Vacuum Interrupter Switching Arrangement for Control Transformers
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Solution Overview
Problem
Existing switching arrangements for control transformers require complex construction and significant space due to the need for galvanic isolation and potential arcing issues between windings, leading to undesirable gas formation in insulating oil, especially at higher system voltages.
Innovation Solution
A compact switching arrangement using a vacuum interrupter in conjunction with moving and fixed contacts, allowing independent placement and preventing arcing, with the vacuum interrupter mounted stationary to minimize space usage and enhance dielectric strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional switching arrangement with galvanic isolation is used, then switching between windings is achieved, but complex construction and large space requirements result
Solution Approach 1:
The patent extracts the vacuum interrupter as a separate, dedicated component from the overall switching arrangement. This isolation allows the vacuum interrupter to handle the high-voltage switching function independently, while the remaining contacts and terminals can be simplified. The vacuum interrupter is mounted on a insulating support structure that separates it from other components, reducing overall construction complexity while maintaining reliable galvanic isolation.
Solution Approach 2:
The patent introduces a insulating support structure as an intermediary element between the vacuum interrupter and other switching components. This mediator provides both mechanical support and electrical isolation, eliminating the need for complex isolation mechanisms while ensuring reliable galvanic separation. The insulating support acts as a bridge that satisfies both structural and electrical requirements simultaneously.
2Reliability
If a conventional switching arrangement with galvanic isolation is used, then switching between windings is achieved, but significant installation space is required
Solution Approach 1:
The patent implements a nested arrangement where the vacuum interrupter is mounted on the insulating support structure that is integrated with the terminal arrangement. The moving contact is positioned within the vacuum interrupter's switching chamber, and fixed contacts are arranged in a compact configuration around the vacuum interrupter. This nesting of components within each other's spatial envelopes significantly reduces the overall installation footprint while maintaining all necessary isolation distances.
Solution Approach 2:
The patent transitions from a planar arrangement of switching components to a three-dimensional configuration. The vacuum interrupter extends in the vertical dimension, with its switching chamber positioned above the insulating support. Fixed contacts are arranged at different heights and radial positions, creating a compact spherical or cylindrical packing of components that utilizes vertical space rather than only horizontal space, thereby reducing the required installation area.
3Reliability
If switching occurs with galvanic isolation, then winding isolation is maintained, but arcing and gas formation in insulating oil occur
Solution Approach 1:
The patent employs a vacuum environment within the vacuum interrupter's switching chamber as an inert atmosphere for the switching arc. The vacuum eliminates oxygen and other reactive gases that would otherwise be present in the insulating oil, preventing the formation of harmful decomposition gases during arcing. The vacuum interrupter creates a localized inert environment that contains the switching arc and prevents it from interacting with the insulating oil, thereby eliminating gas formation while maintaining winding isolation.
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 a simple, compact design that prevents gas formation and arcing, improving the dielectric strength and reducing the need for extensive construction, thus addressing the space and operational challenges of existing systems.
Implementation Method 1
a vacuum interrupter; the first moving contact is connected to the first connection terminal via the vacuum interrupter
Implementation Method 2
The open vacuum interrupter increases the dielectric strength and prevents arcing between the moving contacts and fixed contacts
Data Source
Figure 1
Figure 2a
Figure 2b~2c
AI summary
The invention relates to a switch assembly (1), in particular a preselector, for a variable transformer (4) having a first winding (2) and a second winding (3) with a first and a second tap (3.3, 3.4), said switch assembly comprising: a first connection terminal (2.1) that can be connected to the first winding (2); a second connection terminal (3.1) that can be connected to the first tap (3.3); a third connection terminal (3.2) that can be connected to the second tap (3.4); a first, second, third and fourth fixed contact (5.1, 5.2, 5.3, 5.4); a vacuum interrupter (6); a first moving contact (7) that can be contacted selectively with the first or second fixed contact (5.1, 5.2); a second moving contact (8) that can be contacted selectively with the third or fourth fixed contact (5.3, 5.4), wherein the second and the fourth fixed contact (5.2, 5.4) are connected to the second connection terminal (3.1), the first and the third fixed contact (5.1, 5.3) are connected to the third connection terminal (3.2), the first moving contact (7) is connected to the first connection terminal (2.1) via the vacuum interrupter (6), and the second moving contact (8) is connected to the first connection terminal (2.1).