Extension Handle Stopper for Circuit Breaker Misoperation Prevention
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Solution Overview
Problem
Existing motor protection circuit breakers are prone to accidental switching from the ON state to the manual tripping state due to misoperation of the extension handle assembly, necessitating a solution to increase the required force for such transitions while ensuring smooth operation to the fault tripping state.
Innovation Solution
An extension handle assembly with a stopper mechanism that provides a stopping force during manual tripping but not during fault tripping, combined with a biasing member and return spring, to increase the force needed for manual transitions and prevent accidental switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the extension handle assembly is designed to easily drive the knob for manual tripping, then the ease of operation is improved, but accidental misoperation increases reducing reliability
Solution Approach 1:
The stopper is positioned to provide localized resistance only in the manual tripping direction (from first to second position), while allowing free rotation in the fault tripping direction (from first to third position). This directional differentiation resolves the contradiction by making the operation easy when intended but preventing accidental activation.
Solution Approach 2:
The stopper provides preliminary resistance force against the handle rotation during manual tripping operation. This pre-applied counter force requires deliberate user action to overcome, preventing accidental activation while still allowing intentional operation when sufficient force is applied.
2Reliability
If the stopper provides stopping force during manual tripping, then the force required for manual tripping increases improving reliability, but the fault tripping operation may be hindered worsening ease of operation
Solution Approach 1:
The stopper is pivotally connected to the housing, allowing it to dynamically change its position and function. During manual tripping, it provides stopping force; during fault tripping, it rotates out of the way with the knob, automatically adapting to the operational mode without hindering either function.
Solution Approach 2:
The tripping mechanism is segmented into two independent rotational paths: manual tripping (first to second position) and fault tripping (first to third position). The stopper only interferes with the manual tripping path, allowing both functions to operate independently without mutual interference.
3Ease of operation
If the handle is constrained to rotate only to the second position, then the manual tripping control is improved, but the fault tripping rotation to the third position is restricted worsening adaptability
Solution Approach 1:
The stopper's pivotal connection allows it to dynamically adjust its position based on the rotation direction and force applied. When fault tripping occurs, the stopper rotates along with the knob to the third position, automatically adapting to accommodate both manual and fault tripping operations.
Solution Approach 2:
The rotational space is segmented into distinct zones: the stopper constrains rotation to the second position for manual tripping control, while allowing free rotation to the third position for fault tripping. This spatial segmentation enables both functions to coexist without interference.
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
The solution effectively increases the force required for manual tripping transitions, reducing accidental switches while allowing seamless fault tripping operations.
Implementation Method 1
the stopper is configured to abut against the handle upon the handle rotating from the first position to the second position during the manual tripping period of the motor protection circuit breaker, so as to provide a stopping force for a rotation of the handle
Implementation Method 2
a return spring arranged between the stopper and the housing for providing a return force for the stopper to return after the stopper is pushed by the handle to pivot away from a rotation path of the handle
Implementation Method 3
a biasing member connected between the handle and the housing, wherein the biasing member is configured to provide a biasing force to rotate the handle toward the second position or the third position at the first position of the handle
Data Source
AI summary
An extension handle assembly includes: a housing; a handle driving the knob to rotate from a first position to a second position during a manual tripping period of a motor protection circuit breaker and drives the handle to rotate from the first position to a third position during a fault tripping; a stopper configured to abut against the handle upon the handle rotating from the first position to the second position during the manual tripping period, to provide a stopping force for a rotation of the handle to increase a force required for the rotation of the handle from the first position to the second position; and configured not to abut against the handle upon the handle rotating from the first position to the third position during the fault tripping period, not to provide a stopping force for the rotation of the handle.