On-Load Tap Changer Layout for Spherical Arc Isolation
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Solution Overview
Problem
Existing on-load tap-changers struggle to withstand increased mechanical and electrical loads at higher currents and voltages, leading to operational challenges.
Innovation Solution
An on-load tap-changer design featuring a selector for powerless preselection and a load transfer switch with vacuum interrupters arranged to keep current-carrying parts outside a defined spherical area, allowing for a compact and reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the vacuum interrupters are arranged with current-carrying parts inside the defined spherical area, then the device complexity is reduced, but the reliability decreases under high currents and voltages
Solution Approach 1:
The current-carrying parts are extracted from the defined spherical area around the contact point. By positioning these parts outside the spherical area, the patent eliminates the risk of unintended arcs or discharges that would occur if current-carrying parts were inside the high-electric-field region, thus maintaining reliability while simplifying the overall arrangement.
2Power
If the on-load tap-changer is designed for higher currents and voltages, then the power handling capability increases, but the mechanical and electrical loads on the actuating mechanism increase
Solution Approach 1:
The patent introduces an intermediary arrangement where the actuating mechanism operates the vacuum interrupters, which in turn control the high-power circuit. The vacuum interrupters act as intermediaries that isolate the actuating mechanism from the high mechanical and electrical loads, allowing the system to handle higher power while keeping the actuating mechanism manageable.
3Reliability
If the spherical area radius is increased to at least 80 mm, then the reliability improves by preventing arc discharge, but the volume of the device increases
Solution Approach 1:
The patent applies local quality by creating a specific spherical area with a defined radius (at least 80 mm) around the contact point where no current-carrying parts are placed. This localized restriction ensures arc discharge prevention exactly where needed (at the contact point) without requiring the entire device to be enlarged, thus maintaining compactness while improving reliability.
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
Ensures reliable operation under high currents and voltages by maintaining a compact design and ensuring that current-carrying components are outside the defined area, enhancing durability and efficiency.
Implementation Method 1
at least one vacuum interrupter in the first and second load branches. Each vacuum interrupter has a movable contact and a fixed contact and can assume an open state in which the movable contact and the fixed contact do not touch, and a closed state in which the movable contact and the fixed contact touch at at least one contact point
Data Source
Figure 1~2
Figure 3~4a
Figure 4b~4c
AI summary
The invention relates to an on-load tap changer (1) for uninterrupted switching between winding taps (N1,...Nj,..., Nn) of a step transformer (2). The on-load tap changer (1) comprises a selector (3) and a load transfer switch (4). The load transfer switch (4) consists of a first load branch (5.1) and a second load branch (5.2), each load branch (5.1, 5.2) having at least one vacuum interrupter (6.1, 6.2, 7.1, 7.2). Each vacuum interrupter (6.1, 6.2, 7.1, 7.2) can switch between an open state, in which the movable contact (11) and the fixed contact (12) do not touch, and a closed state in which the movable contact (11) and the fixed contact (12) touch in at least one contact point (13). Starting from the contact point (13), each vacuum interrupter (6.1, 6.2, 7.1, 7.2) has a defined spherical region (14). The load transfer switch (4) is designed in such a way that the vacuum interrupters (6.1, 6.2, 7.1, 7.2) are arranged in a housing (29) in such a way that parts of the load transfer switch (4) through which current flows are arranged outside the defined region (14).