Help the uninnitiated: PID's, SSR's, contactors, and timers

[KAdams4458]

I have to rework my broken oven quickly, and while I've been studying oven building in order to construct a large oven, I'm not prepared to do it yet.

The oven in question is a re-purposed kitchen oven, and it used to hold temperature very closely before the thermostat died. I guess after 30 years, that can happen.

I want to go the PID route, as it is definitely more cost effective than replacing the thermostat/switch, and much simpler than rewiring the oven to use cheap oven parts that are not exact replacements. The oven in question uses two 240 VAC heating elements, one 2600 Watt, and one 3000 Watt. I'd like to control both at the same time, as the oven was originally designed, and since both draw about 23.3 Amps together, I should be able to switch them both with a 40 Amp SSR or contactor.

Do I need a timer? Do I want a timer? Is there such a thing as a PID with a timer built in? The Crumby Martha Stewart oven timer I have been using is anything but accurate. I see Auber Instruments offers a snazzy timer for a decent price, but it almost seems like overkill. Has anyone used one?

Speaking of Auber Instruments, I was thinking of using them for everything I need. Is their basic SYL-1512A PID going to be okay? I have no problem spending a little more on a different model. I'm not cheap, I just want something that I will be pleased with. Maybe I want to be able to control the ramp up rate in order to help powders flow a bit smoother?

SSR's versus contactors... Would the SSR's be worth the extra expense and headache of using heat sinks, etc?

I don't want hand-holding, but I'm completely unprepared for this. A little guidance would be more than welcome. Ideally, I'd like to be able to order the parts before the weekend arrives.

[ed_denu]

I have to rework my broken oven quickly, and while I've been studying oven building in order to construct a large oven, I'm not prepared to do it yet.

The oven in question is a re-purposed kitchen oven, and it used to hold temperature very closely before the thermostat died. I guess after 30 years, that can happen.

I want to go the PID route, as it is definitely more cost effective than replacing the thermostat/switch, and much simpler than rewiring the oven to use cheap oven parts that are not exact replacements. The oven in question uses two 240 VAC heating elements, one 2600 Watt, and one 3000 Watt. I'd like to control both at the same time, as the oven was originally designed, and since both draw about 23.3 Amps together, I should be able to switch them both with a 40 Amp SSR or contactor.

Do I need a timer? If you are using the oven for PC work, then most powders require that they be baked for a specified time period after the part reaches temperature. Therefore timing the duration of the cure cycle is necessary, either manually or electronically. Do I want a timer? Is there such a thing as a PID with a timer built in? Yes, there are models that have timer capabilities built-in. These are the more expensive pid's from Auber, Watlow and others. The Crumby Martha Stewart oven timer I have been using is anything but accurate. I see Auber Instruments offers a snazzy timer for a decent price, but it almost seems like overkill. Has anyone used one? I have not used this model. I have read the documentation and it briefly comments on using the timer connected to an alarm relay of the pid to function as a timer for the elements. The documentation is a little lacking, but apparently you would use the NC contacts of the timer to control the ssr. When the timer is activated by the pid alarm contacts, the timer begins the count and at the conclusion of the count, the NC contacts would open, shutting off the ssr. On my oven I placed a spring wound timer in the circuit.

Speaking of Auber Instruments, I was thinking of using them for everything I need. Is their basic SYL-1512A PID going to be okay? Depends on your needs/wants. The lower priced models function well, they just do not have all the features(ramp/soak) that the higher priced models have. I have no problem spending a little more on a different model. I'm not cheap, I just want something that I will be pleased with. Maybe I want to be able to control the ramp up rate in order to help powders flow a bit smoother? There are people here that are using ramp/soak features. I'm sure someone will comment on the usability of this feature.

SSR's versus contactors... Would the SSR's be worth the extra expense and headache of using heat sinks, etc? Kind of a personal choice imo. There are some pluses and minus to each. Many people like the contactors, I prefer an SSR.

I don't want hand-holding, but I'm completely unprepared for this. A little guidance would be more than welcome. Ideally, I'd like to be able to order the parts before the weekend arrives.

see above comments

[KAdams4458]

see above comments

You know, it might be hard to beat the simplicity of a spring-wound timer. I like the sound of that. I will go read through the various models of PID temp control units they have and see if I can make sense of the features. The documentation available on the Auber site is not very revealing, but I'll give it another shot.

[KAdams4458]

Well, I thought about it for a while, and determined that I don't really need the ability to control temp rise and fall rates, and if I do, well, I'll just upgrade. So, here's what I ordered the other day. From my planning and reading, this should give me a working oven again.

Universal 1/16 DIN PID Temperature Controller [SYL-2362]

MULTIFUNCTION TIMER, COUNTER, TACHOMETER [ASL-51]

K type thermocouple 4probe, Smoker, Oven [TC-K3MM]

Contactor, 2 pole 40 A [CN-PBC402-120V]

I also picked up a few relays and some lighted SPST rocker switches to control power to the timer, PID, and of course, one for the oven lamp. They're LED-illuminated, and light green on closed and red on open. Seems kind of idiot-proof... I hope.

My wife and I have been joking back and forth about how the poor oven is going to look like the illegitimate love child of the original Knight Rider car, and a Whirlpool oven of similar vintage. It's a good thing that I'm really busy, or I'd have the time, and the sense of humour to actually make it talk.

[ed_denu]

A talking oven! I like that idea. Let us know when you work out details.

I'm also curious as to how the timer gets wired into the circuit. The documentation for the timer is a little lacking so when you get it working, please share. I have a guess as to how it would be wired, but I would like to know for certain.

[KAdams4458]

A talking oven! I like that idea. Let us know when you work out details.

I'm also curious as to how the timer gets wired into the circuit. The documentation for the timer is a little lacking so when you get it working, please share. I have a guess as to how it would be wired, but I would like to know for certain.

Your guess is as good as mine at this point. For the time being, I may not even wire it to control the oven. I was just tired of using little countertop oven timers that repeatedly failed or were completely in accurate - They just don't seem to make them like they used to. I'll see what I can figure out about the Auber timer, and will post the details.

By chance, can anyone tell me a thickness range for the panel that the Auber PID mounts to? I'm guessing the timer will be similar. I was hoping I could at least fabricate the new front panel for the oven ahead of time, and don't want to end up using a piece of aluminum that is too thick.

[KAdams4458]

Wow, does Auber ever ship fast. I ordered the stuff on Friday afternoon, and it showed up in my mail box today in Washington State. I really didn't expect that.

Anyway, I've always been a guy that prefers printed papers. Things just always seem to make better sence when I have a paper in hand, compared to reading stuff on a monitor. Well, let me tell you, the documentation that come with the timer and PID just stink in either form. I'll be spending the evening attempting to sort things out.

[KAdams4458]

Well, I had everything working for a little while.

Let me just say something here...

Put a fuse between your PID and the contactor coil! If the coil ever shorts, you'll just need to replace a cheap fuse along with your contactor, and not the entire PID controller.

You can probably guess that the coil in my contactor failed and took the PID with it. Before I hooked everything up, there were several Ohms of resistance in the coil, and now there is not. There was nothing I could do about the contactor going bad, but I could have saved the PID by simply installing a fuse. Oops.

[CarWiz]

The contactor problem seems to be a popular event lately. It's happened with a number of forum posters and email correspondents. The idea of a fuse between the PID and contactor is a good one and should be encouraged for all users.

Maybe a new "sticky" or an update to the parts listings is in order.

[Grumple]

I put one on mine as it seemed like cheap and simple insurance. I guess I will see how good it works later on if/when one on my coils shorts. Its definitely a good idea for a sticky for the new builders and maybe some of the schematic makers could add one to future drawings.
Grumple