Kiln re-wiring help!

Storm Crow

Storm Crow

Joined
Apr 12, 2006
Messages
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I have a 220 amp kiln that I bought to use for hardening large items. It came with a sitter controller that I'm looking to replace with a digital controller. I know nothing about electricity except that it's wise to avoid touching it, but a buddy of mine will be helping to do the work. With his advice, these are what I bought:

http://www.lightobject.com/JLD612-Dual-Display-PID-Temperature-Controller-P43.aspx

http://www.lightobject.com/10ft-3M-K-type-Thermocouple-with-8cm-pole-thread-P488.aspx

http://www.lightobject.com/90A-Solid-State-Relay-SSR-DC-In-AC-Out-P64.aspx

As well as a heat sink for the relay.

He thinks he knows what we need to do to wire it, but isn't certain. Anyone have any words of advice? Did I get all the necessary parts?

Here's the kiln:



It's the one on the right. The one on the left is a 3 phase model with a digital controller that I've had for a while and use for tempering long blades and things that need to be tempered at a higher degree than a toaster oven reaches.
 
The thermocouple might not be ideal; spec shows 450 degC (842 degF). It's a type K so it'll read higher, it'll be either the pot seal or the sheath that limits it. You should be able to keep the pot seal cool enough on the outside of the brick, but it'll probably limit the insertion depth into the chamber.

Sheath material tends to be less of an issue. It'll oxidize when it gets hot and the oxide will flake off when it cools, losing some thickness with each cycle.

If the pot seal is cool enough, it should work OK, but will have a limited life.

The 90A SSR will need a pretty big heatsink if you are using that sort of current and it's worth noting that a lot of the ebay heatsinks are only rated to 15A or so.

The TET612 looks the same as the SET-620. I set one up for a guy on British Blades a while back. The notes I made may, or may not, help.

http://www.britishblades.com/forums...mperature-controller-for-a-heat-treating-oven
 
I sure hope you have BIG wires to your shop....220 AMP kilns draw more power than most whole houses can take. I would use a 220 VOLT kiln running at 30-50 amps or so :)

You need a different TC than the one you listed. Type K with 1/8" (8-10 gauge) leads is what you want. You will need a terminal block for it, as well as type K TC wire to connect it to the PID. The SSR needs a heat sink. The stickies have a section on PID control with all the info needed, including part numbers and suggestions.
http://www.bladeforums.com/forums/showthread.php/782574-PID-CONTROL-FORGE-Salt-Pots-and-more
 
Although that is a good PID, I would suggest the option of a programmable one that you can ramp with. You can also program it to anneal complex alloys. Like this http://www.auberins.com/index.php?main_page=product_info&cPath=1&products_id=4. The Thermocouple you need looks like this with the terminal block http://www.auberins.com/index.php?main_page=product_info&cPath=20_3&products_id=39. If your Oven has exposed elements I would also suggest 2 SSRs so that both legs of the 220 are shut down. Don't know if the current wiring has a shutoff when the door is open which is another thing I believe in iff you have exposed elements. If you look at the wiring diagrams in the stickys Stacy pointed you to, they have both these features. It really isn't that hard to wire an oven. Just use good components and heavy enough wire for the currents involved. Good luck. Jim
 
Thank y'all!

Stacy - Now, I done did told ya that I don't know nothing 'bout no 'lectricity. I'm a English major, durn it! :) Volts, then. I'll show my buddy the sticky and we'll sort out.

Jim - I'm going to be sticking to pretty simple steels. Mostly just want to get to critical temperature on 4140 and 5160, so all I need it to do is heat to that and maintain it.

So is this thermocouple or the one you linked to more appropriate? http://www.lightobject.com/High-Temperature-2370F1300C-10ft-Ceramic-K-type-Thermocouple-P411.aspx I'll buy whichever one you recommend.
 
That one should work. The ceramic sheath will slow the response of the setup a little bit. Might cause you some over shoot. Recommencement you set your target temp a little low then after everything has settled down raise it up the last 10-20 degrees. I run a sheath TC too. I just set my program up so it slows down the last 25 degrees.
 
I got one of those LightObject solid state relays for my scratch built 220v annealing oven. I ran the thermocouple to an Arduino instead of a PID, but that is another story. See the little grey sticker, where it says 90A? You can't see that on mine anymore because it melted. What you can do is run the output of the SSR to a 220v contactor with 120v coils (takes a 120v signal from the SSR to turn on the 220v). That gets both legs of the circuit shut off like SteelSlaver recommends. Contactors are loud clicky things, you can use mercury relays instead, but they cost. Lemme know if I can clarify any of this.
 
Thank y'all! My buddy got it wired up today except for the thermocouple. I stood by and handed him things. :) Got the thermocouple ordered this afternoon and it's supposed to be on its way already. Hopefully I can fire it up and test it later on in the week.
 
Storm Crow said:
I have a 220 amp kiln that I bought to use for hardening large items. It came with a sitter controller that I'm looking to replace with a digital controller. I know nothing about electricity except that it's wise to avoid touching it, but a buddy of mine will be helping to do the work. With his advice, these are what I bought:

http://www.lightobject.com/JLD612-Dual-Display-PID-Temperature-Controller-P43.aspx

http://www.lightobject.com/10ft-3M-K-type-Thermocouple-with-8cm-pole-thread-P488.aspx

http://www.lightobject.com/90A-Solid-State-Relay-SSR-DC-In-AC-Out-P64.aspx

As well as a heat sink for the relay.

He thinks he knows what we need to do to wire it, but isn't certain. Anyone have any words of advice? Did I get all the necessary parts?

Here's the kiln:



It's the one on the right. The one on the left is a 3 phase model with a digital controller that I've had for a while and use for tempering long blades and things that need to be tempered at a higher degree than a toaster oven reaches.
Click to expand...

I work at the factory that made the kiln on the left. It is nice to see one of our kilns in use.

The kiln you are working on has a Dawson Kiln Sitter. After you add the digital controller, the Kiln Sitter might make a handy backup shutoff device.

Sincerely,

Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
 
Arnold - I've appreciated having the Paragon around. It came out of a local high school and is 3 phase, so I picked it up relatively cheaply on Craigslist, and have used it quite a bit, though I don't really challenge its capabilities.

On this new one, I got my thermocouple installed, set the parameters on the PID, ran the Autotune function, set the temperature, and can't figure out how to get the blasted thing to start heating. I've looked through the manual (it'd be great if they got someone who actually speaks English to do the translation), scoured Youtube, and cannot find how you get the darn thing to actually start heating. It's displaying the temperature that I want it to be and the actual temperature, but it's not heating. Anyone have step-by-step instructions for a dummy in getting this thing to turn on?
 
I am not sure about that PID and how it functions, but the ones I use have no off/on type function. Once I set it it starts working unless I place the one that is programmable on hold. I would check to the SSR to see if it is getting turned on. If it is then check the connections to the elements if not, check the wiring from PID to SSR. Do you have a door switch and is it getting closed?
 
No door switch. The SSR did get dropped during the re-wiring, so when I ordered the thermocouple I got a backup SSR too. Maybe I should swap 'em out and see if that does the trick.
 
There are a few things that could keep this from coming on:

1) PID isn't sending an ON signal
2) SSR isn't getting an ON signal
3) SSR isn't getting 220v
4) SSR isn't sending 220v
5) heating element isn't getting 220v
6) heating element is open

You need a meter to debug this. To elaborate on the troubleshooting flow:

1) I build these from scratch because I find the PID manuals nearly incomprehensible. I can't provide much help here except to say pick a setpoint above ambient to get an 8v signal out. Set your meter to DC volts, make sure the bananna plugs for the probes are in the ground socket and DC voltage socket, set your DC voltage range to around 20v, and measure the relay output on the PID. According to the spec sheet, you should get 8v DC output. If you don't see the 8v, something isn't right in you PID.

2) If you can measure 8v out on your PID, do you get 8v at the screw terminals of the SSR? If you disconnect the signal wire from the PID, do you get 8v there, but not on the PID? If the voltage goes away when the wire is connected to the SSR, the SSR could have a dead short internally and need replaced (not likely).

Is the polarity correct between the PID and the SSR? With the grounded black meter probe on the negative (-) side of the SSR input, do you see a minus sign flashing on the voltage reported by the meter? That would indicate the wires are crossed, reverse them. If you haven't done much with a meter, try putting it on a battery to see what shows up when you reverse the connections.

3) Is the SSR getting 220V AC? This is where you can get killed if you do it wrong. Seriously. If this is your first time working with this much voltage, you might get somebody to help show you how to probe this. Make sure your meter is set to measure AC volts (switch it off DC) and make sure your probes don't have any exposed bare wire. Turn off the circuit breaker, connect the probes, get where you can see the meter (but don't touch it) and switch it on. Connect one probe to one of the hot legs of your circuit, where the hot leg is connected to your heating element. Connect the other probe to the hot leg that goes between your breaker box and the input of the SSR. When you trip the breaker, you should get around 220V AC on the meter. If you don't, something is connected wrong between your breaker box and your controller input.

4) At this point, you should have 8v DC on the SSR, 220V AC going into the SSR, and be getting 220V AC out of the SSR. Throw the breaker, connect the meter probe to the side of the SSR that connects to the heating element, turn the breaker back on. You should have 220V AC coming out of the SSR to supply the heating element. If you don't, the SSR is likely bad. To double check, turn the breaker off, and bypass the SSR by connecting the hot leg of the 220V coming from your breaker box directly to the heating elements. Use a wire nut for safety. Turn the breaker back on, the heating elements should get hot. There is nothing to turn the elements off now, so turn the breaker back off before they overheat and replace the SSR.

5) If you are getting 220V AC out of your SSR, turn the breaker off, connect the probes to the terminal block that supplies voltage to the heating element, turn the breaker back on. You should see 220V supplied to the heating element. If you are getting 220V here, but no heat, your element is likely broken somewhere. Kill power with the breaker again. Disconnect both legs of the 220V: the one coming from the breaker box, and the one coming from the SSR. Set the meter to measure resistance in Ohms. Touch the probes together and observe how the meter changes. It should do something similar when you touch the probes to the coil, if the meter just keeps blinking when you connect it to the coils, the coils are likely open. You can replace the coils. I've had some luck just find where it is open, heating the wires with a torch, and twist them back to make a connection. You only have about 500ms after you take the torch off the wire, so twist quick. If you twist after it cools, the element will break.

Let me know if I can clarify any of this.

- James B
 
First thing to check is that the controller is set for heating, not cooling. Rd should be set to 0.

Next, set the setpoint way up high. Wait a few seconds. Is there an output showing on the bottom light on the left-hand side?

If the "out" light does not come on, the problem is within the controller. Most likely it will be something set wrong when you programmed it.

If it won't heat, it can't autotune, so I can't understand what has happened there. Take a look at the P, I, D, SouF, Ot and Filt values and let us know what they are; it's possible they are waaay out.

If the "out" light does come on, check to see whether the output terminals on the back are giving an 8V (or thereabouts) DC output using a voltmeter (you are probably best doing this with the SSR disconnected, since a faulty SSR could pull the voltage right down and a functioning SSR will feed 220V into whatever is on the output side; perhaps you?).

Then it's a case of work through James' sequence above.
 
Ok guys I wired up James kiln, and one of my own as well. They're wired from a diagram I got from Harvey dean, that he got from someone else. I went thru the above and am not getting 220 out of the ssr. When I hooked them direct the elements got hot right away. Could it be that we got the wrong relay? Thanks for helping James and me as well. Thanks Luke
 
SSR looks fine; DC to trigger and switches AC.

There is, I think, an LED on the SSR which should be on when it is triggered.

There is a light on the controller which tells you the controller is trying to trigger the SSR.

Is the controller trying to trigger the SSR?

If so, is the SSR trying to respond to the signal from the controller?
 
I am not sure how to tell if its trying to work or not. I know the voltage is low comin out of the ssr. I wonder if my settings are wrong I'm going to post them later. James are the same as I programmed his pid also. Thanks Later Luke
 
I am willing to bet something is wrong with the wiring. Check all switches, fuses, and connections again.

You need a person who knows what he is doing with electric circuits to check it out. He doesn't need to know about PID controllers to check the circuitry. He should have a good multimeter. He will be checking a circuit with the power on, so he must know what he is doing or he will get a bad shock....or blow up his meter.

Temporarily disconnect the DC SSR control wires from the PID and apply a low voltage from a 9V battery or other DC source. The coils should turn on if you do this. If they turn on, then the problem is in the PID, if they don't turn on, the problem is in the power wires to the coils and SSR, or the SSR is bad.

Things to check:
1) Is there a + and a - DC wire coming from the PID to the SSR ( terminal 3&4 on SSR)? There should be two wires, and they are polarity sensitive. Make sure they are on the right PID and SSR terminals.
2) Is there AC voltage at the incoming terminal on the SSR - terminal 1 or 2. The voltage needs to be checked to ground on each terminal first, Then checked with the probes on 1 and 2. It should read 120VAC on each terminal to ground, and 220VAC across the terminals.
3) Is the thermocouple connected properly. It is polarized, and needs the +/- on the right PID terminals. You should read a few millivolts at the terminals, and if you heat the TC tip with a torch, it should increase the voltage output.
4) If all the above is correct, then turn on the PID so it should be firing the coils. Is there a + and - DC voltage read at the SSR terminals 3&4?
5) If no DC voltage is detected, check the PID to assure it says it is in the RUN mode. If it seems to be ON, and appears to be firing the SSR, but there is no DC output to the SSR, then the PID is bad. If there is DC power from the PID to the SSR, then either the power wiring is wrong, or the SSR is bad.
 
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