Low-Voltage Contact Assembly for Fast Opening Without Bounce
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Solution Overview
Problem
Existing low voltage circuit breakers face issues with mechanical complexity, friction, and component wear due to electrodynamic repulsion forces during short circuit conditions, leading to high contact speeds and potential damage, while requiring a compact and reliable design with minimal components.
Innovation Solution
A low voltage contact group with a rotating movable contact assembly featuring an elastic element and mechanical link system, including levers and pivots, that controls torque and contact pressure, minimizing friction and preventing bouncing, while ensuring adequate contact pressure and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electrodynamic repulsion forces are used to increase contact separation speed under short circuit conditions, then the intervention time is reduced and short-circuit current is prevented from reaching maximum value, but the movable contact gains high speeds and great energy causing violent impacts against the casing and possible bouncing toward the fixed contact
Solution Approach 1:
The patent applies beforehand cushioning by introducing a damping element that absorbs the excessive energy and kinetic momentum of the movable contact before it can cause violent impacts against the casing or bouncing toward the fixed contact. The damping element is positioned to engage with the movable contact assembly during repulsion, providing controlled resistance that dissipates the harmful kinetic energy while allowing the beneficial separation speed to be achieved.
2Reliability
If latching systems are used to control contact pressure and prevent bouncing of the movable contact, then reliability is improved, but the mechanical complexity and number of components increase
Solution Approach 1:
The patent applies the taking out principle by removing the complex latching system from the design and replacing it with a simpler damping element that achieves the same reliability goals. The damping element provides passive energy absorption and contact pressure control without requiring the mechanical complexity of latching mechanisms, thereby reducing the number of components while maintaining bouncing prevention and contact pressure control.
3Reliability
If a movable contact assembly with particular profile is used to change torque intensity and direction during rotation, then contact pressure control is improved, but friction phenomena cause wearing of the movable contact body
Solution Approach 1:
The patent applies mechanics substitution by replacing the complex profiled movable contact body that relies on friction-based torque control with a simpler design that uses a damping element for energy control. This substitution reduces the reliance on friction phenomena between contact surfaces, thereby minimizing wearing of the movable contact body while maintaining adequate contact pressure control through the damping mechanism.
4Force
If spring systems are used to ensure adequate contact pressure between movable and fixed contacts, then contact pressure is maintained in closed position, but the movement of movable contact during opening due to electrodynamic repulsion forces is hindered
Solution Approach 1:
The patent applies dynamics by introducing a damping element that provides dynamic, speed-dependent resistance to the movable contact assembly. Unlike a static spring system that provides constant force, the damping element's resistance varies with the speed of the movable contact, allowing it to provide adequate contact pressure during closed position while offering controlled resistance during opening that does not excessively hinder the electrodynamic repulsion-driven separation speed.
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 manages torque and contact pressure, reducing friction and wear, maintaining contact integrity during repulsion forces, and providing a compact design suitable for low voltage circuit breakers.
Implementation Method 1
an elastic element suitable to ensure an adequate contact pressure when the active surface of the moving contact is coupled to the fixed contact
Implementation Method 2
a mechanical link comprising a first lever and a second lever, wherein the first lever has a first operative end connected to said supporting structure by a third pivot and a second operative end; wherein the second lever has a first operative end connected to the second operative end of said elongated body by a fourth pivot, and a second operative end
Data Source
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AI summary
A low-voltage contacts group for a low-voltage circuit breaker, which comprises: a fixed contact adapted to be electrically connected to an electrical terminal of said circuit breaker; and a movable contact assembly comprising: a rotating supporting shaft adapted to be operatively connected to an actuation mechanism of said circuit breaker and which has a body provided with a first seat; and a rotating moving contact sub-assembly comprising: - a supporting structure positioned in said first seat and rigidly fixed to said rotating supporting shaft; - a rotating moving contact connected to the supporting structure by a first pivot and free to rotate with respect to the supporting structure in a rotation plane substantially perpendicular to a rotation axis of the rotating supporting shaft; wherein the rotating moving contact comprises an elongated body having an active surface that can be coupled to/uncoupled from the fixed contact by rotation of the moving contact in said rotation plane; wherein the active surface is positioned at a first operative end of the elongated body and at least partially protrudes from said supporting structure and from said first seat; wherein the elongated body is connected to said first pivot at an intermediate point between its first operative end and a second operative end thereof; - an elastic element suitable to ensure an adequate contact pressure when the active surface of the moving contact is coupled to said fixed contact, said elastic element having a first operative end connected to said supporting structure by a second pivot, and a second operative end; - a mechanical link comprising a first lever and a second lever, wherein the first lever has a first operative end connected to said supporting structure by a third pivot and a second operative end; wherein the second lever has a first operative end connected to the second operative end of said elongated body by a fourth pivot, and a second operative end; wherein the second operative ends of said first and second levers are connected each other by a fifth pivot; and wherein the second operative end of said elastic element is also connected to said fifth pivot.