US3783354A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phase protection system for ac power lines
Assignee: National Aeronautics and Space Administration
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Filing: 1972-09-29
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Granted: 1974-01-01
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Expires: 1992-09-29
Abstract
Abstract A phase protection system is provided for protecting phase sensitive loads from being or remaining connected to AC power lines whenever a phase reversal occurs. It comprises a solid state phase detection circuit, a DC power relay circuit, an ACto-DC converter for energizing the relay circuit, and a bi-stable 4-terminal transducer coupled between the phase detection circuit and the power relay circuit, for controlling both circuits.
Inventors
- 👤 J Fletcher
- 👤 J Wong Wing
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:41
CPC Classifications
H; H02; H02H; H02H11/00; H02H11/004
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
276 words
A phase protection system for detecting a phase reversal in a polyphase AC power line network including: a phase detection circuit having at least three input terminals and a pair of output terminals, each input terminal being adapted for connection to one of the power lines; a relay circuit having a pair of input terminals and comprising: a current control device, a power relay having relay contacts and a coil connected in series with said current control device, said coil controlling the switching of said contacts which are adapted for connection to the power lines; an AC-to-DC converter whose input is adapted for connection to at least one of said power lines to provide to its output a DC potential for energizing said relay circuit; a four-terminal bi-stable voltage-to-light-to-impedance transducer, coupled between the output terminals of said detection circuit and the input terminals to said relay circuit, said transducer being normally OFF, and said transducer turning ON upon the detection of said phase reversal by said phase detection circuit to thereby energize said coil which activates said contacts to open said lines, comprising a first resistor connected to the first of the phase detection circuit''s input terminals, a second resistor connected to the second of its input terminals, a first capacitor connected to the third of its input terminals, said first resistor and said first capacitor having a junction Y, a third resistor connected to the third terminal, said second resistor and said third resistor having a junction X, a fourth resistor connected between junction X and a first terminal of said transducer, and said junction Y being connected to a second terminal of said transducer.
Claim 2
Dependent Claim
276 words
A phase protection system for detecting a phase reversal in a polyphase AC power line network including: a phase detection circuit having at least three input terminals and a pair of output terminals, each input terminal being adapted for connection to one of the power lines; a relay circuit having a pair of input terminals and comprising: a current control device, a power relay having relay contacts and a coil connected in series with said current control device, said coil controlling the switching of said contacts which are adapted for connection to the power lines; an AC-to-DC converter whose input is adapted for connection to at least one of said power lines to provide to its output a DC potential for energizing said relay circuit; a four-terminal bi-stable voltage-to-light-to-impedance transducer, coupled between the output terminals of said detection circuit and the input terminals to said relay circuit, said transducer being normally OFF, and said transducer turning ON upon the detection of said phase reversal by said phase detection circuit to thereby energize said coil which activates said contacts to open said lines, comprising a first resistor connected to the first of the phase detection circuit''s input terminals, a second resistor connected to the second of its input terminals, a first capacitor connected to the third of its input terminals, said first resistor and said first capacitor having a junction Y, a third resistor connected to the third terminal, said second resistor and said third resistor having a junction X, a fourth resistor connected between junction X and a first terminal of said transducer, and said junction Y being connected to a second terminal of said transducer.
Claim 3
Dependent Claim
16 words
The system of claim 1 wherein said current control device is a silicon controlled rectifier (SCR).
Claim 4
Dependent Claim
81 words
The system of claim 2 wherein said relay circuit comprises: a voltage divider circuit connected in series with the third and fourth terminals of said transducer; and an RC-network connected between the gate of said SCR and one of the terminals of said transducer, whereby the voltage across said RC network is low when said power lines are in phase, and said voltage is increased to a level sufficient to fire the SCR when the power lines are out of phase.
Claim 5
Dependent Claim
28 words
The system of claim 3 wherein, said AC-to-DC converter includes at least three rectifiers, each rectifier being connected between the output of the converter and a power line.
Claim 6
Dependent Claim
279 words
A phase protection system for detecting a phase reversal in a polyphase AC power line network including: a phase detection circuit having at least three input terminals and a pair of output terminals, each input terminal being adapted for connection to one of the power lines; a relay circuit having a pair of input terminals and comprising: a current control device, a power relay having relay contacts and a coil connected in series with said current control device, said coil controlling the switching of said contacts which are adapted for connection to the power lines; an AC-to-DC converter whose input is adapted for connection to at least one of said power lines to provide to its output a DC potential for energizing said relay circuit; a four-terminal bi-stable transducer, coupled between the output terminals of said detection circuit and the input terminals to said relay circuit, said transducer being normally OFF, and said transducer turning ON upon the detection of said phase reversal by said phase detection circuit to thereby energize said coil which activates said contacts to open said lines, said phase detection circuit comprising a first resistor connected to the first of the phase detection circuit''s input terminals, a secoNd resistor connected to the second of its input terminals, a first capacitor connected to the third of its input terminals, said first resistor and said first capacitor having a junction Y, a third resistor connected to the third terminal, said second resistor and said third resistor having a junction X, a fourth resistor connected between junction X and a first terminal of said transducer, and said junction Y being connected to a second terminal of said transducer.
Claim 7
Dependent Claim
279 words
A phase protection system for detecting a phase reversal in a polyphase AC power line network including: a phase detection circuit having at least three input terminals and a pair of output terminals, each input terminal being adapted for connection to one of the power lines; a relay circuit having a pair of input terminals and comprising: a current control device, a power relay having relay contacts and a coil connected in series with said current control device, said coil controlling the switching of said contacts which are adapted for connection to the power lines; an AC-to-DC converter whose input is adapted for connection to at least one of said power lines to provide to its output a DC potential for energizing said relay circuit; a four-terminal bi-stable transducer, coupled between the output terminals of said detection circuit and the input terminals to said relay circuit, said transducer being normally OFF, and said transducer turning ON upon the detection of said phase reversal by said phase detection circuit to thereby energize said coil which activates said contacts to open said lines, said phase detection circuit comprising a first resistor connected to the first of the phase detection circuit''s input terminals, a secoNd resistor connected to the second of its input terminals, a first capacitor connected to the third of its input terminals, said first resistor and said first capacitor having a junction Y, a third resistor connected to the third terminal, said second resistor and said third resistor having a junction X, a fourth resistor connected between junction X and a first terminal of said transducer, and said junction Y being connected to a second terminal of said transducer.
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) | 1976-12-31 | 1977-07-02 | 1978-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-31 | 1981-07-02 | 1982-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-31 | 1985-07-02 | 1986-01-01 | $7700.00 | Window Closed / Lapsed |