DC Cable Joint Sleeve Layout for Space Charge Relief
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Solution Overview
Problem
Conventional direct-current power cable systems experience excessive space charge accumulation leading to electric field distortion and insulation breakdown due to local electric field concentration, particularly at the edge end regions of electrodes and heterogeneous interfaces, which complicates manufacturing and increases costs.
Innovation Solution
A direct-current power cable system with a sleeve member comprising a first electrode, a pair of second electrodes, an electric field alleviation layer, a rubber insulating layer, and a sleeve shielding layer, where the electric field alleviation layer is configured to surround the first electrode and contact the inner surface of the second electrodes, forming a non-contact state with the outer semiconductive layer, and having a specific distance and shape to prevent triple points and facilitate charge discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric field alleviation layer is provided to surround the first electrode and contact the second electrodes, then electric field concentration is alleviated and insulation breakdown is prevented, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The electric field alleviation layer acts as an intermediary component between the first electrode and the second electrodes. It contacts the inner surface of the second electrodes and is surrounded by the rubber insulating layer, serving as a mediator to discharge space charges and alleviate electric field concentration at critical interfaces without requiring fundamental redesign of the electrode structure
Solution Approach 2:
The electric field alleviation layer is constructed from composite material comprising thermosetting rubber resin and filler material (such as carbon black or metal powder). This composite structure provides both insulating properties and charge dissipation capability, achieving reliable insulation performance while maintaining manageable device complexity through material-level solutions rather than structural complexity
2Reliability
If the electric field alleviation layer is expanded to cover more regions, then charge discharge capability is improved, but manufacturing cost increases due to more expensive filler materials
Solution Approach 1:
The electric field alleviation layer is strategically positioned to contact the inner surface of the second electrodes at specific regions where space charge accumulation is most severe (such as edge end regions and heterogeneous interfaces). This localized application ensures effective charge discharge capability while minimizing the quantity of expensive filler material required, avoiding unnecessary expansion to cover entire surfaces
3Reliability
If the electric field alleviation layer is made with higher filler content to improve charge dissipation, then electric field distortion is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The electric field alleviation layer uses thermosetting rubber resin as the base material, which undergoes thermal curing to achieve stable physical and electrical properties. This parameter change (from raw rubber to cured rubber) provides dimensional stability and consistent electrical characteristics, reducing sensitivity to manufacturing precision variations while maintaining effective electric field distribution and charge dissipation
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 system effectively alleviates electric field concentration, prevents insulation breakdown, and reduces manufacturing costs by expanding microcurrent paths for charge discharge, ensuring even electric field distribution and minimizing the use of expensive materials.
Implementation Method 1
the electric field alleviation layer 330 is configured from a thermosetting rubber resin containing a filler material that induces nonlinear electrical behavior according to a specific electric field. Under normal operating conditions, the electric field alleviation layer 330 operates as an insulating layer with sufficiently high resistance; however, when space charges accumulate and an excessive electric field form, the resistance of the electric field alleviation layer 330 nonlinearly decreases, allowing charges to dissipate
Data Source
AI summary
The present disclosure relates to a direct-current power cable system capable of alleviating an electric field in a portion where space charges excessively accumulate inside a sleeve member of an ultra-high voltage direct-current power cable system, thereby preventing or minimizing electric field distortion and insulation breakdown of a cable joint box due to local electric field concentration.