Monarch Instrument Nova-Strobe vbx - Manual (Page 18)

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After the image has been locked and the Narrow or Wide Bandwidth
has been optimized for the speed and/or background noise on the
sensor signal, the Phase knob can be used to adjust the phase of the
output pulse (and image) - refer to the Phase Analysis section later in
this manual for adjusting the Phase Angle control.
After you have the unit in either the wide or narrow lock mode and you
have a steady RPM, you can turn on tracking.
To turn on Filter Tracking:
Press the ALT FUNCTION button and then the PHASE DELAY button.
The strobe will display “TRACK
TRACK TRACK TRACK TRACK” for a moment. Now the Wide or Narrow
bandpass filter will automatically attempt to track input RPM. This is
useful if you want to see how the vibration changes over a wide RPM
range. It will track as long as the RPM doesn’t change too quickly. As
RPMs change, the phase of the image is likely to change as the filter tracks.
To turn off Filter Tracking:
Press the ALT FUNCTION button and then the PHASE DELAY button.
The strobe will display “NO TR
NO TR NO TR NO TR NO TR” for a moment.
4.7 Power Up Features
When the strobe is powered up it will remember the last settings.
Press and hold the x2/MENU button, then turn on the strobe by
depressing the trigger switch. This will turn on all the display segments
for two seconds or until you release the button. It will then show the
software revision, “REV x.x” and then go through a display diagnostic.
Press and hold the ÷2 button, then turn on the strobe by depressing
the trigger switch. This will restore the factory programmed presets.
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5.0 APPLICATIONS
5.1 Using the Stroboscope to Measure RPM
The primary use for a stroboscope is to stop motion for diagnostic
inspection purposes. However the stroboscope can be used to measure
speed (in RPM / RPS). In order to do this several factors need to be
considered. First, the object being measured should be visible for all 360°
of rotation (e.g. The end of a shaft). Second, the object should have some
unique part on it, like a bolt, key way or imperfection to use as a reference
point. If the object being viewed is perfectly symmetrical, then the user
needs to mark the object with a piece of tape or paint in a single location to
be used as a reference point. Look only at the reference point.
If the speed of rotation is within the range of the stroboscope, start at the
highest flash rate and adjust the flash rate down. At some point you will
stop the motion with only a single reference point of the object in view.
Note that at a flash rate twice the actual speed of the image you will see
two images (reference points). As you approach the correct speed you
may see three, four or more images at harmonics of the actual speed. The
first SINGLE image you see is the true speed. To confirm the true speed,
note the reading and adjust the stroboscope to exactly half this reading, or
just press the ÷2 button. You should again see a single image (which may
be phase shifted with respect to the first image seen).
For example, when viewing a shaft with a single key way you will see one
stationary image of the key way at the actual speed and at 1/2,1/3,1/4, etc,
of the actual speed. You will see 2 images of the key way at 2 times the
actual speed, 3 key way at 3 times, etc. The Flashes Per Minute (FPM)
equals the shaft’s Revolutions Per Minute (RPM) at the highest
flash rate that gives only one stationary image of the key way.