The explosionproof resistance temperature detectors RTDi are used for measuring temperatures in measuring and control engineering. Resistance temperature detectors with Pt-100 sensors are temperature sensors that function based on changes in resistance of platinum under temperature influence. They are used in hazardous areas from –50°C to 440°C. Every sensor has a defined resistance characteristic (factory calibration on request). The Pt-100 sensor is designated by its characteristic at a temperature of 0°C, at which it has a rated resistance of 100 Ω (R_o = 100 Ω). This change in resistance is laid down in IEC 60751.