YOKOGAWA MW100 User Manual

4-16
IM MW100-01E
Calibration of Temperature Measurements using Thermocouples
Required Instruments
• DC Voltage/Current Standard
Must meet the following specifications (5520A by FLUKE or equivalent):
Output accuracy: ±(0.005%+1µV) or less
• 0 °C reference temperature device
Must meet the following specifications (ZC-114/ZA-10 by Coper Electronics or
equivalent)
Standard temperature stability accuracy: ±0.05 °C or less
Reference Junction Compensation of Thermocouple Input
Normally, the input terminal of the universal input module is nearly at room temperature,
so the actual thermocouple output differs from the value in the table for the
thermoelectromotive force of the 0°C standard. The universal input module measures
the temperature of the input terminal and compensates by applying a corresponding
thermoelectromotive force to the actual thermocouple output. Therefore, when the
measurement terminal is shorted (equivalent to the case when the detector tip is 0°C),
the measured value indicates the temperature of the input terminal.
When calibrating the universal input module, this compensation voltage
(thermoelectromotive force of the 0°C standard 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 the 0°C standard temperature device to
compensate the reference junction at 0°C, you can input the 0°C thermoelectromotive
force from the DC voltage standard and perform the calibration.
Wiring Diagram
+
-
100Vpk MAX TO
250V MAX CH TO CH
600V MAX TO
Thermocouple wires or
TC extension wires
Thermocouple
wires
Copper
wires
Copper wires
DC voltage standard
Input terminal
–
+
Cold junction
0°C standard temperature device
4-CH, High-Speed Universal
Input Module*
* Make a similar
connection in the
case of a 10-CH,
Medium-Speed
Universal Input
Module.
Note
• Calibration of temperature measurements of the MW100 Data Acquisition Unit using
thermocouples differs from calibration of DC voltage and RTD ranges in that the input
cannot be adjusted. If the temperature measurement calibration using thermocouples does
not meet the accuracy specifications, check thoroughly for input error and other problems,
then contact your Yokogawa dealer or representative.
• If errors exist in the thermocouple wires and TC extension wires, correct calibration is not
possible. Be sure to use a calibrated thermocouple.
4.4 Calibration

YOKOGAWA MW100 Specifications

General

Brand	YOKOGAWA
Model	MW100
Category	Data Loggers
Language	English