F-6
Temperature Equations
Model 2750 Multimeter/Switch System User’s Manual
Thermistor equation
Temperature (in Kelvin) is calculated using the Steinhart-Hart equation as follows:
where: T
K
is the calculated temperature in Kelvin.
lnR is the natural log of the measured resistance of the thermistor.
A, B, and C are the curve fitting constants. The constants for the three thermistor
types used by the Model 2750 are listed in
.
Table F-8
Type T inverse function polynomial
-200°C to 0°C
(-5,603µV to 0µV)
0°C to 400°C
(0µV to 20,872µV)
c
0
=
0.0
0.0
c
1
=
2.594 919 2
×
10
-2
2.592 800
×
10
-2
c
2
=
-2.131 696 7
×
10
-7
-7.602 961
×
10
-7
c
3
=
7.901 869 2
×
10
-10
4.637 791
×
10
-11
c
4
=
4.252 777 7
×
10
-13
-2.165 394
×
10
-15
c
5
=
1.330 447 3
×
10
-16
6.048 144
×
10
-20
c
6
=
2.024 144 6
×
10
-20
-7.293 422
×
10
-25
c
7
=
1.266 817 1
×
10
-24
Error:
0.04°C to -0.02°C
0.03°C to -0.03°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.
Table F-9
Model 2750 curve fitting constants for thermistors
Constant
2252
Ω
at 25°C
(Series 44004)
5000
Ω
at 25°C
(Series 44007)
10k
Ω
at 25°C
(Series 44006)
A
0.0014733
0.001288
0.0010295
B
0.0002372
0.0002356
0.0002391
C
1.074e-7
9.557e-8
1.568e-7
T
K
1
A
BlnR
(
)
C lnR
(
)
3
[
]
+
+
-----------------------------------------------------------
=
2750-900-01.book Page 6 Wednesday, August 3, 2011 7:56 AM
Summary of Contents for 2750
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Page 374: ...B Model7700ConnectionGuide 2750 900 01 book Page 1 Wednesday August 3 2011 7 56 AM...
Page 386: ...C StatusandErrorMessages 2750 900 01 book Page 1 Wednesday August 3 2011 7 56 AM...
Page 394: ...D SignalProcessing SequenceandDataFlow 2750 900 01 book Page 1 Wednesday August 3 2011 7 56 AM...
Page 408: ...E MeasurementConsiderations 2750 900 01 book Page 1 Wednesday August 3 2011 7 56 AM...
Page 428: ...G IEEE 488BusOverview 2750 900 01 book Page 1 Wednesday August 3 2011 7 56 AM...