Monarch Instrument Nova-Strobe vbx - Manual (Page 14)

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6. Once the desired memory location is displayed, press the
MEMORY button to store the current flash rate in that location.
Press any other button to cancel.
7.
DONE will be displayed.
Internal “Phase” Delay / Jog
Once the flash rate has been adjusted to give a stopped motion image,
the PHASE DELAY button may be used with the knob to increase or
decrease the phase of the reference mark location. Use the PHASE
DELAY button and knob to bring a reference mark, such as a key way,
into your line of sight.
To adjust the “Phase” Delay:
1.
Press the PHASE DELAY button.
2. PHASE will be displayed on the bottom line and the current flash
rate will be displayed on the top line.
3. Turn the tuning knob to adjust the phase of the reference mark.
4. Press the PHASE DELAY button again to turn the “Phase” Delay
mode off.
4.2 Internal Mode - TACH Frequency Generator
In the Internal Mode, the strobe can be used as a frequency generator
(outputting TTL pulses) without having the strobe flash.
The pulse
output will still occur at the flash rate; the strobe is just not flashing.
To stop flashing:
Press the ALT FUNCTION button and then the TACH button. The
TACH icon will be displayed.
To start flashing again:
Press the ALT FUNCTION button and then the TACH button. The
TACH icon will go away and the strobe will start flashing again.
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allow it to be placed at a reference location. It may also be noted that slight
adjustment of the Phase Angle control knob may be required before each
measurement, to assure that the reference location is repeated.
If the data collector you are using does not respond to the phase reference
signal supplied to it by the strobe, it is possible that the Trigger Set-up in
the vibration data collector may be reversed. If so, change the set-up from
“positive” trigger slope to “negative”, or vice versa, and try again.
When the strobe is tuned in the Internal (INT) mode, and then switched to
LOCK mode, the filter in the strobe will track slight changes in speed. If
the speed changes too much or too fast, the strobe will lose LOCK/
TRACK and stop flashing. It will be necessary to switch back to Internal
(INT) mode and repeat the adjustments. Also, try switching between the
Narrow and Wide Bandwidth LOCK to optimize results. Generally, the
Wide Bandwidth will give best tracking results but the Narrow Bandwidth
will give better stabilization.
NOTE: When it is necessary to have repeatable phase measurements, it
is necessary to write down the transducer locations used. Also,
the transducer mounting method should be the written down.
Stud mounting or magnetic base mounting is preferred since
data taken with hand-held transducers may lead to significant
phase differences.
5.3 Phase Analysis
The Nova-Strobe vbx can be used to measure movement of parts of a
machine, couplings and machine cases in a machine train. The direction of
movement (Phase) reveals important information about looseness,
unbalance and alignment.
This section is not intended to be a comprehensive review of these
measurements. Refer to one of the many training notes and application
notes written over the years on these techniques.