KROHNE ALTOSONIC V EN - Manual (Page 25)

ALTOSONIC V
Operating Manual rev02 E 7.30850.34.00 Page 25 of 106
4.4 Main menu: F4 Statistics window
The Statistics window shows the statistics and monitors the flow variations for the corrections and
REAL-profile sampling.
Explanation of the Statistics window layout:
TIME CONSTANTS:
•
Tmeas gives the time-constant in seconds as used for the incoming 5 measuring paths flow
percentages. Default the time-constant is 0 sec.
• Tcorr gives the time-constant in seconds as used for the Reynolds and Swirl corrections. Default
the time-constant is 40 sec.
•
Treal gives the time-constant that is used for sampling the REAL-profile. Default the time-constant
is 60 sec. After 3 times Treal (180 seconds) the sampled REAL profile is used for possible
correction.
STATISTICS:
•
The average and relative standard deviation of the 5 channels and the calculated velocity is
calculated over 200 (default) measurements (about 7 seconds).
So every 7 seconds there is an update on these standard deviation values.
•
The average for the channels is presented as flow-rate promillage (-1250…+1250), especially
practical to measure the zero point deviation per channel at zero flow rate. Note that there will be
temperature differences in the proces liquid causing local flows at zero flow.
•
Normal is that channels 1 and 5 have a larger standard deviation then channels 2, 3 and 4. For
ALTOSONIC V ‘s without straightener the shown readings for the standard deviation are normal.
With a flow straightener build-in these values can be reduced by approximately a factor 2.
DEVIATION:
The flow variations for the corrections and REAL-profile are monitored as described below:
•
All channels and calculated velocity are monitored with the normally used time-constant and with
the normal time-constant divided by 10. If the difference between those two time-constants is more