Dual Magnetic Circuit Current Sensor for Wide-Range Fault Detection
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Solution Overview
Problem
Existing fault current detection devices are limited in detecting currents of wide amplitude and frequency ranges, as they often become ineffective due to magnetic core saturation and spectrum aliasing phenomena, especially with the introduction of electronic loads and photovoltaic systems which generate continuous or pulsating fault currents.
Innovation Solution
A device comprising a direct current sensor with a first magnetic circuit and an alternating current sensor connected in series, using a generator to alternately saturate the magnetic field, and a current measurement circuit with low-pass filters and comparators to detect fault currents across a wide frequency and amplitude range, including a voltage shunt regulator to manage peak amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single magnetic circuit sensor is used to detect fault currents, then the device structure is simple, but the detection range is limited and blind zones appear at high amplitudes and frequencies
Solution Approach 1:
The sensor is divided into two independent magnetic circuits: a first magnetic circuit for detecting low-frequency and DC fault currents, and a second magnetic circuit for detecting high-frequency fault currents. This segmentation allows each circuit to be optimized for its specific frequency range, eliminating detection blind zones while maintaining manageable structural complexity
Solution Approach 2:
The sensor system is designed to perform multiple detection functions simultaneously through two magnetic circuits that can detect different frequency ranges. The first magnetic circuit handles DC and low-frequency currents, while the second handles high-frequency currents, creating a universal sensor capable of detecting the entire spectrum of fault currents
2Measurement precision
If the magnetic excitation amplitude is increased to improve signal strength, then detection sensitivity improves, but magnetic core saturation occurs causing detection failure
Solution Approach 1:
The system uses different excitation amplitudes for different magnetic circuits: the first magnetic circuit uses a first excitation amplitude optimized for low-frequency and DC detection, while the second magnetic circuit uses a second excitation amplitude optimized for high-frequency detection. This parameter adaptation prevents saturation in each circuit's optimal operating range while maintaining detection sensitivity
Solution Approach 2:
The excitation amplitudes are made adaptable to the detection requirements of different frequency ranges. The system dynamically selects appropriate excitation levels based on the target detection frequency, allowing optimal sensitivity without saturation for each operating condition
3Measurement precision
If high-frequency components are removed from the measurement signal, then detection accuracy for high-frequency currents improves, but information about the original fault current is lost
Solution Approach 1:
The system extracts high-frequency components from the measurement signal to eliminate interference and improve detection accuracy for DC and low-frequency fault currents. By separating and removing only the problematic high-frequency noise while preserving the essential fault current information, the system achieves accurate detection without significant information loss
Solution Approach 2:
The patent introduces an intermediary processing step that selectively filters high-frequency components from the measurement signal. This intermediary filter acts as a mediator between the raw measurement signal and the final detection output, removing harmful high-frequency interference while preserving the essential fault current information needed for accurate detection
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
Enables detection of fault currents across extremely wide amplitude and frequency ranges without blind zones, ensuring operational safety and effective protection against electrical faults in various installations.
Implementation Method 1
a generator connected to the terminals of the first winding to generate an alternating current to excite the first magnetic circuit and induce a magnetic field in the first magnetic circuit
Implementation Method 2
said magnetic field alternately saturates the first magnetic circuit in a given direction and then in the opposite direction
Implementation Method 3
a first winding wound on said first magnetic circuit to form a first secondary circuit and provide a first signal representative of the fault current, and a second winding wound on the second magnetic circuit to provide a second signal representative of the fault current
Data Source
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AI summary
The present invention relates to a device for detecting direct or alternating electric current flowing in a current line of an electrical installation, comprising a direct current sensor associated with an alternating current sensor and a current measurement circuit. The invention also relates to a module for protection against an electrical fault and an electrical protection device.