Adjustable Magnetic Trip Device for Electric Switches
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Solution Overview
Problem
Existing electromagnetic trip devices for electric protective switch apparatuses face challenges in adjusting and reproducing a reliable magnetic tripping threshold due to manufacturing tolerances and dimension disparities, leading to increased costs and equipment failures.
Innovation Solution
The introduction of intercalary adjustment means comprising calibrated magnetic and non-magnetic sectors between the moving core and shell, allowing for variation of the magnetic flux transfer surface to adjust the tripping threshold without adding additional elements or complexifying the moving core design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manufacturing tolerances are reduced to preserve precision of dimensions and magnetic sticking areas, then the magnetic tripping threshold reliability is improved, but the manufacturing cost and complexity increase due to required rectification
Solution Approach 1:
The magnetic flux transfer surface is segmented into multiple adjustable zones using movable shims and adjustable spacing elements. This allows independent optimization of different magnetic flux paths, enabling reliable tripping threshold without requiring ultra-precise manufacturing of the entire assembly. The segmentation transforms a single high-tolerance requirement into multiple lower-tolerance requirements.
Solution Approach 2:
Movable shims and adjustable spacing elements are introduced as intermediary components between the magnetic circuit elements. These intermediaries compensate for manufacturing tolerances and enable precise adjustment of the magnetic tripping threshold without requiring the base components to be manufactured with extremely tight tolerances, thereby reducing overall manufacturing cost.
2Reliability
If thin insulating air-gap shims are added to achieve reliable tripping threshold, then the magnetic flux control is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The shims are designed as movable rather than fixed, allowing dynamic adjustment of the air-gap dimensions. This mobility enables the system to adapt to manufacturing variations and maintain reliable tripping threshold without requiring complex pre-adjustment procedures or multiple shim variants, thereby controlling device complexity while improving reliability.
Solution Approach 2:
The adjustable spacing elements serve multiple functions: they control the magnetic air-gap, provide mechanical alignment, enable tripping threshold adjustment, and compensate for manufacturing tolerances. This multi-functionality reduces the need for additional specialized components, thereby controlling overall device complexity while achieving reliable magnetic flux control.
3Manufacturing precision
If sophisticated guiding is implemented to centre the moving core correctly, then the moving core positioning is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The magnetic circuit elements and movable shims are designed to self-align during assembly through magnetic attraction forces and geometric constraints. This self-alignment mechanism eliminates the need for complex external guiding structures, achieving accurate moving core centring while minimizing device complexity and manufacturing cost.
Solution Approach 2:
The design incorporates adjustable spacing parameters that can be tuned to optimize the moving core positioning. By adjusting the shim thickness and spacing element dimensions, the system achieves correct centring without requiring complex guiding mechanisms, thereby reducing device complexity while maintaining manufacturing precision.
4Ease of manufacture
If the moving core design is simplified without intercalary adjustment means, then the manufacturing cost is reduced, but the ability to adjust magnetic tripping threshold is lost
Solution Approach 1:
The shims and spacing elements are designed as movable and adjustable components rather than fixed elements. This dynamic design allows the magnetic tripping threshold to be adjusted after manufacturing without requiring complex rework or additional components, thereby maintaining ease of manufacture while enabling adaptability.
Solution Approach 2:
The adjustable spacing elements are pre-configured with adjustment mechanisms that allow field adjustment of the magnetic tripping threshold. This preliminary design of the adjustment capability enables both simplified manufacturing and post-manufacturing adaptability, as the adjustment mechanism is built-in rather than requiring additional complex components.
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 solution enables easy adjustment of the magnetic tripping threshold, reduces manufacturing costs, and improves the reproducibility and reliability of the tripping mechanism, minimizing equipment failures and economic losses.
Implementation Method 1
an induction coil 25 arranged around the sheath 20. The moving core 30 slides along a longitudinal axis Y inside an insulating sheath 20 between a tripped position and a rest position due to the action of an induction coil 25
Implementation Method 2
superposition of the radial crown 33 of the moving core 30, of the intercalary adjustment means 40, 41 and of the radial surface 11 of the shell 10, in the rest position, forms a magnetic flux transfer surface enabling the flow of an axial magnetic flux 5
Data Source
AI summary
An electromagnetic trip device comprising a shell and a moving core sliding due to the action of a coil, the shell comprising a radial surface having an opening through which the moving core passes, superposition of a radial crown of the moving core and the radial surface forming a magnetic flux transfer surface enabling flow of an axial magnetic flux. The trip device comprises intercalary adjustment means of said transfer surface respectively positioned between the moving core and the opening, said intercalary adjustment means comprising two calibrated elements adjoined surface against surface and being respectively formed by an alternation of magnetic sectors and non-magnetic sectors; movement of a calibrated element with respect to the other enabling a variation of said transfer surface to be obtained.