STC-1000 Quit on me

[sestd]

I bought a STC-1000 PID for controlling my mash temp and assembled it myself(I use 2 120v tea kettle elements). I used the diagrams on a bunch of these threads to put it together with two plugs (one for hot, one cold). It worked brilliantly for one brew session, but now it is not working.

When I plug it in, the PID still comes on and the prob still gives me an accurate temp reading, but the plugs will not work. I've checked and re-checked the wiring and everything looks fine. What do you think I screwed up? Blown fuse? Did I fry the plugs somehow? Any feedback would be appreciated.

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[cbzdel]

how many amps do your tea kettle elements pull?

 

[PeteNMA]

The STC1000 is a thermostatic relay controller, not a PID. It sounds like you have fried the relays with excess load.


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[sestd]

12 amps

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[cbzdel]

I believe the papers I just got with mine said 10amps max, so you have probably burned out the relays if you were pulling 12 amps..

 

[sestd]

That is very possible. I do not have the information in front of me, but I would bet that you are correct. Fortunately, it didn't cost me any more than a good thermometer, so I suppose that is how i will use it. Thanks for the help.

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[PeteNMA]

Yeah the STC is 10a maximum. If you're going to keep using one to control those elements you need to use the STC to drive an external relay with an appropriate current handling ability.


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[atoughram]

Or do what I did and use the STC to drive a 120V input SSR.

like these

http://www.ebay.com/itm/Crydom-Soli...050?pt=LH_DefaultDomain_0&hash=item35d0c7e592

 

[sestd]

Awesome, great info. I need to hit the drawing board and get this all figured out. The first time may have been slightly impulsive, but who can blame me?

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[Indian_villager]

Invest in an auber PID setup. It is more robust and has better control software.

 

[IslandLizard]

Although the STC is rated at 10A, the relays in the STC are actually rated at 15A @125V (or 10A @ 250V). There is no fuse in the STC. The relay contacts could have been damaged, or the traces melted off the board under the high currents.

What is the actual wattage of each of those elements? Also the rush-in current could be way more until it heats up to operating temps.

You can measure the relays' continuity (outputs). Do you hear the relays click when C/H activates?
I'd say open it up and see what's what, if you're savvy with electrical.

 

[sestd]

The elements are 1200 watts each. I don't think the relays are clicking anymore when either hot or cold is activated.

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[IslandLizard]

So you put 2x1200=2400W load on the STC at 120V. That's 20 Amps, while the STC is rated at 10A, and perhaps 15A. It's very possible the contacts have fused together, like welded, or got burned.

Using a single one of those elements would have been about the max. You'll need an SSR to drive that kinda power.