Intelligent Meter Internal Calibration RC Decay Waveform
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Solution Overview
Problem
Existing electrical power meters face challenges in accurately calibrating for integral nonlinearities, requiring costly external signal sources and time-consuming processes, which can delay manufacturing and increase costs.
Innovation Solution
An intelligent electronic device with an internal calibration system that generates a clean RC decay waveform, samples it, and uses best-fit curve estimation to calculate distortions, applying correction factors to improve measurement accuracy across the entire measurement range without external equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external signal sources and equipment are used for calibration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The electrical power meter performs self-calibration using an internal RC decay waveform source. The calibration waveform generator creates test signals internally, the analog-to-digital converter processes them, and the processor analyzes the results to generate correction factors. This eliminates the need for external calibration equipment and signal sources, making the system self-sufficient while maintaining calibration accuracy.
Solution Approach 2:
The internal RC decay waveform source serves multiple functions: it generates calibration test signals for non-linearity correction, and can potentially be used for other diagnostic and testing functions within the meter. The same analog-to-digital converter and processor used for normal measurement operations are also employed for calibration analysis, maximizing the utility of existing components.
2Measurement precision
If external calibration equipment is used, then measurement precision is improved, but productivity decreases due to time-consuming processes
Solution Approach 1:
The self-calibration capability allows meters to be calibrated quickly during manufacturing without requiring setup and operation of external calibration equipment. The internal RC decay waveform source and automated correction factor generation streamline the calibration process, reducing manufacturing cycle time and increasing production throughput while maintaining accuracy.
3Measurement precision
If external signal sources are used for calibration, then measurement precision is improved, but cost increases
Solution Approach 1:
By using an internal RC decay waveform source instead of external calibration equipment, the meter eliminates the need for expensive external signal generators and calibration instruments. The calibration functionality is achieved using existing internal components (RC circuit, analog-to-digital converter, processor), significantly reducing manufacturing costs while maintaining calibration accuracy.
4Measurement precision
If traditional calibration methods are used, then measurement precision is improved, but device complexity increases due to additional components
Solution Approach 1:
The calibration system uses only internal components that are already present in the meter's normal operation circuitry. The RC decay waveform source, analog-to-digital converter, and processor work together to perform calibration without requiring any additional external equipment or specialized calibration components, thus avoiding increased device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables fast and accurate calibration, achieving a more stringent Class 0.1% accuracy specification, reducing errors by half compared to prior meters, and eliminating the need for external calibration sources, thus optimizing production time and cost.
Implementation Method 1
generating, within the enclosure or on the same one or more circuit boards which make up the IED and also contain the analog-to-digital converter, a calibration waveform
Data Source
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AI summary
An intelligent electrical power meter with an internal calibration system for calibrating its analog - to - digital converter is disclosed. The analog- to-digital converter is coupled with at least one sensor which is operable to sense electrical energy in one or more conductors and output a corresponding electrical signal indicative thereof, the analog - to - digital converter being operative to convert the electrical signal output by the sensor to at least one corresponding digital signal. Internal integral non-linearity calibration using a relatively low cost, low accuracy internal signal source is used, obviating the need for costly external signal sources or measurement systems.