, and the integration time is mad wrong, it thinks there is a loop break when there is no loop break because its just too slow?When it cools off tommorow I will try to get all the values it has.

author: Poroit
author_rank: Frequent Contributor
timestamp: July 26, 2024, 03:11:39 am
content: Have a read of Section 4.2 of the Omega Manual.It will be a Time issue that is bringing up EE3.Look at your setting for SP2 Operating Mode as it can also effect EE3.Lets see your parameter settings when available.I see a few of you posts where you are concerned about the spade terminals on the controller.Mainly used a space savers....Not my preference but have used them successfully in applications.The Cold Junction is where you introduce a dissimilar metal to the thermocouple so in your case it will be at the rear of the controller where you have the spade connectors.The controller will look after the Cold Junction from there so don't be concerned."thermocouple non linear"...this is not an issue as controllers have built in Linearization Tables for all the Thermocouples, RTD's and Thermistors they offer.

author: coppercone2
author_rank: Super Contributor
timestamp: July 26, 2024, 11:38:48 pm
content: Controller Settings.What Operating Range have you selected?-not sure what you mean. Its type K with a limit to 1150C (the instrument manual says 1200 but I gave it a bit of margin)What Operating Mode have you selected?-Autotune ATAre you also using Setpoint2?-NoOutput 1 Cycle Time?-0.3 seconds. I read that high cycle time can loosen the bolt on the SSR and that if possible use the fastest you can for a solid state application unless its a problem.What are the existing PID settings?Proportional : 2.0. - This means 2 % I thinkDerivative : 2 - this means 2 seconds I thinkApproach Control : 2.5. - multiple of 2.5 proportional bandIntegral : 1.1. - does it mean 11 minutes?To get those settings I needed to disable Autotune because it just keeps trying to Auto tune ever time I boot the controllerMaybe I set the LBA for 30 minutes? If I understand it correctly it set for 22 minutes right now. maybe thats too fast.

author: coppercone2
author_rank: Super Contributor
timestamp: July 27, 2024, 12:53:50 am
content: I put the timeout at 30 minutes and now its ee5 ing me againwhat the hell is this time limit. time limit is only mentioned in the document once under the definition of EE5.Where are the auto tune time limits in the manual? I don't know what you meancould it be unhappy because its empty? maybe I should run it with a crucible or something?

author: coppercone2
author_rank: Super Contributor
timestamp: July 27, 2024, 03:51:13 am
content: I let it warm up to 750C with out the auto thing, then I turned on the Push to tune (02) option, instead of full auto tune. it almost immediatly gave me EE5.I guess this has something to do with the temperature change of the kiln being wayyyy too slow for the controller?unless anyone has any insight, I guess I need to buy a thermocouple adapter for my graphing DMM so I can manually tune this sucker. I think I will anyway, because if I see EE5 again this kiln might get re-entry crash landing qualification

author: Poroit
author_rank: Frequent Contributor
timestamp: July 27, 2024, 05:51:12 am
content: How long did your kiln take to reach 750°C?

author: coppercone2
author_rank: Super Contributor
timestamp: July 27, 2024, 02:49:18 pm
content: not sure like a few hours I think.I bought a adapter from fluke so I can get a high temp probe in there to graph it on a fluke 289 because I am not going to write it down by hand like a graduate student. The probe I have right now that can connect to banana jack is like 300C max... so next week I will get a graphA long time ago I saw my tax money being spent to get two kids to sit infront of a gieger counter manually logging it for 10+hours. I walked by in the morning for work they were there. I walked by at night after a lab lecture they were still there. I decided I will try to avoid getting into that pickle. And it was graph paper, with full scholarship physics grad studentsIt was studying the decay of a particle accelerator target. I know those samples were very important to them.I actually thought it was some kind of hazing ritual, the way they were sitting on stools in the middle of the room looking at the sample. I wanted to throw some paper balls at them. I may have even seen them at some other time, like a few days later.In a sense its the ultimate "watching paint dry" experience. A number of particles evaporate into gamma steam.My experience would serve as a excellent into to one of the Stargate episodes about a time loop. "weren't you guys here.. doing the same thing.. way before?" Is it some kinda hologram ? Can this be real?For all I know they are still there, reliving the same 5 minutes of time over and over and over again. Perhaps they made a naked singularity in there. I wonder what would happen if you threw a paper ball in there, it would probobly get stuck in mid air half way into the room.

author: Poroit
author_rank: Frequent Contributor
timestamp: July 28, 2024, 07:18:35 am
content: That is slow and would explain why you are seeing Timeouts.I assume you have your Heating Output Limit(Output1) set at 100%.Forget Auto Tune for your higher temperatures and set the controller as Proportional only.Start with 2% Proportional as it sounds like this Kiln will limp to the Setpoint.You can use Manual Reset to adjust any variation between the Steady State and the Setpoint.

author: coppercone2
author_rank: Super Contributor
timestamp: July 28, 2024, 04:45:53 pm
content: Yeah thats what I am thinking since its a low power one for science. I still bought the adapter for my fluke grapher so I can try the manual procedure since someone already wrote it here.... why notI can try to run it with a chunk of copper in there too to see how it changes.Maybe this is so slow because its not exposed elements?

author: Poroit
author_rank: Frequent Contributor
timestamp: July 29, 2024, 06:24:21 am
content: I suggest that it is just a lack of power.9A 120VAC =1080 watts.Most higher temperature Kilns/Ovens start at around 4000 watts.Good luck with the Manual Tuning.

author: coppercone2
author_rank: Super Contributor
timestamp: July 29, 2024, 04:31:46 pm
content: I suspect it won’t matter unless you are worried about a really small over shoot but I wanna seeThe chromalox did auto tune on my pcb cooker toaster, but that has poor insulation and bearly goes above soldering temp on max

author: coppercone2
author_rank: Super Contributor
timestamp: August 02, 2024, 10:24:47 pm
content: Well I am trying to do the manual tune but its not easy. I realized the thermocouple hole is plugged, so I had to lay in a wire in thereThere is also a big difference (100C) in measured from the unit TC and the Fluke 289.I suppose to do it properly I would need to like monitor from the front panel. But I will see what it looks like anyway

author: coppercone2
author_rank: Super Contributor
timestamp: August 03, 2024, 12:01:14 am
content: @700C on/offFrequency came out to be 145samplitude = 25.2Cpppulse time = < 7sproportional band % = > 3.43%dt = < 7.25s∫ = > 145sDAC = 1.5x defaulttimes up, lets do this

author: coppercone2
author_rank: Super Contributor
timestamp: August 03, 2024, 01:56:52 am
content: Ok the little thermocouple that is a bit lower then the big thermocouple sees a small bump (15 degrees) and it drops down pretty flat with a slightly slower decay. I think it might be the DAC rate control, it fits the diagram the best from being too small.However the big thermocouple I don't think over shoots, its linked to the wall. The small one seeing 15 degrees difference does not mean much since its like 28 gauge wire.I am not sure how much utility there is trying to adjust the system with the small TC, when its painfully slow. I can try it again setting the DAC to 2x instead of 1.5x.But with a substantial load, i think this might really be splitting hairs... i think the point was made pretty clear that this kiln is really damn weak and small, so for any of this to matter, you would need more watts.I can still do a disturbance test, see what happens when I put in a empty crucible, because theoretically what I see can be explained by either derivative approach control being too small,or derivative time being too short.... because I don't think you can tell them apart without doing a load test. If I had to guess I would say its derivative approach control, because its the only setting that they expect you to guess on... the other ones are all based on calculations.

author: coppercone2
author_rank: Super Contributor
timestamp: August 03, 2024, 05:19:31 am
content: I monitored it and this time, with the setting set to 2.0x DAC,On first setpoint it reached 712 degrees CAfter a while it dropped to 699 degrees C and then rose up to 700 degrees C.I jostled it by opening the door for a bit until it dropped to like 640 degrees C.When it came back up, It got to around 703 degrees C and it dropped back down.Since the magnitude of the error caused by the disturbance is 3 degrees C, and the turn-on over shoot is 12 degrees C, am I correct in thinking that the deritivie approach control setting is too small, and that the deritative time setting is also too short?or should I leave the derivative time alone, try the approach increase one more time and call it good?How accurate do you think I can get this? Right now the over shoot is ~1.8% and the disturbance compensation is 0.5% of the setpoint.Increase derivative time from 7 to 10 seconds? My calculation came out to 7.25. I have it at 7 right now. 10 seems like alot and going against the rules, but there seem to be no real rules for the DAC control.

author: dietert1
author_rank: Super Contributor
timestamp: August 03, 2024, 09:51:34 am
content: When reading this thread i didn't find the motivation to use a PID controller.In case the aim was getting a faster ramp-up be warned that successful autotune will result in oscillations during ramp-up, reaching temperatures much above setpoint, like +30 %. Exactly what you can't allow as it will destroy the furnace or the thermocouple.I'd guess this control requires an extremely conservative approach with slow heat-up. The important term to observe is D.Regards, Dieter

author: coppercone2
author_rank: Super Contributor
timestamp: August 03, 2024, 02:49:39 pm
content: Well the formula I used for manual tuning in the manual resulted in 12C overshoot and 3 C overshoot after a disturbance.I thought that the over shoot at start up and over shoot from a disturbance would be similar if it was purely a derivative issue.Is it a mixture of DAC and derivative, since the initial over shoot is bigger then the later over shoot if you open the oven for a bit. they draw the wave forms like that in the manual that looks like if it was just derivative it would be same over shoot at start vs disturbance ?Not sure if that is a good disturbance to open it. I thought maybe I should put an object in there, but I don't know the size I need for a disturbance.

author: dietert1
author_rank: Super Contributor
timestamp: August 03, 2024, 04:54:32 pm
content: No, the initial overshoot is proportional to the initial temperature error Tset - Tambient. So 30 % of 750 °C would be 250 °C (still safe). The autotune features i have seen strive for a near critical adjustment for best steady state response. Better adjust the PID manually. As far as i remember the experts translate D as "damping" instead of "differentiator".Regards, Dieter

author: coppercone2
author_rank: Super Contributor
timestamp: August 03, 2024, 06:03:28 pm
content: The autotune fails on this, I did it manually using the manual and a fluke 289 with graph mode to figure out the wave formThe problem I have right now with the numbers I listed is that increasing the DAC control and increasing the proportional time do not seem to effect the over shoot, which is 12C. Like If I open the door for maybe 1 minute (turned off) and let it warm back up, it will consistantly over shoot with little effect from the following changes:*****From********@700C on/offFrequency came out to be 145samplitude = 25.2Cpppulse time = 0.3sproportional band % = 5%dt = 7s∫ = 3 minuteDAC = 2x default*********To***************derivitive time - 7S -> 10SDAC Control -> 2 -> 2.5Since that change had no effect on overshoot,It makes me think the problem might be with the integral or the proportional band %. I could try a longer integral time or a wider proportional band.I thought to Keep the derivative time @ 7 seconds (like the calculation from graph), the DAC control at 2.0, and then try to vary either the band % or the integral time.Maybe for a small kiln I should just make the proportional band % wider since its smaller, then it would have more time to do everything? I am imagining this might be like landing a plane on a runway that is too short (aircraft carrier). I thought maybe to up that from 5% to 10%. I am imagining generally everything lands better if the runway is longer?

author: coppercone2
author_rank: Super Contributor
timestamp: August 03, 2024, 06:39:53 pm
content: Ah I think I read the table wrong.They give you a hysterisis % on the right and a band % on the left. I think I need to take that oscillation I found, which is 4.3%, round to the next higher percent, which is 5%, then find 5% on the right side of the table, and input the number to the left of it (10%) into the machine.So I think my calculations were put in correctly, other then the proportional band, where I put in 5% instead of 10%. I think this basically put the controller in a impossible approach, so my plane keeps ending up in the swamp.

author: coppercone2
author_rank: Super Contributor
timestamp: August 03, 2024, 07:36:35 pm
content: Lol, it made it worse. It jumped up to 715 now after a disturbance. when I made the proportional band 2x longerWell I dunno maybe their tuning method does not work for this machine too good.Only thing I did not fuck with yet is integral time. I can make that longer.

author: coppercone2
author_rank: Super Contributor
timestamp: August 04, 2024, 12:21:54 am
content: Increasing the integral by 1 allowed value reduced the over shoot to 7Cit does not make sense to me but whatever

author: coppercone2
author_rank: Super Contributor
timestamp: August 10, 2025, 06:36:52 am
content: omfg I figured it out, the fucking maximum power was limited to45%by the previous user in a secret menu. I noticed because I measured temp rise rate shorted and PIDed.No wonder nothing was working correctly and it was so god damn slow. I thought the controller had a broken digital logic but that is not likely.Or maybe I did it and forgot when I was playing with it, but I don't think I even got into that menu before.I got 1 degree over shoot and a very reasonable rise time with the coefficents I was screwing with. I am going to put the results of the equations into it to see if I can get it to settle at 900 on the mark.It was telling me the whole time, because it was blinking when it should have been solid. I thought it was a feature to show that its working in PID mode. But its supposed to be solid up until the proportional band %.I guess it does not work right when its restricted to EZ-bake oven mode. It would have been like running the original analog controller at like 60 volts.So the PID math works. Its just the god awful interface on this controller confused/illuded me.I thought I did some kind of factory reset on it. Poroit suggested it might be this, but I did not check it because I assumed it was defaulting at 100%. my chromalox SSR PID did not do anything like this when I reset it (for my PCB oven). However the chromalox is a much more capable controller, this one is very simplified. I thought something insane is going on with the insulation. It was in bad shape and I did alot of patching to it with various compounds.Although, the chromalox interface is even worse. At least the omega is theoretically simple to interface. It's clean in comparison. When you learn them, I guess they are not so bad.