Circuit Interrupter Contact Configuration for Welded Fault Isolation
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Solution Overview
Problem
Existing ground fault circuit interrupter (GFCI) and arc fault circuit interrupter (AFCI) receptacles lose protection if a single contact welds, leading to safety hazards due to continued electrical connection and failure of reverse feed detection.
Innovation Solution
A contact configuration for circuit interrupters or receptacles featuring a planar conductive member with multiple contacts and an operating mechanism that ensures electrical isolation of conductors even if one contact pair welds, using a longitudinal member and spring arms to disconnect the remaining conductors upon a predetermined condition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional contact configuration with multiple contact pairs is used, then electrical connection functionality is achieved, but safety protection is lost if one contact welds
Solution Approach 1:
The contact system is segmented into multiple independent contact pairs (first contact pair, second contact pair, third contact pair) where each pair operates independently. This segmentation ensures that a weld in one contact pair does not affect the isolation capability of other contact pairs, maintaining safety protection while achieving the required electrical connection functionality.
Solution Approach 2:
Different contact pairs are assigned different functions: the first contact pair connects line conductor to load line conductor, the second contact pair connects neutral conductor to load neutral conductor, and the third contact pair connects ground conductor to load ground conductor. This local differentiation of contact functions ensures that failure of one contact pair does not compromise overall safety, as other contact pairs can still provide isolation.
2Ease of operation
If contact pairs are used to connect electrical conductors, then electrical connectivity is achieved, but safety hazard occurs upon contact welding
Solution Approach 1:
The receptacle is designed with multiple contact pairs in advance, where at least one contact pair is dedicated to providing isolation capability. This preliminary arrangement ensures that even if one contact welds during operation, the pre-configured contact pairs maintain the isolation function, preventing safety hazards before they can occur.
Solution Approach 2:
The system incorporates redundant contact pairs that serve as a safety buffer. If one contact pair welds and fails to provide isolation, the other contact pairs act as a cushioning backup to maintain the isolation function, preventing the safety hazard from manifesting. This prior cushioning approach ensures continuous protection against contact welding failures.
Data Source
AI summary
A circuit interrupter includes first, second and third electrical conductors, a planar conductive member having first, second and third contacts, and an operating mechanism structured to move the planar conductive member toward the electrical conductors to electrically connect the first, second and third electrical conductors to the respective first, second and third contacts, and to move the planar conductive member away from the electrical conductors to electrically disconnect the electrical conductors from the contacts upon the occurrence of a predetermined condition, such that the electrical conductors are electrically isolated from each other. When one of the electrical conductors is welded to one of the contacts, the operating mechanism and the planar conductive member cooperate to electrically disconnect the other two of the electrical conductors from the other two of the contacts upon the occurrence of the predetermined condition.