IM CA71-E
App1-1
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App
Appendix 1 Reference Junction Compensation
Standard thermocouple tables give 0°C as the temperature of
the reference junction. Normally, the input terminal part
(reference junction) of a thermometer (device under calibration)
is at room temperature. (This results in an error equivalent to
the difference between 0°C and room temperature.)
Reference junction compensation means measuring (detecting)
the temperature of the reference junction, calculating the temperature
difference (difference of thermoelectromotive force) from 0°C,
and then carrying out compensation based on the result.
Use an external RJ sensor (or the built-in RJ sensor) for measuring
(detecting) the temperature of the reference junction.
■ Using an External RJ Sensor
Use an external RJ sensor to measure (detect) the temperature
of the thermometer, and compensates thermoelectromotive force.
H L
SOURCE
H
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CA71
<Calibration of thermometer>
Lead cables
Device under calibration
(thermometer)
External RJ sensor