Power Cable Termination Box Reducing Heterojunction Interfaces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The accumulation of space charges at heterojunction interfaces between power cables and termination connection boxes leads to electric field concentration, and existing solutions do not effectively mitigate this issue while also failing to reduce the size of the termination connection box.
Innovation Solution
A power cable with a termination connection box design that incorporates a composite insulating layer with kraft paper and thermoplastic resin, a porcelain tube with an electric-field mitigation cone and shielding layer, and a reinforcing insulating layer made of the same material as the outermost layer of the cable, which reduces heterojunction interfaces and allows for a smaller termination connection box size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the insulating layer is formed of composite insulating paper with multiple materials, then the dielectric strength is improved, but heterojunction interfaces are generated causing space charge accumulation and electric field concentration
Solution Approach 1:
The outermost layer of the insulating layer is formed of the same material (kraft paper) as the reinforcing insulating layer, creating material homogeneity at the interface. This eliminates the heterojunction interface between different materials, preventing space charge accumulation and electric field concentration while maintaining the dielectric strength provided by the composite insulating paper structure.
2Reliability
If the termination connection box is designed with adequate insulation, then the reliability is improved, but the size of the termination connection box increases
Solution Approach 1:
By making the outermost layer of the insulating layer and the reinforcing insulating layer the same material (kraft paper), the interface between them becomes homogeneous. This eliminates the need for additional insulation measures and reduces the required volume of the termination connection box while maintaining insulation reliability.
Solution Approach 2:
The harmful heterojunction interface is extracted or eliminated by using the same material for both layers. This removal of the problematic interface allows for a more compact termination connection box design without compromising reliability.
3Stability of the object's composition
If the insulating oil viscosity is increased to prevent flow, then void formation is reduced, but the insulating oil cannot return to original position when temperature decreases
Solution Approach 1:
The insulating layer uses composite insulating paper combining kraft paper and thermoplastic resin. The thermoplastic resin layer suppresses insulating oil flow during thermal expansion while the kraft paper layers allow oil impregnation and maintenance. This composite structure prevents void formation while maintaining the ability of insulating oil to return to its original position when temperature decreases.
Data Source
Figure 1
Figure 2~3
AI summary
The present invention is to provide a power cable with a termination connection box, in which the occurrence of heterojunction interfaces between the power cable and the termination connection box are reduced to prevent accumulation of space charges and an electric field may be mitigated.