Keithley 2750, User Manual, Page: 419 / 452

F-2 Temperature Equations Model 2750 Multimeter/Switch System User’s Manual
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
90
= c
0
+ c
1
E + c
2
E
2
+ c
3
E
3
... c
i
E
i
where: t
90
is the calculated temperature in °C.
c
0
, c
1
, c
2
, c
3
... c
i
are the coefficients for the thermocouple type.
E is the thermocouple voltage in microvolts (µV).
The coefficients for each thermocouple type are listed in Table F-1 through Table F-8 .
Table F-1
Type B inverse function polynomial
250ºC to 700ºC
(291µV to 2,431µV)
700ºC to 1,820ºC
(2,431µV to 13,820µV)
c
0
=
c
1
=
c
2
=
c
3
=
c
4
=
c
5
=
c
6
=
c
7
=
c
8
=
Error:
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
2.131 507 1 1
×
10
2
2.851 050 4 1
×
10
-1
-5.274 288 7 1
×
10
-5
9.916 080 4 1
×
10
-9
-1.296 530 3 1
×
10
-12
1.119 587 0 1
×
10
-16
-6.062 519 9 1
×
10
-21
1.866 169 6 1
×
10
-25
-2.487 858 5 1
×
10
-30
0.02°C to -0.01°C
t
90
= c
0
+ c
1
E + c
2
E
2
+ c
3
E
3
... c
i
E
i
where: t
90
is the calculated temperature in °C.
E is the measured voltage in microvolts.
2750-900-01.book Page 2 Wednesday, August 3, 2011 7:56 AM