DC Relay Magnetic Loop Layout for Arc Extinction Under Short Circuits
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Solution Overview
Problem
Existing high-voltage DC relays face challenges in maintaining reliable contact and preventing arcing due to short-circuit currents, which can lead to failure and reduced anti-short circuit current capability.
Innovation Solution
The DC relay incorporates a design with two static contact leading-out ends, a movable contact piece, and a pushing rod assembly, featuring a fixed upper yoke, a follow-up upper yoke, and a lower armature to form two magnetic conductive loops. These loops generate an electromagnetic suction force to resist electric repulsion forces during fault currents, enhancing contact stability and arc extinction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic conductive loop with upper yoke and lower armature is installed at the movable contact piece to generate electromagnetic suction force, then the anti-short circuit current capability is improved, but the device complexity increases due to additional components and their installation requirements
Solution Approach 1:
The patent combines the upper yoke and lower armature into an integrated magnetic conductive loop structure that is pre-assembled at the movable contact piece. This merging of components simplifies the overall device complexity while maintaining the electromagnetic suction force generation capability for improved anti-short circuit current performance.
Solution Approach 2:
The magnetic conductive loop is pre-installed at the movable contact piece before final assembly. This preliminary action ensures proper positioning and reduces installation complexity during the final assembly process, while maintaining the reliability improvement from the electromagnetic suction force.
2Device complexity
If the upper yoke is fixed on the inner side of the bottom wall of the U-shaped bracket of the pushing rod assembly, then the structure is simplified, but the gap between the upper yoke and lower armature weakens the electromagnetic suction force
Solution Approach 1:
The patent makes the upper yoke movable by fixing it to the pushing rod assembly rather than the stationary bracket. This dynamic positioning allows the upper yoke to maintain optimal proximity to the lower armature during contact piece movement, preserving electromagnetic suction force while simplifying the overall structure through fewer fixed mounting points.
3Force
If the upper yoke is fixed on a follow-up pushing rod to remain still, then the electromagnetic suction force is maintained, but the coil cannot hold the iron core when short-circuit current reaches certain level causing contact separation
Solution Approach 1:
The patent segments the magnetic conductive loop into separate upper yoke and lower armature components that can move independently. This segmentation allows the upper yoke to move with the pushing rod assembly while the lower armature remains on the movable contact piece, ensuring continuous magnetic coupling and reliable contact maintenance even under high short-circuit currents.
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 design significantly improves the anti-short circuit current capability of the DC relay, effectively resisting electric repulsion forces and preventing arcing, while also ensuring reliable contact pressure and arc extinction.
Implementation Method 1
when the short-circuit current flows through the movable contact piece, an annular magnetic field is generated around the movable contact piece; when the annular magnetic field acts on the upper yoke and the lower armature, the upper yoke and the lower armature can generate suction force
Implementation Method 2
a permanent magnet is arranged around a contact where the two movable and static contacts are in contact, and a magnetic field formed by the permanent magnet is used to realize the magnetic blowing arc extinction
Implementation Method 3
the energized movable contact piece is subjected to Lorentz force under the magnetic field of the magnetic blowing arc extinction, due to a magnetic circuit layout of the magnetic blowing arc extinction, the movable contact piece is subjected to the Lorentz force to move downward under the magnetic field
Data Source
AI summary
A DC relay for anti-short circuit current and arc extinction including two static contact leading-out ends, a pushing rod assembly, a movable contact piece and three permanent magnets. Two of the three permanent magnets are respectively arranged at two sides of the movable contact piece in a width direction and are adjacent to one of two movable contacts of the movable contact piece; magnetic polarities of two permanent magnets facing the movable contact are the same; the third permanent magnet is arranged on one side of the movable contact piece in a length direction and is adjacent to another movable contact and a polarity face of the third permanent magnet is substantially perpendicular to the polarity faces of the two permanent magnets, so that an Lorentz force generated by the movable contact piece in an arc extinction magnetic field formed by the three permanent magnets is substantially zero.