In the mechanical body design of SUNJ shear bolt connectors, the distinction between central and eccentric bore designs is not merely a matter of machining variation; rather, it represents a structural choice based on cable type, conductor configuration, clamping path, and installation scenario.
A central bore design features an inner bore centerline that essentially coincides with the outer cylinder’s centerline. Its advantages include balanced wall thickness and excellent structural symmetry, making it easier to maintain the conductor at the center of the connector body after insertion.
This design is particularly well-suited for cross-linked polyethylene (XLPE) insulated cables. Such cables typically feature standardized conductor configurations—commonly round stranded or compacted round conductors—with consistent dimensions. The central bore design facilitates a natural coaxial alignment among the conductor, the connector body, and the subsequent insulation restoration system, promoting consistent external profiles and stable electric field distribution post-installation.
From an installation perspective, the central bore design is ideal for highly standardized new cable projects, such as modern power distribution systems, industrial cable lines, and XLPE cable jointing or termination applications.
An eccentric bore design involves a deliberate offset between the inner bore centerline and the outer cylinder’s centerline. Its design prioritizes maintaining adequate material thickness on the bolt side to reinforce the threaded area and optimizing the path through which the bolt compresses the conductor.
This design is better suited for oil-impregnated paper (OIP) insulated cables, offering distinct advantages in projects involving the retrofitting of older cables, connecting OIP cables to modern accessories, or handling conductors with significant on-site variations. OIP cables often have long service lives, and their conductor shape, dimensional consistency, surface condition, and on-site preparation requirements can be complex. The eccentric bore design ensures that, upon bolt tightening, the conductor is positively directed toward a designated contact surface, creating a concentrated clamping path while guaranteeing sufficient structural support on the bolt side.
In terms of application, the eccentric bore design is best suited for OIP cable retrofit projects, transition joints, large-cross-section conductor connections, and mechanical terminal designs requiring enhanced structural support on the bolt side. Therefore, the choice between a central bore and an eccentric bore is not a matter of one being superior to the other, but rather a reflection of two different engineering design philosophies:
The central bore is better suited for Cross-linked Polyethylene (XLPE) insulated cables, which feature standardized structures, regular conductor shapes, and stricter concentricity requirements.
The eccentric bore is better suited for oil-impregnated paper insulated cables, where field conditions are more complex and the conductor compression path requires greater precision.
The final choice of structure depends on a comprehensive assessment of factors such as cable type, conductor cross-section, conductor geometry, installation space, and project standards. The core objective remains constant: ensuring stable clamping, reliable contact, and consistent installation results for the conductor within the mechanical terminal.
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