Circuit Breaker Arc Shield Design
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Solution Overview
Problem
Circuit breakers face issues with arc generation during switching or tripping, leading to safety hazards, damage to components, and reduced operational lifespan due to arcing, which can cause arcs to short to other objects, create fire hazards, and produce harmful gases and debris.
Innovation Solution
A circuit breaker design incorporating a shielding component with an arc shield and venting mechanism to prevent arcs from shorting to enclosures, allow gas escape, and protect internal mechanisms from debris, featuring a housing with a shield that creates a gap between the contacts and external objects, and a vent for gas release, along with a mechanism shield to isolate moving parts from arcing areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contacts are separated to open the circuit breaker, then the circuit is disconnected and protection is provided, but an electric arc is generated which can short to other objects and create safety hazards
Solution Approach 1:
An arc shield is introduced as an intermediary component between the contacts and surrounding objects. The shield is positioned to intercept and block arcs generated during contact separation, preventing them from reaching other objects in the circuit breaker or surrounding areas, thus eliminating the harmful effect while maintaining the circuit protection function
Solution Approach 2:
The arc shield extends into the housing from the exterior, creating a three-dimensional barrier that adds spatial separation between the arc generation zone and other components. This dimensional approach increases the breakdown voltage path and provides physical blocking without interfering with the normal opening and closing operation
2Reliability
If contacts are separated to open the circuit breaker, then the circuit is disconnected, but contact material is melted and flung into the mechanism destroying it or reducing its lifespan
Solution Approach 1:
The arc shield serves as a protective intermediary that blocks molten contact debris from traveling into the mechanism area. By positioning the shield between the contact separation zone and the mechanism, it intercepts flung material and prevents contamination of moving parts, thereby preserving mechanism integrity and extending operational lifespan
Solution Approach 2:
The housing is divided into functional zones by the arc shield, separating the contact area where arcing occurs from the mechanism area that requires protection. This segmentation isolates the harmful effects to a specific zone while protecting critical components in another zone
3Reliability
If the housing is sealed to protect internal components, then protection is improved, but gases generated by arcing cannot escape creating pressure and safety issues
Solution Approach 1:
The housing is designed with selective sealing - most areas are sealed to protect internal components, but a specific local region includes a vent that allows gas escape. The arc shield is positioned to block arcs from reaching this vent while permitting gas passage, creating localized different qualities in different parts of the housing structure
Solution Approach 2:
The arc shield acts as a selective intermediary that blocks harmful arcs while permitting gas passage through the vent. It differentiates between solid particle/debris (which should be blocked) and gases (which should escape), allowing both protection and venting functions to coexist
4Object-affected harmful factors
If arc shield is added to prevent arcs and debris, then safety and component protection are improved, but device complexity increases
Solution Approach 1:
The arc shield is designed to perform multiple functions simultaneously: blocking arcs from reaching other objects, preventing molten debris from contaminating the mechanism, and allowing gas venting through designated passages. By consolidating these protection functions into a single component, the design adds minimal complexity while achieving comprehensive protection
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 solution effectively prevents arc shorts, ensures safe venting of gases, and protects internal components from debris, enhancing safety and operational longevity by increasing the breakdown voltage and providing a dedicated path for arc quenching and debris containment.
Implementation Method 1
This is because the breakdown voltage between the contacts is positively related to distance under pressure and voltage conditions in typical applications.
Implementation Method 2
a vent disposed to permit gasses to escape the housing
Implementation Method 3
providing a dedicated path for arc quenching and debris containment
Data Source
AI summary
A circuit breaker which includes a shielding component. The shielding component includes an external portion which defines a space external to the circuit breaker housing. The external portion prevents insertion of the circuit breaker into a breaker box closer than the distances defining the space. This can have the advantage of preventing arcing from the breaker contacts to the breaker box. The external portion may also prevent insertion of the circuit breaker into a breaker box such that a vent in the circuit breaker housing is blocked. In some implementations, the shielding component contains an internal portion which extends into the circuit breaker housing and is disposed to impede debris generated by contact arcing, or other debris, from entering the mechanism of the circuit breaker.