Constant SSR output from JLD-612

simpsora
Posts: 2
Joined: Wed Apr 15, 2015 3:18 am

Constant SSR output from JLD-612

Postby simpsora » Wed Apr 15, 2015 3:42 am

Hi,

I bought the JLD-612 controller for use in a sous vide setup. I've just recently wired it up, and don't understand the behavior.

Terminals 1 and 2 are connected to 240VAC. Terminals 8,9,10 are connected to a PT100 thermocouple. Terminals 6 and 7 are connected to a small LED and a multimeter.

The device powers on fine, and seems to read accurate temperature from the thermocouple. When the SV is greater than the PV, the "out" light on the controller illuminates on and off, so does the LED on terminals 6 and 7, and I see voltage on my multimeter. When SV is less than PV, both LEDs stop illuminating, but I still read voltage across terminals 6 & 7 (variable, 3-7V). This seems incorrect -- I'd expect there to be little to no voltage on the SSR terminals when the connected load should be off. The SSR that I intend to use has an activation voltage of 3V, so it would be switched on even though the controller indicates off. Am I missing something? Is my controller possibly damaged? I've confirmed that the settings are all factory defaults (other than Inty = P10.0). Outy is definitely 2, and rd = 0.

Also, could someone tell me what the SSR output specification is? The website says "Dual output SSR(8V, 40mA), Relay(3A 120V AC)", so I'm not sure if the SSR output is AC or DC. I have the wrong type of SSR (DC-DC), so I don't want to plug it in to test.

Thanks for your help!
Ross

richiem
Posts: 270
Joined: Mon Jan 03, 2011 3:47 pm
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Re: Constant SSR output from JLD-612

Postby richiem » Fri Apr 17, 2015 8:39 pm

Hi Ross -- the SSR output is a DC current source with a maximum voltage of 8V (compliance V) at zero current output. The SSR responds to the current flowing into it, not the voltage across its control terminals. The correct polarity of the connections is vital -- the 2011 manual version has a great diagram of the correct hookup for an SSR, which needs to be one that controls an AC load from an AC source.

Getting the Pt100 RTD (it's not a thermocouple, it's a temp variable resistor) probe connections right is also very important. It is not a polarity issue, this is a resistor, but rather a special connection for RTDs that compensates for the resistance of the connecting wires -- blue wire under 10, red wires (doesn't matter which) under 8 and 9.

Then the Inty, Rd, and Outy settings need to be correct for probe type (P10 0, or P100, either will be fine for sous vide), heating (rd=0), and SSR (outy=2).

The manual contains everything needed for proper setup and operation. To test, try putting two red LEDs in series, anode to cathode, with an anode under 6 (+) and the remaining cathode under 7 (-).

simpsora
Posts: 2
Joined: Wed Apr 15, 2015 3:18 am

Re: Constant SSR output from JLD-612

Postby simpsora » Wed Apr 22, 2015 5:40 am

Hi richiem,

Thanks for the reply! Once I got the proper SSR (DC in, AC out) and hooked it up, everything worked properly. Measuring the voltage across the control terminals was a red herring.
It may be helpful for other buyers of the JLD-612 to note in the specifications that the unit's output is in DC (perhaps that's implied -- I'm not familiar with PID controllers).

In any case, thanks for your help, all working now!
Ross


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