US3887849A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Protective circuit
Assignee: AT&T Inc
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Filing: 1973-11-02
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Granted: 1975-06-03
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Expires: 1993-11-02
Abstract
Abstract A protective circuit connected between a source and a load tests the source voltage for proper polarity and amplitude prior to permitting interconnection of the source and the load. A dioderesistor network adapted to respond to source voltage polarity and amplitude and a circuit breaker pole form a series circuit with the source whereby overvoltage or improper polarity provides sufficient current to trip the breaker. The application of source voltage to the load is delayed for a time greater than the circuit breaker tripping time so that the polarity and amplitude test of the source voltage is completed prior to connection of the source to the load.
Inventors
- 👤 Harry Henry Nagel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:22
CPC Classifications
H; H02; H02H; H02H11/00; H02H11/002; H02H11/006
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
199 words
A protective circuit for connecting a source to a load device, said protective circuit comprising in combination circuit breaking means including turnon means for rendering said circuit breaking means conductive and interrupting means for rendering said circuit breaking means nonconductive, means for detecting a first polarity voltage from said source, means for detecting a predetermined overvoltage from said source, said interrupting means being responsive to the operation of said polarity deTecting means for rendering said circuit breaking means conductive, said interrupting means being responsive to the operation of said overvoltage detecting means for rendering said circuit breaking means nonconductive, means responsive to said turnon means for connecting said circuit breaking means to said load device after a predetermined time to complete the connection between the source and the load comprising a semiconductor switch having a conductive state and a nonconductive state, and means responsive to the operation of said turnon means for placing said semiconductive switch in its conductive state after said predetermined time, said predetermined time being greater than the time for rendering said circuit breaking means nonconductive whereby said source voltage is tested for polarity and overvoltage prior to connection of said load device to said source.
Claim 2
Dependent Claim
199 words
A protective circuit for connecting a source to a load device, said protective circuit comprising in combination circuit breaking means including turnon means for rendering said circuit breaking means conductive and interrupting means for rendering said circuit breaking means nonconductive, means for detecting a first polarity voltage from said source, means for detecting a predetermined overvoltage from said source, said interrupting means being responsive to the operation of said polarity deTecting means for rendering said circuit breaking means conductive, said interrupting means being responsive to the operation of said overvoltage detecting means for rendering said circuit breaking means nonconductive, means responsive to said turnon means for connecting said circuit breaking means to said load device after a predetermined time to complete the connection between the source and the load comprising a semiconductor switch having a conductive state and a nonconductive state, and means responsive to the operation of said turnon means for placing said semiconductive switch in its conductive state after said predetermined time, said predetermined time being greater than the time for rendering said circuit breaking means nonconductive whereby said source voltage is tested for polarity and overvoltage prior to connection of said load device to said source.
Claim 3
Dependent Claim
84 words
The combination according to claim 1 wherein said polarity detecting means comprises a diode connected in series with said interrupting means, said overvoltage detecting means comprises a resistor of predetermined value connected in series with said interrupting means, said turnon means comprises a latch type switch, and said interrupting means comprises current sensitive means connected to said latch type switch and to said delaying means and means responsive to a predetermined current through said current sensitive means for rendering said latch type switch nonconductive.
Claim 4
Dependent Claim
67 words
The combination according to claim 2 wherein said current sensitive means comprises a trip initiating coil, said coil being connected in series with the parallel combination of said diode and said resistor, and said means for rendering said latch type switch nonconductive comprises a mechanical linkage connected to said switch and actuated by said predetermined current through said trip initiating coil to open said latch type switch.
Claim 5
Dependent Claim
21 words
The combination according to claim 3 wherein said source comprises telephone terminal equipment and said load device comprises a telephone network.
Claim 6
Dependent Claim
184 words
A protective circuit for connecting an electrical source to a load device comprising a circuit breaker having at least one pole including a latch type switch, means for closing said latch type switch, a trip initiating coil, and a mechanical linkage responsive to the operation of said trip initiating coil for opening said latch type switch, a diode conductive responsive to a first polarity voltage, a resistor for detecting overvoltage thereacross, said diode being connected in parallel with said resistor and said parallel connected diode and resistor, said trip initiating coil, said latch type switch and said source forming a series circuit, said trip initiating coil being responsive to at least a predetermined current through one of said diode and said resistor for actuating said linkage to open said latch type switch within a first time interval, a semiconductor switch connected between said circuit breaker pole and said load device having a conductive state and a nonconductive state, and means responsive to the closing of said latch type switch for placing said semiconductor switch in its conductive state only after said first time interval.
Claim 7
Dependent Claim
184 words
A protective circuit for connecting an electrical source to a load device comprising a circuit breaker having at least one pole including a latch type switch, means for closing said latch type switch, a trip initiating coil, and a mechanical linkage responsive to the operation of said trip initiating coil for opening said latch type switch, a diode conductive responsive to a first polarity voltage, a resistor for detecting overvoltage thereacross, said diode being connected in parallel with said resistor and said parallel connected diode and resistor, said trip initiating coil, said latch type switch and said source forming a series circuit, said trip initiating coil being responsive to at least a predetermined current through one of said diode and said resistor for actuating said linkage to open said latch type switch within a first time interval, a semiconductor switch connected between said circuit breaker pole and said load device having a conductive state and a nonconductive state, and means responsive to the closing of said latch type switch for placing said semiconductor switch in its conductive state only after said first time interval.
Claim 8
Dependent Claim
80 words
A protective circuit according to claim 5 wherein said semiconductor switch comprises a silicon controlled rectifier having an anode, a cathode and a gate, said means for placing said silicon controlled rectifier in its conductive state comprises a delay circuit responsive to the closing of said latch type switch for applying a signal to said gate after said first time interval, and means for connecting said anode to said load device, said cathode being connected to said latch type switch.
Claim 9
Dependent Claim
60 words
A protective circuit according to claim 6 wherein said anode connecting means comprises a second circuit breaker pole connected between said load and said silicon controlled rectifier diode anode, and further comprising means connected across said load device for conducting at least said predetermined current Through said second circuit breaker pole responsive to a predetermined overvoltage across said load device.
Claim 10
Dependent Claim
165 words
In combination, an electrical source, a load device and a protective circuit connected between said source and said load device, said protective circuit comprising first switching means connected to said source, turnon means for rendering said first switching means conductive, turnoff means for rendering said first switching means nonconductive within a first time interval, means for detecting a predetermined condition of said source, said turnoff means being responsive to the operation of said detecting means for rendering said first switching means nonconductive within said first time interval, means responsive to said turnon means for connecting said first switching means to said load after a predetermined time greater than said first time interval comprising a semiconductive switch having a conductive state and a nonconductive state, and means responsive to the operation of said turnon means for placing said semiconductive switch in its conductive state after said predetermined time, whereby said source is tested for said predetermined condition prior to connection of said source to said load.
Claim 11
Dependent Claim
165 words
In combination, an electrical source, a load device and a protective circuit connected between said source and said load device, said protective circuit comprising first switching means connected to said source, turnon means for rendering said first switching means conductive, turnoff means for rendering said first switching means nonconductive within a first time interval, means for detecting a predetermined condition of said source, said turnoff means being responsive to the operation of said detecting means for rendering said first switching means nonconductive within said first time interval, means responsive to said turnon means for connecting said first switching means to said load after a predetermined time greater than said first time interval comprising a semiconductive switch having a conductive state and a nonconductive state, and means responsive to the operation of said turnon means for placing said semiconductive switch in its conductive state after said predetermined time, whereby said source is tested for said predetermined condition prior to connection of said source to said load.
Claim 12
Dependent Claim
154 words
A protective circuit for connecting an electrical source to a load device comprising first switching means connected to said source, turnon means for rendering said first switching means conductive, turnoff means for rendering said first switching means nonconductive within a first time interval, means for detecting a predetermined condition of said source, said turnoff means being responsive to the operation of said detecting means for rendering said first switching means nonconductive within said first time interval, means responsive to said turnon means for connecting said first switching means to said load after a predetermined time greater than said first time interval comprising a semiconductive switch having a conductive state and a nonconductive state and means responsive to the operation of said turnon means for placing said semiconductive switch in its conductive state after said predetermined time, whereby said source is tested for said predetermined condition prior to connection of said source to said load.
Claim 13
Dependent Claim
154 words
A protective circuit for connecting an electrical source to a load device comprising first switching means connected to said source, turnon means for rendering said first switching means conductive, turnoff means for rendering said first switching means nonconductive within a first time interval, means for detecting a predetermined condition of said source, said turnoff means being responsive to the operation of said detecting means for rendering said first switching means nonconductive within said first time interval, means responsive to said turnon means for connecting said first switching means to said load after a predetermined time greater than said first time interval comprising a semiconductive switch having a conductive state and a nonconductive state and means responsive to the operation of said turnon means for placing said semiconductive switch in its conductive state after said predetermined time, whereby said source is tested for said predetermined condition prior to connection of said source to said load.
Claim 14
Dependent Claim
154 words
A protective circuit for connecting an electrical source to a load device comprising first switching means connected to said source, turnon means for rendering said first switching means conductive, turnoff means for rendering said first switching means nonconductive within a first time interval, means for detecting a predetermined condition of said source, said turnoff means being responsive to the operation of said detecting means for rendering said first switching means nonconductive within said first time interval, means responsive to said turnon means for connecting said first switching means to said load after a predetermined time greater than said first time interval comprising a semiconductive switch having a conductive state and a nonconductive state and means responsive to the operation of said turnon means for placing said semiconductive switch in its conductive state after said predetermined time, whereby said source is tested for said predetermined condition prior to connection of said source to said load.
Claim 15
Dependent Claim
154 words
A protective circuit for connecting an electrical source to a load device comprising first switching means connected to said source, turnon means for rendering said first switching means conductive, turnoff means for rendering said first switching means nonconductive within a first time interval, means for detecting a predetermined condition of said source, said turnoff means being responsive to the operation of said detecting means for rendering said first switching means nonconductive within said first time interval, means responsive to said turnon means for connecting said first switching means to said load after a predetermined time greater than said first time interval comprising a semiconductive switch having a conductive state and a nonconductive state and means responsive to the operation of said turnon means for placing said semiconductive switch in its conductive state after said predetermined time, whereby said source is tested for said predetermined condition prior to connection of said source to said load.
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) | 1978-06-02 | 1978-12-02 | 1979-06-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-02 | 1982-12-02 | 1983-06-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-02 | 1986-12-02 | 1987-06-03 | $7700.00 | Window Closed / Lapsed |