PHASE SELECTIVE TELEMETRY SYSTEM

• US 3,714,451 A
• Filed: 07/12/1971
• Issued: 01/30/1973
• Est. Priority Date: 07/12/1971
• Status: Expired due to Term

• Current Assignee: John A. Whitney, Richard E. Woods, William H. Hohman
• Original Assignee: John A. Whitney, Richard E. Woods, William H. Hohman
• Inventors: Whitney, John A., Woods, Richard E., Hohman, William H.
• Primary Examiner(s): Schaefer, Robert K.
• Assistant Examiner(s): Smith, William J.
• Application Number:
  US05/161,530
• Time in Patent Office: 568 Days
• Field of Search: 307/3,136,133 340/310 317/11A
• US Class Current: 307/3
• CPC Class Codes: H02J 13/00009 using pulsed signals
• CPC Class Codes: H02J 13/0001 using modification of a parameter of the network power signal
• CPC Class Codes: H04B 2203/5491 using filtering and bypassing
• CPC Class Codes: H04B 3/54 Systems for transmission via power distribution lines
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/52 Outage or fault management, e.g. fault detection or location
• CPC Class Codes: Y04S 40/121 using the power network as support for the transmission

Abstract

This disclosure deals with a telemetry system adapted to be connected across a pair of transmission lines, the system generating pulses at one location along the line and detecting such pulses at another location. The system is designed for use with a transmission line carrying alternating current and includes one or more pulse transmitters or generators, each of which generates a pulse at a precise phase angle in each cycle of alternating current. The system also includes a pulse receiver or detector associated with each transmitter, each receiver responding only to pulses at the phase angle of the associated transmitter. The phase angle at which a transmitter generates and the associated receiver responds to a pulse is determined by a timing circuit which actuates a device in each AC cycle. In the transmitter, the device is part of a pulse generating circuit and in the receiver the device is part of a pulse responsive circuit.

Claims

1. Phase angle timing circuit means adapted to be connected to two conductors of an AC transmission line, comprising a capacitor, a charging circuit including a resistor connected to said capacitor, and charging means for charging said capacitor through said resistor at a rate dependent on the time constant of said capacitor and said resistor, said charging means being adapted to be connected to a power supply and including means connected in parallel with said capacitor for initiating charging of said capacitor at a fixed point in the period of a cycle of the AC voltage on the transmission line and for maintaining constant the voltage across said capacitor, and a discharging circuit including a breakdown device connected to said capacitor, said breakdown device having a breakdown voltage and a low latching current and remaining conducting from breakdown to substantially the end of said period, said time constant being related to said period of the AC voltage to charge said capacitor to said breakdown voltage at a fixed phase angle in said period.

2. Circuit means as in claim 1, wherein said charging means is adapted to be connected to said transmission line for power, and said means for initiating charging of said capacitor comprises a zener diode.

3. Circuit means as in claim 1, and further including a switch connected to said breakdown device in said discharging circuit, said switch being actuated by current flow upon breakdown of said breakdown device.

4. Circuit means as in claim 3, and further including pulse generatinG means connected to said switch and adapted to be connected to said transmission line for generating a pulse on said line upon actuation of said switch.

5. Phase angle timing circuit means adapted to be connected to two conductors of an AC transmission line, comprising a capacitor, a charging circuit including a resistor connected to said capacitor, and charging means for charging said capacitor through said resistor at a rate dependent on the time constant of said capacitor and said resistor, said charging means being adapted to be connected to a power supply and including means for initiating charging of said capacitor at a fixed point in the period of a cycle of the AC voltage on the transmission line, a discharging circuit including a breakdown device connected to said capacitor, said breakdown device having a breakdown voltage, said time constant being related to said period of the AC voltage to charge said capacitor to said breakdown voltage at a fixed phase angle in said period, and further including monostable multivibrator means connected to said breakdown device in said discharging circuit, said multivibrator means being actuated to its unstable state by current flow upon breakdown of said breakdown device.

6. Circuit means as in claim 5, and further including circuit means adapted to respond to a series of pulses, and switch means connected to said circuit means to control the flow of pulses to said circuit means, said switch means further being connected to respond to said multivibrator means to enable the flow of pulses to said circuit means only during said unstable state.

7. Circuit means as in claim 6, wherein said circuit means comprises integrating means for integrating a plurality of pulses, and switch means connected to said integrating means and actuated by a predetermined number of said pulses.

8. Circuit means as in claim 7, and further including missing pulse detecting means connected to respond both to said multivibrator means and to said pulses for providing a missing pulse signal when a pulse is not received during each unstable state of said multivibrator, said detecting means further being connected to said integrating means to deactivate said integrating means in response to a missing pulse signal.

9. A transmitter circuit adapted to be connected to two conductors of an AC transmission line, comprising a capacitor, a charging circuit including a resistor connected to said capacitor, and charging means for charging said capacitor through said resistor at a rate dependent on the time constant of said capacitor and said resistor, said charging means being adapted to be connected to said two conductors and including means for initiating charging of said capacitor at a fixed point in the period of each cycle of the AC voltage on the transmission line, and a discharging circuit including a breakdown device connected to said capacitor and a current responsive switch connected to said device, said breakdown device having a breakdown voltage, said time constant being related to said period of the AC voltage to charge said capacitor to said breakdown voltage at a fixed phase angle in said period, breakdown of said device resulting in current flow to and actuating of said switch, said switch comprising a TRIAC, and further including a capacitor connected in series with said TRIAC.

10. A circuit as in claim 9, wherein said charging circuit further includes a second resistor connected in parallel with said first-mentioned resistor, and a diode connected in series with each of said resistors, said diodes being connected for current flow in opposite directions through said capacitor.

11. A receiver circuit adapted to be connected to two conductors of an AC transmission line, comprising a capacitor, a charging circuit including a resistor connected to said capacitor, and charging means for charging said capacitor through said resistor at a rate dependent on the time constant of said capacitor and said resistor, said Charging means being adapted to be connected to said two conductors and including means for initiating charging of said capacitor at a fixed point in the period of a cycle of the AC voltage on the transmission line, and a discharging circuit including a breakdown device connected to said capacitor and a monostable multivibrator connected to said breakdown device, said breakdown device having a breakdown voltage, said time constant being related to said period of the AC voltage to charge said capacitor to said breakdown voltage at a fixed phase angle in said period, breakdown of said device resulting in current flow to and triggering of said multivibrator.

12. A circuit as in claim 11, and further including pulse responsive means and switch means adapted to be connected to said two conductors and connected to said pulse responsive means and to said multivibrator, said multivibrator actuating said switch means to control the flow of pulses to said pulse responsive means.

13. A multi-channel telemetry system adapted to be connected to two conductors of an AC transmission line, comprising at least two transmitters and at least two receivers, each of said transmitters being associated with one of said receivers, each of said transmitters and receivers including phase angle timing circuit means comprising a capacitor, a charging circuit including a resistor connected to said capacitor, and charging means for charging said capacitor through said resistor at a rate dependent on the time constant of said capacitor and said resistor, said charging means adapted to be connected to a power supply and including means for initiating charging of said capacitor at a fixed point in the period of a cycle of the AC voltage on the transmission line, and a discharging circuit including a breakdown device connected to said capacitor, said breakdown device having a breakdown voltage, said time constant being related to said period of the AC voltage to charge said capacitor to said breakdown voltage at a fixed phase angle in said period, and said phase angle for each of said transmitters and the receivers associated therewith being different from the other transmitters and the receivers associated therewith.