RTDkäyrät

RTDkäyrät, or resistance temperature detector curves, are graphical representations that illustrate the relationship between the electrical resistance of an RTD sensor and its temperature. These curves are fundamental for understanding and utilizing RTDs in temperature measurement applications.

An RTD is a type of resistor whose resistance changes with temperature. Platinum is the most common material used for RTDs due to its stability and linearity over a wide temperature range. The resistance of a platinum RTD is typically defined by a standard formula, such as the Callendar-Van Dusen equation, which mathematically describes the resistance-temperature characteristic.

The RTDkäyrä plots this relationship, showing resistance on one axis and temperature on the other. For a standard platinum RTD (Pt100), the resistance at 0°C is 100 ohms. As the temperature increases, the resistance also increases in a generally linear fashion, although there is a slight deviation from perfect linearity at higher temperatures. The curve visually depicts this increase.

Different types of RTDs, made from various materials or with different nominal resistances (e.g., Pt1000), will have distinct RTDkäyrät. Understanding these curves is crucial for selecting the correct RTD for a specific application and for accurately interpolating or extrapolating temperature readings based on measured resistance values. Calibration charts and software often rely on the information conveyed by these curves to provide precise temperature outputs.