nonlinearity in PT temperature sensor

saeyd akbar · Nov 23, 2009

non linear error

hi brothers
i have aproblem and asking your help
a platinum resistanc temperture detector is connected as one arm of a wheatstone bridge the Rt,R1,R2,R3,R4=250 ohm at o c, supply voltage=12v.
temperture coff.is 3.9x10-3
what is Vo at 1000 c
if the measured voltage at 500 c is 2.95v,what is the non linear eror in volt

Added after 1 minutes:

soory one more thing
how can this non linear error be reduced

micard · Nov 24, 2009

RTDs in industrial applications are rarely used above 660 °C. At temperatures above 660 °C it becomes increasingly difficult to prevent the platinum from becoming contaminated by impurities from the metal sheath of the thermometer. This is why laboratory standard thermometers replace the metal sheath with a glass construction. At very low temperatures, say below -270 °C (or 3 K), due to the fact that there are very few phonons, the resistance of an RTD is mainly determined by impurities and boundary scattering and thus basically independent of temperature. As a result, the sensitivity of the RTD is essentially zero and therefore not useful.

as wikipedia says, so I'll recommend you to use some thermocouples for measuring temp about 1000 deg C. According nonlinearity - the easiest is to use interpolation table - where you remember 10-15 points of the characteristics with linear interpolation between them.

saeyd akbar · Nov 24, 2009

tahnk you for you reply,but what i need her is to solve the problem mathimaticlly, in caculation

FvM · Nov 24, 2009

Yes, I see. It isn't a real problem, it's an exercise. Just consider rule of three calculus.

nonlinearity in PT temperature sensor

saeyd akbar

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micard

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nonlinearity in PT temperature sensor

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