Sierra InnovaMass 240i Series, Инструкция по эксплуатации, Страница: 56 / 115

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In the example above, all frequencies above 125.35 Hz will be filtered out.
Amplitude:
The Amplitude menu displays the current sensor amplitude. Strong flow signals will
have amplitudes in the range of 2000 to 4000. The strength of the flow signal is dependent on the
density and velocity of the fluid.
Gain:
The Gain menu displays the current Gain Stage. Gain is the ratio of the output to the input.
There are eight Gain Stages from no gain to full gain (1.0, 3.33, 10.0, 33.33, 100.0, 333.33, 511.0,
1697.0).
At low flow rates, the signal is weak and requires amplification to detectable levels. In this case,
Amplitude is low and the Gain value is high. As flow rate increases, the Amplitude will build
until it reaches a maximum, then the Gain will drop to the next lower level (from 333.33 to 100 to
33.3 etc.). If flow rate continues to increase, the Amplitude will build again, and the Gain stage
will drop. So, a very strong flow signal will result in Amplitude of 2000- 4000 and a Gain of 1.0.
Minimum Noise Level: The Minimum Noise Level menu displays a value used for noise cutoff
at zero flow. Electrical or vibrational noise that the sensor detects from the surrounding
application environment (e.g. 60 Hz from power lines) can result in flow output when there is no
actual flow.
In general, the Minimum Noise Level should be a value slightly higher than the value of the
Amplitude divided by the Gain detected by the sensor at zero flow.
For example, if Amp = 900 and Gain = 100 at zero flow, then Amp/Gain = 9. A Minimum Noise
Level > 9 will cut off unwanted noise, which if not done the meter would interpret as flow.
Vortex Coefficient Ck:
The Vortex Coefficient Ck menu displays the current value set for Ck.
Ck is used in the placement of a Low Pass Noise Filter which helps to avoid false frequency
readings. Ck is calculated based on Frequency, Amplitude, and Gain along with the Density of
the fluid under flow.
As the Minimum Noise Level setting increases, the potential for cutting off
actual low flow readings increases. If the target flow rate is being cut off,
reduce the Minimum Noise Level.
Min. Noise
9.2
Gain
3.33
Amplitude
2854.32