YOKOGAWA MX100 User Manual

3-10
IM MX100-01E
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%+1µV)orless
• 0°C standard 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
The input terminal section of the universal input modules are normally near room
temperature, so the actual thermocouple output differs from the 0°C reference
thermoelectromotive value. The universal input module measures the temperature of the
input terminal and compensates by applying a corresponding thermoelectromotive power
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 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 the 0°C standard temperature device to
compensate the reference junction at 0°C, you can input the thermoelectromotive force
of 0°C reference 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
•
Unlike the range calibration of DC voltage or RTD, the input section cannot be adjusted
for calibration of temperature measurement on the MX100 Data Acquisition Unit using a
thermocouple. If accuracy specifications are not upheld after calibration of temperature
measurement using thermocouples (see sections 4.4 and 4.5), check for input error and
other factors, then contact your Yokogawa dealer.
•
If errors exist in the thermocouple wires and extension wires, correct calibration is not
possible. Be sure to use a calibrated thermocouple.
3.3 Calibration

YOKOGAWA MX100 Specifications

General

Brand	YOKOGAWA
Model	MX100
Category	Data Loggers
Language	English