Submarine Cable Landfall Bonding to Reduce Sheath Losses
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High voltage alternating current submarine cables face a thermal bottleneck when transitioning from underwater to landfall regions due to reduced heat dissipating properties, leading to increased conductor cross-sectional area requirements, which is costly and impractical, and results in significant sheath losses and weight increases.
Innovation Solution
The cable system is divided into two sections with a connection point where the second conductive layers are electrically connected to prevent circulating currents, allowing for a reduced cross-sectional area in the landfall region by maintaining ampacity without increasing the conductor size, achieved through single-end bonding configurations using metal strips, semiconducting layers, or alternating segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cross sectional area of the conductor is increased in the landfall region, then the ampacity is maintained, but the material costs, weight, and production complexity increase significantly
Solution Approach 1:
The cable system is divided into two distinct sections: a first section for the submarine region and a second section for the landfall region. Each section is optimized for its specific thermal environment, allowing the landfall section to have reduced conductor cross-sectional area while the submarine section maintains the larger area needed for optimal heat dissipation in water.
Solution Approach 2:
Different conductor cross-sectional areas are applied to different regions based on their specific thermal characteristics. The submarine region receives the larger cross-sectional area design for optimal heat dissipation, while the landfall region uses a reduced cross-sectional area appropriate for its inferior heat dissipating properties, avoiding unnecessary material usage in the landfall section.
2Reliability
If the cross sectional area of the conductor is increased in the landfall region, then the ampacity is maintained, but the sheath losses increase significantly
Solution Approach 1:
The cable system is divided into two distinct sections: a first section for the submarine region and a second section for the landfall region. Each section is optimized for its specific thermal environment, allowing the landfall section to have reduced conductor cross-sectional area while the submarine section maintains the larger area needed for optimal heat dissipation in water.
Solution Approach 2:
Different conductor cross-sectional areas are applied to different regions based on their specific thermal characteristics. The submarine region receives the larger cross-sectional area design for optimal heat dissipation, while the landfall region uses a reduced cross-sectional area appropriate for its inferior heat dissipating properties, avoiding unnecessary material usage in the landfall section.
3Reliability
If the cross sectional area of the conductor is increased in the landfall region, then the ampacity is maintained, but the cable weight and handling difficulty increase
Solution Approach 1:
The cable system is divided into two distinct sections: a first section for the submarine region and a second section for the landfall region. Each section is optimized for its specific thermal environment, allowing the landfall section to have reduced conductor cross-sectional area while the submarine section maintains the larger area needed for optimal heat dissipation in water.
Solution Approach 2:
Different conductor cross-sectional areas are applied to different regions based on their specific thermal characteristics. The submarine region receives the larger cross-sectional area design for optimal heat dissipation, while the landfall region uses a reduced cross-sectional area appropriate for its inferior heat dissipating properties, avoiding unnecessary material usage in the landfall section.
4Object-affected harmful factors
If circulating currents are present in the metallic sheath, then the sheath provides electrical shielding, but power loss and heat generation increase
Solution Approach 1:
The harmful circulating currents are extracted and eliminated from the system by implementing a bonding conductor that provides an alternative path for current flow. The bonding conductor is electrically connected to the metallic sheath at multiple points, preventing the formation of closed circuits that would generate circulating currents, while the sheath maintains its electrical shielding function.
Solution Approach 2:
A bonding conductor is introduced as an intermediary element between the metallic sheath and ground. This bonding conductor provides a controlled path for current flow, preventing circulating currents from forming in the sheath itself, while allowing the sheath to maintain its electrical shielding function. The bonding conductor acts as a mediator that resolves the conflict between shielding and power loss.
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 sheath losses, weight, and material costs by maintaining ampacity without the need for a large cross-sectional area in the landfall region, while preventing circulating currents and minimizing damage from transient events.
Implementation Method 1
a bonding conductor arranged to be in electrical contact with the metallic sheath at a first location and in electrical contact with ground at a second location
Implementation Method 2
in electrical contact with ground at a second location
Implementation Method 3
The ampacity of the cable will be dependent on a number of different factors such as the ambient temperature, the electrical current in the cable, the electrical resistance of the cable and the heat dissipating properties of the surroundings
Implementation Method 4
The current flowing through the conductor induces a voltage in the metallic sheath surrounding the conductor
Implementation Method 5
This circulating current results in power loss and generation of heat in the metallic sheath
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A low loss cable system adapted for use as a cable landfall system. The cable system comprises a cable having a plurality of cores. Each core comprises a conductor, a first insulating layer, a second electrically conductive layer and a third layer. The cable comprises two sections, connected at a connection point CP. A first section of the cable is arranged to be exposed to a landfall area and a second section of the cable is arranged to be exposed to a submarine area. The cable is arranged such that circulating currents are prevented or reduced in the second conductive layers of the cable in the section exposed to the landfall area, thus assisting in maintaining the ampacity of the cable in this section without, or by reducing, the need to increase the cross sectional area of the cable in the landfall area. This is accomplished by electrically connecting the second conductive layers of the cores to each other at the connection point. At a distal end of the first section of the cable, the second layers are arranged to leave an open ended termination, thus avoiding a closed circuit that would otherwise create circulating currents in the second layers of the first section, thus maintaining ampacity.