Composite Insulator Corona Shield Cavity Design
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Solution Overview
Problem
High voltage composite insulators face service life reduction due to corona discharges, which existing field-forming measures often fail to adequately prevent, and current solutions are complex and inefficient in manufacturing.
Innovation Solution
A corona shield made of insulating plastic material, coaxially disposed between the rod and end fitting, forming an inward open cavity filled with a sealant compound, providing enhanced sealing and erosion protection with a separate, easily manufacturable design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If corona rings made of conductive material are mounted at the end fitting to reduce field strength, then the propensity for corona discharge is reduced, but the device complexity increases and manufacturing becomes more complex
Solution Approach 1:
The invention extracts the field-forming function from separate corona rings and integrates it into the insulating jacket itself by creating a cavity at the interface between the rod and end fitting. This eliminates the need for additional conductive corona rings while maintaining the field-strengthening effect through the cavity geometry alone.
Solution Approach 2:
The invention merges the protective function against corona discharge with the insulating jacket structure by forming a cavity directly in the insulating material. This combines the insulating and field-forming functions into a single integrated component, reducing device complexity while maintaining reliability.
2Duration of action of stationary object
If insulating material with greater wall thickness is used to protect against corona discharge erosion, then the service life is extended, but the manufacturing complexity and material usage increase
Solution Approach 1:
The invention segments the insulating jacket into two distinct regions: a thicker protective portion at the rod interface that resists corona erosion, and a thinner portion elsewhere. The cavity creates a localized thickening effect precisely where needed, extending service life without requiring uniform thickness increases throughout the entire jacket.
Solution Approach 2:
The invention applies the quality enhancement (increased material thickness) locally at the rod-end fitting interface where corona discharge occurs, rather than uniformly throughout the entire insulating jacket. This targeted approach extends service life at the critical erosion zone while minimizing additional material usage and manufacturing complexity.
3Reliability
If a cavity is formed in the insulating jacket to serve as corona shield, then the sealing against rain water is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The cavity serves multiple functions simultaneously: it acts as a corona shield to protect against discharge erosion, provides sealing against rain water ingress, and creates the necessary field distribution. This multi-functionality improves reliability without requiring separate components, thereby managing manufacturing precision requirements through design integration rather than additional parts.
Data Source
AI summary
A composite insulator comprises a rod with an insulating jacket and ribs and at least one end fitting and at least one corona shield. The latter is integrally manufactured from plastic material. It is configured to be coaxially disposed on the composite insulator at the transition from the rod to the end fitting. The corona shield forms a cavity, which is open towards the inside and which can be filled with sealant compound through at least one filling channel and which comprises a closing cuff in axial direction on both sides for sealing the cavity. The diameter of the rod side closing cuff is adapted to the diameter of the insulating jacket, and the diameter of the fitting side closing cuff is adapted to the diameter of the end fitting. The filling channel leads to the cavity from the outside.