Patent US4254403A successfully refreshed from Google Patents.
US4254403A
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Systems for transmitting information in an alternating current electricity supply system
Assignee: ABB Metering Systems Ltd
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Filing: 1979-08-06
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Granted: 1981-03-03
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Expires: 1999-08-06
Abstract
Abstract A system for transmitting information in an alternating current supply system wherein information is transmitted by reducing the instantaneous value of the supply voltage during a corresponding period in each of a selection of cycles of the supply voltage, the selection of cycles determining the information transmitted. To minimize disturbance of the system voltage the period of alteration includes a voltage zero. The alteration is effected by closing a switch connected across the system for the period the voltage reduction is required.
Inventors
- 👤 Leonardo Perez-Cavero
- 👤 Michael W. A. Cross
- 👤 Geoffrey Fielding
- 👤 Frederick M. Gray
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:52
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/54; H04B3/542; H02; H02J; H02J13/00; H02J13/13; H02J13/1311; H02J13/1313; H02J13/1315; H04B2203/00; H04B2203/54; H04B2203/5404; H04B2203/542; H04B2203/5462; H04B2203/5495; Y; Y04; Y04S; Y04S10/00; Y04S10/50; Y04S10/52
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
154 words
In a system for transmitting information in an A.C. electricity supply system by reducing the instantaneous value of the A.C. supply voltage during the same small fractional part of each of a selection of cycles of the supply voltage waveform, said part including a time of voltage zero, a transmitter comprising: controllable switch means connected across said supply system in an effective zero impedance path so as to effectively shortcircuit said supply system throughout the whole of any period that the switch means is closed and thereby draw from said system throughout the whole of any period that said switch means is closed a current of sufficient magnitude to reduce the instantaneous value of the A.C. supply voltage during the time that said switch means is closed and conducting; and switch control means for closing said switch means for a said small fractional part of any selected single cycle of the supply voltage waveform.
Claim 2
Dependent Claim
154 words
In a system for transmitting information in an A.C. electricity supply system by reducing the instantaneous value of the A.C. supply voltage during the same small fractional part of each of a selection of cycles of the supply voltage waveform, said part including a time of voltage zero, a transmitter comprising: controllable switch means connected across said supply system in an effective zero impedance path so as to effectively shortcircuit said supply system throughout the whole of any period that the switch means is closed and thereby draw from said system throughout the whole of any period that said switch means is closed a current of sufficient magnitude to reduce the instantaneous value of the A.C. supply voltage during the time that said switch means is closed and conducting; and switch control means for closing said switch means for a said small fractional part of any selected single cycle of the supply voltage waveform.
Claim 3
Dependent Claim
53 words
A transmitter according to claim 1 wherein said switch means comprises an electronic switch of the kind which, once closed, remains closed until the current through the switch means returns to zero so that in each selected cycle the switch means is closed and conducting for a period determined by the system impedance.
Claim 4
Dependent Claim
77 words
A transmitter according to claim 2 wherein said switch control means comprises: peak detection means which produces an output indicative of the occurrence of a peak value of the voltage of the supply system; timing means which initiates a timing period in response to the output of said peak detection means; and a pulse generator which generates an operating pulse for the switch in response to the end of the timing period defined by said timing means.
Claim 5
Dependent Claim
63 words
A transmitter according to claim 3 including an AND gate having a first input to which the output of the pulse generator is applied; and a code generator for supplying pulses to a second input of the AND gate in accordance with the desired selection of cycles, the output of the AND gate being utilized to control the operation of said electronic switch.
Claim 6
Dependent Claim
73 words
A transmitter according to claim 4 including means for applying a signal to a further input of the gate so as to allow the gate to open only when the supply voltage waveform has a predetermined slope, and means for applying a signal to a further input of the gate so as to allow the gate to open only when the instantaneous value of the supply voltage is less than a predetermined value.
Claim 7
Dependent Claim
34 words
A transmitter according to claim 2 in combination with an alternating current electricity supply system distribution transformer having primary and secondary windings, said switch being connected across a secondary winding of said distribution transformer.
Claim 8
Dependent Claim
121 words
In a system for transmitting information in an A.C. electricity supply system by reducing the instantaneous value of the A.C. supply voltage during the same small fractional part of each of a selection of cycles of the supply voltage waveform, said part including a time of voltage zero, a receiver comprising: an integrator which integrates the instantaneous value of the supply voltage system for short periods each less than the supply voltage cycle period and each starting at a zero crossing of the waveform of said voltage, the integrator being reset between successive integration periods; and means for detecting when the output of said integrator for an integration period differs from the output of the integrator for the preceding integration period.
Claim 9
Dependent Claim
121 words
In a system for transmitting information in an A.C. electricity supply system by reducing the instantaneous value of the A.C. supply voltage during the same small fractional part of each of a selection of cycles of the supply voltage waveform, said part including a time of voltage zero, a receiver comprising: an integrator which integrates the instantaneous value of the supply voltage system for short periods each less than the supply voltage cycle period and each starting at a zero crossing of the waveform of said voltage, the integrator being reset between successive integration periods; and means for detecting when the output of said integrator for an integration period differs from the output of the integrator for the preceding integration period.
Claim 10
Dependent Claim
47 words
A receiver according to claim 7 wherein said detecting means comprises a capacitance arranged to charge to the peak value of the output of said integrator; means for partly discharging said capacitance between integration periods; and means for monitoring the supply of charging current to said capacitance.
Claim 11
Dependent Claim
40 words
A receiver according to claim 8 wherein said integrator comprises: a capacitance connected in series with a resistance across said voltage; an electronic switch connected across said integrator capacitance; and means for opening said switch during each said integration period.
Claim 12
Dependent Claim
69 words
A receiver according to claim 9 wherein said means for opening said switch comprises: reference means arranged to produce an output indicative of the occurrence of zero-crossings in said voltage at the receiver; timing means responsive to the output of the reference means to produce an output signal for a predetermined period following said each zero-crossing; and driver means for utilizing the timing means output to open said switch.
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) | 1984-03-02 | 1984-09-01 | 1985-03-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-02 | 1988-09-01 | 1989-03-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-02 | 1992-09-01 | 1993-03-03 | $7700.00 | Window Closed / Lapsed |