Stainless Steel Screen and Conductive Jacket for HV Cable Loss Reduction
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Solution Overview
Problem
High voltage cables experience significant electrical losses due to induced currents in metallic screens and jackets, leading to heating, inductive/dielectric losses, and voltage accumulation, which affect their performance and require costly solutions like sheath voltage limiters and thick jackets for protection.
Innovation Solution
A high voltage cable design featuring a thin, non-corrugated stainless steel laminate screen bonded to the cable core or jacket, and a conductive jacket material with carbon black to reduce induced currents and losses, while maintaining structural integrity and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metallic screen (aluminum or copper) is used to provide moisture barrier and screen effect, then protection from environment and short circuit discharge is improved, but induced circulating screen currents and eddy current losses increase, reducing electrical performance
Solution Approach 1:
The patent changes the electrical conductivity parameter of the screen material from highly conductive (copper, aluminum) to low conductivity (stainless steel). This parameter change allows the screen to maintain its moisture barrier and short circuit discharge functions while significantly reducing induced circulating currents and eddy current losses, as the lower conductivity material naturally resists the flow of induced currents.
Solution Approach 2:
The patent employs stainless steel as a composite material solution that combines the necessary mechanical properties (flexibility, strength) with appropriate electrical properties (low but not zero conductivity). This composite approach provides both the protective functions of a traditional metallic screen and the electrical loss reduction needed for improved cable performance.
2Reliability
If the cable jacket is made of insulating polymer material to protect against induced voltage, then voltage withstand capability is improved, but inductive/dielectric losses over cable length increase significantly
Solution Approach 1:
The patent changes the electrical conductivity parameter of the jacket material from insulating (polymer) to semi-conductive (carbon black loaded). This parameter change allows the jacket to provide a path for induced currents to dissipate, reducing voltage accumulation and dielectric losses, while still providing adequate protection and maintaining structural integrity.
Solution Approach 2:
The patent converts the previously harmful effect of induced currents in the insulating jacket (which caused dielectric losses and voltage accumulation) into a beneficial effect by making the jacket semi-conductive. The induced currents now flow through the semi-conductive jacket rather than being dissipated as heat in the dielectric material, reducing overall energy losses.
3Reliability
If the metallic screen and jacket are grounded at both ends to prevent voltage accumulation, then voltage control is improved, but circulating currents in screen and jacket increase, increasing electrical losses
Solution Approach 1:
The patent changes the conductivity parameters of both the screen (to low conductivity stainless steel) and jacket (to semi-conductive carbon black loaded material). This dual parameter change breaks the circuit for circulating currents while maintaining adequate voltage control, as the high resistance path prevents significant current flow even when grounded at both ends.
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 solution significantly reduces electrical losses, prevents voltage accumulation, and enhances cable performance by minimizing circulating and eddy currents, thereby improving the cable's efficiency and reducing material costs.
Implementation Method 1
a conductive jacket material with carbon black to reduce induced currents and losses
Implementation Method 2
minimizing circulating and eddy currents
Implementation Method 3
thin, non-corrugated stainless steel laminate screen
Data Source
AI summary
A cable including a conductor. An insulation system surrounds the conductor. A metallic screen surrounds the insulation system. A jacket surrounds the insulation system. The metallic screen is constructed of stainless steel.