<p><span style="color: #000000;">Resistance thermometers</span><span style="color: #000000;">, also called&nbsp;resistance temperature detectors&nbsp;(RTDs), are&nbsp;<a style="color: #000000;" title="Sensor" href="https://en.wikipedia.org/wiki/Sensor">sensors</a>&nbsp;used to measure temperature. Many RTD elements consist of a length of fine wire wrapped around a ceramic or glass core but other constructions are also used. The RTD wire is a pure material, typically platinum, nickel, or copper. The material has an accurate resistance/temperature relationship which is used to provide an indication of temperature. As RTD elements are fragile, they are often housed in protective probes.</span></p> <p><span style="color: #000000;">RTDs, which have higher accuracy and repeatability, are slowly replacing&nbsp;<a style="color: #000000;" title="Thermocouple" href="https://en.wikipedia.org/wiki/Thermocouple">thermocouples</a>&nbsp;in industrial applications below 600&nbsp;°<a style="color: #000000;" title="Celsius" href="https://en.wikipedia.org/wiki/Celsius">C</a>.</span><sup id="cite_ref-sensortech_1-0" class="reference"></sup></p>