Spring-Biased Static Contact Unit for Fast Tap Changer Switching
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Solution Overview
Problem
Existing tap changers face challenges in providing a stable and reliable mechanism for electrically engaging movable and stationary contacts, often requiring additional space and complexity due to the use of tie-in resistors, which increases production time and cost.
Innovation Solution
A static contact unit with pivotably coupled contact elements and spring elements that allow for high-speed disconnecting and double breaking, eliminating the need for tie-in resistors by using snap contact fingers and a cam profile for rapid switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tie-in resistors are used in the pre-selector structure, then the mechanism provides stable electrical switching, but the device complexity and space requirements increase
Solution Approach 1:
The patent removes the tie-in resistors from the pre-selector structure entirely. The static contact unit is designed to function without these additional components, extracting the unnecessary elements that caused complexity while maintaining the essential switching function through the spring-biased contact elements and cam profile mechanism.
Solution Approach 2:
The patent integrates the switching function directly into the pre-selector structure by combining the static contact elements with the cam profile and spring mechanism. This merging eliminates the need for separate tie-in resistors, as the contact elements themselves provide the necessary electrical switching function through their pivotable engagement with the cam profile.
2Reliability
If tie-in resistors are mounted to the pre-selector structure, then electrical switching is achieved, but the area occupied in the transformer tank assembly increases
Solution Approach 1:
The tie-in resistors are completely removed from the structure. The static contact unit achieves electrical switching through the pivotable contact elements that engage with the cam profile, eliminating the need for additional resistor components that would occupy space in the transformer tank assembly.
Solution Approach 2:
The static contact unit serves multiple functions: the spring-biased contact elements provide both the mechanical switching action and the electrical connection function that previously required separate tie-in resistors. This multi-functionality reduces the overall space requirement in the transformer tank assembly.
3Device complexity
If conventional switching mechanisms are used, then the structure is simpler, but the disconnecting speed is lower
Solution Approach 1:
The patent employs dynamic elements including spring-biased contact elements that can rapidly pivot and cam profiles designed for high-speed operation. The spring mechanism provides rapid response during switching, enabling disconnecting velocities of 4-6 m/s while maintaining a relatively simple overall structure through the use of these dynamic components.
Solution Approach 2:
The cam profile is specifically designed with optimized geometry to achieve high-speed switching. By changing the geometric parameters of the cam profile and the spring characteristics, the system achieves rapid disconnecting velocities while maintaining structural simplicity and avoiding the need for complex additional components.
4Reliability
If the pre-selector design includes additional components for reliable switching, then switching reliability improves, but the production time increases
Solution Approach 1:
The patent eliminates tie-in resistors and other additional components from the pre-selector design. The simplified structure with spring-biased contact elements and cam profiles reduces the number of parts that need to be manufactured and assembled, thereby reducing production time while maintaining switching reliability through the optimized contact mechanism.
Solution Approach 2:
By merging the switching function into the basic contact element structure, the patent reduces the total component count. The spring-biased contact elements and cam profiles work together as an integrated system, eliminating the need for separate tie-in resistors and reducing assembly steps, which directly reduces production time.
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
Enables secure and reliable electrical switching with high-speed disconnecting velocities of 4-6 m/s, reducing arcing times and eliminating the need for tie-in resistors, resulting in a more efficient and cost-effective pre-selector design.
Implementation Method 1
a spring element that is coupled to the contact element configured to bias the contact element so that, with respect to a state in which the tap changer is assembled, the contact element is preloaded in direction of the moving shaft
Implementation Method 2
The one or more pivotable contact elements enable to achieve double breaking, because of the simultaneously disconnecting on both sides of an interacting movable contact
Data Source
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AI summary
A static contact unit (20) for a tap changer comprises a contact body (4), one or more contact elements and a spring element. The contact body (4) is configured to be arranged statically with respect to a movable contact of a moving shaft (1) of the tap changer. The at least one contact element (5) is pivotably coupled to the contact body (4) configured to establish an electrical contact to a movable contact (3) that is arranged at the moving shaft (1). The spring element (6) is coupled to the contact element (5) configured to bias the contact element (5) so that, with respect to a state in which the tap changer is assembled, the contact element (5) is preloaded in direction of the moving shaft (1) with respect to a longitudinal axis (L) of the moving shaft (1).