Measuring electrical parameters of power line operation, using a digital computer

Claim 3

The method of claim 1 including the additional step of: supplying a calculated electrical parameter from said digital computer to apparatus generating indications of the calculated electrical parameter of a form perceptible to a human being.

Claim 4

The method of claim 2 wherein the additional step of supplying a calculated electrical parameter from said digital computer to apparatus generating indications of the calculated electrical parameter of a form perceptible to a human being comprises applying the calculated electrical parameter to a digital read-out device.

Claim 5

The method of claim 2 wherein the additional step of supplying a calculated electrical parameter from said digital computer to apparatus generating indications of the calculated electrical parameter of a form perceptible to a human being comprises the substeps of: using a pulse-duration modulator to generate pulses having a duration directly related to the calculated electrical parameter from said digital computer; and applying the pulses to a D'Arsonval meter.

Claim 6

The method of claim 1, employed for measuring the r-m-s value of a voltage associated with a power line phase of a p-phase alternating-current power line having p+1 conductors including a neutral conductor and at least one other conductor, wherein said step of arranging respective sensing apparatus to sense at least one of the voltages and currents associated with each phase of said power line includes arranging a voltage sensing apparatus to sense the voltage associated with the phase of said power line the r-m-s voltage of which is being measured, as referred to a voltage appearing on said neutral conductor, thereby to generate an analog signal for being digitized using said analog-to-digital conversion apparatus, and wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: squaring the digitized response to signal from said voltage sensing apparatus after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, low-pass digitally filtering the squared digitized response to generate a low-pass filter response, and taking the positive square root of said low-pass filter response to calculate the r-m-s voltage associated with the power line phase.

Claim 7

The method of claim 1, employed for measuring the r-m-s value of a voltage associated with a power line phase of a p-phase alternating-current power line having a respective conductor for each phase, p being at least three, wherein said step of arranging respective sensing apparatus to sense at least one of the voltages and currents associated with each phase of said power line includes arranging a voltage sensing apparatus to sense the voltage associated with the phase of said power line the r-m-s voltage of which is being measured, as referred to the voltage associated with another phase of said power line, thereby to generate an analog signal for being digitized using said analog-to-digital conversion apparatus, and wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: squaring the digitized response to signal from said voltage sensing apparatus after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, low-pass digitally filtering the squared digitized response to generate a low-pass filter response, and taking the positive square root of said low-pass filter response to calculate the r-m-s voltage associated with the power line phase.

Claim 8

The method of claim 1, employed for measuring the r-m-s value of a current associated with a power line phase, wherein said step of arranging respective sensing apparatus to sense at least one of the voltages and currents associated with each phase of said power line includes arranging a current sensing apparatus to sense the current flowing through a power line conductor associated with the phase of said power line the r-m-s current of which is being measured, thereby to generate an analog signal for being digitized using said analog-to-digital conversion apparatus, and wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: squaring the digitized response to signal from said current sensing apparatus after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, low-pass digitally filtering the squared digitized response to generate a low-pass filter response, and taking the positive square root of said low-pass filter response to calculate the r-m-s current associated with the power line phase.

Claim 9

The method of claim 1, employed for measuring the r-m-s value of a voltage associated with a power line phase of a p-phase alternating-current power line having p+1 conductors including a neutral conductor and at least one other conductor, wherein said step of arranging respective sensing apparatus to sense at least one of the voltages and currents associated with each phase of said power line includes arranging a voltage sensing apparatus to sense the voltage associated with the phase of said power line the r-m-s voltage of which is being measured, as referred to a voltage appearing on said neutral conductor, thereby to generate an analog signal for being digitized using said analog-to-digital conversion apparatus, and wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: calculating the frequency of the digitized response to signal from said voltage sensing apparatus after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered; squaring the digitized response to signal from said voltage sensing apparatus after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered; low-pass digitally filtering the squared digitized response to generate a low-pass filter response, generating the kernel for said substep of low-pass digitally filtering with a width determined from the calculated frequency of the digitized response to signal from said voltage to extend over an integral number of cycles of said voltage associated with a power line phase; and taking the positive square root of said low-pass filter response to calculate the value of the r-m-s voltage associated with the power line phase.

Claim 10

The method of claim 1, employed for measuring the r-m-s value of a voltage associated with a power line phase of a p-phase alternating-current power line having a respective conductor for each phase, p being at least three, wherein said step of arranging respective sensing apparatus to sense at least one of the voltages and currents associated with each phase of said power line includes arranging a voltage sensing apparatus to sense the voltage associated with the phase of said power line the r-m-s voltage of which is being measured, as referred to the voltage associated with another phase of said power line, thereby to generate an analog signal for being digitized using said analog-to-digital conversion apparatus, and wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: calculating the frequency of the digitized response to signal from said voltage sensing apparatus after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered; squaring the digitized response to signal from said voltage sensing apparatus after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered; low-pass digitally filtering the squared digitized response to generate a low-pass filter response, generating the kernel for said substep of low-pass digitally filtering with a width determined from the calculated frequency of the digitized response to signal from said voltage to extend over an integral number of cycles of said voltage associated with a power line phase; and taking the positive square root of said low-pass filter response to calculate the value of the r-m-s voltage associated with the power line phase.

Claim 11

The method of claim 1, employed for measuring the r-m-s value of a current associated with a power line phase, wherein said step of arranging respective sensing apparatus to sense at least one of the voltages and currents associated with each phase of said power line includes arranging a current sensing apparatus to sense the current flowing through a power line conductor associated with the phase of said power line the r-m-s current of which is being measured, thereby to generate an analog signal for being digitized using said analog-to-digital conversion apparatus, and wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: calculating the frequency of the digitized response to signal from said current sensing apparatus after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered; squaring the digitized response to signal from said current sensing apparatus after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, low-pass digitally filtering the squared digitized response to generate a low-pass filter response, generating the kernel for said substep of low-pass digitally filtering with a width determined from the calculated frequency of the digitized response to signal from said current to extend over an integral number of cycles of said current associated with a power line phase; and taking the positive square root of said low-pass filter response to calculate the value of the r-m-s current associated with the power line phase.

Claim 14

The method of claim 11 wherein said step of using the digital computer to calculate each said electrical parameter includes substeps of: low-pass digitally filtering to generate a low-pass filter response, and generating the kernel for said substep of low-pass digitally filtering with a width determined from said calculated frequency to extend over an integral number of cycles of said electrical parameter.

Claim 15

The method of claim 12, employed for measuring the real power of a single power line phase, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: multiplying the digitized response to signal from said voltage sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a digital product signal; and low-pass digitally filtering the digital product signal to generate a low-pass filter response that corresponds to a calculation of the real power for said single power line phase.

Claim 16

The method of claim 12, employed for measuring the real power of a plural-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase, multiplying the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective digital product signal for that phase; adding together the respective digital product signals for all the phases to generate a digital sum signal; and low-pass digitally filtering the digital sum signal to generate a low-pass filter response that corresponds to a calculation of the real power of the plural-phase power line.

Claim 17

The method of claim 12, employed for measuring the reactive power of a single power line phase, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response; multiplying the digital quadrature voltage response by the digitized response to signal from said current sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a digital product signal; and low-pass digitally filtering the digital product signal to generate a low-pass filter response that corresponds to a calculation of the reactive power for said single power line phase.

Claim 18

The method of claim 12, employed for measuring the reactive power of a plural-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase, phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response for that phase; for each phase, multiplying the digital quadrature voltage response for that phase by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective digital product signal for that phase; adding together the respective digital product signals for all the phases to generate a digital sum signal; and low-pass digitally filtering the digital sum signal to generate a low-pass filter response that corresponds to a calculation of the reactive power of the plural-phase power line.

Claim 19

The method of claim 12, employed for measuring the apparent power of a single power line phase, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: multiplying the digitized response to signal from said voltage sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a first digital product signal; low-pass digitally filtering the first digital product signal to generate a first low-pass filter response that corresponds to a calculation of the real power for said single power line phase; phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response; multiplying the digital quadrature voltage response by the digitized response to signal from said current sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a second digital product signal; low-pass digitally filtering the digital product signal to generate a second low-pass filter response that corresponds to a calculation of the reactive power for said single power line phase; and generating the vector sum of said first and second low-pass filter responses, that corresponds to a calculation of the apparent power for said single power line phase.

Claim 20

The method of claim 17 wherein said step of generating the vector sum of said first and second low-pass filter responses is carried out using a CORDIC procedure.

Claim 21

The method of claim 17, being employed for measuring the power factor of a single power line phase and including the further step of: dividing said first low-pass filter response by said vector sum of said first and second low-pass filter responses, thereby to calculate the power factor for said single power line phase.

Claim 22

The method of claim 12, employed for measuring the apparent power of a plural-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase, multiplying the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective first digital product signal for that phase; adding together the respective first digital product signals for all the phases to generate a first digital sum signal; low-pass digitally filtering the first digital sum signal to generate a first low-pass filter response that corresponds to a calculation of the real power of the plural-phase power line; for each phase, phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response for that phase; for each phase, multiplying the digital quadrature voltage response for that phase by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective second digital product signal for that phase; adding together the respective second digital product signals for all the phases to generate a second digital sum signal; and low-pass digitally filtering the second digital sum signal to generate a second low-pass filter response that corresponds to a calculation of the reactive power of the plural-phase power line; and generating the vector sum of said first and second low-pass filter responses, that corresponds to a calculation of the apparent power of the plural-phase power line.

Claim 23

The method of claim 20 wherein said step of generating the vector sum of said first and second low-pass filter responses is carried out using a CORDIC procedure.

Claim 24

The method of claim 20, being employed for measuring the power factor of a plural-phase power line and including the further step of: dividing said first low-pass filter response by said vector sum of said first and second low-pass filter responses, thereby to calculate the power factor of said plural-phase power line.

Claim 25

The method of claim 12, employed for measuring the phase angle of a single power line phase, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: multiplying the digitized response to signal from said voltage sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a first digital product signal; low-pass digitally filtering the first digital product signal to generate a first low-pass filter response that corresponds to a calculation of the real power for said single power line phase; phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response; multiplying the digital quadrature voltage response by the digitized response to signal from said current sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a second digital product signal; low-pass digitally filtering the digital product signal to generate a second low-pass filter response that corresponds to a calculation of the reactive power for said single power line phase; and calculating the angle between said first and second low-pass filter responses, which corresponds to the phase angle for said single power line phase.

Claim 26

The method of claim 23 wherein said step of calculating the angle between said first and second low-pass filter responses is carried out using a CORDIC procedure.

Claim 27

The method of claim 12, employed for measuring the phase angle of a plural-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase, multiplying the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective first digital product signal for that phase; adding together the respective first digital product signals for all the phases to generate a first digital sum signal; and low-pass digitally filtering the first digital sum signal to generate a first low-pass filter response that corresponds to a calculation of the real power of the plural-phase power line. for each phase, phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response for that phase; for each phase, multiplying the digital quadrature voltage response for that phase by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective second digital product signal for that phase; adding together the respective second digital product signals for all the phases to generate a second digital sum signal; and low-pass digitally filtering the second digital sum signal to generate a second low-pass filter response that corresponds to a calculation of the reactive power of the plural-phase power line; and calculating the angle between said first and second low-pass filter responses, which corresponds to the phase angle of the plural-phase power line.

Claim 28

The method of claim 25 wherein said step of calculating the angle between said first and second low-pass filter responsed is carried out using a CORDIC procedure.

Claim 29

The method of claim 11, employed for measuring the real power of a single power line phase, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: multiplying the digitized response to signal from said voltage sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a digital product signal; and low-pass digitally filtering the digital product signal to generate a low-pass filter response that corresponds to a calculation of the real power for said single power line phase.

Claim 30

The method of claim 11, employed for measuring the real power of a plural-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substep of: for each phase, multiplying the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective digital product signal for that phase; adding together the respective digital product signals for all the phases to generate a digital sum signal; and low-pass digitally filtering the digital sum signal to generate a low-pass filter response that corresponds to a calculation of the real power of the plural-phase power line.

Claim 31

The method of claim 11, employed for measuring the reactive power of a single power line phase, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response; multiplying the digital quadrature voltage response by the digitized response to signal from said current sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a digital product signal; and low-pass digitally filtering the digital product signal to generate a low-pass filter response that corresponds to a calculation of the reactive power for said single power line phase.

Claim 32

The method of claim 11, employed for measuring the reactive power of a plural-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase, phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response for that phase; for each phase, multiplying the digital quadrature voltage response for that phase by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective digital product signal for that phase; adding together the respective digital product signals for all the phases to generate a digital sum signal; and low-pass digitally filtering the digital sum signal to generate a low-pass filter response that corresponds to a calculation of the reactive power of the plural-phase power line.

Claim 33

The method of claim 11, employed for measuring the apparent power of a single power line phase, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: multiplying the digitized response to signal from said voltage sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a first digital product signal; low-pass digitally filtering the first digital product signal to generate a first low-pass filter response that corresponds to a calculation of the real power for said single power line phase; phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response; multiplying the digital quadrature voltage response by the digitized response to signal from said current sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a second digital product signal; low pass digitally filtering the digital product signal to generate a second low-pass filter response that corresponds to a calculation of the reactive power for said single power line phase; and generating the vector sum of said first and second low-pass filter responses, that corresponds to a calculation of the apparent power for said single power line phase.

Claim 34

The method of claim 31, being employed for measuring the power factor for said single power line phase and including the further step of: dividing said first low-pass filter response by said vector sum of said first and second low-pass filter responses, thereby to calculate the power factor of said single-phase power line.

Claim 35

The method of claim 11, employed for measuring the apparent power of a plural-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase, multiplying the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective first digital product signal for that phase; adding together the respective first digital product signals for all the phases to generate a first digital sum signal; and low-pass digitally filtering the first digital sum signal to generate a first low-pass filter response that corresponds to a calculation of the real power of the plural-phase power line. for each phase, phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response for that phase; for each phase, multiplying the digital quadrature voltage response for that phase by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective second digital product signal for that phase; adding together the respective second digital product signals for all the phases to generate a second digital sum signal; and low-pass digitally filtering the second digital sum signal to generate a second low-pass filter response that corresponds to a calculation of the reactive power of the plural-phase power line; and generating the vector sum of said first and second low-pass filter responses, that corresponds to a calculation of the apparent power of the plural-phase power line.

Claim 36

The method of claim 33, being employed for measuring the power factor of a plural-phase power line and including the further step of: dividing said first low-pass filter response by said vector sum of said first and second low-pass filter responses, thereby to calculate the power factor of said plural-phase power line.

Claim 37

The method of claim 11, employed for measuring the phase angle of a single power line phase, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: multiplying the digitized response to signal from said voltage sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a first digital product signal; low-pass digitally filtering the first digital product signal to generate a first low-pass filter response that corresponds to a calculation of the real power for said single power line phase; phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response; multiplying the digital quadrature voltage response by the digitized response to signal from said current sensing apparatus for said single power line phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a second digital product signal; low-pass digitally filtering the digital product signal to generate a second low-pass filter response that corresponds to a calculation of the reactive power for said single power line phase; and calculating the angle between said first and second low-pass filter responses, which corresponds to the phase angle for said single power line phase.

Claim 38

The method of claim 11, employed for measuring the phase angle of a plural-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase, multiplying the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective first digital product signal for that phase; adding together the respective first digital product signals for all the phases to generate a first digital sum signal; and low-pass digitally filtering the first digital sum signal to generate a first low-pass filter response that corresponds to a calculation of the real power of the plural-phase power line. for each phase, phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response for that phase; for each phase, multiplying the digital quadrature voltage response for that phase by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective second digital product signal for that phase; adding together the respective second digital product signals for all the phases to generate a second digital sum signal; and low-pass digitally filtering the second digital sum signal to generate a second low-pass filter response that corresponds to a calculation of the reactive power of the plural-phase power line; and calculating the angle between said first and second low-pass filter responses, which corresponds to the phase angle of the plural-phase power line.

Claim 39

The method of claim 11 including the additional step of: supplying a calculated electrical parameter from said digital computer to apparatus generating indications of the calculated electrical parameter of a form perceptible to a human being.

Claim 40

The method of claim 37 wherein the additional step of supplying a calculated electrical parameter from said digital computer to apparatus generating indications of the calculated electrical parameter of a form perceptible to a human being comprises applying the calculated electrical parameter to a digital read-out device.

Claim 41

The method of claim 37 wherein the additional step of supplying a calculated electrical parameter from said digital computer to apparatus generating indications of the calculated electrical parameter of a form perceptible to a human being comprises the substeps of: using a pulse-duration modulator to generate pulses having a duration directly related to the calculated electrical parameter from said digital computer; and applying the pulses to a D'Arsonval meter.

Claim 48

The method of claim 42 wherein said step of using the digital computer to calculate each said electrical parameter includes substeps of: low-pass digitally filtering to generate a low-pass filter response, and generating the kernel for said substep of low-pass digitally filtering with a width determined from said calculated frequency to extend over an integral number of cycles of said electrical parameter.

Claim 49

The method of claim 43 for measuring the real power of said p-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase except said first, multiplying the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective digital product signal for that phase; adding together the respective digital product signals for all the phases except said first to generate a digital sum signal; multiplying said digital sum signal by a weighting factor; and low-pass digitally filtering the resulting weighted digital sum signal to generate a low-pass filter response that corresponds to a calculation of the real power of the plural-phase power line.

Claim 50

The method of claim 43 for measuring the reactive power of said p-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase except said first, phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response for that phase; for each phase except said first, multiplying the digital quadrature voltage response for that phase by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective digital product signal for that phase; adding together the respective digital product signals for all the phases to generate a digital sum signal; multiplying said digital sum signal by a weighting factor; and low-pass digitally filtering the resulting weighted digital sum signal to generate a low-pass filter response that corresponds to a calculation of the reactive power of the plural-phase power line.

Claim 51

The method of claim 43 for measuring the apparent power of said p-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase except said first, multiplying the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective first digital product signal for that phase; adding together the respective first digital product signals for all the phases except said to generate a first digital sum signal; multiplying said first digital sum signal by a first weighting factor; low-pass digitally filtering the resulting weighted first digital sum signal to generate a first low-pass filter response that corresponds to a calculation of the real power of the plural-phase power line; for each phase except said first, phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response for that phase; for each phase except said first, multiplying the digital quadrature voltage response for that phase by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective second digital product signal for that phase; adding together the respective second digital product signals for all the phases except said first to generate a second digital sum signal; multiplying said second digital sum signal by a second weighting factor; low-pass digitally filtering the resulting weighted second digital sum signal to generate a second low-pass filter response that corresponds to a calculation of the reactive power of the plural-phase power line; and generating the vector sum of said first and second low-pass filter responses, that corresponds to a calculation of the apparent power of the plural-phase power line.

Claim 52

The method of claim 46 wherein said step of generating the vector sum of said first and second low-pass filter responses is carried out using a CORDIC procedure.

Claim 53

The method of claim 46, being employed for measuring the power factor of said p-phase power line and including the further step of: dividing said first low-pass filter response by said vector sum of said first and second low-pass filter responses, thereby to calculate the power factor of said plural-phase power line.

Claim 54

The method of claim 43, employed for measuring the phase angle of said p-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase except said first, multiplying the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective first digital product signal for that phase; adding together the respective first digital product signals for all the phases except said first to generate a first digital sum signal; multiplying said first digital sum signal by a first weighting factor; low-pass digitally filtering the resulting weighted first digital sum signal to generate a first low-pass filter response that corresponds to a calculation of the the real power of the plural-phase power line; for each phase, phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response for that phase; for each phase, multiplying the digital quadrature voltage response for that phase by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective second digital product signal for that phase; adding together the respective second digital product signals for all the phases to generate a second digital sum signal; multiplying said second digital sum signal by a second weighting factor; low-pass digitally filtering the resulting weighted second digital sum signal to generate a second low-pass filter response that corresponds to a calculation of the reactive power of the plural-phase power line; and calculating the angle between said first and second low-pass filter responses, which corresponds to the phase angle of the plural-phase power line.

Claim 55

The method of claim 49 wherein said step of calculating the angle between said first and second low-pass filter responses is carried out using a CORDIC procedure.

Claim 56

The method of claim 42 for measuring the real power of said p-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase except said first, multiplying the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective digital product signal for that phase; adding together the respective digital product signals for all the phases except said first to generate a digital sum signal; multiplying said digital sum signal by a weighting factor; and low-pass digitally filtering the resulting weighted digital sum signal to generate a low-pass filter response that corresponds to a calculation of the real power of the plural-phase power line.

Claim 57

The method of claim 42 for measuring the reactive power of said p-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase except said first, phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response for that phase; for each phase except said first, multiplying the digital quadrature voltage response for that phase by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective digital product signal for that phase; adding together the respective digital product signals for all the phases to generate a digital sum signal; multiplying said digital sum signal by a weighting factor; and low-pass digitally filtering the resulting weighted digital sum signal to generate a low-pass filter response that corresponds to a calculation of the reactive power of the plural-phase power line.

Claim 58

The method of claim 42 for measuring the apparent power of said p-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase except said first, multiplying the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective first digital product signal for that phase; adding together the respective first digital product signals for all the phases except said to generate a first digital sum signal; multiplying said first digital sum signal by a first weighting factor; low-pass digitally filtering the resulting weighted first digital sum signal to generate a first low-pass filter response that corresponds to a calculation of the real power of the plural-phase power line; for each phase except said first, phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response for that phase; for each phase except said first, multiplying the digital quadrature voltage response for that phase by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective second digital product signal for that phase; adding together the respective second digital product signals for all the phases except said first to generate a second digital sum signal; multiplying said second digital sum signal by a second weighting factor; low-pass digitally filtering the resulting weighted second digital sum signal to generate a second low-pass filter response that corresponds to a calculation of the reactive power of the plural-phase power line; and generating the vector sum of said first and second low-pass filter responses, that corresponds to a calculation of the apparent power of the plural-phase power line.

Claim 59

The method of claim 53, being employed for measuring the power factor of said p-phase power line and including the further step of: dividing said first low-pass filter response by said vector sum of said first and second low-pass filter responses, thereby to calculate the power factor of said plural-phase power line.

Claim 60

The method of claim 42, employed for measuring the phase angle of said p-phase power line, wherein said step of using the digital computer to calculate each said electrical parameter comprises the substeps of: for each phase except said first, multiplying the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective first digital product signal for that phase; adding together the respective first digital product signals for all the phases except said first to generate a first digital sum signal; multiplying said first digital sum signal by a first weighting factor; low-pass digitally filtering the resulting weighted first digital sum signal to generate a first low-pass filter response that corresponds to a calculation of the real power of the plural-phase power line; for each phase, phase-shifting by ninety degrees the digitized response to signal from said voltage sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors and has been high-pass digitally filtered, thereby to generate a digital quadrature voltage response for that phase; for each phase, multiplying the digital quadrature voltage response for that phase by the digitized response to signal from said current sensing apparatus for that phase, after it has been corrected for non-linearities and gain errors, has been high-pass digitally filtered and has been phase-corrected, thereby to generate a respective second digital product signal for that phase; adding together the respective second digital product signals for all the phases to generate a second digital sum signal; multiplying said second digital sum signal by a second weighting factor; low-pass digitally filtering the resulting weighted second digital sum signal to generate a second low-pass filter response that corresponds to a calculation of the reactive power of the plural-phase power line; and calculating the angle between said first and second low-pass filter responses, which corresponds to the phase angle of the plural-phase power line.

Claim 61

The method of claim 42 including the additional step of: supplying a calculated electrical parameter from said digital computer to apparatus generating indications of the calculated electrical parameter of a form perceptible to a human being.

Claim 62

The method of claim 56 wherein the additional step of supplying a calculated electrical parameter from said digital computer to apparatus generating indications of the calculated electrical parameter of a form perceptible to a human being comprises applying the calculated electrical parameter to a digital read-out device.

Claim 63

The method of claim 56 wherein the additional step of supplying a calculated electrical parameter from said digital computer to apparatus generating indications of the calculated electrical parameter of a form perceptible to a human being comprises the substeps of: using a pulse-duration modulator to generate pulses having a duration directly related to the calculated electrical parameter from said digital computer; and applying the pulses to a D'Arsonval meter.