Keithley 2700 - Page 128

Model 2700 Multimeter/Switch System User’s Manual Basic DMM Operation 3-37
reference junction may be inconvenient but it will provide more accurate temperature
measurements (assuming the user enters a precise reference temperature).
With open thermocouple detection disabled, the Model 2700 can calculate the average
temperature of two thermocouple channels using Channel Average (see
Section 5 for
details). As shown in Figure 3-14D, one thermocouple is connected to a primary channel
(1 through 10), and the other thermocouple is connected to its paired channel (11 through
20). Channel 1 is paired to channel 11, channel 2 is paired to channel 12, and so on. Keep
in mind that a simulated reference junction (i.e. ice bath) can instead be used for these
thermocouple temperature measurements.
Figure 3-14
Thermocouple connections
Thermocouple
Ice Bath
Model 2700
A. Simulated reference junction (front panel inputs)
H
L
CH 1-10
Model 7700
Switching
Module
H
L
CH 11-20
D. Channel average calculation, internal reference junction (Model 7700)
Thermocouple
Thermocouple
Thermocouple
C. Internal reference junction (Model 7700)
H
L
CH 1-20
Model 7700
Switching Module
Thermocouple
Ice Bath
Copper wire to thermocouple
wire connection (one of two)
B. Simulated reference junction (Model 7700)
H
L
Model 7700
Switching Module
Copper wires
CH 1-20
Copper wires
Copper wire to thermocouple
wire connection (one of two)
Input HI
Input LO
+
-
+
+
++
-
-
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