Vastuslämpömittari

Vastuslämpömittari, also known as a resistance thermometer or resistance temperature detector (RTD), is a type of temperature sensor that measures temperature by assessing the resistance of a metal wire. The electrical resistance of most metals increases with increasing temperature in a predictable and repeatable manner. This property is utilized in resistance thermometers.

The most common material used for the sensing element in a resistance thermometer is platinum, often in the form of a thin wire wound around a ceramic core or deposited as a thin film. Other metals like nickel and copper are also used, but platinum offers a good combination of accuracy, stability, and a wide operating temperature range.

A resistance thermometer typically consists of a sensing element, a protective sheath, and connecting wires. The sensing element's resistance is measured using a bridge circuit or a simple ohmmeter. As the temperature changes, the resistance of the element changes, and this change is converted into a temperature reading. The relationship between resistance and temperature is usually calibrated and expressed as a specific curve or equation, such as the Callendar-Van Dusen equation for platinum RTDs.

Resistance thermometers are known for their accuracy, stability, and wide measurement range. They are commonly used in industrial applications, scientific research, and laboratory settings where precise temperature measurements are critical. Common types include Pt100, which has a resistance of 100 ohms at 0 degrees Celsius.