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Operation
Error on 4/20 mA output or during 4/20 mA test 20 mA high
LED
SEQUENCE
POWER
G
SYSTEM
Y
Y
CALIBRATE
R
FAULT
mA FAULT
R
SOURCE
G
ATMOS
G
To resolve this issue, Place a resistor having at least
100 to 250 ohms across the signal output (SIG) and
ground (GND). The "mA fault" LED will stop blinking
indicating the load or wiring has a problem.
Sensor Output at 0 mA
Verify +24 VDC at the sensor terminal block (see
Figure 10, Note 1 on previous page).
Check signal voltage between Test(+) and Test(—)
(see Figure 10, Note 2). Voltage should be in the
range of 40 to 200 mV corresponding to an actual
current flow of 4 to 20 mA. If this voltage is 0 mV, the
signal has no path to ground. Check monitoring
equipment connections and configuration. Input
impedance must be 500 ohms or less.
Sensor Output at .5 mA
Please see Section D on page 15 for possible fault
conditions related to .5 mA output.
Gas Concentration Indicated With No Refrigerant
Present
TM
The AirScan
iR is designed to be quite specific to
CFC/HCFC/HFC's that are colorless, odorless gases
which can't be sensed by humans at low levels.
Always double-check with another instrument before
assuming refrigerants are not present.
Performing a zero and a span calibration using
certified calibration gas will confirm or correct the
sensor's reading.
Manning AirScan-iR Refrigerant Sensor
continued
N/A
N/A
N/A
N/A
18908 AirScan-iR-comm 01/2006 REVA Copyright © 2006 Manning Systems, Inc. All Rights Reserved.
IR Source Failure
If the IR source signal strength drops to the point that
the unit can no longer function satisfactorily, the "fault"
LED will remain continuous ON and the 4/20 mA
output will be set to 0.5 mA. See example below. This
condition can also occur in environments where there
is a significant amount of particulate contamination.
Usually is takes an appreciable amount of time for the
particles to pose signal degradation, however, under
long-term exposure the filter surface could be dirty
causing low thermal readings, hence marginal
operation for signal analysis.
LED
SEQUENCE
G
POWER
N/A
SYSTEM
Y
CALIBRATE
Y
N/A
FAULT
R
mA FAULT
R
N/A
N/A
SOURCE
G
N/A
ATMOS
G
NOTE: 4/20 mA will be set to 0.5 mA.
22
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