Stretch Bolt Electrical Connection for High Voltage Switchgears
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Solution Overview
Problem
Existing electrical connections in medium and high voltage switchgears with external screws or bolts create high electrical fields and are uncomfortable to handle due to sharp edges, leading to increased transition contact resistance.
Innovation Solution
A connecting system using a stretch bolt with elastic properties that eliminates external edges and screws, ensuring a close electrical and mechanical connection by deforming within its elastic range to maintain contact, and optionally using flat, conductive surfaces and foils like gold or silver to enhance conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If external screws or bolts are used to connect the electrical terminal and connector, then the mechanical connection is simple and easy to manufacture, but high electrical fields are generated at sharp edges and handling becomes uncomfortable
Solution Approach 1:
Instead of using external screws or bolts that extend outward from the connection, the patent inverts the approach by using an internal threaded cavity where the bolt is concealed within the connector housing. The bolt head is received in a recessed cavity, eliminating external sharp edges that generate high electrical fields, while still providing secure mechanical fastening through internal threading.
Solution Approach 2:
The bolt head is nested within a cavity in the connector housing, with the bolt shaft extending through the terminal and connector bodies. This nesting arrangement hides the fastening mechanism within the structure, eliminating external edges while maintaining the mechanical connection function.
2Ease of manufacture
If external screws or bolts are used to connect the electrical terminal and connector, then the mechanical connection is simple and easy to manufacture, but handling becomes uncomfortable due to sharp edges
Solution Approach 1:
The patent inverts the conventional external fastening approach by using internal threading with a recessed cavity that receives the bolt head. This eliminates protruding sharp edges that interfere with handling and positioning, making the connector safer and more comfortable to manipulate during installation and operation.
Solution Approach 2:
The bolt and cavity arrangement nests the fastening mechanism within the connector structure, removing external sharp edges that would otherwise complicate handling and positioning of the electrical connector during assembly and maintenance operations.
3Object-affected harmful factors
If a stretch bolt with elastic properties is used to eliminate external edges, then handling comfort and electrical field reduction are improved, but the connection complexity increases
Solution Approach 1:
The patent applies internal threading with a recessed cavity to eliminate external edges, achieving the goal of reducing electrical fields and improving handling comfort. The complexity increase is minimal, confined to the internal cavity structure, while the external profile remains smooth and simple.
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 solution reduces transition contact resistance and improves handling by eliminating visible bolts, providing a reliable and efficient electrical connection without external screws, enhancing both mechanical and electrical contact quality.
Implementation Method 1
The fixation element (3’) is a stretch bolt, which consist at least in its middle part of its length of elastic stretchable material. By that the stretch bolt will be deformed in its middle zone, until the momentum of force reaches a predetermined value, in order to keep within the Hook's value of elasticity.
Data Source
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AI summary
The invention relates to an electrical connection for medium and high voltage switchgears, with an electrical terminal of a switchgear, wherein an electrical contacting surface of the electrical terminal is electrically connected with a contacting surface of an external electrical connector part via a connecting system, according to the preamble of claim 1. In order to to ensure a low restistance electrical connection, the invention is, that the connecting system comprises a female screw thread in a stud hole of the electrical terminal as well as in a stud hole of the external connector part, and a stretch bolt with male screw threads at each opposite ends, screwed into the female screw thread of the electrical terminal with one end of the stretch bolt, and into the female screw thread of the external connector part at the other end of the stretch bolt.