Thomson Coil Damping for Fast Circuit Interrupter Contact Motion

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Solution Overview

Problem

Circuit interrupters face challenges in quickly opening and closing separable contacts without causing damage due to the significant forces required, which can lead to wear and tear, necessitating frequent replacements.

Innovation Solution

The use of conductive coils and eddy current members to provide increased initial velocity for opening strokes and faster damping at the conclusion of strokes, eliminating the need for contact springs and mechanical damping mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If significant force is applied to open separable contacts quickly, then opening speed is improved, but damage to components increases

Engineering Contradiction:

Improveopening speedVSAvoidcomponent durability

Core Design Contradiction:

SpeedVSStrength

Solution Approach 1:

The eddy current member is positioned and configured in advance to generate damping forces just before the moving assembly completes its opening stroke. This preliminary damping action prepares the system to absorb the impact energy, allowing high opening speeds without component damage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention converts the harmful impact force that would normally damage components into a beneficial controlled deceleration. The eddy current damping mechanism transforms the kinetic energy of the rapidly moving assembly into electromagnetic damping forces, stopping the movement in a controlled manner that protects components while maintaining high opening speeds.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Speed

If significant force is applied to close separable contacts quickly, then closing speed is improved, but wear and tear on contacts increases

Engineering Contradiction:

Improveclosing speedVSAvoidcontact lifespan

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The eddy current damping mechanism is positioned to activate just before the separable contacts make contact during closing. This preliminary action reduces the closing speed at the critical moment, preventing excessive impact and wear on the contacts while maintaining overall fast closing performance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention converts the potentially harmful impact that causes contact wear into a beneficial controlled deceleration. The eddy current forces transform the kinetic energy into electromagnetic damping, reducing contact impact and extending contact lifespan while preserving fast closing capability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Stability of the object's composition

If mechanical damping mechanisms are used to control opening strokes, then damping effectiveness is improved, but device complexity increases

Engineering Contradiction:

Improvedamping effectivenessVSAvoidmechanical mechanism complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The invention replaces traditional mechanical damping mechanisms (such as springs, shock absorbers, or friction-based dampers) with an electromagnetic damping system. The eddy current member interacts with a magnetic field to generate damping forces without any moving mechanical damping components, significantly reducing device complexity while maintaining damping effectiveness.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The eddy current member acts as an intermediary between the moving assembly and the magnetic field. It transfers the kinetic energy of the moving assembly into electromagnetic forces that provide damping, eliminating the need for direct mechanical damping components while achieving the desired damping effect.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 approach allows for rapid and controlled movement of separable contacts, reducing wear and tear while maintaining robustness, thus extending the lifespan of components and preventing restrike.

Implementation Method 1

a first coil member having an opening through which the shaft passes; and a first eddy current member having an opening through which the shaft passes and coupled to the shaft

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the shaft and first eddy current member are structured to move in response to a force exerted on the first eddy current member

Methodology Applied

Scientific EffectLorentz force: Lorentz Force

Implementation Method 3

the first eddy current member is structured to stop moving in response to changes in a damping current supplied to the first coil member

Methodology Applied

Scientific EffectEddy current damping: Eddy Current Damping

Implementation Method 4

the first eddy current member is structured to move in response to changes in a current supplied to the second coil member

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS12424404B2Thomson coil with energized coil damping

Publication Date: 2025.09.23 EATON INTELLIGENT POWER LTD

AI summary

Coil-based actuators for use in opening and closing the separable contacts of circuit interrupters provide increased initial velocity for opening strokes and improved damping at the end of opening strokes by utilizing current-based damping and omitting contact springs and contact dampeners.