This International Standard specifies the requirements, in addition to the resistance versus temperature relationship, for both industrial platinum resistance thermometers (later referred to as "thermometers") and industrial platinum resistance temperature sensors (later referred to as "platinum resistors") whose electrical resistance is derived from defined functions of temperature.
Values of temperature in this document are in terms of the International Temperature Scale of 1990, ITS-90. A temperature in the unit °C of this scale is denoted by the symbol t, except in Table A.1 where the full nomenclature t90 /°C is used.
This document applies to platinum resistors whose temperature coefficient α, defined as
α= R100 − R0
R0 ⋅ 100°C
is conventionally written as α = 3,851⋅10-3 °C-1, where R100 is the resistance at t = 100 °C and R0 is the resistance at t = 0 °C.
This document covers platinum resistors and thermometers for the temperature range −200 °C to +850 °C with different tolerance classes. It can also cover particular platinum resistors or thermometers for a part of this temperature range.
For resistance versus temperature relationships with uncertainties less than 0,1 °C, which are possible only for platinum resistors or thermometers with exceptionally high stability and individual calibration, a more complex interpolation equation than is presented in this document can be necessary. The specification of such equations is outside the scope of this document.