Fmax - GE SCOUT100-Ex Reference Manual

Fmax

Fmax is the maximum frequency displayed on the spectrum (i.e. the
frequency range, over which vibration amplitudes are displayed, starting
from zero).
In general, the higher the operating speed of the machine, the higher the
Fmax needs to be to capture all crucial information. For vibration
involving fingered elements such as gear teeth, fan blades, pump vanes,
and bearing elements, an Fmax equal to three times the number of
fingers multiplied by the operating speed is usually sufficient. For
vibration not involving fingered elements, an Fmax equal to 40 times the
operating speed is usually sufficient.
Some instruments support 60 KHz and 80 kHz Fmax options. This is in
addition to the normal options of up to 40 kHz. The special 60 kHz and
80 kHz high frequency ranges can be recorded in Acceleration and
single channel only. Instruments that support these Fmax ranges will
provide consistent, trendable readings, even though their normal noise,
distortion, and anti-aliasing specification (-70 dB) is not met in the 60 kHz
and 80 kHz high frequency ranges.
NOTE: If you want to add support for up to 80 kHz Fmax on an
instrument manufactured before 1 March 2013, you will need to
return the instrument to New Zealand for calibration.
MORE: Contact your local sales representative for details.
You can specify the Fmax of a measurement as an exact value or a
multiple (order) of a machine's running speed. To do this:
1. Select your measurement type.
2. Press
Fmax Fmin.
3. Press the ORD orders keys.
4. Enter an Fmax orders value.
5. Press twice to return to the measurement setup.
NOTE: When you take a measurement, the resulting display will
use an Fmax with the specified number of orders. The value will be
rounded up to the closest Fmax if an exact match is NOT available.
Section 5 — Set Measurement Options
117