US3577041A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Overcurrent relay circuit
Assignee: ABB Norden Holding AB
•
Filing: 1969-03-10
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Granted: 1971-05-04
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Expires: 1989-03-10
Abstract
Abstract An overcurrent relay circuit, the pickup value of which is substantially independent of the DC-component in an asymmetrical alternating current, has an input transformer, the magnetic circuit of which is provided with air gaps while the secondary load of this transformer is high-resistive. To the secondary winding of the transformer is connected a rectifier with a smoothing device connected to level-sensing circuit and an output magnetic relay in the output circuit of the level-sensing circuit.
Inventors
- 👤 Arne Kring
- 👤 Arne Johansson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:30
CPC Classifications
H; H02; H02H; H02H1/00; H02H1/04
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
144 words
Overcurrent sensing circuit, the pickup value of which is independent of the DC component in asymmetrical alternating current, said circuit including an input transformer, a rectifier bridge connected to the secondary winding of the transformer, a first transistor the base electrode of which is connected to one output terminal of said rectifier bridge across a first resistor and to the second output of the rectifier bridge across a second resistor, a potentiometer, the emitter electrode of said first transistor being connected to the wiper arm of the potentiometer, one end of the wiper arm being connected to the second output of the rectifier bridge, a second transistor the base electrode of which is connected to the collector of the first transistor and having an emitter-collector circuit, and an output relay the winding of which is included in the emitter-collector circuit of the second transistor.
Claim 2
Dependent Claim
144 words
Overcurrent sensing circuit, the pickup value of which is independent of the DC component in asymmetrical alternating current, said circuit including an input transformer, a rectifier bridge connected to the secondary winding of the transformer, a first transistor the base electrode of which is connected to one output terminal of said rectifier bridge across a first resistor and to the second output of the rectifier bridge across a second resistor, a potentiometer, the emitter electrode of said first transistor being connected to the wiper arm of the potentiometer, one end of the wiper arm being connected to the second output of the rectifier bridge, a second transistor the base electrode of which is connected to the collector of the first transistor and having an emitter-collector circuit, and an output relay the winding of which is included in the emitter-collector circuit of the second transistor.
Claim 3
Dependent Claim
33 words
Overcurrent sensing circuit according to claim 1, said first and second resistors constituting the secondary load for the transformer, a smoothing capacitor and a Zener diode connected in parallel with said secondary load.
Claim 4
Dependent Claim
27 words
Overcurrent sensing circuit according to claim 1, a voltage-restricting element connected in parallel with the series-connection of the emitter-collector circuit and the winding of the output relay.
References Cited (Backward Citations)
US3345539A
Cited
US3363144A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-05-03 | 1974-11-02 | 1975-05-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-03 | 1978-11-02 | 1979-05-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-03 | 1982-11-02 | 1983-05-04 | $7700.00 | Window Closed / Lapsed |