Combined Current Sensor for Arc Fault and Power Line Monitoring
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Solution Overview
Problem
Existing arc fault detection devices are complex, costly, and lack efficiency in simultaneously detecting high frequency arc faults and low frequency over-current faults in power lines, particularly in providing accurate and compact solutions for branch circuit protection.
Innovation Solution
A powdered core bead body with a ferromagnetic material acts as an inductive impedance to radio frequencies between 1MHz to 40MHz, combined with a magnetic flux-density sensing device, enabling both high frequency arc fault detection and low frequency current measurement, which is filtered and amplified through an analog front end for accurate tripping indications and power metering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate high frequency sensor and low frequency current sensor are used for arc fault detection, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines high frequency arc fault detection and low frequency current measurement functions into a single integrated sensor device. The sensor simultaneously detects both RF signals (1MHz-40MHz) indicative of arc faults and low frequency current (DC-20kHz) for over-current protection, eliminating the need for separate sensors and reducing overall device complexity while maintaining detection accuracy for both fault types
Solution Approach 2:
The integrated sensor serves multiple functions: detecting high frequency arc faults through RF signal detection, measuring low frequency current for over-current protection, and providing both signals to the control circuit. This multi-functional approach allows a single sensor to replace what would traditionally require multiple separate sensing components
2Adaptability or versatility
If multiple sensors are used for simultaneous high frequency and low frequency detection, then detection capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent integrates multiple detection functions into a single sensor unit that can simultaneously detect high frequency arc faults and low frequency current. This consolidation reduces the total number of components required, simplifying assembly procedures and reducing manufacturing costs while maintaining the versatility to detect multiple fault types
3Reliability
If traditional arc fault circuit interrupter components are used, then detection reliability is improved, but device size increases
Solution Approach 1:
The integrated sensor combines high frequency RF detection and low frequency current measurement in a single compact unit, reducing the overall space required for sensing components. This consolidation maintains reliable detection of both arc faults and over-current conditions while minimizing the device footprint
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 provides a smaller, simpler, and cost-effective device capable of detecting arc faults and over-currents, adhering to standards like UL and IEC, while optimizing space and sensitivity, with reduced sensor count and assembly complexity.
Implementation Method 1
a powdered core bead body, such as a ferromagnetic bead, is configured to become an inductive impedance to current signals with radio frequencies (RF) between 1MHz to 40MHz flowing through a power wire passing through the bead
Implementation Method 2
The powdered core bead body includes a magnetic flux-density sensing device, such as a Hall-effect device or magnetic field sensor device, embedded in a cavity in the bead body
Data Source
Figure 1A~1B
Figure 1C
Figure 1D~1F
AI summary
Example embodiments of the invention include a powdered core bead body configured to become an inductive impedance to current signals in a power wire with high frequencies. The signals are detectable by a high frequency voltage sensor, which is configured to output an arc fault tripping indication to an arc fault tripping circuit. The bead body includes a magnetic flux-density sensing device embedded in an air cavity of the bead body, having a magnetic field sensing surface oriented substantially perpendicular to the circumferential periphery of the bead body. The bead body is configured to provide measurable magnetic flux through the magnetic flux-density sensing device, for currents in the power wire having low frequencies. The measurable magnetic flux is detectable by a low frequency magnetic flux-density sensing device, to output a low frequency current measurement for power metering devices or to determine power consumption within a protected branch.