Thermocouple Equation - Keithley 2750 User Manual

F-2 Temperature Equations

Thermocouple equation

The Model 2750 uses the ITS-90 inverse function coefficients for the polynomial to calcu-
late thermocouple temperature. The Model 2750 measures the thermocouple voltage, and
then calculates temperature (in °C) as follows:
t = c
90
where: t
The coefficients for each thermocouple type are listed in
Table F-1
Type B inverse function polynomial
c =
0
c =
1
c =
2
c =
3
c =
4
c =
5
c =
6
c =
7
c =
8
Error:
t = c
90
where: t
2 3
+ c E + c E + c E
0 1 2 3
is the calculated temperature in °C.
90
c , c , c , c ... c are the coefficients for the thermocouple type.
0 1 2 3 i
E is the thermocouple voltage in microvolts (µV).
250ºC to 700ºC
(291µV to 2,431µV)
9.842 332 1 × 10 1
6.997 150 0 × 10 -1
-8.476 530 4 × 10 -4
1.005 264 4 × 10 -6
-8.334 595 2 × 10 -10
4.550 854 2 × 10 -13
-1.552 303 7 × 10 -16
2.988 675 0 × 10 -20
-2.474 286 0 × 10 -24
0.03°C to -0.02°C
2 3
+ c E + c E + c E
0 1 2 3
is the calculated temperature in °C.
90
E is the measured voltage in microvolts.
Model 2750 Multimeter/Switch System User's Manual
i
... c E
i
700ºC to 1,820ºC
(2,431µV to 13,820µV)
2.131 507 1 1 × 10
2.851 050 4 1 × 10
-5.274 288 7 1 × 10
9.916 080 4 1 × 10
-1.296 530 3 1 × 10
1.119 587 0 1 × 10
-6.062 519 9 1 × 10
1.866 169 6 1 × 10
-2.487 858 5 1 × 10
0.02°C to -0.01°C
i
... c E
i
Table F-1 through Table
2
-1
-5
-9
-12
-16
-21
-25
-30
F-8.