Dual-Breakpoint Rotational Contact Structure for Arc Extinction
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Solution Overview
Problem
Existing low-voltage electrical apparatuses face challenges in achieving high short-circuit breaking ability, high operating frequency, and long mechanical and electrical lifetime due to limitations in contact structures, particularly in control-and-protection switching electrical apparatuses, where contacts often rebound quickly, leading to burnings and reduced lifespan.
Innovation Solution
A dual-breakpoint contact structure comprising U-shaped static contacts, a contact bridge, movable contacts, main contact springs, and a spring support member, with adjustable angles between the main contact springs and the contact bridge, allowing for a larger repulsed open distance and incorporating a reset mechanism to enhance short-circuit breaking ability and operational efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dual-breakpoint translational contact structure is used, then the contact can be repulsed to achieve short-circuit breaking ability, but the contact rebounds after repulsion which causes burnings and reduces lifetime
Solution Approach 1:
The patent transforms the static translational contact structure into a dynamic rotational structure. The contact bridge rotates about a pivot point, allowing the contact to swing open rapidly during short-circuit breaking while maintaining stability during normal operation. This dynamic motion prevents rebound by utilizing rotational inertia and controlled arc extinction, thereby extending contact lifetime while preserving short-circuit breaking ability.
Solution Approach 2:
The patent inverts the motion mechanism from linear translation to rotational movement. Instead of the contact moving back and forth along a straight line (translational), the contact bridge rotates about a pivot point. This inversion changes the kinematic characteristics, allowing the contact to swing open quickly and extinguish arcs effectively without rebounding, thus resolving the contradiction between breaking ability and contact lifetime.
2Reliability
If contact pressure is increased to reduce rebounding, then electric arc burnings are decreased, but electromagnet volume and product cost increase
Solution Approach 1:
The rotational contact structure dynamically controls contact separation during fault conditions. The pivot point and rotational motion allow the contact to swing open rapidly under electromagnetic repulsion, achieving reliable arc extinction without requiring excessively high contact pressure. This reduces the electromagnet size needed while maintaining contact stability.
3Reliability
If a dual-breakpoint rotational contact structure is used, then short-circuit breaking ability is increased, but operating frequency and mechanical lifetime cannot be achieved
Solution Approach 1:
The patent segments the contact system into two independent rotational contacts on the contact bridge. Each contact can rotate independently about the pivot point, allowing simultaneous operation of multiple contacts without mechanical interference. This segmentation enables high operating frequency while maintaining the short-circuit breaking ability provided by the rotational dual-breakpoint structure.
Solution Approach 2:
The rotational mechanism provides dynamic motion control that allows rapid contact opening during short-circuit breaking while maintaining stability during normal frequent operations. The pivot point acts as a fulcrum that enables quick arc extinction without excessive mechanical stress, thereby supporting both high breaking ability and high operating frequency.
4Reliability
If a single-breakpoint or dual-breakpoint rotational contact structure is used, then short-circuit breaking ability is greatly increased, but high operating frequency and mechanical lifetime cannot be achieved
Solution Approach 1:
The contact bridge is segmented into two independent rotational contacts that can operate simultaneously. Each contact rotates about the pivot point independently, distributing mechanical stress and reducing wear on individual components. This segmentation extends mechanical lifetime while maintaining the high short-circuit breaking ability provided by the rotational dual-breakpoint structure.
Solution Approach 2:
The rotational mechanism with pivot point provides dynamic motion that allows rapid contact separation during short-circuit breaking while minimizing mechanical impact and wear during normal operation. The controlled rotational motion extends the mechanical lifetime of the contact components while preserving the greatly increased short-circuit breaking ability.
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 contact structure significantly enhances short-circuit breaking ability, extends the operational lifespan, and reduces energy consumption by allowing a larger repulsed open distance for arc extinction, while minimizing the size and cost of the electromagnet, thus meeting the demands of control-and-protection switching electrical apparatuses.
Implementation Method 1
two main contact springs, in a normal open position and a closed position symmetrically disposed under the movable contacts, connected to the contact bridge and forming an angle with the contact bridge
Implementation Method 2
An actuator of a contactor is usually driven by an electromagnet
Implementation Method 3
When the contact of the contactor is closed, electric arcs generated by contact rebounding will burn the contact and shorter its lifetime
Data Source
Figure 1a~1c
Figure 2a~2d
Figure 3a~3b
AI summary
The present invention discloses a contact structure of a low-voltage electrical apparatus. The contact structure is in a dual-breakpoint form, and comprises: two U-shaped static contacts, the U-shaped static contact enabling the current direction in the static contact to be opposite to the current direction in a movable contact; a contact bridge; two movable contacts, disposed on the contact bridge, and respectively corresponding to the two static contacts; a contact support member, disposed on the movable contacts and connected to the movable contacts; two main contact springs, symmetrically disposed under the movable contacts and forming an angle with the contact bridge; and a spring support member, disposed under the two movable contacts and connected to the two main contact springs. At a contact position of the static contact and the movable contact and at a repulsed open position of the static contact and the movable contact, the angle between the main contact spring and the contact bridge is between -β and +α.