Fluke 9933 3.8 Methods used for calculating coefficients

b) c2

9. The following standard Thermocouple coefficients are also produced

unaltered:

Type

Range 1 Coefficients Range 2 Coefficients Range 3 Coefficients Other

(see above)

TypeB c3...c6 c0, c3...c8 N/A N/A

TypeE c3...c13 c3...c10 N/A N/A

TypeJ c3...c8 c0, c3...c5 N/A N/A

TypeK c3...c10 c0, c3...c9 N/A N/A

TypeN c 3...c8 c3...c10 N/A N/A

TypeR c 3...c9 c0, c3...c5 c0, c3...c4 c3...c9

TypeS c3...c8 c0, c3...c4 c0, c3...c4 c3...c8

TypeT c3...c14 c3...c8 N/A N/A

TypeAuPt c3...c8 c3..c9 N/A N/A

3.8 Methods used for calculating coefficients

The thermometric expressions used by this software are wellknown expres-

sions and as such are described in detail elsewhere.This section touches on

some specifics as they relate to the methods used to arriveat solutions.

The coefficients for all solutions with the exception of the IPTS-68 platinum

probe are calculated using matrix methods. The IPTS-68 platinum probe solu-

tion is calculated using iteration. The solutions are either exact solutions or

overdetermined solutionsdepending on the number of set-points used in rela-

tion to the number of set-points required. Exact solutionsresult when the exact

number of set-points required for simultaneous solution of sets of equationsare

used (i.e., two coefficientsfrom two set-points). Overdetermined solutions re-

sult when more set-points are used than the unknowns require (i.e., two coeffi-

cients from three or more set-points).

The ITS-90 is expressed in terms of resistance ratio(W) vs. temperature (K)

rather than resistance (R) vs. temperature. The resistance ratio is defined as the

resistance at a temperature divided by the resistance at the triplepoint of water,

or:

tpw

Because ratios are used in the ITS-90, the Rtpw is required in addition to the re-

sistance values at the test temperatures, thus, three set-points arerequired to

9933 TableWare

User’s Guide