64
MAN0530 Issue 10 - 11/09
Searchline Excel
2104M0506
5. PROBLEM SOLVING
Fault/Problem
Causes
Remedies
No signal or
Receiver misaligned
Re-align the Receiver, first using the
very low signal
telescope and then using the Interrogator.
at Receiver
Transmitter misaligned
Re-align the Transmitter using the telescope.
The beam path has become
Check that the beam path is clear from
obscured
Transmitter to Receiver.
Remove any obstruction if present.
No output from Transmitter
1) Check that the Transmitter is flashing.
Alternatively, listen for a distinct ticking
sound when the lamp flashes.
Note: The infrared beam is invisible and eye
safe.
2) If the Transmitter is not flashing, check
that the +24V supply is reaching the
Transmitter correctly.
Unit does not
Plastic test filters are only
Searchline Excel units are calibrated on
respond exactly
an approximate simulation of gas
real gas. This results in a variation of the
as expected to
response
test filters
of different Excel
units to plastic test filters. See section
5.1.2.
1) Check that the response to the test
filters is within the limits stated in this
handbook. See section 5.1.2.
2) Check that the value being used for
response testing corresponds correctly to the
target gas that the unit has been calibrated for.
Receiver misaligned
1) Use the telescope and Interrogator to
optimise Receiver alignment.
2) Re-zero unit.
Contamination of windows
1) Check the Transmitter and Receiver
windows for build up of contamination.
Clean windows if required. See
Chapter 5
.
2) Re-zero unit.
Drift of unit’s zero position
1) Verify that there is no gas in the beam path.
2) Re-zero the unit.
Unit appears to
Misinterpretation of iNhibit,
Searchline Excel does
not
report
be reporting a
beam-bloCK or loW
negative gas readings on the 4-20mA.
negative gas
siGNalcurrents that are
1) Configure controller/PLC to interpret
reading on the
output on the 4-20mA
and present currents below 4mA correctly,
4-20mA
or
,
2) Familiarise operators with the
interpretation of sub-4mA output currents
from Excel as follows:
FAULT
0mA
INHIBIT
2mA
BEAM-BLOCK
2.5mA*
LOW SIGNAL
3mA*
or,
3) Reconfigure the
INHIBIT
,
BEAM-BLOCK
and
LOW SIGNAL
currents output by the
Excel unit.
