Monarch Instrument Nova-Strobe vbx - Manual (Page 12)

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user to vary the stopped motion image at any point in the cycle without
having to move the trigger source location. The Lock modes use the signal
from an accelerometer/input source.
4.1 Internal Mode - Standard Strobe Operation
In the Internal Mode the stroboscope generates it’s own signals and
functions like a tunable stroboscope. The strobe is in the Internal
Mode when nothing is plugged into the input jack or when manually
set using the INPUT button.
To change the flash rate:
With the power on, turn the knob counter clockwise to increase the flash
rate and clockwise to decrease it. The knob is velocity sensitive. Turn the
knob slowly to have each “click” is equal to 0.01 FPM. Turning the knob
more quickly will adjust the FPM by larger steps. When adjusting flash
rate, quickly turn the knob (or use the x2 or ÷2 buttons) to coarsely
change the FPM. Then slowly turn the knob for fine adjustments.
NOTE: There are maximum and minimum values in each mode
beyond which you cannot adjust. If you are adjusting the
rate and you reach a value which on the next increment would
exceed the maximum flash rate, the display will not increment.
The same is true if you try to adjust the flash rate below the
minimum flash rate.
To multiply or divide the current flash rate by 2:
In addition to the knob, there are two buttons on the display panel
marked x2 and ÷2. This enables the user to instantly double or halve
the reading on the display to the maximum or minimum values allowed.
This feature is useful for checking harmonics in the internal flashing
mode.
to an area above any split line, to the bearing cap. Note the phase
angle at each of these locations.
2. The reference mark should stay at the 12:00 o’clock position for each
of these measurements. If phase changes/shifts (probably to 6:00
o’clock) at any of these measurement points, there is looseness at the
mechanical joint.
Checking for unbalance:
1. If the vibration transducer is moved from the vertical position on the
bearing to another radial position, the reference mark will move to the
new position if there is a significant amount of unbalance. The
reference mark will follow the vibration transducer around the clock
only if the once per turn vibration is caused by unbalance.
Checking for alignment:
1. Alignment checks can be made by moving the vibration transducer to
each end of the machines in a train. The vibration transducer is
positioned axially at these locations for these measurements. Keep
track of the phase for each measurement location.
2. As the vibration transducer is moved to each location, it’s direction
keeps changing from North to South, for example. When it changes
direction, phase will shift from 12:00 o’clock to 6:00 o’clock.
3. If you move across a coupling and phase does not change as expected,
a misalignment condition can be the cause.
5.4 Motion Studies
The Nova-Strobe vbx can be a useful tool to determine how a mechanical
support or a piping system is moving. It allows the user to find points of
maximum motion as well as minimum motion. This is important if a new
pipe hanger is to be installed or if a brace is going to be added to dampen a
vibration condition.
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