Method and apparatus for digitally measuring electrical energy consumption
First Claim
1. The method of measuring electrical energy consumption from a plurality of transmission line conductors carrying alternating current, comprising the steps of, measuring the time derivative of the magnetic field induced by an electrical current flowing in a transmission line conductor thereby obtaining a reading proportional to the time derivative of the current flow, mathematically approximating the time derivative of the current flowing in the conductor by expressing said magnetic field rate of change with an algorithmic series for expressing cyclic phenomena, measuring the voltage between conductors of the transmission line, computing an approximation of the power being consumed through the transmission line by converting the time derivative of the current as expressed in an algorithmic series and the voltage measurement mathematically to a power reading, and summing the power reading to obtain a number value proportional to the energy consumed through said conductors.
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Abstract
A method and apparatus for digitally measuring electrical energy consumption from a transmission line carrying alternating current. Instead of actually measuring current from a transmission line conductor, the time derivative of the magnetic field induced by current flowing in the conductor is measured thereby obtaining a reading which is proportional to the time derivative of the current flow. Using an appropriate microcomputer, the time derivative of the magnetic field (the magnetic field rate of change) is represented with an algorithmic series for expressing cyclic phenomena, such as the Fourier series of low order. An approximation of the power consumption is then computed by converting the time derivative of the current as expressed in the algorithmic series and a voltage measurement from the conductor mathematically to 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 algorithmic 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.
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Citations
47 Claims
- 1. The method of measuring electrical energy consumption from a plurality of transmission line conductors carrying alternating current, comprising the steps of, measuring the time derivative of the magnetic field induced by an electrical current flowing in a transmission line conductor thereby obtaining a reading proportional to the time derivative of the current flow, mathematically approximating the time derivative of the current flowing in the conductor by expressing said magnetic field rate of change with an algorithmic series for expressing cyclic phenomena, measuring the voltage between conductors of the transmission line, computing an approximation of the power being consumed through the transmission line by converting the time derivative of the current as expressed in an algorithmic series and the voltage measurement mathematically to a power reading, and summing the power reading to obtain a number value proportional to the energy consumed through said conductors.
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24. A digital electrical energy consumption meter for measuring electrical energy consumption from a plurality of transmission line conductors carrying alternating current comprising;
- a magnetic field rate of change pick-up adapted for measuring the time derivative of the magnetic field induced by an electrical current flowing in a transmission line conductor thereby obtaining a reading proportional to the time derivative of the current flow, and voltage pickup measuring means adapted to measure the voltage between conductors of the transmission line;
computer means connected to said pick-up and to said voltage measuring means and programmed for representing said derivative of the current with an algorithmic series for expressing cyclic phenomena, for computing an approximation of the power being consumed by converting the time derivative of the current as expressed in an algorithmic series and the voltage measurement mathematically to a power reading, and for summing the power reading to thereby obtain a measurement number value proportional to the energy consumed by a load connected to the conductors. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
- a magnetic field rate of change pick-up adapted for measuring the time derivative of the magnetic field induced by an electrical current flowing in a transmission line conductor thereby obtaining a reading proportional to the time derivative of the current flow, and voltage pickup measuring means adapted to measure the voltage between conductors of the transmission line;
Specification