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6.5 Calibration example
The BA304NC is required to display:
25.0 with 4.000mA input
115.0 with 20.000mA input
i.e. A zero of positive 250 (Ignoring decimal point)
A span of 900 (Ignoring decimal point)
A decimal point in position 00.0
The following adjustments are required:
Step 1
The BA304NC is required to display a
positive zero therefore the suppression
/ elevation links should be put in the
elevation position.
Step 2
The required zero is 250, therefore the
zero link should be put in the 0 to 500
position.
Step 3
The required span is 900, therefore the
span links should be placed in the 500
to 1000 position.
Step 4
The decimal point is required in front of
the least significant digit, therefore the
decimal point link should be placed in
the 00.0 position.
Step 5
With 4.000mA input adjust the zero
potentiometer until the indicator
displays 25.0
Step 6
With 20.000mA input adjust the span
potentiometer until the indicator
displays 115.0
Step 7
Repeat steps 5 and 6 until both
calibration points are correct. The span
and zero controls are almost
independent so it should only be
necessary to repeat each adjustment
twice.
6.6 Over and under-range
If the indicator display range is exceeded, the three
least significant digits will be blanked. Under-
range is indicated by -1 and over-range by 1. If
the display range is not exceeded, the BA304NC
will produce accurate readings outside the 4/20mA
current range. Although not guaranteed, most
BA304NC indicators will operate between 3 and
25mA.
