Relay Contact Magnetic Shielding for Short-Circuit Arc Suppression
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Solution Overview
Problem
High-voltage DC relays face challenges with heat loss, anti-short circuit current capacity, and anti-short circuit voltage capacity, leading to contact bouncing and arcing due to electrodynamic repulsion forces, which existing solutions cannot adequately address within the constraints of small volume and low power consumption.
Innovation Solution
A magnetic shielding structure for relay contacts, comprising a movable contact piece, stationary contact lead-out terminals, an anti-short circuit assembly, and a permanent magnet, which generates a magnetic field to resist electrodynamic repulsion forces and absorb magnetic fields, thereby reducing contact resistance and improving the anti-short circuit effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the coil size is increased to improve holding force, then the electrodynamic repulsion force resistance improves, but the device volume increases and power consumption increases
Solution Approach 1:
The magnetic field generation is segmented into two independent sources: the coil for normal holding force and permanent magnets for short-circuit resistance. This allows the coil to be kept small for low power consumption while permanent magnets provide additional magnetic force during short-circuit conditions without increasing coil size or power consumption.
Solution Approach 2:
Permanent magnets are pre-installed in the relay structure to provide magnetic field in advance. During normal operation, the coil provides holding force. During short-circuit conditions, the pre-positioned permanent magnets automatically provide additional magnetic force to counteract electrodynamic repulsion without requiring real-time adjustment or increased coil capacity.
2Reliability
If the contact pressure is increased to reduce contact resistance, then the contact reliability improves, but the device complexity and power consumption increase
Solution Approach 1:
The permanent magnets provide magnetic attraction force that automatically increases contact pressure during short-circuit conditions. The magnetic field from permanent magnets directly acts on the movable contact piece to maintain contact pressure without requiring additional power consumption from the coil or external control systems.
3Force
If the coil ampere-turn value is increased to improve holding force, then the electrodynamic repulsion force resistance improves, but the power consumption increases
Solution Approach 1:
The magnetic field generation is segmented into two independent sources: the coil for normal holding force and permanent magnets for short-circuit resistance. This allows the coil to be kept small for low power consumption while permanent magnets provide additional magnetic force during short-circuit conditions without increasing coil size or power consumption.
Solution Approach 2:
The magnetic field strength is dynamically adjusted by combining the coil's magnetic field during normal operation with the permanent magnets' magnetic field during short-circuit conditions. This parameter change approach allows the system to achieve high holding force during faults without continuously operating the coil at high power levels.
4Volume of moving object
If the relay structure is simplified to reduce volume, then the manufacturing cost decreases, but the anti-short circuit capacity decreases
Solution Approach 1:
The permanent magnets serve multiple functions: they provide magnetic field for arc extinguishing, generate additional magnetic force to counteract electrodynamic repulsion during short-circuit, and contribute to the overall magnetic circuit. This multi-functionality allows small-volume design while maintaining anti-short circuit capacity.
Solution Approach 2:
The permanent magnets act as an intermediary element that bridges the gap between small coil capacity and high short-circuit resistance requirement. They provide the additional magnetic force needed during faults without requiring the coil to be oversized, thus enabling compact relay design with adequate anti-short circuit capacity.
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 magnetic shielding structure effectively reduces electrodynamic repulsion forces, prevents contact arcing, and enhances the safety and reliability of high-voltage DC relays by maintaining reliable contact and prolonging service life, even under large short-circuit conditions.
Implementation Method 1
a permanent magnet, disposed around the contact assembly to achieve arc extinguishing by using a magnetic field formed by the permanent magnet
Implementation Method 2
an anti-short circuit assembly, which is at least disposed at a side of the movable contact piece facing the stationary contact lead-out terminals, and is configured to generate suction force in the event of a faulty high current in the movable contact piece for resisting an electrodynamic repulsion force between the movable contact piece and the stationary contact lead-out terminals
Implementation Method 3
a first magnetic shielding member, disposed at an outside of a stationary contact lead-out terminal for shielding a magnetic field generated by the stationary contact lead-out terminal when energized; where, the first magnetic shielding member is configured to absorb the magnetic field transmitted from the permanent magnet to the anti-short circuit assembly
Data Source
AI summary
A magnetic shielding structure for a relay contact and a relay are provided, the magnetic shielding structure includes a contact assembly, which includes a movable contact piece and a pair of stationary contact lead-out terminals, which can contact with or separate from each other; an anti-short circuit assembly, which is at least disposed at a side of the movable contact piece along a third direction, and can generate suction force when a faulty high current in the movable contact piece for resisting an electrodynamic repulsion force between the movable contact piece and the stationary contact lead-out terminals; a permanent magnet, which is disposed around the contact assembly to achieve arc extinguishing; a first magnetic shielding member, which is sleeved on the outside of a stationary contact lead-out terminal and blocks the magnetic field transmitted from the permanent magnet to the anti-short circuit assembly.