D-582-3-E
2
Gain Down
Gain Up
AMP Potentiometer
AMP
TLV Potentiometer
Potentiometer
Amplifier Board
Fig. .3
Fig. .2
TLV
Adjustabl
Range
350mVp-p
80mVp-p
160mVp-p
（Factory Set）
Potentiometer
Amplifier Board A
Fig. .
Trigger Level Potentiometer
Amplifier Board A
：
ＴＬＶ
Flow sensitivity is accurately adjusted over the
specified flow range before the meter leaves the
factory.
If no output appears at the minimum flowrate
presumably due to your specific operating
conditions (disturbance from external interference,
for example), readjust the sensitivity (trigger
level).
The same sensitivity readjustment is also required
in cases where the receiving instrument registers
erratic counts at meter shutoff due to noises
caused by pipeline oscillation, etc. after sensor re-
placement.
9. FLOW SENSITIVITY ADJUSTMENT PROCEDURE
9.1 Amplifier Gain
Amplifier gain (amplification) is adjusted to the
sensor used. Do not attempt to readjust it except
when the sensor has been replaced.
A m p l i f i e r g a i n i s a d j u s t a b l e w i t h A M P
potentiometer on the amplifier board A. Monitor
the vortex waveform following amplification on the
oscilloscope and adjust such that the peak value
of vortex waveform is 00mV p-p approx. at the
minimum flowrate.
Sensitivity Potentiometer
Vortex Waveform After Amplification
Amplifier Board A: AMP
Amplifier Board A: VTX
（＋）
to
OV
（－）
9.2 Trigger Level
Trigger level (pulse generation sensitivity)
determines the peak value of amplified vortex
signal above which signal-to-pulse conversion
takes place.
It follows that trigger level adjustment allows flow
sensitivity adjustment.
With increasing TLV pot position (clockwise
rotation), flow sensitivity decreases; with
decreasing it (counterclockwise rotation)
increases flow sensitivity.
If measurement is made near the minimum
flowrate and resultant signal output is too small,
adjust TLV pot to a smaller position. An important
precaution to remember: setting TLV pot to an extremely small position can lead to failure of pulse
generation due to noises caused by pipeline oscillation or other external disturbances.
①
By increasing the trigger level, the flowrate sensitivity decreases with the ratio of trigger level (sensitivity
ratio).
Example:
When a trigger level 0mVp-p is changed to 350mVp-p, the resultant sensitivity will be
0/350
≒
/2.2 (sensitivity ratio) times.
②
When sensitivity is changed, the resultant minimum flowrate (measurable lower bound flowrate) is
approximately the standard minimum flowrate multiplied by /(Sensitivity ratio).
Example:
When a trigger level 0mVp-p is changed to 350mVp-p, the resultant minimum flowrate
will be approximately 350/0
≒
.8 times the minimum flowrate.
Summary of Contents for Smart EX DELTA II Series
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