GF Signet 2551 Magmeter Flow Sensor - Display - Manual (Page 11)

11 2551 Magmeter
Sensitivity
• The SENSITIVITY setting determines how the 2551 responds
to sudden surges in the À ow rate. It "overrides" the Averaging
function just long enough to allow an actual change in À ow rate
to be displayed, then resumes the averaging. The result is a
smooth À ow display and a quick response to large shifts in the
À ow rate.
The settings for Sensitivity represent a percentage of the
magmeter's maximum range, or 10 milliseconds (ms).
Example: A sensitivity setting of 25% means that the À ow rate
must change instantly and by more than 2.5 ms before the
function is enabled.
NOTE: The SENSITIVITY function is ineffective if the AVERAGING
function is set to zero.
No Averaging
With AVERAGING set to zero, the À ow rate will be displayed
immediately and with no ¿ ltering. This line represents the
actual output of the À ow sensor as it responds to unstable À ow
conditions in the pipe.
Averaging Only
With AVERAGING set to 50 seconds and SENSITIVITY still set to
zero the À ow rate is stabilized, but a sharp change in À ow rate is
not represented on the display or at the output for 50 seconds or
longer.
Averaging and Sensitivity
With AVERAGING at 50 seconds and SENSITIVITY set to
25%, the À ow rate is stabilized, while the sudden shift in À ow is
reÀ ected very quickly.
Averaging
• The AVERAGING setting dictates the time over which the
magmeter will average the À ow signal.
The LCD display is updated every second. With averaging at
14 seconds, the À ow rate on the display is an average of the
previous 14 seconds input.
Short averaging times provide the fastest display and output
response to changes in the À ow rate.
Higher averaging times help to smooth the display and current
output where the À ow in the pipe is erratic or unstable due to
installation limitations.
10 s 20 s 30 s 40 s 50 s 60 s 70 s Time
V
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locity
10 s 20 s 30 s 40 s 50 s 60 s 70 s
Time
V
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10 s 20 s 30 s 40 s 50 s 60 s 70 s Time
Ve
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Even the most carefully engineered À ow systems may experience
erratic and unstable conditions. If the instability is communicated
to the output functions, the results may create problems for
control devices.
To alleviate these issues, the 2551 provides two adjustments that
operate in tandem. The information here will help in determining
the appropriate settings for any speci¿ c application.
7.1 Averaging and Sensitivity
CAUTION
The SENSITIVITY function changes the response
characteristics of the magmeter. If used as part of a
tuned closed loop control system, such a change may be
undesirable.