Closed Magnetic Circuit Current Sensing With Fewer Installation Sensors
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Solution Overview
Problem
Existing methods for measuring main currents in electrical installations require multiple sensors per conductor, leading to bulkiness and high costs due to the need for both main current and differential current measurement sensors.
Innovation Solution
A device comprising a closed magnetic circuit with N-1 main current measuring windings and a single computing unit that measures voltages across these windings to deduce the main currents using geometry or calibration, eliminating the need for multiple sensors by leveraging the magnetic flux differences generated by non-coaxial conductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are installed per conductor for measuring main currents, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple current measurement functions into a single sensor device. The sensor simultaneously measures both the main current flowing through the conductor and the differential current in the surrounding insulation, replacing what would traditionally require separate sensors. This merging reduces device complexity while maintaining measurement precision through integrated measurement coils and a unified signal processing approach.
Solution Approach 2:
The single sensor device performs multiple measurement functions: it measures the main current through the conductor using one winding and simultaneously measures the differential current (leakage current) through the insulation using another winding. This multi-functional sensor eliminates the need for separate sensors for different measurement purposes, reducing overall device complexity while providing comprehensive electrical monitoring.
2Reliability
If multiple sensors are installed in the electrical installation, then comprehensive current measurement is achieved, but space occupation and cost increase
Solution Approach 1:
The patent merges multiple measurement capabilities into a single compact sensor that can be installed around a conductor. The sensor housing contains multiple measurement coils (for main current and differential current measurement) that work simultaneously within a single device footprint, significantly reducing the space required compared to multiple separate sensors while maintaining comprehensive measurement coverage.
Solution Approach 2:
The sensor structure employs a nested arrangement where measurement coils are wound around a common magnetic core or housing. The first winding for main current measurement and the second winding for differential current measurement are nested within the same sensor assembly, with each winding utilizing the magnetic circuit efficiently. This nested configuration minimizes the overall sensor dimensions while providing multiple measurement functions.
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
This approach reduces the number of sensors needed, saving space and cost while accurately measuring main currents and detecting leakage currents for protective purposes.
Implementation Method 1
the main current I circulating in said at least one conductor generates a different magnetic flux at each of the two windings... have an opposite winding direction from one winding to the other, so that a uniform magnetic field in the magnetic circuit generates a voltage that cancels out across the terminals of the main current measuring winding
Data Source
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AI summary
The invention relates to a device for measuring the main currents (1) of an electrical installation comprising N conductors (3). The device comprises a closed magnetic circuit (5), at least N-1 main current measuring windings (11), a support structure (6), means (13) for measuring a voltage (V11) across the main current measuring windings (11), and a calculation unit (15). Each main current measuring winding comprises two windings in series (111, 112), each wound around a portion of the magnetic circuit (5), not equidistant from at least one of the conductors (3), and having opposite winding directions from one winding (111, 112) to the other, such that a uniform magnetic field in the magnetic circuit (5) generates a zero voltage across the main current measuring winding (11).