Martel Electronics 235 - Manual (Page 36)

To display the 235 input and output in % ERR and % Scale units, press
the % Key. Subsequent presses of the % key, will toggle the 235
between engineering unit and % ERR/% Scale unit displays.
Once the calibrator is turned off, all % Error setup are lost.
External Temperature Compensation Module
The External Temperature Compensation Module allows the calibrator
to perform thermocouple calibration using copper wire and to operate
under harsh temperature variations.
Under normal circumstances, the calibrator should be connected to the
instrument under test using the same type wire as the thermocouple
being simulated. This allows differences in temperature between the
calibrator and instrument to be compensated automatically.
If the proper thermocouple wire is not available when making a
calibration, the External Temperature Compensation Module may be
extended from the calibrator using the Lead Extension Kit, and
connected to the instrument with very short copper leads. The Module
should then be positioned as close as possible to the instrument’s
terminals, and allowed to stabilize to the instrument’s terminal
temperature.
When making thermocouple calibrations in extreme temperature
conditions, the External Temperature Compensation Module must be
used to provide optimum performance. The internal sensor response
time may lag that of the module’s response time.
The External Temperature Compensation Module can be attached to
either the input or output TC jacks. The sensor plug attaches to the ECJ
jack on the calibrator face. The calibrator will automatically switch to
the External Module as soon as the sensor plug is attached.
Operation
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