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Electronic watthour meter

  • US 5,245,275 A
  • Filed: 06/09/1992
  • Issued: 09/14/1993
  • Est. Priority Date: 09/25/1989
  • Status: Expired due to Fees
First Claim
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1. In an electronic digital electricity meter having at least one line current sensor and at least one phase voltage sensor for providing samples of analog current and voltage signals to current and voltage analog to digital converters, respectively, whereby the analog current and voltage signals are converted to digital current and voltage words, respectively, for transfer to a digital signal processor for processing the current and voltage words and generating output pulses proportional to energy consumption, a method for self testing circuits and elements in said electronic digital electricity meter comprising the steps of:

  • (a) generating a self check enable signal for enabling said electronic digital electricity meter to perform self check operations;

    (b) providing said self check enable signal to the current sensor to enable a checking of the integrity thereof;

    (c) applying, in response to said self check enable signal, a voltage test signal of a prescribed level to each of said current and voltage analog to digital converters and converting said voltage test signal to digital current and voltage words respectively;

    (d) processing, in said digital signal processor, the current and voltage digital words from said current and voltage analog to digital converters, respectively, to effect the generation of output pulses therefrom proportional to electrical energy consumption test samples as determined by the level of said voltage test signal; and

    (e) while performing the self check operations,(i) generating a current test fail signal if the current sensor fails to pass a current signal,(ii) generating a voltage test fail signal if the voltage phase sensor fails to pass a voltage signal of a prescribed magnitude to the voltage analog to digital converter, and(iii) generating a digital signal processor fail signal if the processor fails to generate a prescribed number of pulses within a prescribed period of time following the generation of said self check enable signal.

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