Page 21 - Vibrations-2
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Although a few years old the Agilent 35670A is designed
for low frequency spectral analysis.
Sub-Synchronous Peaks
Vibration spectra can exhibit a third type of feature
known as sub synchronous peaks.
They are caused by any physical element of the system
that operates at a frequency below that of the main shaft.
A loose belt on an axis rotating at 30 Hz, for example,
might slip enough to move at just 29.19 Hz.
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