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[KZC]

I have the SWA 2451 on my electric powder coating oven. It has been working fine, but I think something has gone wrong. I remember when it would ramp up, it would turn the burner on and off every few seconds, seemingly random. Now, when I start it, it cycles about 4 times, then it stays on until about 10 degrees from my set temp of 400. It will hold 400 and cycle fine, but it stays burner on until about 390- which I don't remember it doing this previously. Is my PID failing?
thanks in advance
Don

[Kkane]

It is normally to see the output/burner cycling on/off. See guide below.

https://www.auberins.com/index.php?main_page=page&id=9&chapter=0#4

It is hard to say when to start the cycling process. It may also be related to other facts such as your ambient temp. SWA-2451 does not control the ramp rate. If the temp control at your end temp (400 for your case) is fine, no need to worry about the controller.

[KZC]

Thanks for the reply - as you stated, "its normal to see it cycle on and off" - that's why I'm concerned, it doesn't cycle anymore (at least not like it used to). And yes, it's not a big concern that because doesn't go over the max temp of 400 - except that with the burner on constantly until 400, the items on my lower shelf (close to the burner) are getting way too hot exposed to the burners that are constantly on. When it used to cycle on and off up to 400, it didn't over heat the bottom of the oven area and the lower hanging items.....something just seems different.
Thanks for your reply, I appreciate any help

[Kkane]

In that case, you can consider running auto-tune at 400 degree to tune the controller itself and see how it works. If you have run auto-tune before, please write down your current P, I and D values somewhere else, then start the auto-tune.

[KZC]

thanks for the advice, I will give auto tune a whirl and see what happens. I got a little time this weekend to watch and play with it. It seems pretty consistent that it will cycle pretty quickly for the first 4 minutes, then it goes solid ON. I noticed if I kill the master switch and the power, it cycles again for 3-4 minutes then solid again. UNitl it gets to about 390, then it cycles again.

I will try auto and report back, thanks
Don