Thermocouple Measurement/Simulation, Connections and Troubleshooting
MC4 User Guide 117
Error situations
The easiest way to avoid errors in thermocouple measurement and
simulation is to check carefully the used wiring and the Reference
Junction mode. The following table describes the typical error
situations and possible causes/corrections when working with
thermocouples:
PROBLEM CAUSE
MC4 (or the instrument under test
when simulating thermovoltages)
measures the temperature/millivolt
signal, but the displayed
temperature reading is all wrong.
(The error may vary from 0 to
about ±50°C depending on the
type of the error)
•
The thermocouple type selected in MC4
does not correspond with the used
thermocouple.
•
The selected Reference Junction mode
is not in accordance with the used wiring.
•
Extension or compensation cable type or
connections are incorrect.
•
The polarity of the cables are incorrect.
MC4 (or the instrument under test)
displays random readings during
thermocouple measurement.
•
Incorrect connections.
•
The wiring is broken.
•
Interference from a mobile phone or a
radio transmitter affects the
measurement.
MC4 displays unstable readings
during thermocouple simulation.
•
The instrument to be calibrated uses
voltage pulses to detect an open sensor.
When MC4 detects these pulses, it tries
to compensate for them, which causes
the unstable output. Prevent these
pulses for the time of calibration. Refer to
the service manual of the instrument to
be calibrated on how to prevent these
open sensor detection pulses.
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