Stress Control Adaptor for High Voltage Cable Termination
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Solution Overview
Problem
High electrical stress at cable shield discontinuities in high voltage cables with reduced insulation thickness can lead to electrical discharges and failure of cable accessories, necessitating the use of higher-rated accessories that are costly.
Innovation Solution
An adaptor system comprising a longitudinal insulative member and a semi-conductive member is used to overlay exposed portions of the cable insulation and semi-conductive shield, increasing the effective insulation thickness and reducing electrical stress, allowing the use of standard cable accessories with cables having reduced insulation thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the insulation thickness of high voltage cable is reduced to decrease cable size and cost, then the cable size, weight and manufacturing cost are reduced, but the electrical stress at cable shield discontinuities increases leading to electrical discharges and failure of cable accessories
Solution Approach 1:
The patent introduces a stress control adaptor as an intermediary component between the reduced-thickness cable insulation and the cable accessory. This adaptor includes an insulative member with a specific geometry (tapered or curved surfaces) that redistributes the electrical stress field, and a semiconductive member that restores the shield continuity. The adaptor mediates the electrical stress distribution, allowing standard cable accessories to be used with reduced-thickness cables without compromising reliability.
Solution Approach 2:
The patent changes the geometric parameters of the insulation structure by introducing a stress control adaptor with specific dimensional characteristics (taper angle, curvature radius, thickness distribution). These parameter changes transform the electrical stress distribution pattern from a concentrated high-stress field at the shield discontinuity to a more uniformly distributed stress field, enabling the use of thinner cable insulation while maintaining accessory reliability.
2Quantity of substance
If the insulation thickness is reduced to reduce the amount of insulating material used, then the cable cost is reduced, but higher-rated and more expensive cable accessories are required to withstand the additional electrical stress
Solution Approach 1:
The stress control adaptor serves as a cost-effective intermediary solution that allows standard, lower-rated cable accessories to be used with reduced-thickness cables. By introducing this relatively simple adaptor component, the system avoids the need to purchase expensive higher-rated accessories, thereby reducing overall cable system cost while maintaining electrical performance and reliability.
Solution Approach 2:
The adaptor modifies the electrical stress parameters through its geometric design, transforming the stress distribution to match the capabilities of standard cable accessories. This parameter transformation allows the use of conventional, cost-effective accessories rather than requiring expensive high-rated alternatives.
3Ease of operation
If cable shield discontinuity is created during termination to expose the insulation layer, then the cable can be terminated and connected, but high electric field strength and electrical stress concentrate at the cut ends causing breakdown of the insulating layer
Solution Approach 1:
The stress control adaptor acts as an intermediary structure installed at the cable termination point where the shield is cut back. The adaptor's insulative member with tapered or curved geometry and semiconductive member work together to redistribute the electrical field and eliminate stress concentration at the shield discontinuity, enabling safe cable termination without harmful electrical stress buildup.
Solution Approach 2:
The patent employs curved or tapered surfaces in the insulative member of the stress control adaptor. These curved geometries help to smooth out the electrical field distribution at the shield discontinuity, eliminating sharp field concentrations that would occur with abrupt geometric transitions. The curved surfaces gradually transition the electrical field, preventing breakdown at the termination point.
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
The adaptor system effectively reduces electrical stress, enabling the use of standard cable accessories with high voltage cables, thereby preventing failures and reducing costs associated with higher-rated accessories.
Implementation Method 1
a reduced-thickness electrical insulation covering the conductor shield... the insulative member is configured to overlay an exposed portion of the reduced-thickness electrical insulation
Implementation Method 2
a semi-conductive member in contacting engagement with the first end of the insulative member... configured to overlay an exposed portion of the cable semi-conductive shield
Data Source
AI summary
An adaptor for controlling electrical stress in an electrical power cable includes a longitudinal insulative member and a semi-conductive member in contacting engagement with an end of the insulative member. A portion of the insulative member overlays a portion of the electrical insulation surrounding the electrical conductor, and a portion of the semi-conductive member overlays a portion of the semi-conductive shield.