Electrical Contact Switch Magnetic Pressure Control
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Solution Overview
Problem
Electrical contactors in electricity meters face challenges in preventing contact bounce and arcing during high current operations, which can lead to reduced lifespan and safety issues during short-circuit and dead fault conditions.
Innovation Solution
An electrical contact switch design featuring fixed and moveable ferromagnetic elements that induce a magnetic field to increase contact pressure, combined with a split-blade arrangement and a normally-closed actuation mechanism to minimize arcing and prolong contactor life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional contact switches are used without magnetic attraction elements, then the device complexity is low, but contact bounce occurs during high current operations reducing reliability
Solution Approach 1:
A moveable ferromagnetic element is introduced as an intermediary between the moveable arm and the fixed ferromagnetic element. This intermediary element is attracted by the magnetic field generated during high current flow, and in turn applies magnetic attraction force to the electrical contacts to suppress contact bounce, thereby improving reliability without requiring fundamental redesign of the contact switch structure
Solution Approach 2:
The invention changes the magnetic properties of the contact switch by incorporating ferromagnetic elements. During normal operation, these elements remain relatively inactive, but during high current operations, they become magnetically active and provide dynamic contact pressure enhancement, improving reliability only when needed without continuously increasing device complexity
2Reliability
If contact pressure is increased to prevent contact separation during faults, then contact reliability improves, but precious metal consumption increases
Solution Approach 1:
The magnetic attraction force is applied periodically or dynamically during high current operations rather than maintaining continuous high contact pressure. The ferromagnetic elements become active when current flows and generate magnetic fields, providing contact pressure enhancement only during critical operating conditions, thus preventing welds without continuously consuming precious metals
Solution Approach 2:
The ferromagnetic elements utilize the electrical current already flowing through the contacts to generate the magnetic field needed for attraction. The current serves dual purposes: carrying the electrical load and generating the magnetic field that enhances contact pressure, thereby preventing welds without requiring additional energy or material input
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 effectively reduces contact bounce and arcing, ensuring safe operation and extended lifespan of the contactor under high current conditions while minimizing precious metal usage.
Implementation Method 1
in a closed condition of the electrical contact set, the electrically-conductive moveable arm induces a magnetic field in the fixed and moveable ferromagnetic elements
Implementation Method 2
the moveable ferromagnetic element is magnetically attracted towards the fixed ferromagnetic element by the magnetic field
Data Source
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AI summary
An electrical contact switch (10) for use in an electrical contactor (12), which comprises first and second electrical terminals (14, 16), an electrically-conductive busbar (20) in electrical communication with the first electrical terminal (14), and at least one fixed electrical contact (22) which is attached to the electrically-conductive busbar (20). The switch (10) also has an electrically-conductive moveable arm (24) in electrical communication with the second electrical terminal (16), with at least one moveable electrical contact (26a, 26b) which is attached to the electrically-conductive moveable arm (24) to form an electrical contact set (28) with the fixed electrical contact (22). A fixed ferromagnetic element (30) is positioned at or adjacent to a side of the electrically-conductive moveable arm (24) proximate the second electrical terminal (16), and a moveable ferromagnetic element (32) is provided in physical communication with a side of the electrically-conductive moveable arm (24) which is opposite to the fixed ferromagnetic element (30). In a closed condition of the electrical contact set (28), the electrically-conductive moveable arm (24) induces a magnetic field in the fixed and moveable ferromagnetic elements (30, 32), and thus the moveable ferromagnetic element (32) is magnetically attracted towards the fixed ferromagnetic element (32) to thereby increase a contact pressure on the electrical contact set (28). An electrical contactor (12) and method of preventing or inhibiting contact bounce of an electrical contactor (12) are also provided.