Equipments needed

• Transmitter
• 24VDC supply
• Multimeter

### Theory

• 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.

### 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

###### Example:
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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