217 research outputs found
Effects of Load Magnitude on Diagnosing Broken Bar Faults in Induction Motors Using the Pendulous Oscillation of the Rotor Magnetic Field Orientation
The effects of load level on the ability to diagnose broken bar faults in squirrel-cage induction motors are studied in this paper. The pendulous oscillation of the rotor magnetic field orientation is implemented as a fault signature for rotor fault diagnostic purposes at steady-state operations. Moreover, the effects of load level on the low-side band component of the stator current spectrum, and associated diagnostic difficulties in this approach particularly in the presence of motor operation from pulsewidth-modulation drives, are reported as well. These investigations were performed through testing 2-hp and 5-hp induction motors over a wide range of load levels and control drives. The results of these tests and investigations demonstrate the efficacy of the pendulous oscillation signature as a diagnostic means that can be used for a wide range of motor operating conditions
On the distance-transitivity of the square graph of the hypercube
Let be a graph. The graph of the graph
is the graph with the vertex set in which two vertices
are adjacent if and only if their distance in is at most two. The
square graph of the hypercube has some interesting properties. For
instance, it is highly symmetric and panconnected.
In this paper, we investigate some algebraic properties of the graph
. In particular, we show that the graph is
distance-transitive. We will see that this property, in some aspects, is an
outstanding property in the class of distance-transitive graphs. We show that
the graph is an imprimitive distance-transitive graph if and only if
is an odd integer. Also, we determine the spectrum of the graph .
Moreover, we show that when is an even integer, then is an
graph, that is, is a distance-transitive primitive graph
which is not a complete or line graph.Comment: 17 pages, 1 figur
On Innovative Methods of Induction Motor Interturn and Broken-bar Fault Diagnostics
A fault indicator, the so-called swing angle, for broken-bar and interturn faults is investigated in this paper. This fault indicator is based on the rotating magnetic-field pendulous-oscillation concept in faulty squirrel-cage induction motors. Using the swing-angle indicator, it will be demonstrated here that an interturn fault can be detected even in the presence of machine manufacturing imperfections. Meanwhile, a broken-bar fault can be detected under both direct-line and PWM excitations, even under the more difficult condition of partial-load levels. These two conditions of partial load and motor manufacturing imperfections, which are considered as difficult situations for fault detection, are investigated through experimentally obtained test results for a set of 2- and 5-hp induction motors
Induction Machine Broken-bar Fault Diagnosis Using the Rotor Magnetic Field Space-vector Orientation
A new technique based on rotor magnetic field space vector orientation is presented to diagnose broken-bar faults in induction machines operating at steady state. In this technique, stator currents and voltages are used as inputs to compute and subsequently observe the rotor magnetic field orientation, which has a more significant swing-like pendulous oscillation in case of broken-bar faults than in healthy operation. It will be shown here that the range of this pendulous oscillation is a function of the number of broken bars. Also in this technique, it was found that an inter-turn shorted stator-winding fault, which exhibits similar pendulous oscillation, could be distinguished from rotor broken-bar faults through the use of a variance index. In order to validate this method, experimental evidence is given here for several broken-bar cases in a 2-hp three-phase two-pole squirrel-cage induction machine
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