Temperature Reading Checks - Keithley 2001 Calibration Manual

1.8.7 Temperature reading checks

When using thermocouples, the Model 2001 displays tem-
perature by measuring the DC thermocouple voltage, and
then calculating the corresponding temperature. Similarly,
the instrument computes RTD temperature readings by mea-
suring the resistance of the RTD probe and calculating tem-
perature from the resistance value.
Since the instrument computes temperature from DCV and
resistance measurements, verifying the accuracy of those
DCV and resistance measurement functions guarantees the
accuracy of corresponding temperature measurements.
Thus, it is not necessary to perform a comprehensive temper-
ature verification procedure if DCV and resistance verifica-
tion procedures show the instrument meets its specifications
in those areas. However, those who wish to verify that the
Model 2001 does in fact properly display temperature can
use the following procedure to do so.
Selecting the temperature sensor
Follow the steps below to select the type of temperature sen-
sor:
1. From normal display, press CONFIG then TEMP.
2. Select SENSOR, then press ENTER.
3. Select 4-WIRE RTD or THERMOCOUPLE as desired,
then press ENTER.
4. Select the type of RTD probe or thermocouple you wish
to test, then return to the CONFIG TEMPERATURE
menu.
5. Select UNITS, then press ENTER.
6. Select DEG-C, then press ENTER.
7. Press EXIT as necessary to return to normal display.
8. Press the TEMP key to place the Model 2001 in the tem-
perature display mode. Refer to further information be-
low on how to check thermocouple and RTD probe
readings.
Thermocouple temperature reading checks
To check thermocouple readings, simply apply the appropri-
ate DC voltage listed in Table 1-11 to the Model 2001 IN-
PUT jacks using a precision DC voltage source (such as the
one used to verify DC voltage accuracy in paragraph 1.8.1),
and check the displayed temperature reading. Be sure to use
low-thermal cables for connections between the DC calibra-
tor and the Model 2001 when making these tests.
The voltages shown are based on a 0°C
reference junction temperature. Use CON-
FIG TEMP to set the default reference
junction temperature to 0°C.
Table 1-11
Thermocouple temperature reading checks
Thermo- Applied DC
couple type voltage*
J -4.215mV
0mV
1.277mV
5.268mV
42.283mV
K -3.242mV
0mV
1.000mV
4.095mV
54.125mV
T -3.089mV
0mV
0.992mV
4.277mV
20.252mV
E -4.777mV
0mV
1.495mV
6.317mV
75.608mV
R 0.054mV
0.647mV
4.471mV
20.878mV
S 0.055mV
0.645mV
4.234mV
18.504mV
B 0.632mV
1.241mV
4.833mV
13.585mV
*Voltages shown are based on 0°C reference junction temperature. Use
CONFIG-TEMP menu to set default reference junction to 0°C.
Performance Verification
NOTE
Displayed
temperature (°C)
-90.5 to -89.5
-0.5 to +0.5
24.5 to 25.5
99.5 to 100.5
749.5 to 750.5
-90.5 to -89.5
-0.5 to +0.5
24.5 to 25.5
99.5 to 100.5
1349.5 to 1350.5
-90.5 to -89.5
-0.5 to +0.5
24.5 to 25.5
99.5 to 100.5
389.5 to 390.5
-90.6 to -89.4
-0.6 to +0.6
24.4 to 25.6
99.4 to 100.6
989.4 to 990.6
7 to 13
97 to 103
497 to 503
1747 to 1753
7 to 13
97 to 103
497 to 503
1747 to 1753
355 to 365
495 to 505
995 to 1005
1795 to 1805
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