Withdrawable Circuit Breaker Interlock Mechanism

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Solution Overview

Problem

Current circuit breakers lack a reliable mechanism to prevent undesired opening or closing, especially when mounted on a trolley that can be inserted into and withdrawn from modules, as existing interlocks do not provide clear indication of the breaker's position.

Innovation Solution

A circuit breaker system with a first moveable arm, a second pivotally coupled moveable arm, and a blocking arm, configured to interlock with the second moveable arm, utilizing a threaded rod and spring-loaded mechanism to ensure the breaker can only be moved when in the open position, preventing closure unless manually tripped.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a simple interlock mechanism is used, then the device complexity is reduced, but the reliability of preventing undesired breaker operation is insufficient

Engineering Contradiction:

Improvereliability of preventing undesired breaker operationVSAvoidcomplexity of interlock mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The interlock mechanism uses dynamic blocking arms that can pivot between blocked and unblocked positions based on breaker state. The first blocking arm pivots on the circuit breaker and the second blocking arm pivots on the trolley, allowing the system to adapt its configuration dynamically rather than using fixed mechanical constraints

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent introduces blocking arms as intermediary mechanical elements that mediate between the breaker position and the ability to operate the breaker. These blocking arms transmit the state information and physically prevent undesired operations without requiring complex electronic sensors or control systems

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If multiple blocking arms are used to improve safety, then the reliability increases, but the device complexity increases

Engineering Contradiction:

Improvesafety of breaker operationVSAvoidnumber of interlock components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple blocking functions into a coordinated system where the first blocking arm (on the breaker) and second blocking arm (on the trolley) work together. When both are in their blocked positions, they provide redundant safety protection, but the arms are integrated through the existing breaker-trolley interface rather than adding completely separate interlock systems

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If the breaker is prevented from moving unless open, then the safety is improved, but the ease of operation is reduced

Engineering Contradiction:

Improvesafety during trolley movementVSAvoidconvenience of breaker movement

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The interlock system requires the breaker to be opened (tripped) before the blocking arms will allow trolley movement. This preliminary action of opening the breaker ensures safety before movement, but the mechanism is designed so that once tripped, the breaker remains in the open state and can be moved without additional manual intervention on the interlock itself

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP2482399B1Interlocks for withdrawable circuit breakers

Publication Date: 2019.05.01 ABB (SCHWEIZ) AG

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AI summary

A circuit breaker interlock apparatus can include a circuit breaker (105), a first moveable arm (215) that is moveable when the circuit breaker (105) is open, a second moveable arm (220) pivotally coupled to the first moveable arm (215) that is movable when the first moveable arm (215) is moveable and a blocking arm (230), configured to interlock with the second movable arm (220).