Bently Nevada 3300/50, Руководство по эксплуатации, Страница: 72 / 122

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Tachometer Maintenance
83871-01
13
Threshold and Hysteresis Adjustments (Cont)
18. Close the monitor front panel.
Hysteresis Adjustment:
The Tachometer is shipped with a Hysteresis of 0.5 Volts. This should work well in most installations.
However, if the above Manual Threshold Adjust Procedure cannot be completed successfully, or the
Auto Threshold does not function in a certain application, then the Hysteresis may require adjustment.
See section 10 (Monitor Options) for the Hysteresis jumper configurations.
Threshold and Hysteresis Adjustment Considerations:
THRESHOLD PROPERLY ADJUSTED
FIGURE 1
Figure 1 shows proper adjustment of Threshold
and Hysteresis, resulting in one pulse for each
Transducer input.
Threshold is the point where the Trigger Out pulse
is turned on. Hysteresis is the difference between
the level the Trigger Out pulse turns on and the
level it turns off.
Figure 2 shows improper selection of Hysteresis,
but still one pulse for each Transducer input.
Figure 3 shows improper Threshold adjustment
and improper Hysteresis selection. There is more
than one pulse for each Transducer input.
TRIGGER
OUT
INPUT
HYSTERESIS TOO HIGH
BUT OPERATIONAL
FIGURE 2
TRIGGER
OUT
THRESHOLD AND HYSTERESIS
IMPROPERLY ADJUSTED
FIGURE 3
THRESH.
HYST.
THRESH
HYST
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