DC Relay Magnetic Loop Layout for Short-Circuit Hold and Arc Extinction
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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. The magnetic conductive loop structure used to resist short-circuit currents is inadequate, resulting in electromagnetic suction forces that are insufficient to hold the contacts together during high fault currents.
Innovation Solution
The DC relay incorporates a novel magnetic conductive loop configuration using a fixed upper yoke, a follow-up upper yoke, and a lower armature, arranged in a width direction to form two partially overlapped magnetic conductive loops. This design generates an electromagnetic suction force to keep the movable contacts closed, resisting electric repulsion forces during fault currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a single magnetic conductive loop is used to resist short-circuit current, then the structure is simple, but the electromagnetic suction force is insufficient to hold contacts together during high fault currents
Solution Approach 1:
The patent divides the single magnetic conductive loop into two separate magnetic conductive loops (first magnetic conductive loop with upper yoke and second magnetic conductive loop with lower armature). This segmentation allows each loop to independently generate electromagnetic suction force, collectively providing sufficient holding force during short-circuit conditions while maintaining reasonable structural complexity
Solution Approach 2:
The patent combines the functions of multiple magnetic components (upper yoke, lower armature, and their respective magnetic conductive loops) into a unified magnetic resistance system. The upper yoke and lower armature work together to provide complementary electromagnetic suction forces that collectively resist the electric repulsion force during fault currents
2Force
If the upper yoke is fixed on the pushing rod assembly to allow movement during overtravel, then the contact pressure can be maintained, but the gap between upper yoke and lower armature weakens the electromagnetic suction force
Solution Approach 1:
The patent implements a dynamic magnetic conductive loop structure where the upper yoke is fixed on the movable contact piece and the lower armature is fixed on the pushing rod assembly. This dynamic arrangement allows the magnetic components to maintain optimal positioning and minimal gap during contact closure, maximizing electromagnetic suction force while still allowing the pushing rod assembly to move during overtravel to maintain contact pressure
3Reliability
If the electromagnetic suction force is increased to resist higher short-circuit currents, then the anti-short circuit current capability is improved, but the coil may be released and contacts separated
Solution Approach 1:
The patent segments the electromagnetic suction force generation into two independent magnetic conductive loops, each contributing to the total holding force. This segmentation distributes the electromagnetic force generation across multiple components, providing redundant holding capability that resists short-circuit currents while maintaining stable contact closure through the combined effect of both loops
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 enhanced magnetic conductive loop structure significantly improves the relay's ability to withstand short-circuit currents up to 16 kA, ensuring reliable contact and preventing arcing by generating sufficient electromagnetic suction force.
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 includes a static contact leading-out end; a movable contact piece; a fixed upper yoke and a lower armature respectively placed on an upper side and a lower side of the movable contact piece and can form a magnetic conductive loop; a first U-shaped bracket fixedly installed at an upper end of a pushing rod, the pushing rod can drive the movable contact piece to come into contact and separate from the static contact leading-out end during an up-and-down movement to realize an on-off of the DC relay; and a second U-shaped bracket installed on a stationary component of the DC relay, and the fixed upper yoke is fixedly installed on the second U-shaped bracket.