Need help to confirm wiring .

[ALAN C]

OK I put this together from someone else's idea and changed parts to use for a few applications .I have been seeing the people on here being so helpful and smart so I am here for help . I am not an electrician or anything but I like to tinker. Can anyone tell me if it will work without destroying components . I will be using three wire and ground for power. The light blue is the Neutral wire. The orange wires are low voltage wires and not very heavy . Power is first routed through main disconnect from the panel box.The smaller fuse will (should) protect the PID and Timer . The larger will help with element load protection.
The unit will be connected to a 30 amp circuit with 8-10 gauge wire and double pole 240 volt breaker . One buzzer is used for the timer expiration event and the other is a high temperature alarm controlled by the PID. Light and fan switch self explanatory. Using the Auber PID with an 40 A SSR with one output used for the high temp alarm. The SSR is mounted on large heat sink and has fan under it mounted on nylon standoffs . Fan is powered by 120-12 volt transformer .
The timer has one set of contacts to drive the DC input signal from the PID to the SSR(this allows the timer to turn off the element heating function) and the second is used to sound an alarm at the expiration of the timed event. The (on/off/on DPDT) switch adjacent to the Inkbird timer allows for manual or timed mode. In the off position the elements are disabled but the PID is energized for parameter changes and temperature readouts. In the manual mode, the PID engages the SSR and will manage to the set point. You can then monitor temperature prior to starting the timed cure cycle. Switching to the timer position begins the timed cycle based on the timer’s setting. At expiration of the timer, the elements are disabled and the audible alarm sounds. Switching the toggle to the off position silences the alarm.
Toggle/Timer operational notes: The toggle is wired so that in the off position the PID remains powered on, but has no control over the elements. If the toggle is switched to either manual or timed mode, then the DC power feed from the PID is fed thru the Timer Relay 7 NC contacts to the SSR and the PID can manage to the Set Temperature. The Timer relay contacts change relationship(NO/NC) at expiration of the timer, therefore when the timer expires, the Relay 7 switches to the NO position and the DC power feed from the PID to the SSR is opened. The high temperature alarm functions in a similar manner as it is connected to the NO contacts, so when the Timer expires the Relay9 contacts change from NC to the NO position and the alarm sounds. (Or so I hope). Well Hopefully this has confused everyone as much as me . Thanks

 

[Broken Crow]

I don't want to give bad advice (and since I have brain damage that happens too easily), but something tells me that timers don't pass the signal along that way...though I could well be wrong and will be looking here myself for correction.
In the meantime, Welcome to HBT! There's a recent thread with answers by some of our most competant DIYers:
https://www.homebrewtalk.com/threads/pid-timer-conundrum.725913/

 

[ALAN C]

I don't want to give bad advice (and since I have brain damage that happens too easily), but something tells me that timers don't pass the signal along that way...though I could well be wrong and will be looking here myself for correction.
In the meantime, Welcome to HBT! There's a recent thread with answers by some of our most competant DIYers:
https://www.homebrewtalk.com/threads/pid-timer-conundrum.725913/

Hi Broken Crow, Lol , Don't worry I have some myself. Yes , I read that thread and it looks close to another diagram that I have been working from which has the same layout for timer ; in a circle with only 8 connections .I just don't know enough about the timer to be sure my connections would coincide with the other one with different layout. In my head I think it will work but that doesn't get me anywhere lol.
Thanx

 

[Broken Crow]

The In/Out's of a single PID is about the limit of complexity that my own cognitive-modeling can handle...But my impression is that the timer output is meant to switch the PID power, not the control signal... again; I could be wrong. If you're using the search function on here; Try using your terms in the search box and clicking the 'search by member' box with @doug293cz ...He's an authority on here and a very large number of us have used his schmatics or had our own corrected by him, so watch for his name in your searches.

 

[doug293cz]

I'm looking at this design, but it is a bit of a rat's nest, so hard to follow. Also, the timer and PID don't have any info on what's connected to each terminal, so I have to go look that up.

Some questions and comments:

• What is your main disconnect device? Whatever it is, you don't have to switch the neutral with it, just the hot lines.
• Why is the thermocouple switched? Thermocouples should use special extension wire, connectors, etc. to prevent false readings, and most switches are not designed for dealing with thermocouple wires.
• Fuses do not protect devices, they protect wires from overheating in the case of device failure, or other types of shorts. If a device causes an over-current event, then the device has already failed.
• Since you are feeding the control panel from a 30A service, you don't need a 30A fuse inside the control panel, the service breaker will protect the wires.
• For the low current 120V wiring, you should have separate bus bars, and a fuse between the high current line 1 and line 2 bus bars and the low current line 1 and line 2 bus bars (two fuses.)
• What is the current draw (or watt rating) of the 120 volt fan and the two 120 volt indicator lights?
• What is the duty cycle of the heaters? If they will be on more than 4 hours, then code requires the load not be more that 80% of the service breaker rating - 24A in your case. 2X 3000W heating elements will draw 25A, which would put you over the limit, unless your heating will be intermittent.
• Depending on switching the control signal inputs to an SSR, will not work if the SSR goes into latch mode, which is the most common failure mode. You need to remove the line power to the SSR if it latches. But it will work as long as the SSR doesn't fail. I like to put a contactor in series with both line 1 and line 2 upstream of the SSR so a failed SSR can be shut off, without having to power down the entire system.
• I like to put a 240V indicator lamp in parallel with the heating elements to tell you when the elements are actually receiving power. This lamp will let you know if the SSR is latched, or if the control signal path to the SSR has failed.
• The ground should be carried thru to the heating elements.
• The 10 AWG wire needs to be continued after the main disconnects for all wires that carry the heating element current. It's best if the drawing makes this obvious.

That's all I've got so far.

Brew on

 

[ALAN C]

Hi Doug293cz ,

First time using wiring program and of course it was free version which made it harder .
My main disconnect is a rotary cam changeover switch 80A 3 pole 2 position . I don't know why thermocouple is switched . I believe he did it that way because he was using two of them . A clip on and a regular one . I guess I can eliminate it .
This is where I got most of my info - https://forum.caswellplating.com/fo...oven-building-forum/11867-oven-controls-build .
The problem was I built it before I asked questions and when I finally asked a question , no one over there answers anymore.

For the low current 120V wiring, you should have separate bus bars, and a fuse between the high current line 1 and line 2 bus bars and the low current line 1 and line 2 bus bars (two fuses.)

Can you explain ? My understanding is each line is 120 volts . Red , Black ,Neutral each 120 on their own .

What is the current draw (or watt rating) of the 120 volt fan and the two 120 volt indicator lights?

The fan I will have to check. It's just a wood stove blower fan 120 v . The buzzers are supposed to be 20 mA

The duty cycle for elements would be 250F for two hours . I haven't got any wire run from main service panel yet so I can go with larger breaker if need be .Would you recommend a 40 amp maybe ?

I definitely have no room for a contactor in box . I will be with it when in use .

I like to put a 240V indicator lamp in parallel with the heating elements to tell you when the elements are actually receiving power. This lamp will let you know if the SSR is latched, or if the control signal path to the SSR has failed.

I guess I can eliminate the switch for thermocouple and plug the hole with a light for the elements and figure out how to wire it correctly . Wouldn't that light flash along with the SSR while elements are getting current ?

The ground should be carried thru to the heating elements.

So connect ground to box mounting the elements ?

So there should be three 10 g wires . One from red buss bar to elements , one from black buss bar to SSR 1 and one from SSR 2 to elements ?

Here are PID and TIMER diagrams

Thank You so much !

​

 

[ALAN C]

Checked circulation fan and it says .45 amps.

 

[ALAN C]

Oh Crap! Was looking at the watlow he used and the wiring will not work the way I have it. I tried to figure out the cross reference of connections and I can not. I did run 8AWG down through conduit to element connections so that should be plenty heavy. I had it on hand. The elements have a solid nickel type high temp wire with high temp connections coming from inside oven to underneath where they go to junction box. Back to drawing board. My electrician friend is supposed to come tomorrow and run some wiring for me .Here is watlow PID ed used . I am getting very disappointed in this project. Had it been easier to buy the exact parts things may have went easier. Live and learn .

 

[ALAN C]

The more I look at it the more I see wrong. My PID has 14 connections , not 12. I guess I concede at this time. Now is the time to offer to pay someone for help.

 

[ALAN C]

I am still stuck on this . I have finished up other projects like sandblaster and a miserable fight with a compressor so am ready to get back to something gentler like wiring . Any help would be appreciated.

 

[doug293cz]

I've been looking at how the timer you have purchased operates. Unfortunately, I don't think this timer will work for what you are trying to do. The problems with the timer are that it resets and starts counting immediately when power is applied. When the timer is running, output A closes the NO contacts, which would allow you to run the PID control signal thru the A output, but before the timer starts running, the NO contacts are open, so no control signal can be passed to the SSR, and you can't run a heat-up phase to get your equipment up to temp.

Brew on

 

[mashdar]

It doesn't look lik you are switching both hots on your 240V. If you don't, you are leaving the "off" element at 120V, which is a recipe for accidents.

 

[doug293cz]

It doesn't look lik you are switching both hots on your 240V. If you don't, you are leaving the "off" element at 120V, which is a recipe for accidents.

You don't sound like you have any design experience. It is standard practice to only put an SSR on one hot leg to control element power, but have another two pole disconnect that will remove all voltage for safety. Two SSRs would double the power lost to the parasitic resistance of an "ON" SSR, and SSRs don't remove voltage anyway, due to the way semiconductor switches work.

Brew on

 

[ALAN C]

Hi doug293cz ,
Can you tell me one that will work ? At this point I am stuck and can't do anything.I should have studied it further , but in the end it still would have confused me. Some days my brain works great others I can't add .Tell me what will do the job and draw me the diagram and I guess I need to put out some more money.All is not lost as in the end I will have functioning oven and stay safe . I will order parts as soon as I know what to get.
Thanx

 

[doug293cz]

Hi doug293cz ,
Can you tell me one that will work ? At this point I am stuck and can't do anything.I should have studied it further , but in the end it still would have confused me. Some days my brain works great others I can't add .Tell me what will do the job and draw me the diagram and I guess I need to put out some more money.All is not lost as in the end I will have functioning oven and stay safe . I will order parts as soon as I know what to get.
Thanx

What temperature will your oven run at? A full description of every operational step that you want to happen, and in what order, is needed to insure that the chosen components will do the complete job.

Have you reviewed this design, which is for an application that sounds very similar to yours? It just doesn't have the alarms or the manual control mode that you have asked for. You can read about this design, and what it is supposed to do in this thread.

Another option is to just build the controller around an Auber EZBoil DSPR300 (or 310D or 320.) These controllers have their own built in timers.

Brew on

 

[mashdar]

You don't sound like you have any design experience. It is standard practice to only put an SSR on one hot leg to control element power, but have another two pole disconnect that will remove all voltage for safety. Two SSRs would double the power lost to the parasitic resistance of an "ON" SSR, and SSRs don't remove voltage anyway, due to the way semiconductor switches work.

Brew on

I didn't realize it was a ssr. Why wouldn't you use a normal power relay for this?

I don't think I've ever seen an ssr in heater circuits, but maybe for this application you're doing very short cycles?

edit: also, I don't deal with appliances, but for building wiring, switching one leg is no bueno

 

[doug293cz]

I didn't realize it was a ssr. Why wouldn't you use a normal power relay for this?

I don't think I've ever seen an ssr in heater circuits, but maybe for this application you're doing very short cycles?

edit: also, I don't deal with appliances, but for building wiring, switching one leg is no bueno

Yes, SSRs are used because of very short cycle times, which would wear out mechanical relays/contactors fairly quickly, and be very noisy as well.

All good 240V (split phase) designs contain a two pole air gap disconnect for completely removing power from all panel power outputs. The SSR on a single line is just for modulating the power to the elements.

Brew on

 

[ALAN C]

Sorry I have been away. Temps will be around 300 . I want to turn on my main disconnect and have the power go to a on off on switch . The (on/off/on DPDT) switch adjacent to the timer allows for manual or timed mode. In the off position the elements are disabled but the PID is energized for parameter changes and temperature readouts. In the manual mode, the PID engages the SSR and will manage to the set point. You can then monitor part metal temperature prior to starting the timed cure cycle. Switching to the timer position begins the timed cure cycle based on the timer’s setting. At expiration of the timer, the elements are disabled and the audible alarm sounds. Switching the toggle to the off position silences the alarm. The toggleshould be wired so that in the off position the PID remains powered on, but has no control over the elements. If the toggle is switched to either manual or timed mode, then the DC power feed from the PID is fed thru the Timer Relay 1 NC contacts to the SSR and the PID can manage to the Set Temperature. The Timer relay contacts change relationship(NO/NC) at expiration of the timer, therefore when the timer expires, the Relay 1 switches to the NO position and the DC power feed from the PID to the SSR is opened. The high temperature alarm functions in a similar manner as it is connected to the NO contacts, so when the Timer expires the Relay 2 contacts change from NC to the NO position and the alarm sounds. If I can't do any of that I will just go with no timer , no alarms, and only the PID to run the elements through the ssr . I looked at that diagram and read post but it's not what I want considering I would have to buy all different pieces .

Thanx