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Real time solid state register having battery backup

  • US 5,216,357 A
  • Filed: 01/14/1991
  • Issued: 06/01/1993
  • Est. Priority Date: 04/10/1987
  • Status: Expired due to Term
First Claim
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1. An electricity meter for obtaining line voltage and current measurements on a power line, comprising:

  • (a) means for making line voltage and line current measurements;

    (b) processor means including a first real time clock means for measuring real time (days, hours, minutes, seconds) and processing said line voltage and current measurements to obtain electrical energy consumption data during predetermined real time intervals, and first memory means for storing said data;

    (c) a power supply for converting line voltage from said power line to an operating voltage to power said processor means;

    (d) a circuit for retaining real time and electrical energy consumption data during a power line outage, said circuit comprising;

    (1) a non-volatile, second memory means, which second memory means does not rely upon a battery for it to be non-volatile;

    (2) a second real time clock means for accumulating elapsed real time (days, hours, minutes, seconds);

    (3) a backup battery;

    (4) line power detector means for detecting line power outages and resumptions, said line power detector means being immediately operable upon the resumption of line power;

    (5) first output means responsive to a line power outage detected by said detector means for (i) transferring real time and electrical energy consumption data stored in the first memory means of said processor means to said second memory means, (ii) connecting said backup battery to energize only said second real time clock means, and (iii) resetting said second real time clock means to enable said second real time clock means to accumulate the total, actual real time (days, hours, minutes, seconds) elapsed from the time of the beginning of the power outage;

    (6) second output means responsive to a line power resumption detected by said detector means for (i) transferring said real time and electrical energy consumption data stored in said second memory means to said processor means, (ii) transferring the elapsed real time accumulated by said second real time clock means to said processor means, and (iii) in said processor means, updating said real time data of said first real time clock means by said elapsed real time;

    (7) battery testing means for testing said backup battery; and

    (8) means responsive to said battery testing means for reading the content of said second real time clock means only if said backup battery has at least a predetermined supply capacity,whereby the updated real time data of said first real time clock means corresponds to the total time of said power outage added to the real time at which said power outage occurred.

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