Contact Assembly Shifted Finger Segmentation for Racking Force
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Solution Overview
Problem
Tulip-contact-assemblies in the medium voltage field experience high racking-in force during connection, leading to unreliable electrical connections and potential issues like high electrical resistance and overheating, due to the large number of contact-finger-elements that need to be opened and connected simultaneously.
Innovation Solution
The contact assembly features shifted main contact portions on the contact-finger-elements, which are arranged in alternating positions around the support frame, reducing the peak racking-in force by partitioning the force required for engagement and minimizing the simultaneous engagement of all contact-finger-elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large number of contact-finger-elements are used to ensure high connection force, then the connection reliability is improved, but the racking-in force increases significantly
Solution Approach 1:
The contact-finger-elements are divided into multiple groups that engage with the contact pin in sequence rather than simultaneously. Each group engages at a different position along the axial direction, segmenting the total engagement force into multiple smaller peaks occurring at different times during the racking-in process.
2Force
If all contact-finger-elements engage simultaneously with the contact pin, then the connection force is maximized, but the peak racking-in force becomes excessively high
Solution Approach 1:
The contact-finger-elements are pre-positioned at different axial locations on the support frame before engagement. This preliminary arrangement ensures that during the racking-in motion, different groups engage sequentially at predetermined positions, preventing simultaneous engagement and reducing the peak force required.
3Force
If the contact-finger-elements are arranged in alternating positions, then the racking-in force is reduced, but the structural complexity increases
Solution Approach 1:
The contact-finger-elements are arranged asymmetrically in alternating positions around the support frame rather than in symmetric patterns. This asymmetric arrangement naturally distributes the engagement forces more evenly during rotation, reducing peak racking-in force while maintaining a relatively simple overall structure.
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
This design significantly lowers the maximum racking-in force during the connection phase, ensuring a stable and reliable electrical connection with reduced friction and maintaining high connection force, thereby preventing issues like high electrical resistance and overheating.
Implementation Method 1
spring elements (9), for urging the contact-finger-elements radially against the stationary conducting-terminal
Data Source
AI summary
A contact assembly for connecting electrically and mechanically a first terminal of a first apparatus to a second terminal of a second apparatus, wherein at least one of the first and the second apparatus is movable with respect to the other along a connection/disconnection direction, includes: a plurality of electrically conducting contact-finger-elements, each including a main contact portion configured for engaging the second terminal and an auxiliary contact portion for engaging the first terminal, wherein the finger-contact-elements are supported by a support frame of the contact assembly connectable to the first terminal or are configured for being directly connectable and supportable by the first terminal; one or more spring elements configured for acting on the contact-finger-elements so to urge the main contact portions against the second terminal when the first and the second apparatus are connected. The main contact portions of at least two of the plurality of contact-finger-elements are shifted one relative to the other in such a manner so to engage the second terminal in subsequent moments when the first apparatus is being connected to the second apparatus by a relative movement thereof along the connection/disconnection direction.