Double-Contact Switch Staggered Opening Vacuum Interrupter
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Solution Overview
Problem
Existing double-contact switches with vacuum interrupters face challenges in minimizing installation space and preventing premature contact erosion and welding due to the simultaneous opening of contact pairs, especially under high currents, leading to reduced service life and potential loss of galvanic isolation.
Innovation Solution
Designing a compact double-contact switch with vacuum interrupters where the gas-tight barriers of movable electrodes are differentiated to create a time delay in opening the contact pairs, allowing the first pair to open before the second, utilizing flexible metal bellows with varying diameters, wall thickness, and corrugation numbers to set different forces and achieve staggered opening, thereby preventing arcs and reducing material migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact pairs open simultaneously in a double-contact switch, then the structure is simple and compact, but vacuum arcs form causing contact erosion and reduced service life
Solution Approach 1:
The first contact pair opens before the second contact pair, creating a time sequence where the commutation contacts separate first to allow current transfer to the IGBT, and only after the current reaches zero do the break contacts open. This preliminary action prevents vacuum arcs from forming at the break contacts during high current conditions, eliminating contact erosion and extending service life without requiring complex additional components.
2Reliability
If break contacts open prematurely during high current, then galvanic isolation is achieved quickly, but vacuum arcs cause contact erosion and material migration
Solution Approach 1:
The switching mechanism is designed so that the commutation contacts (first pair) open in advance before the break contacts (second pair). This preliminary opening allows the load current to commutate to the parallel IGBT and reach zero before the break contacts separate. By waiting until current zero-crossing, the break contacts open under minimal current conditions, preventing vacuum arcs, contact erosion, and material migration that would otherwise occur during high current switching.
3Speed
If mechanical bouncing occurs after contact closure, then switching is fast, but vacuum arcs cause local melting and potential contact welding
Solution Approach 1:
The double-contact switch design ensures that break contacts only open after the commutation contacts have already separated and current has transferred to the IGBT. This preliminary action sequence means that if mechanical bouncing occurs during contact closure, it happens when minimal or zero current is present at the break contacts, preventing vacuum arcs from forming during bounce events. This eliminates local melting and contact welding risks while maintaining fast switching speeds.
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 enables efficient commutation of load current to a semiconductor switch, minimizing arcing and contact erosion, allowing for a compact configuration with lower production costs and extended service life, particularly suitable for high DC and low-frequency current switching.
Implementation Method 1
flexible metal bellows with varying diameters, wall thickness, and corrugation numbers to set different forces
Implementation Method 2
double-contact switch with vacuum interrupters
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a double-contact switch, comprising a first and a second tubular vacuum switching chamber (1, 3), which are designed as partial switching chambers of a switching tube, an electrode (4), which is fastened in the switching tube and arranged between the first and second vacuum switching chambers and which has a first fixed contact protruding into the first vacuum switching chamber (1) and a second fixed contact protruding into the second vacuum switching chamber (3), a first electrode (11), which is arranged in the first vacuum switching chamber (1) and can be moved therein in the axial direction and which has an area bearing a contact (12), which area is sealed off gas-tight from the exterior of the first vacuum switching chamber (1), a second electrode (31), which is arranged in the second vacuum switching chamber (3) and can be moved therein in the axial direction and which has an area bearing a contact (32), which area is sealed off gas-tight from the exterior of the second vacuum switching chamber (3), wherein the gas-tight seal (13') of the area of the first electrode (11) bearing the contact (12) is designed differently from the gas-tight seal (33') of the area of the second electrode (31) bearing the contact (32) in such a way that the opening of the first fixed contact (41) and the contact (12) of the first electrode (11) and the opening of the second fixed contact (42) and the contact (32) of the second electrode (31) occur with a time offset.