RTD Sensor Wiring

Okay, so I finally finished wiring my CP, fired it up and ... no explosions! But I'm getting an error from my RTD sensor (Auber PT100). Since I added a panel mount connection, I suspected an issue with my connections. Then I noticed that the two red wires at the sensor end are soldered to the same post (came this way from Auber). Is that the way they're supposed to be, or is that a wiring mistake? Can't find any wiring details on the Auber site ...

It's best to split the reds apart and run them to their individual terminals. Otherwise, you need to run a jumper to the other red terminal.

CorgiBrew said:

Okay, so I finally finished wiring my CP, fired it up and ... no explosions! But I'm getting an error from my RTD sensor (Auber PT100). Since I added a panel mount connection, I suspected an issue with my connections. Then I noticed that the two red wires at the sensor end are soldered to the same post (came this way from Auber). Is that the way they're supposed to be, or is that a wiring mistake? Can't find any wiring details on the Auber site ...

Click to expand...

RTDs are about 100 ohms resistance so if the cable is extended, it can have a significant impact on the accuracy of the temperature. To correct for this, they often have 3 or 4 wires. With a 3-wire, you would have two wires (red in your case) connected to one lead of the RTD component and the 3rd wire (white?) connected to the other lead of the RTD component.

The actual temperature measurement will come from the resistance across one of the red wires and the white wire. The other red wire will generally need to be terminated to a separate terminal as well and this allows for a more accurate temperature because it now compensates for the resistance of the cable between the two red wires.

Hopefully this makes sense.

So, from what you guys are saying, I guess that it's normal for the two red leads to start from the same pin on the sensor? Hmmm, guess there must be something else causing my PID error message. Interestingly, when I fire up the PID as configured by Auber (i.e. set up for a K-type thermocouple) I don't get an error but the temperature readout is way wrong. When I change the input setting to "21" for the PT100, that's when I get the error. Guess I'd better check that wiring again!

CorgiBrew said:

So, from what you guys are saying, I guess that it's normal for the two red leads to start from the same pin on the sensor? Hmmm, guess there must be something else causing my PID error message. Interestingly, when I fire up the PID as configured by Auber (i.e. set up for a K-type thermocouple) I don't get an error but the temperature readout is way wrong. When I change the input setting to "21" for the PT100, that's when I get the error. Guess I'd better check that wiring again!

Click to expand...

That is correct. The PID is reading the resistance across the two red wires to compensate for error. That's why there's 3 total connections on the PID for an RTD.

CorgiBrew said:

So, from what you guys are saying, I guess that it's normal for the two red leads to start from the same pin on the sensor? Hmmm, guess there must be something else causing my PID error message. Interestingly, when I fire up the PID as configured by Auber (i.e. set up for a K-type thermocouple) I don't get an error but the temperature readout is way wrong. When I change the input setting to "21" for the PT100, that's when I get the error. Guess I'd better check that wiring again!

Click to expand...

What is the part # of your temperature controller? I might be able to help you with wiring if they have a manual online.

Also, a K-type thermocouple is a very different type of sensor than an RTD. Are you terminating all 3 RTD wires?

Thanks knappster & jkarp. Turned out to be just a case of crossed leads. Simple as that!

well if something would have exploded when you powered it up, then you would have known right away!

I'll say! There's nothing like the thrill of throwing that master switch for the first time. Sorta like Hurt Locker.