resitanssilämpötilaanturi

Resistanssilämpötilaanturi, often abbreviated as RTD (Resistance Temperature Detector), is a type of temperature sensor that uses the principle that the electrical resistance of certain metals changes in a predictable way with temperature. As the temperature increases, the electrical resistance of the metal also increases. This relationship is generally linear over a wide range of temperatures, making RTDs accurate and reliable.

The most common materials used for RTD elements are platinum, nickel, and copper. Platinum is favored for its stability, wide temperature range, and linearity, though it is also the most expensive. Nickel is more sensitive to temperature changes than platinum but has a more limited temperature range and can be less stable over time. Copper is inexpensive and has a highly linear response but is prone to oxidation at higher temperatures.

An RTD typically consists of a wire wound into a coil or a thin film deposited onto a ceramic substrate. This element is then encased in a protective sheath. To measure the temperature, a small, constant current is passed through the RTD element, and the voltage drop across it is measured. Since voltage is the product of current and resistance (Ohm's Law), the resistance can be calculated. This resistance value is then converted into a temperature reading using calibration data specific to the RTD. Common RTD configurations include two-wire, three-wire, and four-wire setups, with three-wire and four-wire designs offering greater accuracy by compensating for lead wire resistance. RTDs are widely used in industrial applications, laboratory equipment, and other areas where precise temperature measurement is critical.