Oven Built: Looking to Wire. Wiring Diagram Attached for Review

[KoreyI]

Hi Everyone,

I have built my oven and now I am ready to wire the thing up. I used a rough estimate from a BTU calculator to determine that I will need about three oven elements rated at 2600 watts.

I was following a wiring diagram developed on another website by an individual named k3bguz and it has been incredibly helpful, but his schematic only uses (1) SSR and I figured ~7800 watts is too much for one 40A SSR. That is when I went ahead and tried to modify his schematic for implementation of a second SSR, but I wanted to check with some people before running this all and potentially burning down my garage

I've attached the diagram as I have modified it. Please let me know if you think this looks OK. If anyone has any insights, I greatly appreciate the help in advance.

Best Regards,
Korey

[ed_denu]

Re: Oven Built: Looking to Wire. Wiring Diagram Attached for Review

I believe the addition you made for a second ssr is fine.

That said the person creating this wiring diagram apparently does not understand the difference between a ground and a neutral as he shows a neutral grounded to the enclosure/oven. I'll assume the circuit is a 240 volt 2 wire with a ground. That will work fine as long as there are no 120 volt components such as a light or fan.

Look at the diagram and change any reference from neutral to ground and remove the reference of 120V between the hots and ground on the top of the diagram.

[KoreyI]

Re: Oven Built: Looking to Wire. Wiring Diagram Attached for Review

I believe the addition you made for a second ssr is fine.

That said the person creating this wiring diagram apparently does not understand the difference between a ground and a neutral as he shows a neutral grounded to the enclosure/oven. I'll assume the circuit is a 240 volt 2 wire with a ground. That will work fine as long as there are no 120 volt components such as a light or fan.

Look at the diagram and change any reference from neutral to ground and remove the reference of 120V between the hots and ground on the top of the diagram.

Thank you for the quick response. Appreciate the help. You assumption regarding the 240 2 wire with a ground is correct. I'll make the suggested changes and will follow up here with pictures of the oven once I get it all completed.

[KoreyI]

Re: Oven Built: Looking to Wire. Wiring Diagram Attached for Review

As promised, here are images of the oven completed and running for the first time.
I ended up using only one 40A SSR and decided to add a heatsink and fan. The oven outputs roughly 7600 watts and heats up to 400 in about 24 minutes (from freezing temps).
I am still struggling to get the PID temperature to regulate correctly. I set the target temperature to 400 and it heats up to about 425 before the SSR finally switches off, very strange. NOt sure if its in the wiring or if I have just programmed the PID wrong or whats going on... (shrugs) -- it gets hot though so thats a good start.

[ed_denu]

Re: Oven Built: Looking to Wire. Wiring Diagram Attached for Review

Wiring is not going to influence the pid's ability to maintain the set temperature. Have you run an autotune function yet. If not try that before anything else.

As part metal temperature is the most important aspect of correctly curing a powder coated item the oven being off 25 degrees or so isn't a huge issue imo.

[baz]

Re: Oven Built: Looking to Wire. Wiring Diagram Attached for Review

i agree with Ed, the 25 degree off in your oven is really important .thethging you want is (constant ), if you always get a 425 reading when set to 400 then you have no problem just set the oven to 375 to get a 400 reading .
and like Ed says it is the part metal temp that counts so make sure you have a infra red thermometer and set your cure time according to the part temperature.

[KoreyI]

Re: Oven Built: Looking to Wire. Wiring Diagram Attached for Review

i agree with Ed, the 25 degree off in your oven is really important .thethging you want is (constant ), if you always get a 425 reading when set to 400 then you have no problem just set the oven to 375 to get a 400 reading .
and like Ed says it is the part metal temp that counts so make sure you have a infra red thermometer and set your cure time according to the part temperature.

Hello again,

I am still struggling to get my oven to regulate properly and figured I'd post here to see if anyone had some advice. I have attached the final wiring that I did (not the same as above post) to see if maybe thats the problem.


I will set the target temperature on the PID Controller to 400 degrees. When the oven temperature reaches around 400 degrees, the "Output 1" Light on the MYPIN TA4 PID and the light on the SSR itself will begin to blink on and off. The oven temperature continues to rise until it has exceeded the target temperature. After it exceeds the temperature, both the Output light and the light on the SSR will go off completely. Yet, when I look into the oven, the elements themselves are still glowing on absolutely full power. Even if I turn off the PID using the switch, the elements still keep going.

Eventually, I unplug the unit from the wall and the oven elements immediately go off.

So at that point, it seems to me like the SSR is just stuck closed. But here is where things don't make sense to me:
I will plug the oven back into the wall. At that point, the temperature inside the oven is still above the target temperature. At that point the oven elements DO NOT turn back on. The oven eventually cools off below the target temperature and then at that point, the "Output 1" and SSR light come back on, and the oven elements start glowing again. It again exceeds the target temperature and the process repeats itself.

I additionally tried to troubleshoot and see if the SSR was stuck by completely disconnecting the cables from the PID to the SSR and seeing if the elements would work. They didn't come at all when I did this, so it seems that the relay is working.

As your earlier posts suggested, I tried Autotuning the PID according to the instructions I found on the internet. The Autotune process begins (the tuning light indicator turns on) but it never goes off (it doesn't even complete the autotuning). When I go to check the parameters in the settings, the P value is 2, the I value is 34, and the D value is 0.1, which is the default for this PID so I know that the autotune has not worked.

So, do I have a defective PID? Is my wiring incorrect? Is the SSR bad?

Thanks for any help.

[baz]

Re: Oven Built: Looking to Wire. Wiring Diagram Attached for Review

first i want to correct my previous post , where it says (the 25 degree off in your oven is really important) it should have read (the 25 degree off in your oven is really NOT important).
Ed is better than me at electrical diagrams but from what i see it seems ok , the ssrs also seem to be ok .
either the pid is defective ,wrong settings or pid not properly connected ( if you have multiple outputs on the pid).

[ed_denu]

Re: Oven Built: Looking to Wire. Wiring Diagram Attached for Review

There's nothing wrong with your wiring diagram, but generally I would place the switch between the ssr and pid. That way you can have the pid energized, but not cycling the ssr while you make changes, etc. You can pull the plug to completely shut off the oven as needed.

To make any future wiring diagrams more easy to follow, always be consistent with your conductor colors. IE: with a 240 volt diagram one leg of the hot power should always be colored red and the other black. Keep that throughout the drawing. The ground should be shown as green. For low voltage cabling between the pid and ssr I like to use blue, but any other color that shows clearly on a monitor is fine.

Lastly you need to state which terminals and how you have the pid connected to the ssr as baz questioned. I'm wondering if the pid 'thinks' it's controlling the ssr but it's not because it's wired incorrectly. That's the only scenario that makes sense to me. If that isn't the problem then there are some simple tests you can perform with a multimeter to further trouble shoot the issue.

[KoreyI]

Re: Oven Built: Looking to Wire. Wiring Diagram Attached for Review

Thanks again to both of you. I have found that you are right about the temperature fluctuation not being a super huge problem (I have started doing some coating and they are turning out pretty good, but i've read that inconsistent cure temp could affect durability(?)) ... turning the oven off by just using the plug just seems like a lot of unnecessary voltage to be messing with and on top of that, its a royal pain.

Ed, I have tried to make the changes in colors to the diagram as suggested and I have also included actual pictures of the PID wiring and the SSR here. Finally, I included a real life shot of the system if for some reason that would help.

[baz]

Re: Oven Built: Looking to Wire. Wiring Diagram Attached for Review

a simple test that you could do is when you have reached temp and your lights stop blinking and completly turn off and you say the elements are still on then you could check if you still have power coming in at the ssr on the low voltage side.if you don t have power there and the elements are on then your ssr is at fault and if you have voltage at the ssr then the problem is at the pid.

[ed_denu]

Re: Oven Built: Looking to Wire. Wiring Diagram Attached for Review

All the wiring you show looks fine. If the elements are constant on, then it most likely is a problem with the ssr, especially if what you stated earlier about the pid and ssr lights first blinking and then turning off completely(as they should) is still what you are observing.

I've looked but I can't find a decent version of the mypin manual(prehaps there isn't one) so I don't know if there are any parameters that need to be set. The simplest test if you are comfortable working with a multimeter is to check the voltage on the output side of the ssr when all the pid and ssr lights go off indicating that the elements should be de-energized. If you see 240 volts then the ssr would appear to be stuck closed. You can also check the input side of the ssr(set the meter to something around 20 VDC) and see if you get a DC voltage on the scale.

I guess it's possible the ssr could become stuck in the closed state and then return the the open state if you remove all voltage(input and output). It could be some sort of issue with clamping voltage within the ssr circuitry that's holding the output side closed. I've never seen this occur with an ssr but most anything is possible.

If you do the tests baz and I have pointed out you should be able to zero in on the fault.

[ed_denu]

Re: Oven Built: Looking to Wire. Wiring Diagram Attached for Review

After a little thought if you turn the switch off to the pid and the elements keep glowing red(give it a minute or so) then double check that the wiring is as you show. If it is as you describe it then replace the ssr. With no power to the input side, the ssr output side should always be in an open state.

[20_rc51_00]

Re: Oven Built: Looking to Wire. Wiring Diagram Attached for Review

could the issue be that you are trying to power 2 SSR's with the output from the PID?

[ed_denu]

Re: Oven Built: Looking to Wire. Wiring Diagram Attached for Review

could the issue be that you are trying to power 2 SSR's with the output from the PID?

That wouldn't be a problem as most pids can support multiple relays.