Explain about Resistance temperature detectors (RTDs)?

An RTD sensing element consists of a wire coil or deposited film of pure metal. The element’s resistance increases with temperature in a known and repeatable manner. RTDs exhibit excellent accuracy over a wide temperature range and represent the fastest growing segment among industrial temperature sensors.

Their advantages include:

• Temperature range: Models cover temperatures from -260 to 850°C.

• Repeatability and stability: Industrial RTDs typically drift less than 0.1°C/year.

• Sensitivity: The voltage drop across an RTD provides a much larger output than a thermocouple.

• Linearity: Platinum and copper RTDs produce a more linear response than thermocouples or thermistors. RTD non-linearities can be corrected through proper design of resistive bridge networks.

• Low system cost: RTDs use ordinary copper extension leads and require no cold junction compensation.