What Is Self-Heating in PRTs?

Self-heating is a small temperature rise in the PRT sensing element caused by the electric current passing through the platinum coil during measurement. While usually negligible, self-heating can cause small measurement errors in specific conditions. The measurement current generates a small amount of heat, which slightly increases the sensor's temperature above the actual medium temperature. The effect is more significant in low-flow gases, vacuum, or insulating materials where heat cannot dissipate easily. To reduce self-heating, instruments use very low measurement currents, typically 1 mA or less. High-precision instruments use even lower currents to minimize errors. Self-heating errors are usually smaller than 0.1°C for most industrial applications, making them unnoticeable in general processes. However, they can become relevant in high-precision laboratory measurements, gas monitoring, or low-flow environments. Sensor design also affects self-heating. Thin-film elements with low mass heat more easily than wire-wound elements, while good thermal conductivity improves heat dissipation. For most users, self-heating is not a concern. Only in highly accurate or low-convection applications should it be considered and corrected.