US4122388A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for testing the shaft/bearing insulation of a turbo-machine
Assignee: BBC Brown Boveri AG Switzerland
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Filing: 1977-04-13
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Granted: 1978-10-24
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Expires: 1997-04-13
Abstract
Abstract Apparatus provided for testing the shaft/bearing insulation characteristic of a rotary machine, e.g., a turbo-machine, wherein the shaft is normally earthed by means of an earthing brush on the shaft and connected to ground. A first circuit arrangement is provided for breaking the shaft-earthing connection, a second circuit arrangement is provided for applying an increasing test voltage between the shaft bearing which is grounded and the earthing brush while the shaft-earthing connection remains broken, this being in the form of a progressively charged capacitor connected between the shaft bearing and earthing brush, and a third circuit arrangement is provided for measuring the change in voltage across the capacitor resulting from a breakdown in the insulation between the shaft and its bearing during the testing operation. The testing operation is performed periodically and a test cycle is terminated as soon as the test voltage reaches a predetermined maximum value, or there is a breakdown in the insulation between the shaft and its bearing whichever occurs first.
Inventors
- 👤 Felix R. Bernasconi
- 👤 Max Salm
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 16:29
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/16; G01R27/18; G01R19/00; G01R19/145; G01R27/025
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
98 words
Apparatus for testing the shaft/bearing insulation characteristic of a rotary machine and wherein the shaft is normally earthed by means of an earthing brush on the shaft and connected to ground, comprising a first circuit arrangement for breaking said shaft-earthing connection, a second circuit arrangement for applying an increasing test voltage between te shaft bearing which is grounded and said earthing brush while said shaft-earthing connection remains broken, and a third circuit arrangement for measuring the voltage difference existing between the earthing brush and ground to detect a breakdown in the insulation between the shaft and its bearing.
Claim 2
Dependent Claim
98 words
Apparatus for testing the shaft/bearing insulation characteristic of a rotary machine and wherein the shaft is normally earthed by means of an earthing brush on the shaft and connected to ground, comprising a first circuit arrangement for breaking said shaft-earthing connection, a second circuit arrangement for applying an increasing test voltage between te shaft bearing which is grounded and said earthing brush while said shaft-earthing connection remains broken, and a third circuit arrangement for measuring the voltage difference existing between the earthing brush and ground to detect a breakdown in the insulation between the shaft and its bearing.
Claim 3
Dependent Claim
26 words
Apparatus as defined in claim 1 and which further includes an additional circuit arrangement by which the said testing of said shaft/bearing insulation is effected periodically.
Claim 4
Dependent Claim
47 words
Apparatus as defined in claim 1 and which further includes an additional circuit arrangement for terminating the testing operation as soon as a breakdown occurs in the insulation between the shaft and its bearing or when said test voltage reaches a predetermined maximum value whichever occurs first.
Claim 5
Dependent Claim
44 words
Apparatus as defined in claim 3 wherein said additional circuit arrangement for terminating the testing operation includes a voltage comparator by means of which the test is compared with a reference voltage, a limit switch and a circuit breaker controlled by said limit switch.
Claim 6
Dependent Claim
100 words
Apparatus for testing the shaft/bearing insulation characteristic of a rotary machine and wherein the shaft is normally earthed by means of an earthing brush on the shaft and connected to ground, comprising a first circuit arrangement for breaking said shaft-earthing connection, a capacitor connected between the shaft bearing which is grounded and said earthing brush, a second circuit arrangement for applying a charging voltage to said capacitor while said shaft-earthing connection remains broken, and a third circuit arrangement for measuring the change in voltage across said capacitor resulting from a breakdown in the insulation between the shaft and its bearing.
Claim 7
Dependent Claim
100 words
Apparatus for testing the shaft/bearing insulation characteristic of a rotary machine and wherein the shaft is normally earthed by means of an earthing brush on the shaft and connected to ground, comprising a first circuit arrangement for breaking said shaft-earthing connection, a capacitor connected between the shaft bearing which is grounded and said earthing brush, a second circuit arrangement for applying a charging voltage to said capacitor while said shaft-earthing connection remains broken, and a third circuit arrangement for measuring the change in voltage across said capacitor resulting from a breakdown in the insulation between the shaft and its bearing.
Claim 8
Dependent Claim
22 words
Apparatus as defined in claim 5 wherein said second circuit arrangement functions to apply a progressively increasing charging voltage to said capacitor.
Claim 9
Dependent Claim
22 words
Apparatus as defined in claim 6 wherein said progressively increasing charging voltage to said capacitor is provided by a voltage pulse generator.
Claim 10
Dependent Claim
22 words
Apparatus as defined in claim 6 wherein said progressively increasing charging voltage to said capacitor is provided by a sawtooth voltage generator.
Claim 11
Dependent Claim
20 words
Apparatus as defined in claim 5 and which further includes an additional circuit arrangement for limiting said capacitor charging voltage.
Claim 12
Dependent Claim
25 words
Apparatus as defined in claim 9 and wherein said circuit arrangement for limiting said capacitor charging voltage includes a limit switch and a circuit breaker.
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) | 1981-10-23 | 1982-04-24 | 1982-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-10-23 | 1986-04-24 | 1986-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-10-23 | 1990-04-24 | 1990-10-24 | $7700.00 | Window Closed / Lapsed |