US3597735A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Carrier pilot relaying system
Assignee: Hitachi Ltd
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Filing: 1969-01-29
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Granted: 1971-08-03
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Expires: 1989-01-29
Abstract
Abstract A carrier pilot relaying system in which the current flowing through the power transmission line in each electrical station is detected by a current transformer to be converted into a phase signal and a digital signal representing the magnitude (scalar quantity) of the current, these signals being transmitted from one station to another station in the form of a train of pulse signals. In each station, detection of the phase difference between the phase signals and detection of the difference between the magnitude of the currents are carried out independently of each other so that a circuit breaker can be tripped when a predetermined condition is satisfied.
Inventors
- 👤 Keizo Nakayama
- 👤 Yutaka Ohno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:15
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/26; H02H3/28; H02H3/30
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
200 words
A carrier pilot relaying system for protecting power circuits including two power stations which are connected through a power transmission line by comparing a first and a second information signal respectively representative of line currents carried through said transmission line at said two power stations comprising: means for producing a current signal having scalar and phase components corresponding to the magnitude and phase of said line current at one of said power stations; means for producing a first scalar signal from said current signal; means for producing a first phase signal from said current signal; means for encoding said first scalar signal and transmitting said encoded first scalar sigNal in combination with said first phase signal to the other of said power stations as the first information signal; means for separating a second scalar signal and a second phase signal from the second information signal transmitted from said other power station and received at said first power station; means for comparing said first scalar signal with said second scalar signal, and means for comparing said first phase signal with said second phase signal; whereby said power circuit may be protected when predetermined conditions within said power transmission line are encountered.
Claim 2
Dependent Claim
200 words
A carrier pilot relaying system for protecting power circuits including two power stations which are connected through a power transmission line by comparing a first and a second information signal respectively representative of line currents carried through said transmission line at said two power stations comprising: means for producing a current signal having scalar and phase components corresponding to the magnitude and phase of said line current at one of said power stations; means for producing a first scalar signal from said current signal; means for producing a first phase signal from said current signal; means for encoding said first scalar signal and transmitting said encoded first scalar sigNal in combination with said first phase signal to the other of said power stations as the first information signal; means for separating a second scalar signal and a second phase signal from the second information signal transmitted from said other power station and received at said first power station; means for comparing said first scalar signal with said second scalar signal, and means for comparing said first phase signal with said second phase signal; whereby said power circuit may be protected when predetermined conditions within said power transmission line are encountered.
Claim 3
Dependent Claim
49 words
A carrier pilot relaying system according to claim 1, wherein said means for comparing said first phase signal with said second phase signal includes means for advancing the phase of said second phase signal by a predetermined phase angle from the phase angle corresponding to said first phase signal.
Claim 4
Dependent Claim
43 words
A carrier pilot relaying system according to claim 1, further including means for generating, as one component of said information signal, a part of said encoded scalar signal representing an excess of a predetermined value thereof for transmission to the other power station.
Claim 5
Dependent Claim
33 words
A carrier pilot relaying system according to claim 1 including means for effecting the transmission and comparison of said scalar signal and said phase signals periodically each half cycle of said current signal.
Claim 6
Dependent Claim
37 words
A carrier pilot relaying system according to claim 1, wherein said means for producing said first phase-signal includes means for generating a signal sequence produced at a predetermined phase angle in each cycle of said current signal.
Claim 7
Dependent Claim
37 words
A carrier pilot relaying system according to claim 1, further including means for converting an encoded second scalar signal transmitted from said other power station into an analog signal to be compared with said first scalar signal.
Claim 8
Dependent Claim
117 words
A carrier pilot relaying system according to claim 1, wherein said means for producing said current signal comprises: a current transformer disposed in said power transmission line and a first auxiliary transformer and a second auxiliary transformer connected in series with the secondary winding of said current transformer; and wherein said means for producing a first scalar signal includes a first circuit connected to the output of said first auxiliary transformer for generating a first DC voltage; and said means for producing said first phase signal comprises a second circuit connected to the output of said second auxiliary transformer for generating a signal representative of a predetermined phase of the current flowing through said power transmission line.
Claim 9
Dependent Claim
109 words
A carrier pilot relaying system according to claim 7, wherein said encoding means including means, responsive to said first phase signal, for generating a series of digital signals; a digital-to-analog converter connected to the output of said digital signal generating means for producing an analog signal representative of the analog value of the digital signals; a comparator circuit for comparing said analog signal and said first scalar signal; and a first bistable switching circuit responsive to said first phase signal and the output of said comparator circuit for controlling said digital-signal-generating means; whereby said encoding is dependent upon both the phase and scalar signal portions of said current signal.
Claim 10
Dependent Claim
40 words
A carrier pilot relaying system according to claim 8, wherein said encoding means further includes a parallel-series converter, responsive to the output of said digital-signal-generating means, for converting said digital signals into series form for application to said transmitting means.
Claim 11
Dependent Claim
124 words
A carrier pilot relaying system according to claim 9, wherein said means for generating said series of digital signals includes: a source of clock pulses; a first gating circuit connected to the output of said clock pulse source and to said first bistable switching circuit for gatinG said clock pulses in response to a predetermined condition of said bistable switching circuit; a counter circuit for counting the signals passed by said first gating circuit and providing parallel output signals to said digital-to-analog converter; a frequency divider responsive to said source of a clock pulses for controlling the operation of said parallel-series converter; and means for resetting said counter circuit and said frequency divider in response to a predetermined condition of said first phase signal.
Claim 12
Dependent Claim
93 words
A carrier pilot relaying system according to claim 10, wherein said separating means includes: a demodulator circuit for demodulating said second information signal received from said other power station; a synchronous signal separator circuit and a bit signal generator connected to the output of said demodulator circuit; a phase signal generator circuit connected to the output of said synchronous signal separator for providing said second phase signal; and a series-parallel converter connected to the output of said demodulator circuit and said bit signal generator for providing said second scalar signal in parallel form.
Claim 13
Dependent Claim
84 words
A carrier pilot relaying system according to claim 11, wherein said means for comparing means for said first phase signal with said second phase signal comprises a second bistable switching circuit responsive to the output of said phase signal generator and said resetting means; an integrated circuit connected to the output of said second bistable switching circuit and controlled by said phase signal generator; and a level detecting circuit for providing an output signal when the output of said integrator reaches a predetermined magnitude.
Claim 14
Dependent Claim
62 words
A carrier pilot relaying system according to claim 12, wherein said means for comparing said first scalar signal with said second scalar signal comprises a logic circuit responsive to the output of said counter circuit and said series parallel converter for providing an output when said first and second scalar signals have a difference therebetween which is more than a predetermined value.
Claim 15
Dependent Claim
52 words
A carrier pilot relaying system according to claim 12, further including means responsive to said resetting means for delaying the signal provided by said resetting means by a predetermined phase angle with respect to said first phase signal, so as to compensate for the delay time of transmission between said power stations.
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) | 1974-08-02 | 1975-02-01 | 1975-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-02 | 1979-02-01 | 1979-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-02 | 1983-02-01 | 1983-08-03 | $7700.00 | Window Closed / Lapsed |