Measurement Of Motion Sequences; Repair - Ecom MOVISTROB MS 2700-E Manual De Instrucciones

9.3 Measurement of motion sequences

When measuring and observing vibrational frequencies or speeds the strobe
frequency is to be set in such a way that a still image of the moving object
is produced. When dealing with rotating or vibrating objects of an unknown
speed, the stroboscope's highest strobe frequency f max should be used
and then reduced until a still image is produced for a frequency f<f+ . The
observation mark should only appear in the image once. If f+ < 0.5 f max, then
the following applies: f+ =γ.
A condition for this is that no still image is overlooked when the strobe fre-
quency is reduced.
Therefore it is recommended to alter the frequency slowly while maintaining a
high level of concentration.
To conduct a subsequent check the strobe frequency should be slowly increa-
sed again from f+ to 2f+. A still image with only one mark should not appear
in this range and for f=2f+ two opposite marks are to be observed.
Measurements are thus feasible for all movement frequencies in the frequency
range of the stroboscope (60 rpm < γ < 21000 rpm).
However, movement frequencies can also be determined for speeds and
vibrations γ > f max occurring above the max. range of the stroboscope. The
following procedure can be applied here:
Two neighbouring strobe frequencies are determined initially fn= γ /n and
fn+1= γ /(n+1), which produce still images of the object. The sought after
speed γ of the object is then calculated from this in accordance with the
following formula γ = fn x fn+1 / fn - fn +1.
If, conversely, a movement frequency (speed) γ is to be set at a specified
strobe frequency f, then a movement frequency which is definitely below the
strobe frequency is to be used as a starting point and increased slowly until a
still image of the (true) object is produced. This is then γ = f.

10. Repair

The national regulations and guidelines for repairs vary from country to country.
We therefore recommend that all repairs are conducted by ecom instruments
GmbH, Germany because the safety of the unit needs to be tested after repairs
are implemented.
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