Molded Case Circuit Breaker Insulating Barrier Arc Interruption

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Solution Overview

Problem

Molded case circuit breakers face challenges in effectively extinguishing arcs during interruption, leading to potential damage and reduced performance due to prolonged exposure of contacts to arcs and compromised insulation around the shaft assembly.

Innovation Solution

Incorporating an insulating barrier made of flexible material that rotates with the movable contact and is guided to enter between the fixed and movable contacts during interruption, effectively cutting off the arc before it reaches the arc-extinguishing unit, thereby reducing damage and enhancing insulation performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the circuit breaker uses a conventional arc-extinguishing unit with metal grids, then the arc can be cooled and divided, but the contacts are exposed to the arc for a long time causing damage and insulation deterioration

Engineering Contradiction:

Improvearc interruption performanceVSAvoidarc damage to contacts and insulation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The insulating barrier is positioned in advance between the fixed and movable contacts before arc interruption occurs. When the circuit breaker operates, the insulating barrier is already in place to immediately block the arc, preventing contact damage and insulation deterioration that would otherwise occur during the arc extinction process

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The insulating barrier acts as an intermediary element inserted between the fixed and movable contacts. This barrier mediates the arc interruption process by physically blocking the arc path, protecting the contacts from direct arc exposure while still allowing the arc-extinguishing unit to function

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the insulating barrier is made of flexible material and coupled to the movable contact, then it can rotate and enter between contacts during interruption, but the structure becomes more complex

Engineering Contradiction:

Improveinsulation integrityVSAvoidshaft assembly structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The insulating barrier is constructed from flexible insulating material that can deform and move with the shaft assembly. This flexibility allows the barrier to rotate with the shaft during normal operation and to be guided into the protective position between contacts during interruption, maintaining insulation integrity without requiring complex rigid mechanical structures

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The insulating barrier is integrated with the shaft assembly by coupling it to the movable contact, which is already rotatably coupled to the shaft. This merging of functions allows the insulating barrier to utilize the existing rotational motion of the shaft assembly without requiring separate actuation mechanisms, thereby reducing overall structural complexity

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentEP3567620B1Molded case circuit breaker

Publication Date: 2021.06.02 LSIS CO LTD

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AI summary

A molded case circuit breaker includes a fixed contact (120, 121); a movable contact (140) rotatably provided on a shaft assembly (130) to be brought into contact with or separated from the fixed contact; and an insulating barrier (150) that enters between the fixed contact and the movable contact during interruption, wherein the insulating barrier is coupled to the movable contact to rotate along a circumferential surface of a body of the shaft assembly (130).