Omega RD-MV100 Series User Manual page 263

13.3 Calibration
DC voltage standard
13-4
Temperature measurement using the RTD (example for the RD-MV112)
+/A
Input terminals
(RTD inputs)
Temperature measurement using the TC (example for the RD-MV112)
Copper wires
+
Meter
-
+
-
Copper
wires
Reference junction compensation for the thermocouple input
As the measurement terminal of the recorder is generally at room temperature, the
actual output of the thermocouple is different from the values given on the
thermoelectromotive force table based on 0°C. The recorder measures the temperature
of the terminal and makes adjustments by calculation. Therefore, when the
measurement terminals are shorted (equivalent to 0°C at the detector tip), the
temperature at the measurement terminal is displayed. When calibrating the RD-MV100,
this compensation voltage (thermoelectromotive force of 0 °C reference corresponding to
the input terminal temperature) must be subtracted from the output of the standard
generator before application. As shown in the figure, by using a Model T-MJ reference
junction pot to compensate the reference junction at 0 °C, you can input the
thermoelectromotive force of 0 °C reference from the standard generator and make the
calibration.
The resistance of three lead wires
must be equal.
/b
-/B
Thermocouple wires
or TC extension wires
+
Couple
-
Thermocouple
wires
Bathe in
crushed ice to keep
at 0°C.
Decade resistance box
+
–
Input terminals