Circuit Breaker Interlocking System for Safe Racking
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Solution Overview
Problem
Existing circuit breaker systems rely on external locking mechanisms that are prone to loss or damage, and lack an internal mechanism to prevent power application during servicing, posing safety risks and operational inefficiencies.
Innovation Solution
An internal interlocking system that includes a racking screw, access door, and trip assembly, which provides a mechanical trip signal to open the circuit breaker contacts and verifies their position, ensuring safe operation by preventing power application until the breaker is fully engaged or disengaged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external locking mechanisms (brakes, covers, padlocks, blocks) are used to prevent circuit breaker from being racked in during service, then safety is improved, but device complexity increases and parts can be lost or damaged during transport or storage
Solution Approach 1:
The patent merges the locking function with the existing carriage assembly structure by integrating an internal locking mechanism that uses the carriage's own components (gear system, contact arms, trip mechanism) to prevent racking in during service. This eliminates the need for separate external locking parts like brakes, covers, padlocks, and blocks, thereby reducing device complexity while maintaining safety.
Solution Approach 2:
The internal locking mechanism enables the carriage assembly to lock itself automatically during service position without requiring external locking parts. The mechanism uses the carriage's own gear system and contact arms to engage and prevent further movement, making the system self-sufficient and eliminating dependencies on external components that can be lost or damaged.
2Reliability
If external locking mechanisms are used to prevent power application during servicing, then safety is improved, but ease of operation deteriorates due to additional separate parts
Solution Approach 1:
The patent combines the locking function with the existing carriage assembly operations. The internal locking mechanism is integrated into the gear system and contact arm structure, allowing the locking and unlocking actions to be performed as part of the normal racking in/out operations without requiring separate external locking parts, thereby improving ease of operation while maintaining safety.
3Device complexity
If internal locking mechanism is integrated into the carriage assembly, then device complexity is reduced by eliminating separate parts, but manufacturing precision requirements increase
Solution Approach 1:
The patent integrates the locking function into the existing carriage assembly structure, utilizing the gear system, contact arms, and trip mechanism that are already part of the breaker design. This approach reduces device complexity by eliminating separate external locking parts while distributing the precision requirements across existing components rather than concentrating them in a single new mechanism.
Data Source
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AI summary
An interlocking system (136) for a circuit breaker assembly including a circuit breaker having a plurality of contacts includes a racking screw (128) coupled to the contacts that changes a position of the circuit breaker when engaged by a tool. The interlocking system also includes a front panel (124) defining an opening through which the racking screw is accessible, an access door (140) coupled to the front panel and configured to selectively cover the opening, and an access door stopper (142) coupled to the front panel. The interlocking system also includes a trip assembly (145) coupled to the access door stopper. Each of the access door, the access door stopper, and the trip assembly are moveable between a first position and a second position such that moving to the first position triggers delivery of a trip signal to the circuit breakers to open the plurality of contacts, and wherein, in the second position, the access door is fully open to enable access to the racking screw through the front panel.