High speed power analyzer
First Claim
1. A high speed power analyzer for measuring electrical parameters in an alternating waveform power system having a plurality of distribution circuits, comprising:
- input means for receiving a plurality of analog input signals which represent electrical parameters of the distribution circuits being monitored, where at least one of said analog input signals represents a voltage signal and another of said analog input signals represents a current signal;
multiplexer means connected to said input means for sampling each of said analog input signals by individually transmitting selected ones of said analog input signals;
converter means, connected to said multiplexer means, for converting sampled analog input signals received from said multiplexer means into a digital representation of said analog input signals; and
processor circuit means, coupled to said multiplexer means and said converter means, for controlling the sampling of said analog input signals by said multiplexer means in accordance with a predetermined sampling schedule which is nonsynchronous with the waveform of said power system, and for processing said digital representations of said analog input signals received from said converter means to produce a plurality of output signals which are indicative of predetermined electrical variables related to the power being used in said distribution circuits.
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Accused Products
Abstract
A method and apparatus for rapidly and continuously sampling AC voltage and current signals in a plurality of power distribution circuits. The sampled signals are then analyzed in a sine board computer to derive the number of fundamental electrical variables. These variables include frequency, RMS volts, RMS amps and a phase angular relationship between the voltage and currents in the system. The computer also performs calibration and compensation functions. From these fundamental variables, other useful parameters can be calculated such as watts, watt-hours, VARS, and power factor.
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Citations
21 Claims
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1. A high speed power analyzer for measuring electrical parameters in an alternating waveform power system having a plurality of distribution circuits, comprising:
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input means for receiving a plurality of analog input signals which represent electrical parameters of the distribution circuits being monitored, where at least one of said analog input signals represents a voltage signal and another of said analog input signals represents a current signal; multiplexer means connected to said input means for sampling each of said analog input signals by individually transmitting selected ones of said analog input signals; converter means, connected to said multiplexer means, for converting sampled analog input signals received from said multiplexer means into a digital representation of said analog input signals; and processor circuit means, coupled to said multiplexer means and said converter means, for controlling the sampling of said analog input signals by said multiplexer means in accordance with a predetermined sampling schedule which is nonsynchronous with the waveform of said power system, and for processing said digital representations of said analog input signals received from said converter means to produce a plurality of output signals which are indicative of predetermined electrical variables related to the power being used in said distribution circuits. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A high speed power analyzer for measuring electrical parameters in an alternating waveform power system having a plurality of distribution circuits, comprising:
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input means for receiving a plurality of analog input signals which represent electrical parameters of the distribution circuits being monitored, where at least one of said analog input signals represents a voltage signal and another of said analog input signals represents a current signal; multiplexer means connected to said input means for sampling each of said analog input signals by individually transmitting selected ones of said analog input signals; converter means, connected to said multiplexer means, for converting sampled analog input signals received from said multiplexer means into a digital representation of said analog input signals; and processor circuit means, coupled to said multiplexer means and said converter means, for controlling the sampling of said analog input signals by said multiplexer means in accordance with a predetermined sampling schedule, and for processing said digital representations of said analog input signals received from said converter means to produce a plurality of output signals which are indicative of predetermined electrical variables related to the power being used in said distribution circuits, said processor circuit means including means for determining a zero crossing time in the waveform of at least two of said analog input signals by first detecting that a predetermined number of sampled data points of one numeric sign for an analog input signal have followed a predetermined number of sampled data points of the opposite numeric sign for said analog input signal, and then determining said zero crossing time from a linear extrapolation between the two sampled data points closest to the zero crossing of said analog input signal. - View Dependent Claims (8, 9, 10, 11)
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12. A high speed power analyzer for measuring electrical parameters in an alternating waveform power system having a plurality of distribution circuits, comprising:
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input means for receiving a plurality of reference signals and a plurality of analog input signals which represent electrical parameters of the distribution circuits being monitored, where at least one of said analog input signals represents a voltage signal and another of said analog input signals represents a current signal; multiplexer means connected to said input means for sampling each of said analog input signals by individually transmitting selected ones of said analog input signals; amplifier means, connected to said multiplexer means, for amplifying the magnitude of sampled analog input signals received from said multiplexer means; converter means, connected to said amplifier means, for converting sampled analog input signals received from said amplifier means into a digital representation of said analog input signals; and processor circuit means, coupled to said multiplexer means and said converter means, for controlling the sampling of said reference signals and said analog input signals by said multiplexer means in accordance with a predetermined sampling schedule, and for processing said digital representation of said analog input signals received from said converter means to produce a plurality of output signals which are indicative of predetermined electrical variables related to the power being used in said distribution circuits, said processor circuit means including means for calibrating the conversion coefficients of said converter means by sampling said reference signals in accordance with said predetermined sampling schedule, adjusting said conversion coefficients when said adjustments are within a predetermined limit, and generating an error signal when said adjustments exceed said predetermined limit. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A method of measuring electrical parameters in an alternating waveform power system having a plurality of distribution circuits, comprising the steps of:
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receiving a plurality of analog input signals which represent electrical parameters of the distribution circuits being monitored, where at least one of said analog input signals represents a voltage signal and another of said analog input signals represents a current signal; sampling each of said analog input signals in accordance with a predetermined sampling schedule which is nonsynchronous with the waveform of said power system, said analog input signals being sampled at different times; converting said sampled analog input signals into a digital representation of said analog input signals; compensating for the difference in times that said analog signals are sampled, and determining a zero crossing time in the waveform of at least two of said analog input signals; and producing a plurality of output signals which are indicative of predetermined electrical variables related to the power being used in said distribution circuits. - View Dependent Claims (20, 21)
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Specification