Cross Channel Phase - Commtest Instruments vb Series Instrument Reference Manual

The measurement location should now contain a large number of
measurements. These can now be transferred to the Ascent
software for display as a waterfall chart. Simple bode plots can also
be created provided the tachometer was used during recording.
To store the measurements see Storing Measurements (page 54).
Setting your own parameters
Option Custom Setup allows you to customize this menu to use
your own settings instead of the factory defaults. See Custom Setups
(page 57) for more information.

8. Cross Channel Phase

Note: This functionality is only available to vb3000 users.
Phase analysis is an effective means of diagnosing machine faults
such as misalignment, resonance, soft foot and looseness among
others. Phase analysis is also useful in distinguishing faults that look
like imbalance but are actually caused by something else (such as
misalignment, which can show up at 1X RPM similar to imbalance).
Knowledge of the phase relationships of various machine faults will
help to confirm the existence of a specific machine fault and help to
prevent misdiagnosis.
Cross channel phase is a convenient method of taking phase
measurements that does not require the use of a tachometer or
reflective tape. Instead, phase is measured between two sensors.
Note: When taking measurements, be aware of the direction each
sensor is facing. If you are measuring across the coupling in the axial
direction you will probably turn the sensors in opposite directions,
thereby introducing an additional 180° phase change. Remember to
take this into consideration when analyzing the phase
measurements.
44 Section 3: Onsite Analysis - Measurement Menu
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com