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US 5,517,106 AGranted
Method and apparatus for digitally measuring electrical power
AssigneeDigital KWH Inc.
InventorRichard L. Longini
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AssigneeDigital KWH Inc.
InventorRichard L. Longini
Estimating the term…
A method and apparatus for digitally measuring electrical energy consumption parameters from a transmission line carrying alternating current. Current flowing in the conductor is sampled at multiple times which are independent of the current phase. Using an appropriate microcomputer, this sampled current is analytically filtered by expressing the current with Fourier Series using only selected harmonics thus eliminating those harmonics which define noise. An approximation of the power and power consumption is then computed by multiplying the current as expressed in Fourier Series and a voltage measurement from the conductor to obtain a power reading, and the power reading is summed to obtain a number value proportional to the energy consumption. Even harmonics and high frequency harmonics may be eliminated in the Fourier expression of the current derivative to further simplify computer computations and required hardware, and the magnetic rate of change pickup and the voltage pickup are preferably filtered to remove unwanted noise.
The method of measuring electrical power delivery from a plurality of transmission line conductors carrying alternating current, comprising the steps of, measuring the electrical current flowing in a transmission line conductor at multiple times independent of voltage phase, expressing said current measurment with Fourier Series using only selected harmonics thereof and thus eliminating those harmonics which define noise and thereby analytically filtering the current measurement, measuring the voltage between conductors of the transmission line and ground at multiple times, and computing power being delivered through the transmission lines by coverting the filtered current measurement expressed in Fourier Series and the voltage measurement mathematically to power readings.
A digital meter for measuring electrical power delivery from a plurality of transmission line conductors carrying alternating current comprising;
Dependencies are inferred from the claim text.