PN 305200901, Rev YT
Frequency Oset
Frequency oset is only used with the 3050-SLR, -TE, and -DO models. The
3050-OLV has no Zeroing method but it is important to be aware of what this
parameter is and how it aects the instrument readings.
Frequency oset is dened by AMETEK Process Instruments as the amount of
Delta Frequency deviation from 0.0 Hz (plus or minus), at the end of the Zero
calibration. Remember that during this calibration, the analyzer is running dry
or Zero gas. This means that every time your moisture analyzer performs a Zero
calibration, whatever Delta Frequency the instrument reads at the end of the
Zero, it is stored in memory (ID Number 38 Hex). During normal operation,
this oset is subtracted from the Delta Frequency readings due to sample or
wet gas, thus eliminating the Zero oset.
The 3050-OLV Analyzer uses two Dryers to perform the Zero calibration,
Sample and Reference respectively. Since these Dryers are never exactly the
same and due to the asymmetry of the manifold, tubing, etc., the instrument
will read a Delta frequency slightly dierent from 0.0 Hertz. This is exactly what
the Zero accomplishes. It takes care of those dierences, expressed in Delta
Frequency, by Zeroing the analyzer. As long as the dierences are repeatable,
they can be reliably subtracted to remove any Zero oset.
Normal Zero Delta Frequency will be around ±0.4 Hertz (the smaller the num-
ber the better). If it is greater than ±0.5 Hertz, it will trigger a Zero error alarm.
This is dened by parameter ID Number 86 Hex (MaxZero Error) = 0.5. This
is the limit for any Zero sequence. Although the 3050-OLV does not use this
MaxZeroError parameter, it does have a Zero oset parameter ID Number 38.
This parameter is set during the calibration process in our plant. It is important
to check its integrity because, as explained before, its value aects the ana-
lyzer’s reading.
The last Zero Delta Frequency value can be viewed from the Congurator
Software, on the Monitor tab as shown below or by reading parameter ID# 38
Hex. This parameter is your last successful Zero Delta Frequency. Note that
the 3050-OLV will not have a Frequency Oset on the Monitor tab since it
does not have zeroing capability. In the example below, the Zero Delta Fre-
quency is 0.0000 Hz. This is because the Zero calibration has not been run yet,
or unsuccessful Zero attempts were performed, therefore, the MaxZeroError
(ID Number 86 Hex) did not allow zeroing.
The Zero calibration should be implemented daily (once a day).
Maintenance and Troubleshooting | 4-19
To Next Page
Loading...
Need help?
General
