NewsRTD Sensors

Equipments needed

  • Transmitter
  • 24VDC supply
  • Decade box(resistance)
  • Multimeter


  • RTD has no polarity
  • There are different kinds of RTD (2 wire,3 wire,4 wire)
  • Output of RTD will be change in resistance due to change in temperature.
  • Commonly used RTD materials are nickel, platinum, and copper.

Formula needed for calibration:

Procedure for calibrating RTD transmitter

  • Remove the temperature element (RTD) from transmitter.
  • Connect the circuit as shown in figure above.
  • Put multimeter in ma.
  • By the equation we can find what will be the output resistance of RTD in specific temperature
For a pt100 RTD α = .00385 R0=100 Let’s take the temp= 30 degree Celsius R=R0 (1+α ΔT) So R30=111.35Ω  
  • So by the equation we can find resistance values for 5 point calibration (4ma,8ma,12ma,16ma,20ma)
  • By setting these resistance values using decade box we can find the corresponding ma in multimer.
  • By changing the zero and span potentiometer in transmitter we can do the 5 point calibration.
  • Repeat the process.
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