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Solid state watt-hour meter

  • US 4,467,434 A
  • Filed: 09/18/1981
  • Issued: 08/21/1984
  • Est. Priority Date: 09/18/1981
  • Status: Expired due to Fees
First Claim
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1. A solid state watt-hour meter, comprising:

  • a Hall-Effect watt-hour sensor, connectable to a consumer'"'"'s connection to a source of electric power, for sensing the line voltage supplied to and the line current drawn by the consumer'"'"'s total electric load, said total electric load comprising a plurality of consumer electric loads, and for producing an output signal in the form of a train of square waves indicative of a quantity of watt-hours of power utilized by the consumer;

    a microprocessor coupled to said watt-hour sensor for receiving said output signal, said microprocessor having at least one load control output which operates a circuit breaker which supplies at least one of said consumer loads, and having at least one switch input which senses the position of a switch;

    an electrically alterable ROM operatively coupled to said microprocessor;

    power supply means, having an input operatively coupled to the consumer line voltage and an output coupled to said microprocessor, for supplying a regulated DC voltage thereto;

    clock signal generating means, operatively coupled between said consumer line voltage and said microprocessor, for supplying a 60 Hz clock signal to said microprocessor;

    readout means, operatively coupled to said microprocessor, for providing a readout of the power consumed since the last reading of said solid state watt-hour meter;

    power outage timing means, operated in response to said power supply means, for supplying a signal which is characteristic of the duration that said power supply means was inoperative due to a loss of power to said consumer'"'"'s connection, said power outage timing means including a capacitor which discharges when said power supply means is inoperative and which charges when said power supply means is placed in operation; and

    an override switch coupled to said switch input of said microprocessor and said circuit breaker,said electrically alterable ROM and microprocessor being connected and programmed;

    (a) to compute the time of day as determined from an initial time of day setting and said 60 Hz clock signal and to store said time of day in said electrically alterable ROM;

    (b) to compute the total power used by the consumer and to store said total power in said electrically alterable ROM;

    (c) to provide a readout signal indicative of the total power consumed since the last reading of the meter;

    (d) to automatically open said circuit breaker for a time period during the time of day when power demand on said source of electric power is above a first predetermined value and/or the cost per kilowatt hour of said power is above a second predetermined value;

    (e) to automatically close said circuit breaker during the time of day when the power demand on said source of electric power is at or below said first predetermined value and/or the cost per kilowatt hour of said power is at or below said second predetermined value;

    (f) to allow the consumer to override said microprocessor control of said circuit breaker by operating said override switch to close said circuit breaker;

    (g) to automatically reset said override switch when said microprocessor functions to automatically close said circuit breaker; and

    (h) to correct the value of the time of day stored in said electrically alterable ROM by using the signal from said power outage timing means in the event that said power supply means is temporarily inoperative.

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