Kiln PID Controller retrofit?

So for your 6KW kiln, you want at least a 40 amp SSR.
Its ok to oversize the SSR.
It is not ok to undersize the SSR or the heat sink.
And not less than a #8 wire copper.
And a 2-pole, 40 amp breaker (or a 35 amp breaker if you can find that size).

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You have to be careful with the color coding on the thermocouple too.
I think some of the color markings on thermocouple wires vary.
On mine, blue is negative (-), and red is positive (+).

And don't neglect running a ground wire from your panelboard ground bus to the metal frame of the kiln, and for good measure ground the heat sink too. The ground wire needs to be a #10 copper.

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I think some people use two SSR's, but I only intend on using one.
I don't think two are needed.

I turn the circuit breaker off before I reach into the kiln to either load or unload it.
You can add a 2-pole 240 volt disconnect switch to avoid having to switch the breaker.

Every terminal that has a (+) or a (-) marking has to be connected so that the correct polarity is observed.

If all this is not perfectly clear, I would recommend that you not try to connect a controller and SSR by yourself.


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I've been using a 40 Amp TRIAC with the gate switched directly by the temp controller relay contacts, it has the advantage of being cheap and simple with a known rating of TRIAC device (unlike the cheap SSR's). It relies completely on the temp controller relay contacts entirely for the galvanic isolation. Most semiconductors fail short circuit which would keep the elements on continuously so a second contactor on the "Alarm output" contacts could cut off the power. The BTA40 series TRIACS have an electrically isolated body which makes heatsinking easy.



https://www.st.com/content/ccc/reso...df/jcr:content/translations/en.CD00002263.pdf

 

You'll need thermal paste for the heatsinks to work right. The type that you use for a computer CPU

 

X2. And a cheap computer fan on the heat sink is not overkill, either.

 

The Fotek SSR on my 3D printer bed shorted and overheated it. Replaced it with a Crydom. The REX temperature I bought to experiment with plastic welding at work is so far off we ruined a lot of parts. Replaced it with Fuji that I used years ago and did a fantastic job of controlling temperature using fuzzy logic and autotune. If your kiln, your house and the parts in the kiln are worth nothing then go for it! Tired of Chinese junk.

 

I'm pretty sure that T controller is a single point set type.. I don't recall finding anything on it having multiple segments.

Sure JEFF... take take take... Want me to get you a step ladder so you can stand on the shoulders of giants?

 

Well, something went doololly with aliexpress on that cheap 220vt pid. Had to cancel the order, file a dispute and pissed away 3weeks waiting on these clowns. I grabbed my ankles and got this one off amazon. https://www.amazon.com/gp/product/B01DC3KNS0/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
To add insult to injury, the aliexpress t-couple was shipped in a plastic bag and YUP, some of the ceramic is busted. That clown said he would mail me another one. (yeah right, so sorry joe)
If any one needs an AC/AC 40amp SSR, I've got one. Had to swap that out too. My time was worth way more than the lousy $70 bucks I was going to save. FK IT! Pay the man!

 

New one looks good, Jason. Cheap Chinese Junk just like mine, it works very well for me.

 

Gotta love these slimy little bastards..
You have to be blind not to see the left one is a fake. Who the hell knocks off a 4dollar relay? Who cares, as long as it works. I just find this kind of crap amusing.

 

I'll bite, I'm blind (Braille computer). What is obvious?

 

Color of the case, Font text, shape of the sticker, design of the terminal screws, quality of mounting holes (2nd photo), missing country of manfacture and you can't tell this from the photo, WEIGHT is a dead give away. I HAMMERED the amazon seller for pushing this junk.

 

So the right one is the fake? They felt like they weighed the same to me. After I popped my first one I ordered several, then haven't ruined another one since. I need to inspect the spares I have.

 

Nope.. the left is inferior by a long shot.

 

Look at the label. The fake has the lower right corner cut off at an angle. The authentic has nice curves on the 4 corners of the label. If you go to the FOTEK website, you'll see a photo of the real one.

 

I'm with you. The left one was the only one with a country of manufacture. Although it's probably the wrong China.