Relay-Fuse Protection Circuit for Arc-Assisted Current Interruption
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Solution Overview
Problem
Conventional protection systems face issues with large electric currents causing repulsive magnetic forces and electric arcs, leading to unstable contact and potential damage, which necessitates increased size and weight to maintain contact stability.
Innovation Solution
A protection system comprising a relay and a fuse connected in series, where the relay and fuse initiate arc discharges at specific thresholds, increasing impedance to quickly disconnect the circuit, eliminating the need for mechanical contact maintenance and allowing for a smaller design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressing force applied to the movable unit is increased to stabilize contact, then contact stability is improved, but the size and weight of the relay increase
Solution Approach 1:
The patent replaces the mechanical pressing force system with an electrical field-based solution. Instead of using mechanical springs or magnetic fields to press the movable terminal against the fixed terminal, the invention uses an electrical field generated between the terminals to hold the contact stable during arc discharge, thereby eliminating the need for large mechanical pressing forces and reducing relay size and weight.
Solution Approach 2:
The patent changes the electrical parameters (voltage, current distribution) during arc discharge to maintain contact stability. By controlling the electrical field characteristics and potential difference between terminals, the system maintains stable contact without requiring increased mechanical pressing force, thus avoiding increased size and weight.
2Reliability
If the movable terminal or fixed terminal is formed into a special shape to reduce repulsive magnetic force, then contact stability is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent replaces complex terminal shaping with an electrical field-based control mechanism. Instead of manufacturing terminals with special geometries to reduce repulsive magnetic forces, the invention uses controlled electrical field distribution to achieve the same effect, thereby maintaining simple terminal geometry and ease of manufacture.
3Reliability
If the area of contact between movable terminal and fixed terminal is increased to reduce current density, then contact stability is improved, but the size of the relay increases
Solution Approach 1:
The patent changes the electrical parameters (current distribution, voltage distribution) during operation to maintain stable contact with standard terminal areas. By controlling the electrical field and potential difference, the system achieves contact stability without requiring increased contact area, thus avoiding increased relay size and weight.
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
This solution effectively stabilizes the contact by using arc discharges to increase impedance, ensuring quick disconnection and reducing the size and weight of the protection system while maintaining reliable operation.
Implementation Method 1
When an electric current exceeding a threshold current flows to the first relay, the first contact portion and the second contact portion are separated in the first relay at a first time after an electric current flowing to the first relay exceeds the threshold current. When the first contact portion and the second contact portion are separated, an arc discharge occurs between the first contact portion and the second contact portion.
Implementation Method 2
An arc discharge occurs between the first electrode and the second electrode of the fuse at a second time later than the first time. The arc discharge occurs at both of the first relay and the fuse and a difference in potential between the first electrode of the fuse and the second electrode of the fuse increases during a period between the second time and a third time later than the second time.
Implementation Method 3
If the area of a portion where the movable terminal and the fixed terminal are in contact is small, large electric currents converge and flow through said portion in contact. Accordingly, there are cases where a repulsive magnetic force is generated across the contact, the contact is disconnected, and an electric arc is generated.
Data Source
AI summary
A protection system includes: a first positive terminal; a second positive terminal; a first relay configured to be opened and closed by contact and separation of a first contact portion and a second contact portion; and a fuse. The first relay and the fuse are connected in series between the first positive terminal and the second positive terminal, and when an electric current exceeding a threshold current flows to the first relay, the first contact portion and the second contact portion are separated in the first relay at a first time, and when the first contact portion and the second contact portion are separated, an arc discharge occurs between the first contact portion and the second contact portion, an arc discharge occurs between the first electrode and the second electrode of the fuse at a second time, the arc discharge occurs at both of the first relay and the fuse and a difference in potential between the first electrode and the second electrode of the fuse increases during a period between the second time and a third time, and the first positive terminal and the second positive terminal are disconnected at a fourth time.