The most basic RTD measurement uses a two-wire RTD for temperature measurement. Shown below is a schematic and design for a two-wire RTD measurement with an ADC. A ratiometric measurement is created with the RTD as the input and a precision resistor as the reference input.
RTD Temperature vs. Resistance Table °C Ohms Diff. °C Ohms Diff. °C Ohms Diff. °C Ohms Diff. °C Ohms Diff. °C Ohms Diff. BENELUX Temperature Humidity Measurement Instruments, RTD Probes, Elements
The condensed Resistance VS Temperature Tables on the following pages are provided to aid in the proper RTD element selection. Notice that the tables for the various platinum curves are for the standard 100 ohm @ 0°C sensor.
Z-255 °C Ohms °C Ohms °C Ohms °C Ohms °C Ohms °C Ohms °C Ohms °C Ohms °C Ohms-100 59.57 -38 84.80 24 109.51 86 133.75 148 157.53 210 180.86 272 203.74 334 226.17 396 248.16
The platinum element of the standard industrial type RTD has a base reference resistance of 100 Ωat 0°C. Platinum 100 Ω, temperature coefficient = 0.00385/Ω/Ω/°C. This meets the ASTM standard 1137 and also meets the IEC 751.
The condensed Resistance VS Temperature Tables on the following pages are provided to aid in the proper RTD element selection. Notice that the tables for the various platinum curves are for the standard 100 ohm @ 0°C sensor.
The tables in the links below display the relationship between temperature and the electrical resistance of RTDs. The tables are in 1 degree increments. Linear interpolation can be used for “in-between” temperatures.