Circuit Breaker Interlock Assembly for Safe Panel Maintenance

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Solution Overview

Problem

There is a need for a mechanism that prevents miniature circuit breakers from being inadvertently installed or removed while current is flowing, to avoid hazardous events such as arcing, electrical shock, or load damage, especially when de-energizing the panel is not feasible.

Innovation Solution

An interlock assembly that interacts with the circuit breaker panel to ensure the circuit breaker is in a tripped state before installation or removal, using an interference member and an externally accessible actuator to prevent insertion or removal until the circuit breaker is tripped, with a biasing member like a helical spring to maintain the interfering position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the circuit breaker is made easily installable and removable from the panel, then ease of operation is improved, but safety is worsened due to risk of inadvertent installation/removal while current is flowing

Engineering Contradiction:
Improveease of installation and removalVSAvoidhazardous events (arcing, electrical shock)
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The interlock assembly requires the circuit breaker to be in the tripped state (a preliminary condition) before it can be installed in or removed from the panel. The actuator must be in the unlocked position, which corresponds to the tripped state, allowing the retention member to engage with the panel and permit installation/removal operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The interlock assembly acts as an intermediary mechanism between the circuit breaker and the panel. It includes a retention member that engages with the panel and an actuator that controls whether the circuit breaker can be installed or removed, mediating the interaction to ensure safety conditions are met.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If an interlock mechanism is added to prevent inadvertent installation/removal, then safety is improved, but device complexity increases

Engineering Contradiction:
Improvehazardous events preventionVSAvoidinterlock assembly structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The interlock assembly merges multiple functions into a single integrated mechanism: the retention member provides both the interlocking function (preventing inadvertent installation/removal) and the retention function (holding the circuit breaker in the panel). The actuator combines the tripping mechanism with the interlock control function.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The actuator serves multiple functions: it trips the circuit breaker, controls the interlock state (locked/unlocked), and enables or disables installation/removal operations. The retention member similarly serves both as an interlock component and as a retention mechanism.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Object-affected harmful factors

If the circuit breaker requires de-energized panel for removal, then safety is improved, but productivity decreases due to operational restrictions

Engineering Contradiction:
Improvearcing and electrical shock preventionVSAvoidcircuit breaker installation/removal efficiency
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The interlock assembly provides self-protection by automatically preventing installation or removal operations unless the circuit breaker is in the tripped state. The system serves itself by monitoring its own state (via the actuator position) and controlling access to installation/removal operations without requiring external monitoring or manual verification.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2980827B1Panel board to circuit breaker positive retention interlock
Publication Date: 2017.07.26 SCHNEIDER ELECTRIC USA INC
  • EP2980827B1 patent drawingFigure 1A~1B
  • EP2980827B1 patent drawingFigure 2A~2B
  • EP2980827B1 patent drawingFigure 3~4

AI summary

An interlock assembly for a circuit breaker prevents inadvertent installation or removal of the circuit breaker from a circuit breaker panel while current is flowing. The interlock assembly cooperates with the circuit breaker panel to physically prevent the circuit breaker from being inserted into the circuit breaker panel until the circuit breaker is put into a tripped state. Likewise, the interlock assembly cooperates with the circuit breaker panel to physically prevent the circuit breaker from being taken out of the circuit breaker panel until the circuit breaker is put into a tripped state. This ensures that the circuit breaker will not be inadvertently installed or removed from the circuit breaker panel while current can immediately flow or is flowing through the circuit breaker.