Pid, ssr, wtf ...

[passedpawn]

Now that is beyond funny. I'm 70 and balder than an egg that has been just laid. You know - 'wet and slick'.! You think I have a "hair dryer"..?

I do have a heat gun for paint removal. I'll try that and let you know.

Still ROTFLMAO

Actually I used a heat gun too. Forgot how many nerds hang out in the DIY.

 

[passedpawn]

That's unusual. How did you connect the RTD? Did you go through a bulkhead connector? Did you use the same type of wire all the way to the PID? If there's a difference in wire types, or it's wired incorrectly, you could easily get a 4*F error.

EDIT:
I've attached a link to a page on the Omega site. If the RTD is properly made it's characteristics should meet an industry standard. Therefore, if calibration is required it would be due to the sensor conditioning hardware, not the RTD. So it's possible that the specific controller you're using may require calibration. However, if the conditioner hardware is designed well then calibration shouldn't be necessary.

Description of RTDs/pdf/RTD_Gen_Specs_Ref.pdf

It's pretty easy to build a voltage divider ckt for an RTD (or thermistor) with a 5% resistor. Then, into a buffer amp and on to the A/D. There ya go. Way off. Plus, the A/D voltage reference is probably off too. Lots of inaccuracies just in the PID.

 

[jjyoung]

It's pretty easy to build a voltage divider ckt for an RTD (or thermistor) with a 5% resistor. Then, into a buffer amp and on to the A/D. There ya go. Way off. Plus, the A/D voltage reference is probably off too. Lots of inaccuracies just in the PID.

Maybe, but I wouldn't consider that to be a good design. I'd use precision resisters and a front-end design that compensated for temperature changes and voltage offsets. Hopefully any commercial PID with acquisition hardware would be designed this way.