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Yokogawa Value Series FX1000 User Manual

Page 248

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11-3

IM 04L21B01-01EN

Maintenance

3

2

1

4

5

6

7

8

9

10

11

12

13

14

App

Index

Temperature Measurement Using an RTD (Example for the FX1012)

Decade resistance box

The resistance of three lead

wires must be equal.

(Model 2793-01 from Yokogawa

Meters & Instruments Corporation)

b

A

B

Input terminal

Temperature Measurement Using a Thermocouple

(Example for the FX1012)

Thermocouple wires or TC

extension wires

Thermocouple

wires

Copper

wires

Copper wires

DC voltage standard

+

-

(0 °C standard temperature device ZC-114/ZA-10 by Coper Electronics)

Input terminal

RJC of TC Input

As the measurement terminal of the FX 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 FX performs compensation by measuring the temperature
at the input terminal and adding the corresponding thermoelectromotive force to the
actual output of the thermocouple. 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 FX, 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.

11.2 Calibrating the FX