Fluke NetDAQ 2640A - RTD Linearization

D-1
Appendix D
RTD Linearization
Introduction D-1.
This appendix discusses Fixed-385 and Custom-385 RTD measurements with
NetDAQ.
Fixed-385 RTD D-2.
The Fixed-385 RTD linearization uses segmented polynomials to approximate the
Callendar Van-Dusen equation for a 385 RTD. R
0
may be specified via NetDAQ
Logger but α, δ, and β are fixed. These fixed coefficients are the modified DIN
43760 coefficients that conform to ITS90:
α = 0.00385055
δ = 1.49978574
β = 0.10863383
The accuracy specifications of Fixed-385 measurements with a 385 RTD that
matches the above coefficients are shown in Table A-34 in Appendix A.