2680A/2686A
Users Manual
D-2
Custom-385 RTD
The Custom-385 RTD linearization solves the Callendar Van-Dusen equation for
positive temperatures and uses a polynomial approximation to the Callendar Van-
Dusen equation for negative temperatures. In addition to R
0
,
α
may also be
specified using the Fluke DAQ software.
δ
and
β
are fixed. These fixed
coefficients are the modified DIN 43760 coefficients that conform to ITS90:
δ
= 1.49978574
β
= 0.10863383
Figure D-1 shows the accuracy envelope for a 385 RTD that has
δ
and
β
that
match the above coefficients. Because of the error introduced by the linearization
at low temperatures, it is recommended that use of the Custom-385 RTD type be
limited to temperatures between -100 and 600 °C.
FAI
PAI
-100
0
100
200
300
400
500
600
Temperature - Degrees C
-1.5
-1.0
-0.5
0.0
0.5
1.0
Error - Degrees C
1.5
Accuracy Envelope: Custom RTD, 385 Probe
1 Year Slow: 18-28 Degrees C
Alpha: 0.00385055 Delta: 1.49978574 Beta: 0.10863383
alg61f.eps
Figure D-1. 385 RTD
Summary of Contents for 2680A
Page 8: ......
Page 14: ...2680A 2686A Users Manual vi ...
Page 20: ...2680A 2686A Users Manual 1 2 ...
Page 98: ...2680A 2686A Users Manual 2 62 ...
Page 196: ......
Page 228: ...2680A 2686A Users Manual A 32 ...
Page 236: ...2680A 2686A Users Manual C 4 ...
Page 242: ...2680A 2686A Users Manual D 6 ...
Page 274: ...2680A 2686A Users Manual 6 ...