STATUS SCIENTIFIC CONTROLS
Installation, Commissioning & Routine Gas Testing
FGD10A Oxygen / Toxic Gas Detector
TD18/002
Issue:
16
Change Note:
1904
Page 35
5.2.
Analogue Output Calibration
The analogue output is that of a current source. In order to calibrate the
output it is necessary to monitor the output signal. This can be performed in
one of two ways:
Current measurement:
Connect an ammeter (or multimeter set to measure current in the mA range)
in series with the analogue output.
Advantage: Direct measurement of output.
Disadvantage: The analogue output has to be disconnected to allow the connection of
the meter.
Voltage measurement:
Permanently connect a 10R resistor in series with the analogue output.
When calibration is required, connect a voltmeter (or multimeter set to
measure voltage in the mV range) across the 10R resistor.
Advantage: No need to disturb wiring between FGD10A and control unit.
Disadvantage: Measurement accuracy dependent upon resistor tolerance.
–
+
FGD10
Analogue Output
(4
– 20mA)
Control
Unit
mA
+
Meter range:
0.004A
– 0.020A
4mA
– 20mA
–
+
FGD10
Analogue Output
(4
– 20mA)
Control
Unit
10R
mV
+
Meter range:
0.04V
– 0.20V
40mV
– 200mV
