measured temperature to change. Finally, any changes in metal (e.g.,platinum to cop- per) can result in thermal emf offsets, which require compensation.
Even though the RTD is more linear than the thermocouple, it still requires curve fitting. The coefficients for a 20th-order polynomial are available from most manufacturers of RTDs.
Table 14.4 compares the temperature ranges and temperature coefficients of resistivity (TCs) of commonly used RTD materials.