CEMB USA N100 - Manual (Page 31)

Vibrometer function 5 - 7
For correct measurement ensure that the shaft velocity is stable and is read correctly by the
instrument. One of the following symbols will be displayed in the event that it is not read
correctly, is unstable, or is lower than the minimum value or higher than the maximum one
(see Appendix A):
Symbol Condition Action to be taken
velocity value not stable
over time.
- Check that the rotating body is not
executing an acceleration ramp: otherwise
wait till the end of the ramp .
- Check that the velocity of the rotating
body does not oscillate periodically:
otherwise take any steps possible to
stabilise it.
velocity signal absent, or of
a value below the
minimum acceptable data
for the instrument
-
Check that the photocell and reflecting
sticker are positioned correctly.
-
Check that the photocell is NOT
positioned in a point with excessively high
vibration, which would prevent the light
from being reflected off the reflecting
sticker.
- Check that the velocity of the rotating
body is above the minimum value:
otherwise it must be increased.
velocity greater than the
maximum acceptable value
for the instrument
- Check that the photocell and reflecting
sticker are positioned correctly (if they
produce more than one impulse per turn
they generate a false high speed)
- If the velocity of the rotating body is
effectively higher than the maximum
acceptable value it must be reduced
Note:
Remember that in order to take a synchronous measurement you must connect the
photocell and check that it is positioned correctly, following these instructions:
-
apply a suitable reflecting sticker (or tag) on the rotating body as a point of
reference (0°). Starting from this position, the corners are measured in the
opposite direction compared to that of the shaft’s rotation.