GAA330-M
EMISSION MONITORING SYSTEM | OI/GAA330-M-EN REV. C
49
Cycle time
Cycle time duration
The cycle time is given as the time interval between two automatic starts of
the back-purging procedure. The higher the dust concentration in the sam-
ple gas and the higher the sample gas flow, the shorter this time interval
must be set, to avoid a blocking of the gas sampling probe filter.
Cycle time factory setting
The parameter "Cycle time" is factory-set to 8 h.
The parameter "Next event time" is factory-set to 08:00 / 12:00 / 16:00 /
20:00 / 00:00 / 04:00 o’clock.
Optimum cycle time setting
The cycle time should not be adjusted shorter than needed, because during
the back-purging procedure (approx.28 s) and especially during the post-
purge time (factory-set to 150 s) no measurement can be made. The opti-
mum time will have to be found out by operational experience.
Cycle time minimum value
The cycle time should not be below a lower limit. The back-purging proce-
dure with cold compressed air causes a cooling of the heated probe filter,
and the filter temperature regulation needs some time to correct this tem-
perature decrease. As the filter heating regulation is a rather slow control
loop, this time will be relatively long. Therefore, the cycle time should not fall
below approx. 60 min.
Event-controlled start of the back-purging procedure by filter plugging
Should despite the time controlled back-purging a probe filter blocking oc-
cur caused by temporary larger amounts of dust, with the result of a sample
gas flow decrease beneath the admissible limit, an additional back-purging
procedure is started as a result, and the probe filter is purged free in be-
tween.
Adjustment of the cycle time
To adjust the cycle time the parameters of the AC500 program must be
changed. Please contact ABB service.
