Vastuslämpömittareille

Vastuslämpömittareille, known in English as resistance thermometers or resistance temperature detectors (RTDs), are temperature sensors that function based on the principle that the electrical resistance of certain metals changes predictably with temperature. As temperature increases, the resistance of the metal also increases. This change in resistance can be measured and correlated to a specific temperature value.

Commonly used metals for RTDs include platinum, nickel, and copper. Platinum is favored for its stability, accuracy, and wide temperature range, making it the standard for many industrial and laboratory applications. Nickel offers higher resistance changes than platinum but has a more limited temperature range and can be prone to oxidation. Copper is inexpensive and has a significant resistance change but is susceptible to corrosion and has a narrow operating range.

The most common construction involves a fine wire of the sensing metal wound around a ceramic or glass core, or deposited as a thin film onto a substrate. This element is then enclosed in a protective sheath. RTDs require a small electrical current to be passed through them to measure their resistance, and this current should be kept low to avoid self-heating, which would introduce errors in the temperature reading.

Vastuslämpömittareille are known for their excellent accuracy, repeatability, and long-term stability, especially compared to thermocouples. They are widely employed in industries such as chemical processing, food and beverage production, pharmaceuticals, and automotive manufacturing where precise temperature measurement is critical. Their operating temperature range can extend from cryogenic levels to several hundred degrees Celsius, depending on the specific type and construction.