Answer / manan2347

RTD's output is resistance.
As we know RTD means resistance temperature detector, so we measure resistance across the terminal of RTD by multimeter.

Now assume measured resistance is "X" and RTD we are using is PT100 then,

T(temp)=(X-100)/(0.386)

*PT100 RTD shows 100 ohm at 0°c

Answer / rajesh.

RTD is Resistance Temperature Detector. As temperature varies resistance also change. So the output of RTD is Resistance. Which in terms converted into current (4 – 20 ma) by means of Transmitter. Generally RTD is available as Pt100.
Pt100 means 100OHMS at 0’ C for a platinum resistance bulb.
Formula for RTD:
Rt. =Ro (1+α t)
Rt. =Resistance of zero temperature.
α = Co. off of thermal (expansion)
t = temperature to be measured.
Example:
Calculation of Resistance or Pt 100.
Ro. = 100
α for platinum = 0.00385/c.
To calculate Resistance at 100’c
R100 =100(1+(38.5*104*100))
100+ (100*0.385)
R100 =138.5
Resistance at 100’c = 138.5

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