Ag Oxide Contact Material for DC High-Voltage Relay Heating
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Solution Overview
Problem
DC high-voltage relays face challenges with heat generation and welding at contacts due to increased voltage and current, which are not adequately addressed by conventional Ag oxide-based contact materials, leading to potential failures and safety hazards.
Innovation Solution
A Ag oxide-based contact material with reduced oxide content is developed, optimizing the contact force and opening force to balance low contact resistance and welding resistance, suitable for DC high-voltage relays with rated voltages of 48 V or more and contact forces of 980 mN or more, using a composition with specific metal M content to enhance mechanical properties and welding resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ag oxide-based contact material with high oxide content is used to improve welding resistance and wear resistance, then durability is improved, but contact resistance increases leading to excessive heat generation
Solution Approach 1:
The patent applies parameter changes by precisely controlling the oxide content within 0.03-3 mass% and metal M content within 0.01-10 mass%. This optimization balances the competing requirements: sufficient oxides provide welding resistance through dispersion strengthening, while limited oxides prevent excessive contact resistance and heat generation. The specific quantitative ranges represent a refined parameter optimization that resolves the contradiction between durability and heat control.
Solution Approach 2:
The patent employs composite materials by creating a Ag-based contact material containing dispersed metal oxide particles and metal M elements. This composite structure combines the advantages of Ag (low contact resistance, high conductivity) with the benefits of metal oxides (welding resistance, wear resistance) and metal M (mechanical strength, hardness). The composite formulation allows simultaneous achievement of low heat generation and high durability.
2Reliability
If contact material durability is improved by increasing oxide content, then welding resistance improves, but contact resistance increases causing heat generation problems
Solution Approach 1:
The patent resolves this contradiction through parameter optimization by limiting oxide content to 0.03-3 mass% and adding metal M at 0.01-10 mass%. This controlled composition provides sufficient wear resistance from the composite structure while preventing excessive contact resistance. The metal M component further enhances wear resistance without significantly increasing contact resistance, thereby controlling heat generation.
Solution Approach 2:
The Ag-based composite contact material with dispersed metal oxide and metal M provides wear resistance through the composite structure while maintaining low contact resistance. The metal oxide particles provide hardness and wear resistance, while the Ag matrix maintains electrical conductivity. The balanced composition ensures wear resistance without excessive heat generation.
3Reliability
If contact force is increased to improve contact resistance, then contact resistance decreases, but opening force requirement increases making operation difficult
Solution Approach 1:
The patent addresses this contradiction by optimizing the contact material composition to achieve low contact resistance through material properties rather than solely relying on high contact force. The controlled oxide content (0.03-3 mass%) and metal M content (0.01-10 mass%) provide inherent electrical conductivity and mechanical properties that reduce contact resistance while allowing moderate contact forces, thereby reducing the opening force requirement and improving operability.
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 optimized contact material effectively reduces heat generation and welding, ensuring reliable on/off control while maintaining a compact size and weight, addressing the unique demands of high-voltage relays.
Implementation Method 1
performance of the contact material is improved by a dispersion enhancing action on metal oxide particles to secure required properties such as wear resistance and welding resistance
Implementation Method 2
heat generation and welding at contacts due to increased voltage and current
Data Source
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AI summary
The present invention relates to DC high-voltage relay including at least one contact pair including a movable contact and a fixed contact, the contact pair having a contact force and/or opening force of 100 gf or more, the DC high-voltage relay having a rated voltage of 48 V or more. The movable contact and/or the fixed contact includes a Ag oxide-based contact material. Metal components in the contact material includes at least one metal M essentially containing Sn, and a balance including Ag and inevitable impurity metals. The content of the metal M is 0.2% by mass or more and 8% by mass or less based on the total mass of all metal components in the contact material. The contact material has a material structure in which one or more oxides of the metal M are dispersed in a matrix including Ag or a Ag alloy. As metal M in the contact material, In, Bi, Ni and Te can be added in addition to Sn.