Smart Current Transformer with Encoded Calibration Data
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Solution Overview
Problem
Current transformers used in electrical power systems suffer from phase and ratio errors due to magnetization of the transformer core, leading to inaccuracies in current measurement. These errors require specific correction factors that need to be reprogrammed when replacing or adding a current transformer, which can be cumbersome and time-consuming.
Innovation Solution
A smart current transformer system equipped with a machine-readable code, such as a QR code, that encodes calibration data specific to the transformer's performance characteristics. This calibration data is used to accurately determine the primary current by calibrating the secondary current measurement, allowing for easy and precise programming of phase and ratio error correction factors in power meters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current transformers are used to measure alternating current, then current measurement is enabled, but phase and ratio errors occur due to magnetization of the transformer core
Solution Approach 1:
The patent applies feedback by using the actual measured secondary current to calculate correction factors that compensate for phase and ratio errors. The system continuously monitors the relationship between primary and secondary currents and adjusts measurements based on observed deviations, thereby maintaining measurement precision despite the harmful magnetization effects in the transformer core.
Solution Approach 2:
The patent changes parameters by introducing correction factors (phase error correction factor and ratio error correction factor) that modify the measured current values. These parameters are calculated based on the transformer's actual performance characteristics and are applied to compensate for the inherent phase and ratio errors, effectively transforming inaccurate measurements into accurate ones.
2Measurement precision
If correction factors are reprogrammed when replacing or adding a current transformer, then measurement accuracy is maintained, but the process becomes cumbersome and time-consuming
Solution Approach 1:
The patent applies copying by creating a digital copy of the correction factor data that can be easily transferred and applied. Instead of manually reprogramming correction factors when replacing a current transformer, the system uses stored correction factor data (potentially in a database or memory device) that can be quickly retrieved and applied, significantly reducing the time required while maintaining measurement accuracy.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and storing correction factors before the current transformer is installed or replaced. The correction factors are determined in advance based on the transformer's characteristics and are made available for immediate use, eliminating the need for time-consuming on-site reprogramming operations.
3Device complexity
If a single loop primary winding is used in the current transformer, then the transformer structure is simplified, but the secondary current deviates from the theoretical relationship due to magnetization
Solution Approach 1:
The patent applies self-service by having the current transformer system compensate for its own inherent limitations. The single-loop primary winding structure remains simple, but the system automatically calculates and applies correction factors based on actual measurement data, allowing the simplified structure to achieve accurate measurements without requiring complex multi-loop windings or additional components.
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 system significantly enhances the accuracy of primary current measurements by using calibrated current transformers with encoded calibration data, improving power management and energy efficiency by reducing the need for frequent reprogramming and minimizing measurement errors.
Implementation Method 1
The cable carrying the load current runs through the opening at the center of the toroidal core, forming the primary winding of the transformer. The wire encircling the core's cross-section make up the secondary winding. The primary current flowing in the primary winding generates a corresponding secondary voltage and current in the secondary winding.
Data Source
AI summary
The present invention pertains to a device designed for accurate current measurement in a primary conductor. Key components include a current transformer, equipped with a secondary winding and a specified turns ratio, capable of converting the primary current into a proportionally scaled-down secondary current. Integral to the device's operation is a machine-readable code affixed to the current transformer. This code, encoded with calibration data specific to the current transformer's performance characteristics, ensures precise measurements and enhances the device's overall reliability and functionality.