Accurate measurements (up to 1/10 DIN ) at temperatures as high as 850 °C , require a specialized resistance temperature detector (RTD). Ceramic wire wound sensors, are the most accurate RTD’s for the upper temperature ranges. The coil inside the ceramic wire wound sensors can move freely which gives it stability and excellent resistance to vibration. Acceleration levels of up to 30g over the frequency range of 10Hz to 1kHz are tolerated.
Ceramic wire wound RTD sensors are manufactured by hand: Winding the fine platinum wire into a small coil, the coil is inserted into a high purity alumina (aluminium oxide) ceramic tube. The outside diameter (OD) of the alumina tubes vary from 0.8 mm to 2.6 mm, so they are even suitable for the thinnest mineral insulated RTD cables. The excellent insulation properties of the aluminium oxide allows the wire wound element to withstand high temperatures (up to 850°C). These sensors offer the widest temperature measuring range of all platinum temperature sensors.
Ceramic wire wound sensors are also the most accurate temperature sensors available: some of the wire wound elements can even measure up to Class 1/10 DIN B. Because the relation between temperature and resistance is almost linear, ceramic wire wound sensors are very stable. This combined with their very wide temperature measuring range makes them a suitable choice for many industries.
The cryogenic platinum cobalt resistance sensor, CERACOIL, is a type of RTD sensor for extremely low temperatures. It is designed by Okazaki for ultra-low temperatures down to 1.5K (-271°C). Aimed at applications requiring high accuracy and reliability such as in the aerospace and medical industries, it is available in Pt100 and Pt1000 resistances. This sensor is noted for its exceptional performance in extreme conditions, including high-vibration environments, and offers advantages over silicon diodes in terms of accuracy and minimal magnetic field influence.
The ceramic wire wound sensors are the solution for processes requiring stability at extreme temperatures and excellent thermal shock resistance. Examples of such industries are chemical and power generation plants, analytical equipment and process monitoring. Ceramic wire wounds are also highly suitable for cryogenic temperature measurement.
Kamet is expert with regard to the application and configuration options and can advise you as to which of our extensive RTD product range would be the perfect match for your parameters. Our products include a variety of dimensions, temperature range as well as tolerance classes. We also have simplex and duplex variants.
Another kind of Pt100 RTD which we stock is a thin film Pt100 sensor. There is some overlap in the properties of both thin film and wire wound sensors. A thin film RTD is cheaper, has a very flat profile and is even more resistant to vibration.
However, in general terms if you need a very accurate RTD along a wide temperature range, especially at the upper ranges, the higher cost of a wire-wound resistor is worth the extra investment.
For a more detailed comparison of these two platinum RTD’s please visit our knowlegde base about RTD sensors. Alternatively, our advisors would be happy to assess your situation and help you select the ideal product.
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