US4432031A
Expired / Lapsed
US
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Method for overcurrent protection
Assignee: General Electric Co
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Filing: 1982-05-03
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Granted: 1984-02-14
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Expires: 2002-05-03
Abstract
Abstract A method for detecting excessive current in a system and interrupting the delivery of further current thereto comprises determining actual system current, obtaining a value of a predetermined system parameter indicative of the time the actual system current can safely exist in the system, creating a dynamic history of the predetermined system parameter by repetitively modifying the predetermined system parameter in accordance with actual system current, and interrupting power to the system if the dynamic history of the predetermined system parameter exceeds a predetermined threshold. The predetermined system parameter may be quadratically extended into an undefined region in order to decrease the response time to an overload or fault condition.
Inventors
- 👤 William J. Premerlani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:37
CPC Classifications
H; H02; H02H; H02H6/00; H02H6/005; H02H3/00; H02H3/08; H02H3/093; H02H3/0935
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
201 words
A method for protecting a power distribution system from excessive current, the system including circuit interruption means for interrupting power to the system, comprising: (a) storing a predetermined system parameter, wherein the predetermined system parameter includes a forcing function F(I) defined by: ##EQU8## wherein T(I) is the desired time to remove power from the system, Δt is the time during which an actual system parameter is determined, Q ref is a first predetermined threshold and is the thermal time constant of said circuit interruption means, and wherein the predetermined system parameter is indicative of the predetermined time the actual system parameter is permitted to safely exist in the system; (b) quadratically extending said forcing function F(I) into the region between F(I)=0 and ##EQU9## whereby the response time to interrupt power to the system when threshold Q ref is exceeded is decreased; (c) determining the value of the actual system parameter; (d) repetitively modifying the value of said predetermined system parameter in accordance with said actual system parameter, thereby creating a dynamic history of said predetermined system parameter; and (e) generating a control signal to actuate said circuit interruption means if the predetermined system parameter dynamic history exceeds a second predetermined threshold.
Claim 2
Independent Claim
201 words
A method for protecting a power distribution system from excessive current, the system including circuit interruption means for interrupting power to the system, comprising: (a) storing a predetermined system parameter, wherein the predetermined system parameter includes a forcing function F(I) defined by: ##EQU8## wherein T(I) is the desired time to remove power from the system, Δt is the time during which an actual system parameter is determined, Q ref is a first predetermined threshold and is the thermal time constant of said circuit interruption means, and wherein the predetermined system parameter is indicative of the predetermined time the actual system parameter is permitted to safely exist in the system; (b) quadratically extending said forcing function F(I) into the region between F(I)=0 and ##EQU9## whereby the response time to interrupt power to the system when threshold Q ref is exceeded is decreased; (c) determining the value of the actual system parameter; (d) repetitively modifying the value of said predetermined system parameter in accordance with said actual system parameter, thereby creating a dynamic history of said predetermined system parameter; and (e) generating a control signal to actuate said circuit interruption means if the predetermined system parameter dynamic history exceeds a second predetermined threshold.
Claim 3
Dependent Claim
23 words
A method as in claim 1, wherein storing and comparing of the predetermined and actual system parameter, respectively, are performed by a microprocessor.
Claim 4
Dependent Claim
18 words
The method of claim 1, further comprising repeating steps b, c, d and e thereof at predetermined intervals.
Claim 5
Dependent Claim
15 words
The method of claim 1, wherein the actual system parameter comprises current in the system.
Claim 6
Dependent Claim
18 words
The method of claim 1, wherein the predetermined system parameter includes a forcing function (F(I) defined by ##EQU10##
Claim 7
Dependent Claim
29 words
The method of claim 5, wherein the dynamic history of the predetermined system parameter is created by adding the forcing function F(I) to an accumulated value Q old .
Claim 8
Dependent Claim
37 words
The method of claim 1, wherein the history of the predetermined system parameter is created by adding the forcing function F(I) to an accumulated value Q old and subtracting a portion of the accumulated value ##EQU11## therefrom.
Claim 9
Dependent Claim
44 words
The method of claim 1, further comprising the steps of comparing the actual system parameter with a third predetermined threshold and resetting the dynamic history of the predetermined system parameter to zero if the actual system parameter is less than said third predetermined threshold.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-02-13 | 1987-08-15 | 1988-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-02-13 | 1991-08-15 | 1992-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-02-13 | 1995-08-15 | 1996-02-14 | $7700.00 | Window Closed / Lapsed |