Residual Current Protection Switch Gentle Resetting Mechanism
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Solution Overview
Problem
Residual current circuit breakers face challenges in resetting the tripping plunger without causing shocks or vibrations, which can damage the sensitive tripping relay, and the force required for resetting varies with the number of poles and switch-off conditions.
Innovation Solution
A residual current circuit breaker design featuring a kinematically coupled switching mechanism with a rotatably mounted contact lever and a mechanical spring providing a restoring force, decoupling the contact lever's movement from the switching mechanism's dynamic motion, ensuring gentle and shock-free resetting of the tripping plunger, independent of the contact force and number of poles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a toggle lever switching mechanism is used to implement high tripping forces, then the switching contacts can be reliably disconnected, but the tripping plunger is subjected to shocks and vibrations during reset
Solution Approach 1:
The patent divides the force transmission path into two independent segments: one for tripping (via toggle lever mechanism) and one for resetting (via application lever with spring). This segmentation allows the tripping function to use high-force mechanical advantage while the resetting function uses a controlled, low-impact spring mechanism, preventing shock transmission to the tripping plunger.
Solution Approach 2:
The application lever acts as an intermediary between the switching mechanism and the tripping plunger during reset operations. The spring-loaded application lever mediates the force transmission, providing a cushioned, controlled reset action rather than direct mechanical coupling, thereby preventing shocks from reaching the sensitive tripping plunger.
2Device complexity
If the switching mechanism is directly coupled to the tripping plunger, then the structure is simpler, but the resetting force varies with number of poles and switch-off conditions
Solution Approach 1:
The patent changes the parameter of force transmission from a directly coupled mechanical linkage to a spring-loaded system. The spring mechanism provides a consistent resetting force that is independent of the number of poles or specific switch-off conditions, as the spring force is determined by its mechanical properties rather than by operational variables.
Solution Approach 2:
The application lever is designed to be movable and spring-loaded rather than fixed, allowing it to dynamically adapt to different operating conditions. This dynamic design ensures that the resetting force remains consistent regardless of variations in switch-off conditions or number of poles, as the spring automatically adjusts to provide the required force.
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 ensures reliable and gentle resetting of the tripping plunger, preventing damage to the tripping relay and maintaining consistent resetting force regardless of the number of poles or switch-off conditions, thereby enhancing the reliability and safety of the circuit breaker.
Implementation Method 1
a mechanical spring (42) which exerts a restoring force on the contact lever (40)
Implementation Method 2
The so-called knee lever effect is used, according to which the force introduced in the area of the almost fully extended knee can be greatly increased
Data Source
Figure 1
Figure 2~4
Figure 3A~3B
AI summary
A trip rod (21) coupled with a switching mechanism moves from an initial position to a tripped position on occurrence of fault current. An application lever (40) is provided to reset the trip rod through restoring force to starting position. The application lever is held against the restoring force when the switching contact of switching mechanism is held in one position. The application lever is coupled to switching mechanism, and equipped with a control cam formed region that slides on a switching mechanism control element (31) until the application lever is released.