Circuit Breaker Contact Latch Release for Fast Blow-Open Switching
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Solution Overview
Problem
Circuit breakers face challenges in quickly opening contacts during short circuit conditions while maintaining them closed during normal operation, as existing designs often fail to rapidly disengage at short circuit current levels.
Innovation Solution
A contact system with a moveable contact arm assembly, carrier assembly, latch plate, and trip shaft, where an electromagnetic force at a threshold level rotates the trip shaft out of engagement with the latch plate, facilitating rapid opening of the circuit breaker from a closed to a blow open condition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contacts are clamped or maintained in a tight closed condition to maintain high withstand current rating, then the contacts remain closed during normal operation, but the contacts may not be able to open quickly at the short circuit current level
Solution Approach 1:
The trip shaft is pre-positioned in engagement with the latch plate during normal operation, creating a mechanical lock that prevents contact opening. This preliminary engagement ensures reliable contact closure while being ready to release when electromagnetic force exceeds the threshold, enabling rapid contact opening during short circuits
Solution Approach 2:
The system changes the engagement state of the trip shaft based on the electromagnetic force parameter. During normal operation, the trip shaft engages the latch plate to maintain contact closure. When electromagnetic force reaches the threshold level during a short circuit, the trip shaft rotates to disengage from the latch plate, allowing rapid contact opening
2Duration of action of stationary object
If the contacts are maintained in a closed condition during normal operation, then the circuit breaker ensures continuous current flow, but the clearing time during short circuits is increased
Solution Approach 1:
The patent replaces a purely mechanical release system with an electromagnetic force-based release mechanism. The electromagnetic force directly acts on the moveable contact arm to rotate the trip shaft, eliminating the need for complex mechanical trip mechanisms and enabling faster clearing time during short circuits while maintaining contact closure during normal operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables rapid contact disengagement during short circuits, reducing clearing time and maintaining contact closure during normal operation, thus enhancing the circuit breaker's current rating and response efficiency.
Implementation Method 1
configured to rotate the trip shaft out of engagement with the latch plate directly by an electromagnetic force on the movable contact arm
Data Source
AI summary
A contact system of a circuit breaker includes a fixed contact. The contact system also includes a moveable contact arm assembly comprising at least one moveable contact arm having a moveable contact thereon, the moveable contact arm moveable to define a closed condition and a blow open condition. The contact system further includes a carrier assembly operatively coupled to the moveable contact arm. The contact system yet further includes a latch plate operatively coupled to the carrier assembly. The contact system also includes a trip shaft operatively coupled to the carrier assembly, the trip shaft having a non-circular region defining an engagement surface disposed in contact with the latch plate in the closed condition. The contact system further includes a biasing portion of the moveable contact arm configured to rotate the trip shaft out of engagement with the latch plate and into the blow open condition.