Method and apparatus of detecting internal motor faults in an induction machine
First Claim
1. A method of identifying load and motor fault information in a condition monitoring system comprising the steps of:
- simultaneously sampling voltage and current data of an induction machine in operation;
determining an indicator of reactive power from a portion of the sampled voltage and current data; and
determining an internal motor fault using the indicator of reactive power.
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Accused Products
Abstract
The present invention is directed to a condition monitoring system for determining internal motor fault information. Voltage and current data are acquired from an induction machine in operation. Reactive and real power delivered to the induction machine is then determined from the voltage and current data. An inspection of the frequency spectrum of the real power as well as the reactive power is then used to ascertain load and motor condition. Specifically, an analysis of the frequency spectrum of the reactive power may be inspected for information relating to an internal motor fault whereas the frequency spectrum of the real power may be inspected for information relating to motor-driven or load faults.
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Citations
23 Claims
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1. A method of identifying load and motor fault information in a condition monitoring system comprising the steps of:
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simultaneously sampling voltage and current data of an induction machine in operation;
determining an indicator of reactive power from a portion of the sampled voltage and current data; and
determining an internal motor fault using the indicator of reactive power. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An induction motor monitoring system comprising:
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at least one voltage sensor and at lease one current sensor; and
a controller connected to the at least one voltage and the at least one current sensors and configured to;
receive voltage and current data from the at least one voltage and the at least one current sensor;
determine instantaneous reactive power from the voltage and current data;
generate a frequency spectrum of the instantaneous reactive power; and
determine a motor fault from at least the frequency spectrum. - View Dependent Claims (9, 10, 11, 12)
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13. An apparatus to distinguish between a motor fault and a load fault in an AC induction motor, the apparatus comprising:
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at least two current sensors for obtaining at least two AC motor current signals;
at least two voltage sensors for obtaining at least two AC motor voltage signals;
an analog-to-digital converter for converting the at least two AC motor current signals to digitized current signals and the at least two AC motor voltage signals to digitized voltage signals; and
a microprocessor to receive the digitized signals and compare instantaneous reactive power values to a set of baseline reactive power values to determine a motor fault in the motor. - View Dependent Claims (14, 15, 16, 17)
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18. A computer readable storage medium having a computer program stored thereon to determine faults in an AC induction motor and representing a set of instructions that when executed by a computer causes the computer to:
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model operation of an AC motor having a load thereon and known to be operating normally and determine baseline operation therefrom;
acquire real-time voltage and real-time current data of the AC motor in operation;
determine reactive power of the AC motor from the real time voltage and real-time current data;
compare the reactive power to the baseline operation; and
determine presence of fault conditions in the AC motor from at least the comparison. - View Dependent Claims (19, 20, 21, 22)
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23. A motor fault detector for an AC induction motor, the detector comprising:
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means for acquiring voltage and current data of an AC motor in operation;
means for determining instantaneous reactive power in the AC motor from the voltage and current data; and
means for determining an internal fault in the AC motor from the instantaneous reactive power.
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Specification