Double Break Contact System for Circuit Breakers

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Solution Overview

Problem

Conventional contact systems in circuit breakers face issues such as reduced opening speed, instability, increased friction, and loss of contact pressure due to complex spring arrangements and open shaft constructions, which hinder efficient short-circuit breaking and lead to higher temperature rises and component damage.

Innovation Solution

A double break contact system with a unique spring arrangement where the spring force initially opposes and then aids electromagnetic force for increased opening velocity, combined with a movable shaft cover that rotates with the moving contact during short circuits, maintaining contact pressure and reducing friction through a simplified shaft construction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If compression springs continuously oppose electromagnetic repulsion force, then contact pressure is maintained, but opening speed is reduced

Engineering Contradiction:

Improvecontact pressureVSAvoidopening speed

Core Design Contradiction:

ForceVSSpeed

Solution Approach 1:

The spring arrangement transitions from continuous opposition to periodic action: initially opposing electromagnetic force to maintain contact pressure, then aiding opening motion after contact separation. This temporal variation in spring force direction resolves the contradiction between maintaining contact pressure and achieving high opening speed.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The spring system dynamically changes its mechanical configuration during operation. The springs are initially compressed to provide contact pressure, then as the moving contact opens, the spring arrangement allows the moving contact to flip open rapidly. This dynamic adaptation enables both contact pressure maintenance and high opening speed.

Inventive Principle:

Principle #15Dynamics

2Force

If extension springs are used to provide contact pressure, then contact pressure is maintained, but construction complexity increases

Engineering Contradiction:

Improvecontact pressureVSAvoidspring arrangement complexity

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

Multiple compression springs are merged into a single integrated spring arrangement that serves dual functions: maintaining contact pressure during normal operation and aiding opening motion during fault conditions. This consolidation reduces construction complexity compared to using extension springs while maintaining contact pressure.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If open shaft construction is used, then manufacturing is simplified, but friction increases and stability decreases

Engineering Contradiction:

Improveshaft construction simplicityVSAvoidcontact stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

A shaft cover is introduced to enclose the shaft construction, creating a closed system that reduces friction between moving parts and improves contact stability. The shaft cover acts as a protective shell that maintains proper alignment and reduces environmental interference while preserving manufacturing simplicity.

Inventive Principle:

Principle #30Flexible shells and thin films

4Productivity

If moving contact flips open rapidly during short circuit, then fault clearing efficiency is improved, but contact pressure maintenance becomes difficult

Engineering Contradiction:

Improvefault clearing efficiencyVSAvoidcontact pressure

Core Design Contradiction:

ProductivityVSForce

Solution Approach 1:

The spring arrangement provides periodic action by initially opposing electromagnetic force to maintain contact pressure, then after contact separation, the moving contact flips open rapidly under electromagnetic force while the spring arrangement aids this motion. This temporal variation enables both contact pressure maintenance and rapid fault clearing.

Inventive Principle:

Principle #19Periodic action

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 enhances short-circuit breaking efficiency, maintains performance after contact wear, and provides improved thermal and electrical life, while protecting internal components and preventing arc failure through a closed shaft construction.

Implementation Method 1

a spring arrangement where the spring force initially opposes and then aids electromagnetic force for increased opening velocity

Methodology Applied

Scientific EffectSpring force: Spring

Implementation Method 2

During any fault (short-circuit) in the line, the moving contact is opens up and clears the fault. During this movement the electromagnetic force has to fully act against the springs providing contact pressure.

Methodology Applied

Scientific EffectElectromagnetic force: Electromagnetic Induction

Data Source

PatentEP2831897B1An improved double break contact system for moulded case circuit breakers

Publication Date: 2017.03.01 LARSEN & TOUBRO LTD

AI summary

The invention relates to an improved double break contact system for use in moulded case circuit breakers. The system comprises shaft means (8), fixed contact means (1 and 2) and moving contact means (3) mounted on shaft means (8), spring means (4) operatively mounted on the shaft means (8), holder means (5) securing said spring means (4) wherein holder means being rotatably mounted on the shaft means in a manner that rotation of the shaft means in operation rotates said holder means. The spring means is adapted to provide force opposing the electromagnetic