Terminal Shield Protrusions for Circuit Breaker Spacing
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Solution Overview
Problem
Existing electrical switching apparatus, such as circuit breakers, face challenges in minimizing space usage while meeting industry safety standards for terminal spacing, particularly in densely packed configurations like panelboards or load centers, where it is difficult to satisfy both 'through air' and 'over surface' minimum spacing requirements.
Innovation Solution
The implementation of terminal shields with protrusions that extend outwardly from the case on opposing sides of terminal openings, providing both over surface and through air terminal spacing, and a vented case design with multiple venting passages to efficiently discharge ionized gases, meeting Underwriter's Laboratory (UL) 489 standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If circuit breakers are disposed adjacent one another in parallel rows to maximize space efficiency, then space utilization is improved, but terminal spacing requirements (through air and over surface) cannot be satisfied
Solution Approach 1:
The patent introduces terminal shields that extend in the dimensional space between adjacent circuit breakers, specifically adding protrusions that project from the terminal region. This dimensional addition creates the necessary spacing without increasing the overall footprint of the circuit breaker assembly, thereby resolving the contradiction between compact arrangement and spacing requirements.
Solution Approach 2:
The terminal shield acts as an intermediary structure between adjacent circuit breakers. The protrusions on the terminal shield create physical barriers that enforce the required through air and over surface spacing between terminals of adjacent breakers, while the shield itself is integrated into the circuit breaker housing to maintain compact overall dimensions.
2Device complexity
If a single vent is used to ventilate ionized gases from circuit breakers, then device complexity is minimized, but venting efficiency is insufficient for multiple circuit breakers
Solution Approach 1:
The venting system is segmented into multiple independent vent channels within the terminal shield structure. Each vent channel provides a dedicated pathway for ionized gases from specific circuit breaker regions, allowing simultaneous ventilation of multiple breakers through what appears to be a single integrated shield component. This segmentation improves venting efficiency while maintaining relatively simple overall structure.
Data Source
AI summary
A terminal shield is provided for an electrical switching apparatus including a case having a first housing member, a second housing member coupled to and disposed opposite from the first housing member, a first end, a second end, a number of terminals, and a number of terminal openings. Each of the first and second housing members has a first side and a second side. The terminal shield includes at least one pair of protrusions extending outwardly from the case on opposing sides of a corresponding one of the terminal openings. Each protrusion has an interior surface facing a corresponding one of the terminals, and an exterior surface disposed opposite the interior surface. The exterior surface of each protrusion aligns with the first side of a corresponding one of the first and second housing members.