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Analysis of incipient fault signatures in inductive loads energized by a common voltage bus

Recent research has demonstrated the use of electrical signature analysis (ESA),
that is, the use of induction motor currents and voltages, for early detection of motor
faults in the form of embedded algorithms. In the event of multiple motors energized
by a common voltage bus, the cost of installing and maintaining fault monitoring and
detection devices on each motor may be avoided, by using bus level aggregate electrical
measurements to assess the health of the entire population of motors. In this research
an approach for detecting commonly encountered induction motor mechanical faults
from bus level aggregate electrical measurements is investigated.
A mechanical fault indicator is computed processing the raw electrical measurements
through a series of signal processing algorithms. Inference of an incipient fault
is made by the percentage relative change of the fault indicator from the “healthy”
baseline, thus defining a Fault Indicator Change (FIC).
To investigate the posed research problem, healthy and faulty motors with broken
rotor bar faults are simulated using a detailed transient motor model. The FIC
based on aggregate electrical measurements is studied through simulations of different
motor banks containing the same faulty motor. The degradation in the FIC when
using aggregate measurements, as compared to using individual motor measurements,
is investigated. For a given motor bank configuration, the variation in FIC with
increasing number of faulty motors is also studied. In addition to simulation studies
experimental results from a two-motor setup are analyzed. The FIC and degradation
in the FIC in the case of load eccentricity fault, and a combination of shaft looseness
and bearing damage is studied through staged fault experiments in the laboratory
In this research, the viability of using bus level aggregate electrical measurements
for detecting incipient faults in motors energized by a common voltage bus is
demonstrated. The proposed approach is limited in that as the power rating fraction
of faulty motors to healthy motors in a given configuration decreases, it becomes far
more difficult to detect the presence of incipient faults at very early stages.
Date12 April 2006
CreatorsBade, Rajesh Kumar
ContributorsParlos, Alexander G.
PublisherTexas A&M University
Source SetsTexas A and M University
Detected LanguageEnglish
TypeBook, Thesis, Electronic Thesis, text
Format528062 bytes, electronic, application/pdf, born digital

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