Shunt Integrated Bus Bar for AC DC Current Detection
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Solution Overview
Problem
Conventional electronic overload relays are physically large and only capable of detecting alternating current (AC), making them inefficient for both AC and direct current (DC) applications, necessitating a reduction in size while maintaining functionality across both types of currents.
Innovation Solution
The integration of a shunt integrated bus bar with a resistor part, made from high-resistivity materials like manganin, within an electromagnetic switch, allowing for both AC and DC current detection, reducing the size of the electronic overload relay and enabling compact mounting without the need for a current transformer (CT).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current transformer (CT) is used for current detection, then the detection function is achieved, but the device size becomes physically large
Solution Approach 1:
The patent extracts the current detection function from the bulky CT structure and implements it using a simple shunt resistor integrated into the bus bar. This removes the unnecessary magnetic core and winding components, retaining only the essential resistive element for current measurement, thereby dramatically reducing device size while maintaining detection capability.
Solution Approach 2:
The patent changes the detection parameter from magnetic field transformation (CT method) to direct voltage measurement across a shunt resistor. By using a high-resistivity material like manganin with controlled resistance value, the system measures current through voltage drop (V=IR) rather than magnetic induction, enabling compact implementation without sacrificing measurement accuracy.
2Adaptability or versatility
If a conventional CT-based detector is used, then AC current detection is achieved, but the device cannot cope with DC current
Solution Approach 1:
The patent implements a universal current detection mechanism using a shunt resistor that functions identically for both AC and DC currents. The resistive element responds to any current type by producing a proportional voltage drop, eliminating the need for separate AC and DC detection circuits and enabling the device to handle multiple current types with consistent accuracy.
3Measurement precision
If a CT is used for current detection, then the detection function is achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces the expensive, complex CT assembly with an inexpensive shunt resistor made from common high-resistivity materials like manganin. The shunt can be directly formed from resistive alloy bars or plates, eliminating the need for precision-wound copper coils, magnetic cores, and complex assembly processes, thereby dramatically reducing manufacturing cost while maintaining adequate detection accuracy for overload protection applications.
4Measurement precision
If a CT-based design is used, then current detection is achieved, but the device complexity increases
Solution Approach 1:
The patent segments the current detection function from the overall bus bar structure and integrates a dedicated shunt resistor portion directly into the bus bar design. This segmentation allows the shunt to be a simple, isolated resistive element within the bus bar, reducing structural complexity by eliminating the need for separate CT components, magnetic circuits, and complex wiring arrangements.
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 configuration allows for a compact electronic overload relay that effectively detects both AC and DC currents, reducing manufacturing costs, improving maintenance efficiency, and enabling mass production with reduced size constraints, while maintaining accurate current detection and protection capabilities.
Implementation Method 1
a shunt integrated bus bar with a resistor part made from high-resistivity materials like manganin, within an electromagnetic switch, allowing for both AC and DC current detection
Implementation Method 2
an electromagnetic contactor having coil terminals to which the shunt integrated bus bar is connected
Data Source
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AI summary
An electronic overload relay includes a bus bar formed by a conductive metallic material, provided between an electromagnetic contactor and a load, or between a circuit breaker and the electromagnetic contactor, and a resistor part arranged between one end and the other end of the bus bar, and including a shunt resistor for detecting a value of a current flowing through the bus bar.