Patent US4788620A successfully refreshed from Google Patents.
US4788620A
Expired / Lapsed
US
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Static trip circuit breaker with automatic circuit trimming
Assignee: General Electric Co
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Filing: 1987-11-09
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Granted: 1988-11-29
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Expires: 2007-11-09
Abstract
Abstract Electronic trip units employed within static trip circuit breakers are individually calibrated and automatically adjusted to ensure that the trip transfer characteristics are within specification requirements. A trimming network within the trip unit circuit contains a plurality of parallel resistors each separately connected within the circuit by means of a fusible link. Test input and output values are compard to idealized values that are binary-weighted within a look-up table in the test equipment computer. The percent correction required is determined and the appropriate links are interrupted to provide ideal trip response.
Inventors
- 👤 Graham A. Scott
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:18
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/006
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
119 words
A method for calibrating a circuit breaker electronic trip unit comprising the steps of: providing a circuit breaker electronic trip unit containing a resistance network arranged as a plurality of trimming resistors electrically in parallel with a base resistor through a corresponding plurality of fusible links; applying a test input signal to said trip unit and reading a first pickup level output response; comparing said first pickup level output response to a predetermined pickup level and determining a first difference value; comparing said first difference value to predetermined binary weighted resistance values to provide a first calibration resistance value; and adjusting said resistance network within said trip unit to provide said first calibration resistance value to said trip unit.
Claim 2
Independent Claim
119 words
A method for calibrating a circuit breaker electronic trip unit comprising the steps of: providing a circuit breaker electronic trip unit containing a resistance network arranged as a plurality of trimming resistors electrically in parallel with a base resistor through a corresponding plurality of fusible links; applying a test input signal to said trip unit and reading a first pickup level output response; comparing said first pickup level output response to a predetermined pickup level and determining a first difference value; comparing said first difference value to predetermined binary weighted resistance values to provide a first calibration resistance value; and adjusting said resistance network within said trip unit to provide said first calibration resistance value to said trip unit.
Claim 3
Dependent Claim
50 words
The method of claim 1 including the steps of: re-applying said test input signal to said trip unit and reading a second pickup level output; and comparing said second pickup level output to a second predetermined pickup level to determine a second difference value lower than said first difference value.
Claim 4
Dependent Claim
29 words
The method of claim 1 wherein said step of adjusting said resistance network comprises: melting a predetermined combination of said fusible links to provide said first calibration resistance value.
Claim 5
Dependent Claim
17 words
The method of claim 3 wherein said step of melting said fusible links comprises electrical resistance heating.
Claim 6
Dependent Claim
17 words
The method of claim 3 wherein said step of melting said fusible links comprises optical laser heating.
Claim 7
Dependent Claim
27 words
The method of claim 1 wherein said steps of comparing said first pickup level response and comparing said difference value comprise look-up tables in a digital processor.
References Cited (Backward Citations)
US4016483A
Cited
US4345288A
Cited
US4494212A
Cited
US4550360A
Cited
US4589052A
Cited
US4710844A
Cited
US4649455A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-11-29 | 1992-05-30 | 1992-11-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-29 | 1996-05-30 | 1996-11-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-29 | 2000-05-30 | 2000-11-29 | $7700.00 | Window Closed / Lapsed |