Interference-Fit Current Transducer for Compact Magnetic Core Sensing
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Solution Overview
Problem
Existing open loop current transducers are voluminous and costly, limiting their use in space-constrained applications, while compact solutions are either expensive or complex to manufacture.
Innovation Solution
A compact open loop current transducer design featuring a U-shaped magnetic core with a primary conductor bar in an interference force fit, a magnetic field detector in the air gap, and a housing that optimizes the magnetic core's size and assembly, allowing for efficient magnetic flux capture and reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional open loop current transducer with magnetic core surrounding primary conductor is used, then measurement functionality is achieved, but the device becomes voluminous and space-consuming
Solution Approach 1:
The magnetic core is segmented into two separate C-shaped pieces that are positioned on opposite sides of the primary conductor bar. This segmentation allows the magnetic core to wrap around the conductor more compactly, reducing the overall transducer volume while maintaining the magnetic circuit functionality for accurate current measurement.
Solution Approach 2:
The magnetic core pieces are nested around the primary conductor bar in a compact configuration, with the conductor passing through the opening of each C-shaped piece. This nesting arrangement allows the magnetic core and conductor to be integrated in a space-efficient manner, reducing the transducer's external dimensions while preserving measurement capability.
2Volume of moving object
If compact current transducer designs without magnetic cores or closed loop type are used, then space requirements are satisfied, but manufacturing cost increases
Solution Approach 1:
The magnetic core pieces are directly integrated with the primary conductor bar through interference force fit, eliminating the need for separate mounting brackets, insulating housings, and complex assembly fixtures. This merging of components simplifies the manufacturing process and reduces assembly steps while achieving compact dimensions.
Solution Approach 2:
The interference force fit between the magnetic core pieces and primary conductor bar creates a self-aligning, self-securing connection that requires no additional fastening elements or complex positioning mechanisms. The components automatically assume their correct relative positions during assembly, reducing manufacturing complexity and cost.
3Ease of manufacture
If primary conductor bar is clamped with interference force fit between lateral branches, then assembly is simplified and compactness is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The width of the air gap between the lateral branches is specifically designed to be slightly less than the width of the primary conductor bar, creating a controlled interference condition. This parameter change transforms the assembly process into a simple forced insertion that generates automatic self-centering and secure clamping, achieving both ease of assembly and reliable mechanical connection.
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 design results in a cost-effective, robust, and compact current transducer that is easy to assemble and offers a large measurement range, suitable for harsh environments.
Implementation Method 1
a magnetic core configured to surround a primary conductor through which a current to be measured flows, the magnetic core having an air gap in which a magnetic field detector is positioned to measure a portion of the magnetic flux circulating in the magnetic core due to the magnetic field generated by the primary conductor
Implementation Method 2
measure a portion of the magnetic flux circulating in the magnetic core
Implementation Method 3
The magnetic field detector is very often a Hall effect detector that is typically provided in the form of an application specific integrated circuit (ASIC)
Data Source
AI summary
An open loop electrical current transducer including a primary conductor bar, for carrying a current to be measured, a magnetic core having a U shape formed by an end branch and lateral branches upstanding therefrom to free ends, a magnetic circuit gap formed between inner surfaces of the lateral branches at the free ends of the lateral branches, a magnetic field detector positioned in the magnetic circuit gap, and a housing surrounding the magnetic core and a section of the primary conductor bar extending through the magnetic core and beyond the magnetic core either side thereof. The primary conductor bar includes a central portion having a width (Wc) equal to the width of a magnetic field gap (Wg) such that the central portion is clamped between said lateral branches in an interference force fit.