Intelligent electronic device with broad-range high accuracy
First Claim
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1. An intelligent electronic device comprising:
- a sensing circuit having one or more sensors for sensing at least one parameter of an AC electrical service, each of the one or more sensors generating a first signal representative of the sensed parameter;
a plurality of gain-adjustable channels, each channel having at least one gain adjustment circuit for individually adjusting a gain factor and each channel comprising at least one first signal generated by the one or more sensors, the at least one first signal representative of the sensed parameter, wherein the plurality of gain-adjustable channels include a first channel for energy calculations, a second channel for harmonics calculations, and a third channel for waveform capture;
one or more computer-readable storage devices; and
a plurality of calibration factors stored in the one or more computer-readable storage devices, the plurality of calibration factors corresponding to a plurality of calibration measurements, the plurality of calibration measurements comprising measurements of a second signal representative of a known value of the parameter at a plurality of signal amplitudes in each of a plurality of calibration ranges.
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Abstract
A method and apparatus provides high-accuracy measurements of an electrical parameter across a broad range of parameter input values. In one embodiment, an intelligent electronic device (IED), e.g., a digital electrical power and energy meter, with a plurality of independently-adjustable gain factors measures a parameter, and calculates and stores calibration factors associated with known values of the measured parameter. The IED or meter applies the stored calibration factors when measuring unknown values of the measured parameter, to improve the accuracy of the measurement.
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Citations
22 Claims
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1. An intelligent electronic device comprising:
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a sensing circuit having one or more sensors for sensing at least one parameter of an AC electrical service, each of the one or more sensors generating a first signal representative of the sensed parameter; a plurality of gain-adjustable channels, each channel having at least one gain adjustment circuit for individually adjusting a gain factor and each channel comprising at least one first signal generated by the one or more sensors, the at least one first signal representative of the sensed parameter, wherein the plurality of gain-adjustable channels include a first channel for energy calculations, a second channel for harmonics calculations, and a third channel for waveform capture; one or more computer-readable storage devices; and a plurality of calibration factors stored in the one or more computer-readable storage devices, the plurality of calibration factors corresponding to a plurality of calibration measurements, the plurality of calibration measurements comprising measurements of a second signal representative of a known value of the parameter at a plurality of signal amplitudes in each of a plurality of calibration ranges. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for determining at least one parameter of an AC electrical service using a digital electrical power and energy meter, the method comprising:
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sensing a plurality of first signals, each of the plurality of first signals comprising a supply voltage or a supply current of the AC electrical service; generating a signal representative of each of the plurality of first signals; communicating each of the plurality of first signals across each of a plurality of gain-adjustable channels, each channel having at least one individually-adjustable gain factor, wherein the plurality of gain-adjustable channels include a first channel for energy calculations, a second channel for harmonics calculations, and a third channel for waveform capture; retrieving, from one or more computer-readable storage devices, one or more calibration factors corresponding to one or more of a plurality of calibration measurements, the plurality of calibration measurements comprising measurements of a second signal representative of a known voltage or a signal representative of a known current at a plurality of signal amplitudes in each of a plurality of calibration ranges; and applying a one of the one or more calibration factors to each of the plurality of first signals to generate a measured value of the first signal, the measured value of the first signal equal to determine an actual value of the parameter. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method for calibrating a digital power and energy meter, the method comprising:
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providing a plurality of signals in each of a plurality of calibration ranges, each of the plurality of signals comprising one of a known voltage signal or a known current signal; taking a measurement, at each of a plurality of signal amplitudes, of each of the plurality of signals using the digital power and energy meter; comparing, for each measurement, the measured value of the known voltage signal or the known current signal to the actual value of the known voltage signal or the known current signal; determining, for each measurement, a corresponding calibration factor; and storing the plurality of calibration factors in a computer-readable storage device, to allow the digital power and energy meter to apply a corresponding one of the plurality of calibration factors in response to a measurement of an unknown voltage signal or an unknown current signal to determine the value of the unknown voltage signal or the unknown current signal with at least a pre-determined level of accuracy; and providing a plurality of gain-adjustable channels, each channel having at least one individually-adjustable gain factor and comprising a plurality of signals representative of a sensed voltage or current, wherein the plurality of gain-adjustable channels include a first channel for energy calculations, a second channel for harmonics calculations, and a third channel for waveform capture. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification