US3665252A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical protective circuit
Assignee: Individual
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Filing: 1970-07-17
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Granted: 1972-05-23
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Expires: 1990-07-17
Abstract
Abstract A protective circuit for an isolated load circuit utilizing an isolation transformer having a primary winding connected to an associated source of power and a secondary winding connected to a load by a pair of load conductors which includes fault condition responsive means, a normally inoperative control circuit having a normally open electrical valve and a relay connected to the source of electrical power by an auxiliary transformer with an auxiliary circuit connected to the control circuit and to the load conductors for closing the valve at a predetermined voltage to operatively condition the control circuit upon the presence of a ground fault on one of the load conductors to energize the relay and actuate the fault condition responsive means.
Inventors
- 👤 Charles J Rogers Sr
- 👤 Paul E Stanley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 15:49
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/16; H02H3/162
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
323 words
An electrical protective circuit for a power distribution system comprising, in combination, a transformer having a primary winding and a secondary winding, a pair of line conductors for connecting said primary to an associated source of electrical power, a pair of load conductors for connecting said secondary winding to an electrical load, an auxiliary circuit connected to said load conductors, a normally inoperative control circuit connected to said auxiliary circuit, means including an auxiliary transformer for connecting said control circuit to said line conductors, fault condition responsive means connected to said control circuit, means for grounding said control circuit, said auxiliary circuit being arranged to provide a ground fault circuit upon the presence of a ground fault on one of said load conductors for operatively conditioning said control circuit for actuation of said fault condition responsive means, and means in said auxiliary circuit for limiting the voltage in said ground fault circuit to a predetermined magnitude, a silicon controlled rectifier having a gate in said control circuit in said normally inoperative condition and wherein said gate is connected to said auxiliary circuit for actuation of said control circuit at a predetermined magnitude of fault current, said auxiliary circuit comprising a first pair of reversely positioned rectifiers having corresponding sides connected together and each connected at their opposite sides to one of said load conductors, a second pair of rectifiers reversely positioned oppositely from the position of said first pair of rectifiers and having corresponding sides connected together and each connected at their opposite sides to one of said load conductors, and wherein said means for limiting the voltage in said ground fault circuit comprises a zener diode connected at one side to the corresponding sides of said second pair of reversely positioned rectifiers and means for connecting the other side of said zener diode to the corresponding sides of said first pair of reversely positioned rectifiers and to said silicon controlled rectifier gate.
Claim 2
Dependent Claim
323 words
An electrical protective circuit for a power distribution system comprising, in combination, a transformer having a primary winding and a secondary winding, a pair of line conductors for connecting said primary to an associated source of electrical power, a pair of load conductors for connecting said secondary winding to an electrical load, an auxiliary circuit connected to said load conductors, a normally inoperative control circuit connected to said auxiliary circuit, means including an auxiliary transformer for connecting said control circuit to said line conductors, fault condition responsive means connected to said control circuit, means for grounding said control circuit, said auxiliary circuit being arranged to provide a ground fault circuit upon the presence of a ground fault on one of said load conductors for operatively conditioning said control circuit for actuation of said fault condition responsive means, and means in said auxiliary circuit for limiting the voltage in said ground fault circuit to a predetermined magnitude, a silicon controlled rectifier having a gate in said control circuit in said normally inoperative condition and wherein said gate is connected to said auxiliary circuit for actuation of said control circuit at a predetermined magnitude of fault current, said auxiliary circuit comprising a first pair of reversely positioned rectifiers having corresponding sides connected together and each connected at their opposite sides to one of said load conductors, a second pair of rectifiers reversely positioned oppositely from the position of said first pair of rectifiers and having corresponding sides connected together and each connected at their opposite sides to one of said load conductors, and wherein said means for limiting the voltage in said ground fault circuit comprises a zener diode connected at one side to the corresponding sides of said second pair of reversely positioned rectifiers and means for connecting the other side of said zener diode to the corresponding sides of said first pair of reversely positioned rectifiers and to said silicon controlled rectifier gate.
Claim 3
Dependent Claim
148 words
An electrical protective circuit in accordance with claim 1 wherein said control circuit includes a relay having a coil operatively associated with said fault condition responsive means anD wherein said fault condition responsive means comprises an electrically operatied signal having one side connected to one side of said relay coil, means including a switch operatively associated with said relay for connecting the other side of said signal to said auxiliary transformer, means for connecting said switch to said silicon controlled rectifier, said switch being normally maintained in one position for disconnecting said signal the other side from said auxiliary transformer and for connecting the other side of said silicon controlled rectifier to said auxiliary transformer, said switch being movable by said relay into a second position upon the operative conditioning of said control circuit for interrupting said auxiliary circuit and for connecting said signal to said auxiliary transformer.
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) | 1975-05-23 | 1975-11-22 | 1976-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-23 | 1979-11-22 | 1980-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-23 | 1983-11-22 | 1984-05-23 | $7700.00 | Window Closed / Lapsed |