Strobe Light
5 - 1
User Manual
5
Applications
Using the Stroboscope to Measure RPM
The primary use for a stroboscope is to stop motion
for diagnostic inspection purposes. However, the
stroboscope can also be used to measure speed (in
RPM / RPS). To do this, several factors must 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 must 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).
