Electric Power Cable Shield Design for Reduced Losses
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Solution Overview
Problem
Existing high-pressure fluid-filled and high-pressure gas-filled transmission cable systems face challenges with increased electrical stress and shield losses due to reduced insulation thickness and conventional electrical impedance, limiting their capacity and installation length in existing steel pipes.
Innovation Solution
The development of electric power cables with a higher electrical impedance shield design and conventional extruded dielectric cable insulation thickness, incorporating a bedding layer with semi-conductive materials and metallic tapes intercalated with insulating tapes, which reduces shield losses and allows for longer installation lengths in existing conduits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If reduced insulation thickness is used to reduce overall cable diameter, then cable diameter is reduced, but electrical stress across the insulation increases
Solution Approach 1:
The patent changes the electrical impedance parameter of the shield by using metallic tapes with higher electrical impedance than conventional shields. This parameter change allows the cable to maintain conventional insulation thickness (avoiding high electrical stress) while still achieving a reduced overall cable diameter through optimized shielding structure
Solution Approach 2:
The patent employs composite shielding structures using metallic tapes (such as aluminum or stainless steel) intercalated with insulating tapes. This composite approach provides both the mechanical protection and electrical shielding functions while maintaining higher electrical impedance, resolving the contradiction between reduced diameter and electrical stress
2Device complexity
If conventional electrical impedance shield design is used, then shield structure is simple, but shield losses increase due to induced sheath currents
Solution Approach 1:
The patent changes the electrical impedance parameter of the shield by using metallic tapes with higher electrical impedance than conventional shields. This parameter change reduces shield losses by minimizing induced sheath currents while maintaining a relatively simple shield structure through the use of helically wound metallic tapes
3Productivity
If three-core cable design is used, then cable capacity is increased, but installation length is reduced due to higher electrical stress
Solution Approach 1:
The patent changes the electrical impedance parameter of the shield, which reduces electrical stress for a given insulation thickness. This allows three-core cable designs to achieve both high cable capacity and long installation lengths, as the reduced electrical stress enables longer cable sections to be installed into existing conduits without exceeding stress limits
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 provides lower shield losses and higher transmission capacity, enabling longer cable sections to be installed or retrofitted into existing conduits while maintaining conventional electrical stress levels, thus enhancing the performance and capacity of underground transmission systems.
Implementation Method 1
a higher electrical impedance shield design than what is conventionally used for extruded dielectric cable insulation
Data Source
AI summary
A cable for transmitting electricity may include a core including a first conductive material, a core shield surrounding the core, an insulation layer surrounding the core shield, the insulation layer comprising a material providing electrical insulating properties, an insulation shield surrounding the insulation layer; and at least one of the following at least partially surrounding the insulation shield: (a) a bedding layer including a first semi-conductive material, (b) a tape layer including a metallic tape intercalated with an insulating tape, and (c) a protection layer.