Interconnect Assembly for Bus Bar and Contactor Coupling
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Solution Overview
Problem
Existing power switching contactor mounting methods on rigid bus bars face issues such as thread damage, galvanic corrosion, and increased resistance due to thermal expansion, leading to overheating and labor-intensive installation and repair.
Innovation Solution
An interconnect assembly with a post assembly and locking member that extends through the contactor bus and engages a socket member on the bus bar, providing a secure mechanical and electrical connection without threads, using materials like copper or beryllium copper to minimize thermal expansion effects and prevent loosening over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional thread bolts and locking hardware are used to mount contactor buses to bus bars, then mechanical coupling and electrical connection are achieved, but threads in the bus bars become easily damaged and plating is removed leading to galvanic corrosion
Solution Approach 1:
The invention extracts the threading function from the bus bar itself by providing a separate socket member that contains the threading. This allows the bus bar to remain smooth and undamaged while still achieving secure mechanical coupling through the socket's internal threads that engage with the post assembly.
Solution Approach 2:
The socket member acts as an intermediary component between the bus bar and the post assembly. It provides the threading interface without requiring threads in the bus bar, and its material composition (copper or beryllium copper) prevents galvanic corrosion by being compatible with aluminum bus bars.
2Strength
If bolts are threaded into bus bars, then mechanical connection is established, but plating is removed from bolts leading to galvanic corrosion
Solution Approach 1:
The invention changes the material parameter of the socket member to copper or beryllium copper, which have electrochemical compatibility with aluminum bus bars. This material selection eliminates the galvanic corrosion issue that occurs when dissimilar metals (such as steel bolts with plating) are in direct contact with aluminum.
3Ease of manufacture
If conventional threaded connections are used, then installation is achieved, but labor is required for installation, removal and repair
Solution Approach 1:
The connection system is segmented into separate functional components: the socket member remains permanently attached to the bus bar, while the post assembly with locking member can be easily inserted and removed. This segmentation allows for quick installation and maintenance without requiring threading operations.
Solution Approach 2:
The socket member is pre-installed and permanently attached to the bus bar during manufacturing or initial setup. This preliminary action eliminates the need for threading operations during field installation, as the post assembly simply needs to be inserted into the pre-positioned socket.
4Reliability
If aluminum bus bars are used, then electrical conduction is achieved, but large coefficients of thermal expansion cause clamp forces to decrease over time creating high resistance connections
Solution Approach 1:
The invention uses composite material construction for the interconnect assembly, with the socket member made of copper or beryllium copper and the post assembly providing structural support. This combination of materials with different thermal expansion properties compensates for the aluminum bus bar's thermal expansion, maintaining stable clamp forces across temperature variations.
Data Source
Figure 1~2
Figure 3A~3E
Figure 4A~5
AI summary
An interconnect assembly for a switching assembly in which the switching assembly includes a bus bar and an electromagnetic switching device having a contactor bus. The interconnect assembly is structured to mechanically couple and electrically connect the contactor bus to the bus bar. The interconnect assembly includes a socket member structured to engage the bus bar, a post assembly that includes a post member structured to extend through the contactor bus, in which at least a portion of the post member extends into the socket member, and a locking member disposed on the post member. The locking member is structured to extend through and removably engage the socket member in order to mechanically couple and electrically connect the contactor bus to the bus bar.