HVDC Relay Step-Surface Insulation Against Arc Spatter
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Solution Overview
Problem
High-voltage direct current relays suffer from insulation issues due to arc splashing, leading to short circuits and reduced insulation resistance, which is particularly problematic in applications requiring load connection and disconnection.
Innovation Solution
A high-voltage direct current relay design featuring staggered step surfaces on fixed contacts and the ceramic cover to prevent arc spatter entry, enhancing insulation capability and increasing creepage distance without significantly increasing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fixed contacts are mounted in a ceramic or plastic case with clearance fit, then assembly is simplified and manufacturing cost is reduced, but arc spatter enters the clearance region causing insulation short circuit and insulation reduction
Solution Approach 1:
The through hole is segmented into multiple regions by introducing step surfaces at different heights. The first step surface on the fixed contact and the second step surface on the ceramic cover create distinct clearance regions (first clearance region above first step surface, second clearance region between first and second step surfaces, third clearance region below second step surface). This segmentation prevents arc spatter from directly entering the upper clearance region while maintaining assembly simplicity.
Solution Approach 2:
The solution transitions from a single-plane clearance fit to a multi-level stepped structure. By adding the vertical dimension with step surfaces at different heights, the patent creates a three-dimensional staggered fit arrangement that blocks arc spatter pathways while preserving the clearance fit assembly method.
2Reliability
If the creepage distance is increased to improve insulation resistance, then arc extinction capability is enhanced, but the product structure becomes more complex and production cost increases
Solution Approach 1:
The patent utilizes the dynamic arc spatter trajectory and gravity-driven downward movement of spatter particles. By positioning step surfaces to create staggered clearance regions, the design exploits the natural downward motion of arc spatter to prevent it from reaching upper clearance zones, thereby increasing effective creepage distance without extending the physical path length.
Solution Approach 2:
The step surfaces act as intermediary structures that mediate between the fixed contact and the ceramic cover. These intermediate surfaces create barrier zones that intercept arc spatter, effectively increasing insulation capability without requiring a proportionally longer creepage path or more complex structural arrangements.
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 design effectively reduces insulation short circuits and enhances insulation resistance, meeting arc extinction requirements for high voltage and current while maintaining a simple structure and assembly process.
Implementation Method 1
prevent arc spatter from entering into a region of fitting clearance between a fixed contact and a through hole of the ceramic cover above a location where the first step surface fits with the second step surface utilizing staggered fitting between the first step surface and the second step surface
Data Source
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AI summary
A high-voltage direct current relay capable of improving insulation capability, including a ceramic cover, two fixed contacts for respectively providing inflow and outflow current and one movable contact spring; a through hole for assembling the fixed contact being provided at a top wall of the ceramic cover; one segment of a body of the fixed contact being in clearance fitted with the through hole of the ceramic cover, a first step surface downward being provided at an outer peripheral wall of one segment of the body of the fixed contact, at a corresponding position, a second step surface upward being provided at an inner peripheral wall of the through hole of the ceramic cover, and the projections of the first step surface and the second step surface on the horizontal plane having an overlapped region.