Switchgear Contact Bridge Damping for Bounce Prevention
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Solution Overview
Problem
Generic installation switching devices face issues with contact bounce due to mechanical inertia differences, causing contacts to close prematurely before the switching mechanism can ensure a permanent opening during short-circuit current interruption.
Innovation Solution
A damping element is integrated into the contact bridge's movement path to slow down the return movement, either attached to the pusher or contact bridge, converting kinetic energy into heat through friction, allowing sufficient time for the operating lever to maintain the contact opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional switching mechanism with mechanical inertia is used, then the structure is simple, but contact bounce occurs because the contacts close prematurely before the operating lever can secure the permanent opening
Solution Approach 1:
A damping element is introduced as an intermediary component between the contact bridge and the operating lever. This damping element mediates the force transmission by selectively dampening the return movement of the contact bridge while allowing the operating lever to function normally for permanent opening. The damping element acts as a buffer that prevents direct force transmission that would cause contact bounce, thereby improving reliability without requiring fundamental changes to the switching mechanism structure.
2Speed
If the contact bridge returns quickly after electrodynamic opening, then the switching speed is high, but contact bounce occurs due to the contact pressure spring closing the contacts before the operating lever can maintain the open position
Solution Approach 1:
The damping element is positioned to act on the contact bridge or pusher during its return movement toward the closed position. By placing the damping element in advance in the force transmission path, it cushions the return movement before the contacts can close again. This beforehand cushioning prevents the harmful rapid closing action that would cause contact bounce, while the electrodynamic opening speed remains high because the damping only affects the return phase, not the opening phase.
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 damping element effectively prevents contact bounce by slowing the return movement, ensuring the contact remains open long enough for the operating lever to secure the position, thus enhancing the dynamic behavior of the switching device.
Implementation Method 1
converting kinetic energy into heat through friction
Data Source
Figure 1~2
AI summary
The device (1) has a switchgear comprising an electromagnetic trigger (13) whose striker armature strikes a contact bridge (7) during occurrence of short-circuit by a pusher (12) in a direction of an opening (O) and unlatches a latch point of a switch latch (15). An absorption member (30) is arranged in a part of a pole current path (2) of the bridge, so that the bridge or the pusher is effectively connected with the absorption member after striking the bridge to slow down movement of the bridge. The absorption member comprises a piece of material made of an elastic material.