Patent US4262099A successfully refreshed from Google Patents.
US4097794A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Static means for detecting ground insulation failure for rotary electric machines
Assignee: Allis Chalmers Corp
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Filing: 1976-11-15
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Granted: 1978-06-27
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Expires: 1996-11-15
Abstract
Abstract Electrical potentials are induced in the rotating shaft of many rotary electrical machines because of stray flux that exists in the machines. Unless provided with adequate ground insulation to interrupt the circuit, currents can flow through the machine bearings and other parts to ground and thereby expose the machine to severe damage. The device of this invention provides a sandwich-like ground insulation with a conductor therebetween and measures the voltage across that portion of the insulation between the conductor and either the bearing housing or ground to indicate if there is a circuit for excessive current leakage from the bearing to ground.
Inventors
- 👤 Joe H. Burrus, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 13:06
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/34
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
145 words
In combination with a dynamoelectric machine having an electrically grounded rotating shaft with electrical potential generated therein, a bearing rotatably supporting said shaft on a film of oil, said oil providing electrical insulation between said shaft and said bearing sufficient to cause a voltage potential across said oil film and electrical insulation isolating said bearing from electrical ground said insulation being dividing into at least two insulation portions by an electrical conductor, a device for detecting electrical potential from said bearing to said ground which avoids providing a path for current flow around the complete insulation to ground and is not subject to wear comprising a voltage sensing means connected across said conductor and said bearing, said voltage sensing means indicating a change in voltage when there is a condition exposing the unit to an increase in current flow from said bearing to said ground.
Claim 2
Dependent Claim
145 words
In combination with a dynamoelectric machine having an electrically grounded rotating shaft with electrical potential generated therein, a bearing rotatably supporting said shaft on a film of oil, said oil providing electrical insulation between said shaft and said bearing sufficient to cause a voltage potential across said oil film and electrical insulation isolating said bearing from electrical ground said insulation being dividing into at least two insulation portions by an electrical conductor, a device for detecting electrical potential from said bearing to said ground which avoids providing a path for current flow around the complete insulation to ground and is not subject to wear comprising a voltage sensing means connected across said conductor and said bearing, said voltage sensing means indicating a change in voltage when there is a condition exposing the unit to an increase in current flow from said bearing to said ground.
Claim 3
Dependent Claim
32 words
The combination as set forth in claim 1 wherein said electrical insulation is divided into three insulation portions by two electrical conductors and said voltage sensing means is connected across said conductors.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-06-26 | 1981-12-26 | 1982-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-06-26 | 1985-12-26 | 1986-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-06-26 | 1989-12-26 | 1990-06-27 | $7700.00 | Window Closed / Lapsed |