US5270640A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for incipient failure detection in electric machines
Assignee: Penn State Research Foundation
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Filing: 1992-04-23
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Granted: 1993-12-14
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Expires: 2012-04-23
Abstract
Abstract An improved method for detecting an incipient failure in a multiphase electric motor includes the following steps: periodically measuring or continuously monitoring voltage and current values at each input to the motor; determining negative sequence voltage and current values for each periodic measured input voltage and current value; calculating an effective negative sequence impedance phasor value angle from each of the determined negative sequence voltages and current values; and comparing the calculated negative sequence impedance phasor angles and/or real and imaginary components over a plurality of periodic measurements to detect a change therein, which change is indicative of an incipient failure mode.
Inventors
- 👤 Jeffrey L. Kohler
- 👤 Joseph Sottile, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:10
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/34; G01R31/343
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
108 words
A method for detecting an incipient failure in a multiphase electric motor, said motor having an input for each phase from a supply source, said method comprising the steps of: (a) performing a plurality of successive measurements of simultaneous voltage and current values at each said input; (b) determining negative sequence voltage and current vector values for a plurality of said measured voltage and current values; (c) calculating effective negative sequence impedance phasor angles from said determined negative sequence voltage and current vector values; and (d) comparing a plurality of said effective negative sequence impedance phasor angles to detect a change therein as indicative of said incipient failure.
Claim 2
Independent Claim
108 words
A method for detecting an incipient failure in a multiphase electric motor, said motor having an input for each phase from a supply source, said method comprising the steps of: (a) performing a plurality of successive measurements of simultaneous voltage and current values at each said input; (b) determining negative sequence voltage and current vector values for a plurality of said measured voltage and current values; (c) calculating effective negative sequence impedance phasor angles from said determined negative sequence voltage and current vector values; and (d) comparing a plurality of said effective negative sequence impedance phasor angles to detect a change therein as indicative of said incipient failure.
Claim 3
Dependent Claim
22 words
The method as recited in claim 1, wherein said supply source provides three phases, said phases arbitrarily designated A, B, and C.
Claim 4
Dependent Claim
23 words
The method as recited in claim 2, wherein each negative sequence current and voltage vector value is determined from the following relations: ##EQU5##
Claim 5
Dependent Claim
22 words
The method as recited in claim 3, wherein said negative sequence impedance phasor angle θ a2 (eff) is derived as follows: ##EQU6##
Claim 6
Dependent Claim
36 words
The method as recited in claim 3, wherein each said negative sequence impedance vector value is derived from a ratio of negative sequence voltage to negative sequence current vector values, whereby supply source variations are negated.
Claim 7
Dependent Claim
27 words
The method as recited in claim 5 wherein an incipient failure is indicated only when said negative sequence phasor angle changes by more than a predetermined limit.
Claim 8
Independent Claim
113 words
A method for detecting an incipient failure in a multiphase electric motor, said motor having an input for each phase from a supply source, said method comprising the steps of: (a) performing a plurality of successive measurements of simultaneous voltage and current values at each said input; (b) determining negative sequence voltage and current vector values for a plurality of said measured voltage and current values; (c) calculating effective negative sequence impedance vector values from said determined negative sequence voltage and current vector values; and (d) comparing like components of said effective negative sequence impedance vector values over a plurality of measurements to detect a change therein as indicative of said incipient failure.
Claim 9
Independent Claim
113 words
A method for detecting an incipient failure in a multiphase electric motor, said motor having an input for each phase from a supply source, said method comprising the steps of: (a) performing a plurality of successive measurements of simultaneous voltage and current values at each said input; (b) determining negative sequence voltage and current vector values for a plurality of said measured voltage and current values; (c) calculating effective negative sequence impedance vector values from said determined negative sequence voltage and current vector values; and (d) comparing like components of said effective negative sequence impedance vector values over a plurality of measurements to detect a change therein as indicative of said incipient failure.
Claim 10
Dependent Claim
21 words
The method as recited in claim 7 wherein step (d) compares real components of said effective negative sequence impedance vector values.
Claim 11
Dependent Claim
20 words
The method as recited in claim 7 wherein step (d) compares imaginary components of said negative sequence impedance vector values.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-12-13 | 1997-06-14 | 1997-12-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-12-13 | 2001-06-14 | 2001-12-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-12-13 | 2005-06-14 | 2005-12-14 | $7700.00 | Window Closed / Lapsed |