US3660723A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Current transfer circuit as part of high voltage dc circuit
Assignee: Raytheon Co
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Filing: 1971-03-09
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Granted: 1972-05-02
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Expires: 1991-03-09
Abstract
Abstract The current transfer circuit transfers current in a high voltage DC circuit breaker from an in-line switching device which carries the current in normal conduction to a shunt current interrupter which is capable of increasing the breaker impedance to break the high voltage DC circuit. The current transfer device employs first and second serially connected in-line switches, the first of which has a serially connected precharged capacitor, switch, and inductor paralleled therearound to force commutate the first in-line switch to transfer current to the shunt current interrupter. The first switch and the forced commutation equipment need only be of sufficient voltage rating to withstand the initial conduction voltage across the shunt current interrupter. Opening of the second switch isolates the first switch and the forced commutation equipment from the line voltage.
Inventors
- 👤 Michael A Lutz
- 👤 Willis F Long
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 03:34
CPC Classifications
H; H01; H01H; H01H33/00; H01H33/02; H01H33/59; H01H33/596
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
142 words
A current transfer circuit for a circuit breaker for offswitching electric current, said circuit breaker comprising: first and second serially connected line switches having contacts serially connected in a circuit in which offswitching is desired and; impedance-increasing means connected in parallel with said line switches for progressively increasing impedance in said circuit, the improvement comprising: power means connected across said first line switch for causing a current zero in said first line switch after said contacts in said first line switch are opened to cause a sufficient increase in potential to transfer current from said line switches to said impedance-increasing means so that said first line switch and said power means need withstand only the initial voltage drop through said impedance-increasing means, said second line switch withstanding the balance of the potential across said impedance-increasing means as the impedance-increasing means increases impedance.
Claim 2
Dependent Claim
142 words
A current transfer circuit for a circuit breaker for offswitching electric current, said circuit breaker comprising: first and second serially connected line switches having contacts serially connected in a circuit in which offswitching is desired and; impedance-increasing means connected in parallel with said line switches for progressively increasing impedance in said circuit, the improvement comprising: power means connected across said first line switch for causing a current zero in said first line switch after said contacts in said first line switch are opened to cause a sufficient increase in potential to transfer current from said line switches to said impedance-increasing means so that said first line switch and said power means need withstand only the initial voltage drop through said impedance-increasing means, said second line switch withstanding the balance of the potential across said impedance-increasing means as the impedance-increasing means increases impedance.
Claim 3
Dependent Claim
24 words
The circuit of claim 1 wherein voltage divider means is connected in parallel to said first and second switches to divide the voltage thereacross.
Claim 4
Dependent Claim
35 words
The circuit of claim 2 wherein said voltage divider means comprises first and second serially connected resistors and first and second capacitors respectively connected in parallel to each other and said first and second switches.
Claim 5
Dependent Claim
33 words
The circuit of claim 1 wherein said first line switch is fast-opening and said second line switch has sufficient voltage holdoff capacity when open to hold off the voltage across said circuit breaker.
Claim 6
Dependent Claim
13 words
The circuit of claim 4 wherein said first switch is a vacuum relay.
Claim 7
Dependent Claim
24 words
The circuit of claim 4 wherein said power means comprises a capacitor and an inductor serially connected in parallel across said first line switch.
Claim 8
Dependent Claim
34 words
The circuit of claim 6 wherein a power supply is connected across said capacitor to charge said capacitor so that capacitor discharge through said inductor causes a current zero in said first line switch.
Claim 9
Dependent Claim
53 words
The circuit of claim 7 wherein said first and second line switches are connected in series between a rectifier and a load, and a capacitor is connected to said rectifier so that, upon opening of said first line switch, said capacitor limits the rate of voltage rise applied to said first line switch.
Claim 10
Dependent Claim
61 words
The circuit of claim 1 wherein said impedance-increasing means comprises at least one electronic switch capable of offswitching while direct current flows therethrough, a resistor connected to said electronic switch, said electronic switch and said resistor being connected to said line switch means to maintain voltage across said line switch means at reduced value during opening of said line switch means.
Claim 11
Dependent Claim
24 words
The circuit of claim 9 wherein voltage divider means is connected in parallel to said first and second switches to divide the voltage thereacross.
Claim 12
Dependent Claim
35 words
The circuit of claim 10 wherein said voltage divider means comprises first and second serially connected resistors and first and second capacitors respectively connected in parallel to each other and said first and second switches.
Claim 13
Dependent Claim
31 words
The circuit of claim 1 wherein there are a plurality of electronic switches, and a separate resistance is connected to each of said plurality beyond the first of said electronic switches.
Claim 14
Dependent Claim
33 words
The circuit of claim 12 wherein said first line switch is fast-opening and said second line switch has sufficient voltage holdoff capacity when open to hold off the voltage across the circuit breaker.
Claim 15
Dependent Claim
24 words
The circuit of claim 13 wherein said power means comprises a capacitor and an inductor serially connected in parallel across said first line switch.
Claim 16
Dependent Claim
18 words
The circuit of claim 14 wherein a power supply is connected across said capacitor to charge said capacitor.
Claim 17
Dependent Claim
51 words
The circuit of claim 15 wherein said first and second line switches are connected in series between a rectifier and a load, and a capacitor is connected to said rectifier so that, upon opening of said circuit breaker, said capacitor limits the rate of voltage rise applied to said line switches.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-02 | 1975-11-01 | 1976-05-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-02 | 1979-11-01 | 1980-05-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-02 | 1983-11-01 | 1984-05-02 | $7700.00 | Window Closed / Lapsed |