High speed power analyzer

Claim 2

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.

Claim 3

The invention according to claim 1, wherein said analog input signals vary sinusoidally at a given frequency, and said analog input signals include at least one voltage signal and a plurality of current signals.

Claim 4

The invention according to claim 2, wherein said predetermined sampling schedule requires that each of said analog input signals be sampled over 1000 times per second.

Claim 5

The invention according to claim 3, wherein the sampling frequency of said predetermined sampling schedule is not a multiple of the given frequency of said analog input signals.

Claim 6

The invention according to claim 1, wherein said predetermined variables include the phase difference between said voltage and current signals, the frequency of said voltage signal, and the RMS values of each of said analog input signals.

Claim 7

The invention according to claim 1, wherein said processor circuit means includes means for compensating for the difference between the times that said analog input signals are sampled.

Claim 8

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, 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.

Claim 9

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, 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.

Claim 10

The invention according to claim 7, wherein said one numeric sign is positive and said other numeric sign is negative.

Claim 11

The invention according to claim 7, wherein said predetermined number of sampled data points for both of said numeric signs is two.

Claim 12

The invention according to claim 7, wherein said predetermined sampling schedule is nonsynchronous with the waveform of said power system.

Claim 13

The invention according to claim 7, wherein said processor circuit means includes means for compensating for the difference between the times that said analog input signals are samples.

Claim 14

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 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.

Claim 15

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 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.

Claim 16

The invention according to claim 12, wherein said processor circuit means includes 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 signal 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.

Claim 17

The invention according to claim 12, wherein said processor circuit means includes means for compensating for the difference between the times that said analog input signals are sampled.

Claim 18

The invention according to claim 12, wherein said reference signals are sampled at least once per second.

Claim 19

The invention according to claim 15, wherein said predetermined sampling schedule requires that each of said analog input signals be sampled over 1000 times per second.

Claim 20

The invention according to claim 12 wherein said predetermined sampling schedule is nonsynchronous with the waveform of said power system.

Claim 21

The invention according to claim 17 wherein said processor circuit means includes 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.

Claim 24

The invention according to claim 19, wherein said zero crossing time is determined 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 performing a linear extrapolation between the two sampled data points closest to the zero crossing of said analog input signal.

Claim 25

The invention according to claim 19, further including the steps of periodically sampling a plurality of reference signals, calibrating the coefficients used during said analog to digital conversion step from the measurement of said reference signals, adjusting said conversion coefficients when said adjustments are within a predetermined limit, and generating an error signal when said adjustments exceed said predetermined limit.