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BAM 1020-9800 Manual Rev W.docx
Page 56
L
Power Failure
or
Processor Reset
This error occurs if AC input power is lost even momentarily, or if the power switch is
turned off
. Frequent “L” errors usually indicate poor quality AC power. If frequent
power errors occur even when the BAM 1020 is connected to a UPS backup system,
contact Met One Instruments for instructions on possible power supply upgrades.
Anything that causes the microprocessor to reset will also result in a
n “L” error, such
as low voltage on the 5.25V Vcc bus, bad connections on the internal DC power
harness, or in rare cases electrical interference. All power failure errors cause the
digital concentration value to go full-scale.
R
Reference Error
or
Membrane Timeout
This error indicates that the span reference membrane assembly may not be
mechanically extending or withdrawing properly. The error is generated if photo
sensors S2 and S3 never change state after 15 seconds despite drive commands to
the membrane motor. The digital error log will indicate which photosensor timed out.
It may be a simple sensor/flag alignment problem that can be identified and
corrected using the TEST > ALIGN menu. However, if the span foil assembly is
stalled in a partially extended position, it could block the beta signal and prevent
valid data collection.
N
Nozzle Error
or
Delta-T Alarm
This error indicates that the nozzle motor is not operating correctly. The error is
triggered if photo sensors S4 and S5 never change state within 12 seconds, despite
drive commands to nozzle motor. The concentration value is set to full-scale if the
nozzle motor or sensors have failed. The digital error log will indicate which
photosensor timed out.
Important Note:
The nozzle sensors watch the motor cam rotation, not the actual
action of the nozzle itself, so it is technically possible for the nozzle to become stuck
in the UP position even if the motor and sensors indicate no error. This could result
in a massive flow leak and useless data with no errors or alarms being generated!
Proper maintenance of the nozzle O-ring and proper inlet alignment prevent this.
Due to a limited number of discrete alarms, t
he “N” alarm is also used to indicate that
the Delta-Temperature set-point was exceeded by more than 1 degree, if Delta-T
control is enabled. In this case the alarm is used as a flag, and valid concentrations
are still stored. Delta-T control is disabled in almost all applications. See Section 6.9.
Download the error log file to tell if the alarm is from a nozzle failure or simply a
Delta-T event.