vastuslämpömittareilla

Vastuslämpömittareilla, often referred to as resistance temperature detectors (RTDs), are a type of temperature sensor that exploits the predictable change in electrical resistance of certain materials with temperature. As the temperature of the RTD element increases, its electrical resistance also increases. This relationship is typically linear over a significant temperature range, making RTDs quite accurate and reliable.

The most common material used in RTDs is platinum, often denoted as Pt100, where the '100' indicates its resistance in ohms at 0 degrees Celsius. Other materials like nickel and copper can also be used, each offering different temperature ranges and sensitivities. The RTD element is usually housed in a protective sheath, often made of metal, to shield it from the environment it is measuring.

To measure the temperature, an RTD requires a small, constant current to be passed through it. A voltmeter then measures the voltage drop across the RTD. By knowing the relationship between resistance and temperature for the specific RTD material and using Ohm's Law (V = IR), the temperature can be accurately calculated. RTDs are widely used in industrial applications, laboratory equipment, and scientific instruments due to their stability, accuracy, and good repeatability. They are generally more expensive than thermocouples but offer superior performance in many applications.