Medium Voltage Connection Screen Positioning
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Solution Overview
Problem
Existing medium voltage connections face issues with high rejection rates due to misaligned and deformed screens, air pockets, and high electrical field density, as well as mechanical stresses from thermal expansion and cable weight, leading to cracks in the isolating layer.
Innovation Solution
A conducting layer is applied on the isolating layer, allowing the grounding screen to be correctly positioned post-casting, with a conducting rubber sleeve extending the screen into the airgap between isolating layers, reducing field concentration and enhancing mechanical durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the grounding screen is embedded in the isolating layer during casting, then the screen positioning is fixed, but this results in misaligned screens, deformed screens and air pockets in the resin leading to high rejection rates
Solution Approach 1:
The grounding screen is divided into two separate components: a screen portion and a conducting portion. The screen portion is embedded in the isolating layer while the conducting portion extends into the airgap, allowing each part to fulfill its function independently without compromising the other.
Solution Approach 2:
The conducting portion is extracted from the isolating layer and extended into the airgap between isolating layers. This extraction allows the screen edge to be positioned optimally for electrical field management without being constrained by the casting process limitations.
2Strength
If the screen is embedded in isolating material, then the screen is protected, but the high field density extends into the air surrounding the medium voltage connection causing undesired electrical discharges
Solution Approach 1:
The conducting portion extends the screen into the third dimension (into the airgap between isolating layers), moving the screen edge away from the surface of the isolating layer and into a position where it can better control the electrical field distribution in the surrounding air.
3Device complexity
If the screen is embedded in the isolating layer, then the structure is compact, but mechanical stresses from cable weight and thermal expansion cause cracks in the isolating layer over time
Solution Approach 1:
By separating the screen into two portions, the conducting portion can extend into the airgap where it can better accommodate mechanical stresses from thermal expansion and cable weight, preventing stress concentration that would otherwise cause cracks in the isolating layer.
4Reliability
If a thicker layer of insulating material is used between the screen and conductor, then dielectric robustness increases, but the overall connection size increases
Solution Approach 1:
The conducting portion extends the screen into the airgap, effectively increasing the dielectric protection in a vertical dimension without increasing the horizontal dimensions of the connection, thus maintaining compact size while enhancing dielectric robustness.
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 significantly reduces manufacturing rejects, maintains electrical integrity by encapsulating field concentrations within isolating material, and increases mechanical durability by distributing mechanical stresses more evenly.
Implementation Method 1
a conducting layer (28) arranged on the outer surface of the first isolating layer (25)
Implementation Method 2
a first isolating layer (25) arranged around the first conductor (21) and a second isolating layer (26) arranged around the second conductor (22)
Implementation Method 3
an isolating rubber sleeve (29) arranged between the first isolating layer (25) and the second isolating layer (26) to fill the airgap
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a medium voltage connection, comprising: -a firstconductor and a second conductor electrically attached to each other; -a first isolating layer arranged around the first conductor and a second isolating layer arranged around the second conductor, leaving an airgap between both isolating layers; -an isolating rubber sleeve arranged between the first isolating layer and the second isolating layer to fill the airgap between the two isolating layers; wherein -a conducting layer is arranged on the first isolating layer; and wherein -the rubber sleeve is provided with a conducting portion, which overlaps with the conducting layer.