Magnetic Core Arc Detection with HF Bypass for DC Wiring
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Solution Overview
Problem
Existing arc detection methods using magnetic field detection in current sensors can cause magnetic saturation, leading to inaccurate detection of arcs.
Innovation Solution
An arc detection device with a magnetic core configuration that allows direct currents to flow in opposite directions through separate paths, combined with a low impedance circuit to bypass high frequency components, ensuring accurate detection by canceling out magnetic saturation and preserving the high frequency signals indicative of arcs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If arc detection is performed by disassembling the connection box to access the terminal, then detection can be performed, but the work is troublesome and time-consuming
Solution Approach 1:
A magnetic field sensor is introduced as an intermediary detection means that can sense arcs through the connection box wall without direct contact with the terminal. The sensor detects the magnetic field generated by the arc current, enabling arc detection while keeping the connection box assembled and accessible.
Solution Approach 2:
The mechanical approach of disassembling the connection box to visually inspect or test the terminal is replaced by a magnetic field-based detection system. The sensor magnetically senses the arc through the wall, substituting mechanical disassembly with non-contact magnetic detection.
2Object-affected harmful factors
If the connection box wall is made thick for insulation and protection, then safety is improved, but magnetic field sensors cannot effectively detect arcs through the wall
Solution Approach 1:
The detection function is extracted from the interior of the connection box and placed on the exterior surface. The magnetic field sensor is mounted on the outer wall, allowing it to detect arcs through the wall material without being constrained by wall thickness requirements for insulation.
Solution Approach 2:
The detection method changes from direct electrical contact or visual inspection to magnetic field sensing. This parameter change allows detection through insulating materials, as magnetic fields can penetrate non-magnetic wall materials regardless of thickness.
3Device complexity
If general-purpose circuit breakers are used without arc detection function, then device complexity is reduced, but arc faults cannot be detected and may cause fires
Solution Approach 1:
The arc detection function is merged with the existing circuit breaker structure. The magnetic field sensor is integrated into the breaker housing, and the detection circuit is combined with the breaker's control circuitry, allowing arc detection capability to be added without creating a separate complex system.
Solution Approach 2:
The circuit breaker is designed to perform multiple functions: conventional circuit protection and arc fault detection. The magnetic field sensor and detection circuit enable the breaker to simultaneously monitor for arcs while maintaining its primary protection functions, making the device universally applicable for both purposes.
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 device accurately detects arcs by isolating high frequency components from direct currents, thereby enhancing the reliability of arc detection in electrical systems.
Implementation Method 1
an arc is detected by a magnetic field sensor through a wall of the connection box
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 3A~3C
AI summary
An arc detection device (10a) includes: a current detector (20a) that includes a magnetic core (21) penetrated by first and second paths (51a) and (52a) each connecting a DC power source (40) and a device (50), and detects a current flowing through each of the first and second paths (51a) and (52a) in accordance with a magnetic field generated at the magnetic core (21); a low impedance circuit (11a) having a lower impedance than the DC power source (40) and the device (50), the low impedance circuit (11a) being connected to the first path (51a) and the second path (52a) to cause a high frequency component to bypass one of the first path (51a) or the second path (52a); and an arc determiner (30) that determines an occurrence of an arc based on a current detected by the current detector (20a). In the magnetic core (21), a direct current flows through the first path (51a) in a direction opposite to a direction in which a direct current flows through the second path (52a).