Locomotive Roof Composite Insulator Shed Structure for Impulse Voltage Tolerance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing locomotive roof composite insulators face issues with impulse voltage tolerance, leading to interface breakdowns, particularly due to the arrangement of sheds which do not adequately manage longitudinal electric fields, resulting in frequent and severe flashover and tripping accidents as train speeds increase and electrified railway layouts diversify.
Innovation Solution
The design incorporates at least five shed groups along the axial direction around the support body, with specific diameter and pitch configurations for large and small sheds, and a creepage distance increasing shed on the lower fitting, enhancing impulse voltage tolerance and preventing interface breakdowns, while maintaining a compact structure and increasing arcing distance without adding height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulating creepage distance between the shed housing and the shed is increased to meet the standard (exceeding 1000 mm), then the insulation performance is improved, but the arrangement of the shed goes against impulse voltage tolerance and the longitudinal electric field of the interface increases
Solution Approach 1:
The patent applies local quality by creating different shed configurations in different regions. The first shed group has a larger diameter than the second shed group, and the creepage distance increasing shed is positioned specifically at the lower end of the support body. This local variation optimizes the electric field distribution at the interface while maintaining adequate creepage distance, resolving the contradiction between insulation performance and impulse voltage tolerance.
Solution Approach 2:
The patent introduces a new dimension by adding the creepage distance increasing shed at the lower end of the support body, which extends the creepage path in the axial direction. This dimensional addition allows the design to meet the 1000 mm creepage distance requirement while managing the longitudinal electric field through proper spatial arrangement of multiple shed groups with different diameters.
2Reliability
If more shed groups are arranged along the axial direction to increase creepage distance, then the insulation margin is improved, but the height of the insulator increases
Solution Approach 1:
The patent applies parameter changes by varying the diameter parameter of sheds in different groups. The first shed group has a larger diameter while the second shed group has a smaller diameter, and the creepage distance increasing shed compensates for the reduced height by optimizing the radial and axial configuration. This parameter variation allows achieving adequate creepage distance and insulation margin without proportionally increasing the overall height.
3Reliability
If the shed diameter is increased to reduce the longitudinal electric field, then the impulse voltage tolerance is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies segmentation by dividing the sheds into distinct groups along the axial direction. The first shed group with larger diameter sheds is separated from the second shed group with smaller diameter sheds, and the creepage distance increasing shed is positioned at the lower end. This segmentation allows each group to be optimized for specific functions while simplifying the overall manufacturing process through modular construction.
Data Source
AI summary
An interface breakdown-proof locomotive roof composite insulator. The composite insulator comprises: a support body; and at least five shed groups arranged side by side along the axial direction that are provided around the sidewall of the support body, the at least five shed groups includes: at least four shed groups located on the upper end with each group including a large shed and a small shed; and at least one shed group located on the undermost end with each group including two small sheds. For such a shed structure, it is favorable to tolerate impulse voltage, and it is difficult for the interface to be broken down; the electric field on the interface even does not exceed 3 kV/mm, and even if a gas exists on the interface, it will not break through the interface.