Answer Posted / richard marks
an i/p converter converts current to pressure. To calibrate
we first need to determin the range of the input and the
output. The current input is usually 4-20mA and the output
is usually 3-15psi (usual industry standards).
Calibration assuming the above input/output:
First connect a milliamp source to the input and a pressure
indicator (pressure gauge, druck etc.) to the output.
Inject a 4mA signal (0%) and check the output is reading
3psi, if not adjust the zero until the output reads 3psi.
Next inject a 20mA signal (100%) and check the output is
reading 15psi, if not adjust the span until the output
reads 15psi. Again inject a 4mA signal and check the 3psi
output as adjusting the span can alter the zero and if it
has changed and adjust as required. Check the span again at
20mA and repeat until the converter reads 3psi at 4mA and
15psi at 20mA repeatedly. Next check the linearity by
injecting signals for 0, 25, 50, 75 & 100% the output
should read as follows;
0% (4mA) 3psi
25% (8mA) 6psi
50% (12mA) 9psi
75% (16mA) 12psi
100% (20mA) 15psi
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