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US4390920A
Expired / Lapsed
US
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Switching device for the short-circuit and overload protection of a power switching circuit
Assignee: BBC Brown Boveri AG Germany
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Filing: 1981-12-17
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Granted: 1983-06-28
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Expires: 2001-12-17
Abstract
Abstract Switching device for the short-circuit and overload protection of a power switching circuit, including an input, an output, a first AND gate, a power amplifier, a current limiter circuit and a current sensor connected in series between the input and output, the first AND gate having an inverting input, a threshold value switch connected to the current sensor for producing a current sensor-shaped signal to be fed to the inverting input of the first AND gate, a digital switch-in retarder for delaying the arrival of the current sensor-shaped signal at the inverting input of the first AND gate by producing a given switch-in time lag for blocking the first AND gate until a given switch-off time lag has run out in case of short-circuits and overloads, the digital switch-in retarder including a second AND gate having a first input, a second input, a third inverting input and an output, and a first counter being after-connected to the second AND gate and having a pulse timing input, a resetting input and an output, the first input of the second AND gate being connected to the threshold value switch, an oscillator connected to the second input of the second AND gate, the third inverting input of the second AND gate being connected to the output of the first counter, the output of the second AND gate being connected to the pulse timing input of the first counter, the output of the first counter being connected to the inverting input of the first AND gate, and a second counter for producing the given switch-off time lag, the second counter having an input connected to the oscillator and an output connected to the resetting input of the first counter.
Inventors
- 👤 Waldemar Lau
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:15
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/08; H02H3/093; H02H3/0935; H02H3/02; H02H3/06
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
285 words
Switching device for the short-circuit and overload protection of a power switching circuit, comprising an input, an output, a first AND gate, a power amplifier, a current limiter circuit and a current sensor connected in series between said input and output, said first AND gate having an inverting input, a threshold value switch connected to said current sensor for producing a current sensor-shaped signal to be fed to said inverting input of said first AND gate, a digital switch-in retarder for delaying the arrival of the current sensor-shaped signal at said inverting input of said first AND gate by producing a given switch-in time lag for blocking said first AND gate until a given switch-off time lag has run out in case of short-circuits and overloads, said digital switch-in retarder including a second AND gate having a first input, a second input, a third inverting input and an output, and a first counter being after-connected to said second AND gate and having a pulse timing input, a resetting input and an output, said first input of said second AND gate being connected to said threshold value switch, an oscillator connected to said second input of said second AND gate, said third inverting input of said second AND gate being connected to said output of said first counter, said output of said second AND gate being connected to said pulse timing input of said first counter, said output of said first counter being connected to said inverting input of said first AND gate, and a second counter for producing said given switch-off time lag, said second counter having an input connected to said oscillator and an output connected to said resetting input of said first counter.
Claim 2
Dependent Claim
285 words
Switching device for the short-circuit and overload protection of a power switching circuit, comprising an input, an output, a first AND gate, a power amplifier, a current limiter circuit and a current sensor connected in series between said input and output, said first AND gate having an inverting input, a threshold value switch connected to said current sensor for producing a current sensor-shaped signal to be fed to said inverting input of said first AND gate, a digital switch-in retarder for delaying the arrival of the current sensor-shaped signal at said inverting input of said first AND gate by producing a given switch-in time lag for blocking said first AND gate until a given switch-off time lag has run out in case of short-circuits and overloads, said digital switch-in retarder including a second AND gate having a first input, a second input, a third inverting input and an output, and a first counter being after-connected to said second AND gate and having a pulse timing input, a resetting input and an output, said first input of said second AND gate being connected to said threshold value switch, an oscillator connected to said second input of said second AND gate, said third inverting input of said second AND gate being connected to said output of said first counter, said output of said second AND gate being connected to said pulse timing input of said first counter, said output of said first counter being connected to said inverting input of said first AND gate, and a second counter for producing said given switch-off time lag, said second counter having an input connected to said oscillator and an output connected to said resetting input of said first counter.
Claim 3
Dependent Claim
20 words
Switching device according to claim 1, including a capacitor and another input terminal connected between said capacitor and said oscillator.
Claim 4
Dependent Claim
63 words
Switching device according to claim 1, including an OR gate having two inputs and an output, one of said inputs of said OR gate being connected to the output of said threshold value switch and the other of said inputs being connected to said output of said first counter, and a message signal output terminal connected to said output of said OR gate.
Claim 5
Dependent Claim
75 words
Switching device according to claim 1, including a NOR gate having one input connected to the output of said threshold value switch, another input connected to said oscillator and an output, a message memory having a dominantly settable input connected to said output of said first counter, a further input connected to said output of said NOR gate and an output, and a message signal output terminal connected to said output of said message memory.
Claim 6
Dependent Claim
147 words
Switching device according to claim 1, wherein said first counter has a further input and a further output, and including an OR gate having an output connected to an input of said first counter, an input connected to said output of said second AND gate and another input, and a third AND gate having an output connected to said other input of said OR gate, first and second inverting inputs and first and second further inputs, said third AND gate having said first inverting input thereof connected to said output of said first counter, said second inverting input connected to the output of said threshold value switch, said first further input connected to said oscillator and said second further input connected to said further output of said first counter, and said further input of said first counter being connected to the output of said threshold value switch.
Claim 7
Dependent Claim
91 words
Switching device according to claim 1, wherein said current limiter circuit has at least two inputs and said current sensor has at least one output, and including a reference voltage terminal, and a reference element having an input being connected to said reference voltage terminal for loading, an output being connected to one of said inputs of said current limiter circuit and another output being connected to said threshold value switch, another of said inputs of said current limiter circuit being connected to one of said outputs of said current sensor.
References Cited (Backward Citations)
US3899718A
Cited
US3979645A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-06-27 | 1986-12-27 | 1987-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-06-27 | 1990-12-27 | 1991-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-06-27 | 1994-12-27 | 1995-06-28 | $7700.00 | Window Closed / Lapsed |