Circuit Breaker Trip Device Arc-Resistive Member
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Solution Overview
Problem
The existing trip devices for circuit breakers using bimetal mechanisms often experience reliability issues due to thermal bonding and resistance value changes caused by arc generation between the bimetal and terminals, leading to delayed trips.
Innovation Solution
Incorporating an arc-resistive member, such as silver carbide or insulating paper, between the bimetal and terminals to prevent arc generation, ensuring stable current flow and reliable trip operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bimetal is in surface-contact with the terminals, then good electrical connection is achieved, but arc generation causes thermal bonding and reliability degradation
Solution Approach 1:
An arc-resistive member is introduced as an intermediary component between the bimetal and the terminals. This member has high arc resistance properties that prevent arc generation while maintaining electrical conductivity. The arc-resistive member acts as a mediator that allows current flow without allowing harmful arcs to form at the contact surfaces, thereby solving the contradiction between good electrical connection and arc prevention.
Solution Approach 2:
The arc-resistive member is made from composite materials that combine high arc resistance with good electrical conductivity. These composite materials enable the component to simultaneously provide electrical connection and protect against arc generation, resolving the contradiction between maintaining electrical contact and preventing harmful arcs.
2Object-affected harmful factors
If arc-resistive member is inserted between bimetal and terminals, then arc generation is prevented, but contact surface area is reduced
Solution Approach 1:
The arc-resistive member is applied locally at the critical contact points where arcs are most likely to form, rather than covering the entire contact surface. This localized application prevents arc generation at the bimetal-terminal interface while maintaining adequate contact surface area for electrical conduction. The arc-resistive coating or insert is positioned precisely where needed to protect against arcs without unnecessarily reducing the overall contact area.
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
Prevents thermal bonding and resistance value changes, enhancing the reliability of trip operations by eliminating arc generation and ensuring timely tripping during fault currents.
Implementation Method 1
when a fault current flows, the bimetal 66 may generate heat due to the flowed current
Implementation Method 2
arc may be generated in a micropore (fine pore) between the contact surface 62a of the first terminal 62 and the first contact surface 66a of the bimetal 66... arc-resistive member therebetween
Data Source
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AI summary
A trip device for a circuit breaker disclosed herein includes a first terminal (62) connected to a power source side, a second terminal (64)connected to a load side, and a bimetal (66) having one side connected with the first terminal (62) and the other side connected with the second terminal (64), such that a current can flow therethrough, wherein the bimetal (66) comes in surface-contact with at least one of the first terminal (62) and the second terminal (64), with interposing an arc-resistive member (168a, 168b, 268a, 268b) therebetween.