A Small Circuit Breaker with Strong Arc Extinguishing Capability

Abstract

The invention provides a miniature circuit breaker having the relatively strong arc-extinguishing capacity. The miniature circuit breaker comprises a shell, a static contact, a movable contact, a tripping mechanism, an arc-extinguish chamber and an auxiliary arc-extinguishing mechanism. The auxiliary arc-extinguishing mechanism comprises a shielding plate, a magnetic yoke and a torsion spring. The magnetic yoke is fixed on the static contact. The shielding plate is placed corresponding to a gap between the movable contact and the static contact and is positioned on one side of the movable contact and the static contact. The two side edges of the shielding plate are in sliding connection with the shell of the circuit breaker through arc-shaped sliding rails. The side wall of the shielding plate is rotationally connected with the shell of the circuit breaker through a rotating shaft configured to pass through the central hole of the torsion spring. One end of the shielding plate, far away from the static contact, is provided with an armature corresponding to the magnetic yoke. The two ends of the torsion spring are respectively pressed on the side wall and the shell of the circuit breaker. According to the invention, the shielding plate can be rapidly inserted in the gap between the movable contact and the static contact when the short-circuit current is broken by the circuit breaker. Therefore, the electric arc between the movable contact and the static contact is extinguished. In this way, the arc energy amplification time is shortened. The circuit breaker has a short flashover or even no flashover. The capacity of the circuit breaker in breaking the short-circuit current is greatly improved.

Description

technical field [0001] The invention relates to a high-quality small circuit breaker used in low-voltage power distribution equipment, and belongs to the technical field of switches. Background technique [0002] Miniature circuit breaker (MCB) is an important electrical component in industrial and civil low-voltage power distribution equipment. It is mostly used at the end of low-voltage power distribution system to protect the overload and short-circuit faults of power distribution lines. Among them, the short-circuit fault protection is its most important function. Since the short-circuit current of the line is very large when the short-circuit fault occurs, a plasma arc with high energy will be generated between the moving and static contacts of the circuit breaker when breaking the short-circuit current. Only the arc extinguishing parts provided can quickly extinguish the arc, and the circuit breaker can complete the task of breaking the short-circuit current. [0003]...

AI Technical Summary

Problems solved by technology

The arc extinguishing effect of this method is affected by factors such as the material of the arc extinguishing chamber, the breaking speed of the contacts, the distance between the contacts, the material of the contacts, etc. Relatively poor, generally no more than AC 230V, 6kA, and the DC short-circuit current is more difficult to break because there is no zero-crossing process

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