TDI Technical

International Standards

The current international standard for platinum resistance thermometers is the IEC publication 751 Amendment 2, 1995.

It defines the relationship between Temperature and resistance thus,

For the range -200°C to 0°C

R_t=R₀ [ 1 + At + Bt² + C(t-100°C)t³]

For the range °C to 850°C

R_t=R₀( 1 + At + Bt²)

For the quality of platinum commonly used in industrial platinum resistance thermometers, the values of the constants are:

A = 3,9083 x 10 ^-3°C^-1
B = -5,775 x 10 ^-7°C^-2
C = -4,183 x 10 ^-12°C^-4

There is much more information available in our printed catalogue.