Temperature sensors are split into two categories, namely thermocouples and Resistance Temperature Devices (RTD’s). Thermocouples output signals is in the form of a minute mV signal, whilst a RTD is resistance. Temperature sensors vary in accuracy with the RTD (Pt100) being the most accurate sensor. These sensors can measure temperatures from as low as -200°C to + 1300°C. They are extremely versatile with sheath materials and construction varying from application to application.