XITRON 2000I, Руководство пользователя

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Applications 57
achieve thermocouple simulation,
the
accuracies approach 0.1ºC. When
using external ice-point reference junction to achieve thermocouple
simulation, accuracies approach 0.02ºC
The 2000M instrument simulates the thermocouple system by computing the
hot and reference junction-E.M.F. voltages from the N.I.S.T. tables with
linear interpolation. The output level is set to the difference between these
two levels (V
HOT
-V
REF
). Thus single thermocouple (uncompensated) systems
can be simulated by setting the cold junction simulation temperature to 0ºC
using the “Passive CJ” mode.
Select the “Active CJC” mode of operation in the 2000M instrument, and
connect the equipment being calibrated to the rear panel connector using the
correct thermocouple wire (verify polarity). The instrument will
automatically measure and compensate for any ambient temperature at the
actual junction between the connecting thermocouple and the CJC #80-
BARS.
•
To set up thermocouple simulation:
1. Select the thermocouple type: B, E, J, K, N, R, S or T;
2. Choose active or passive cold junction compensation;
3. Enter the required hot junction simulation temperature in either ºC or ºF
units.
Note: In cases where an external reference junction exists, and this junction
has a known temperature with an accuracy of better than 0.1ºC, the 2000M
should be operated in the PASSIVE CJC mode.
Measuring Thermocouple Outputs
The 2000M also offers thermocouple measurement capabilities. You can
calibrate both the receiver and the thermocouple itself
.
•
To measure a thermocouple output:
1. Select the desired thermocouple type and cold junction compensation
method.
2. Connect the thermocouple to the 2000M instrument.