The Analyzer Module
How to Measure Shaft Orbit
Independent Autoranging
For two channel measurements, autoranging is performed simultaneously on both
channels. This allows you to use two probes of differing sensitivity, and allows you to
analyze two axes of differing amplitudes while ensuring optimum gain setting for each
channel.
In all cases, the same filters, integrator, and Fmax are used on both channels.
However, input range and coupling are independent.
For cross-channel phase, dual time and dual spectrum measurements, if the collection
specification is "Overall and Spectrum or Overall Only" then the overall value shall be
calculated from the spectrum as an RSS overall: there is no support for two channel
analog overalls.
How to Measure Shaft Orbit
Orbit Overview
An “orbit” measures the path of a shaft centerline motion during rotation. Orbit
measurements measure CH1 time vs. Ch2 time, unfiltered or order-filtered (up to 8
orders).
Typically, machines such as large centrifugal compressors, primary and secondary
steam turbines, and large gearboxes do not have standby systems available and rarely
have spare rotors available. Machinery that uses pressure fed sleeve bearings is
normally both critical to plant operations and very expensive to repair. It is therefore
essential that these rotors are effectively monitored, protected, and maintained to the
highest standard.
Orbit measurements may be quickly applied using their factory default settings, or you
may change their settings and then perform the measurement. We’ll first describe how
to perform orbit measurements using the default configuration.
How to Take Orbit Data
To perform an orbit measurement (using its default settings):
• From the Analyzer screen use the arrow keys to highlight the Orbit icon, and press
the Start function button. The measurement is performed and the initial
measurement results display.
If you highlight a measurement’s icon and press the Enter (Fire)
button instead of the Start function button, you will display the
measurement’s setup screen, not start the measurement.
SKF Microlog - GX Series 4 - 29
User Manual
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