![]() Designing them into systems, however, is complicated by the need for special extension wires and reference junction compensation. This millivolt-level emf, when compensated for the known temperature of the reference junction, indicates the temperature at the sensing tip. Heating the sensing junction generates a thermoelectric potential (emf ) proportional to the temperature difference between the two junctions. ![]() At the other end of the signal wires, usually as part of the input instrument, is another junction called the reference junction, which is electronically compensated for its ambient temperature. ThermocouplesĪ thermocouple consists of two wires of dissimilar metals welded together into a junction. Standardization: Manufacturers offer RTDs to industry standard curves, most commonly 100 Ω platinum to EN60751 (Minco element code PD or PE).Low system cost: RTDs use ordinary copper extension leads and require no cold junction compensation.RTD non-linearities can be corrected through proper design of resistive bridge networks. Linearity: Platinum and copper RTDs produce a more linear response than thermocouples or thermistors.Sensitivity: The voltage drop across an RTD provides a much larger output than a thermocouple.Ordinary industrial RTDs typically drift less than 0.1☌/year. Repeatability and stability: The platinum resistance thermometer is the primary interpolation instrument used by the National Institute of Standards and Technology from -260 to 962☌. ![]()
0 Comments
Leave a Reply. |