Morning,

I am looking for equations that solve for temperature in terms of RTD resistance. I find lots of references to equations that only include the lower order terms or that solve for resistance.

I am writing firmware for a temperature measurement instrument. The instrument will work with 100pt, 1000pt, 120ni, and 10cu type RTDs and cover below zero ranges. I have found second order equations that solve for temperature for Platinum and Nickel. I have found just a first order equation for Copper. It looks like I need to include higher order terms for accuracy below zero.

Any ideas where to look?

Thanks,
Jim

 

Come on Jim. Be pro-active!
A simple Google search for "RTD +polynom" provided tens (probably hundreds) of articles with coefficient up to 6.

Same thing for "nickel +polynom".