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I fried my SSR........ HELP!!!
jwilson:
Hey guys, I'm a newbie and really need some help.
I'm trying to replace the old controls in a Paragon kiln and use a PID with 2 SSR's using 220v.
Here's a list of the equipment I'm using:
SSR - 2 x Inkbird Solid State Relay 40DA DC SSR
PID - Auber Instruments PID TEMPERATURE CONTROLLER,W/ 30 RAMP / SOAK,SSR OUTPUT
Here's how I wired everything and killed an SSR.....
220V coming into the box and the white leg going to SSR #1 on terminal 2.
The black leg of the 220V going to SSR #2 on terminal 2.
I wired the SSR's in series going from SSR #1 I wired terminal 4 to terminal 4 on SSR #2.
I wired SSR #1's terminal 3 to SSR #2's terminal 3.
Then I ran a wire from SSR #2's terminal 4, negative, to terminal 8 on the PID.
I ran a wire from SSR #2's terminal 3 to terminal 7 on the PID.
I ran a wire from SSR #1's terminal 2 to to terminal 9 on the PID.
I ran a wire from SSR #2's terminal 2 to a rocker switch and then to terminal 10 on the PID.
I also hooked up the thermocouple to the PID via terminals 4 and 5.
So, I was using terminal #1 on BOTH SSR's to go to the heating elements on the kiln.
When I switched the PID on and the output light kicked on, the elements started to heat up and then SSR #2, with the black 220V wire going to it, started smoking and made a POP!!! It's dead.
How should I wire this thing up????????? This is killing me and I don't get it.
Please help!!!!
duak:
Ouch!
A few questions:
1.) what is the element power rating or the rated current?
2.) is the element isolated from ground? Please check with a meter.
3.) has this kiln worked before, perhaps with a different controller?
james_s:
Are these cheap SSR's from China? I'm not familiar with that brand but they sure look like it. Keep in mind the specs on those are hugely exaggerated, I think you'd be lucky to reliably switch 15A with a "40A" SSR. Buy SSRs from a reputable company like Crydom, they will cost a lot more but you can rely on their specs to be honest. Also make sure you mount them on an adequate heatsink, if you are pushing 30-40A through SSRs they're going to get hot, they have a much higher dissipation than mechanical relays though they are superior for applications that do frequent cycling such as PID temperature controllers.
You'll also probably want to have some sort of backup protection, see this for an example of what can happen when one of thee fails: https://hackaday.com/2018/08/24/fail-of-the-week-solid-state-relay-fails-spectacularly/
When a SSR fails it usually fails closed, this can be a very bad situation when you are controlling a heating device. I would probably add an additional mechanical relay controlled by a thermal fuse.
james_s:
This is the sort of thing you want. You can either get a pair of single ones like this:
https://www.digikey.com/product-detail/en/sensata-crydom/D2440/CC1071-ND/221764
Or you can get a double one like this and only need one of them.
https://www.digikey.com/product-detail/en/sensata-crydom/D2440D/CC1122-ND/221840
jwilson:
--- Quote from: duak on January 24, 2020, 11:06:15 pm ---Ouch!
A few questions:
1.) what is the element power rating or the rated current?
2.) is the element isolated from ground? Please check with a meter.
3.) has this kiln worked before, perhaps with a different controller?
--- End quote ---
1. The element power rating is 30 Amps and 7200 Watts
2. The element wasn't grounded.......That's probably the problem.
3. The kiln did work before, but I'm a knife maker and need to hold precise temps in order to heat treat knives.
Thanks for chiming in!!!
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