Compact Contactor Fuse Housing with Dynamic Arc Venting
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Solution Overview
Problem
Conventional fused circuit breakers occupy excessive volume, making them unsuitable for integration into mobile contactors in limited spaces, as they require significant space for operation and cannot be mounted without altering the contactor's volume.
Innovation Solution
A compact protection device with a housing that separates into two portions driven by elastic means, allowing the housing to open and close to manage pressure and facilitate the expansion and breaking of electric arcs, utilizing a fuse element with brazed joints and non-carbonizable materials to control arc generation and prevent reformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional fused circuit breaker is used for circuit protection, then reliable overcurrent protection is achieved, but the occupied volume increases significantly
Solution Approach 1:
The housing is divided into two separate portions that can move relative to each other. The first portion contains the fuse element and connection terminals, while the second portion contains the arc extinction chamber. This segmentation allows the housing to open during arc generation, directing the arc outside the housing, and close during normal operation, maintaining a compact form factor.
Solution Approach 2:
The housing transitions from a static structure to a dynamic one where the two portions can move relative to each other. Elastic means provide the restoring force to close the housing after arc extinction, while the overcurrent force opens it. This dynamic behavior enables the housing to adapt its volume during different operational states, resolving the contradiction between protection reliability and volume occupancy.
2Volume of stationary object
If the housing is kept closed during fuse melting, then the compact volume is maintained, but the electric arc cannot expand and may cause damage
Solution Approach 1:
The housing dynamically opens during overcurrent events to allow the electric arc to expand outside the housing, preventing damage from confined arc pressure. The elastic means ensure the housing returns to its closed compact state after arc extinction, maintaining small volume during normal operation. This dynamic volume adjustment resolves the contradiction between maintaining compact size and allowing safe arc expansion.
Solution Approach 2:
The harmful electric arc and associated pressure increase are utilized beneficially to open the housing automatically. The overcurrent that creates the dangerous arc also generates the force needed to open the housing, directing the arc safely outside. This converts the harmful arc energy into the mechanical work needed for housing opening, eliminating the need for external actuation mechanisms.
3Object-affected harmful factors
If elastic means are added to enable housing separation, then arc management is improved, but the device complexity increases
Solution Approach 1:
The elastic means are pre-loaded during housing assembly, storing potential energy ready for arc extinction. During normal operation, the elastic force keeps the housing closed. During overcurrent, the arc pressure overcomes the elastic force to open the housing, and after arc extinction, the stored elastic energy automatically closes the housing without external intervention. This self-service mechanism minimizes complexity by eliminating the need for external actuators, sensors, or control systems.
Solution Approach 2:
The harmful overcurrent and arc generation are converted into the beneficial mechanical work needed to open the housing. The thermal and mechanical energy from the arc directly drives the housing opening, while the elastic means provide the restoring force for closing. This energy conversion approach simplifies the overall system by using the problem's own energy to drive the solution.
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 allows for effective protection of electrical circuits in reduced spaces by minimizing additional volume occupancy and ensuring reliable arc breaking and reformation management, maintaining circuit integrity while preventing disruptive discharges and carbon residue formation.
Implementation Method 1
The melting of the fuse element is caused by the temperature rise due to the overcurrent passing over the fuse
Implementation Method 2
The melting of the fuse element and its consecutive vaporization cause an increase in the temperature and consequently the pressure inside the housing
Implementation Method 3
elastic means suitable for causing the first portion to bear against the second portion and causing the housing to be set in a closed state
Implementation Method 4
an opening of the housing, an expansion of the electric arc outside the housing
Data Source
AI summary
Device for protecting an electrical circuit fed by an alternating current, comprising a housing and a fuse element disposed in the housing. The housing comprises a first portion and a second portion which are mobile in relation to one another, and elastic means suitable for causing the first portion to bear against the second portion and causing the housing to be set in a closed state.