9
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:
1.
Press the
ALT FUNCTION
button and then the
TACH
button.
2.
The
TACH
icon will be displayed.
To start flashing again:
1.
Press the
ALT FUNCTION
button and then the
TACH
button.
2.
The
TACH
icon will go away and the strobe will start flashing
again.
12
5.0 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.
