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3.7 Calibrating the 4 to 20mA Output
The 4 to 20mA output of the
miniCHEM-Redox
is factory calibrated. However,
TPS has provided calibration controls for the 4mA and 20mA points in case this
requires adjustment in the field. Only a limited amount of adjustment is available,
as the
miniCHEM-Redox
is designed for 4 to 20mA output for the full scale of
the instrument.
Calibrating the 4 to 20mA output…
1.
Connect a Digital Milliamp Meter between terminals 7 and 8.
2.
Switch the
miniCHEM-Redox
to
SET LIMIT
.
3.
Adjust the
LIMIT
control until the display reads 0.
4.
Adjust the
ZERO/4mA
trimmer in the terminal area until the Digital
Milliamp Meter reads 4 mA.
5.
Adjust the
LIMIT
control until the display reads 1000 (or -1000).
6.
Adjust the
SPAN/20mA
trimmer in the terminal area until the Digital
Milliamp Meter reads 20 mA.
In the event that the
LIMIT
control does not have sufficient adjustment to
reach 0 or 1000 (or -1000), calculate the expected output level and use this
for calibration. Remember that the difference between 0 and 1000 (or -1000)
mV is to be made 16mA.
