A molded case circuit breaker with compound arc extinguishing performance

Abstract

The invention provides a moulded-case circuit breaker having the composite arc-extinguishing performance. The moulded-case circuit breaker comprises a static contact mounted within a shell, a movable contact connected with a tripping mechanism, and an insulated arc-extinguishing device. The insulated arc-extinguishing device comprises a magnetic yoke, an armature, an insulation shielding plate, a swinging rod and a supporting seat. The magnetic yoke and the supporting seat are fixed on the fixed contact. The supporting seat is positioned below the magnetic yoke. The insulation shielding plate is arranged on one side of the static contact and is positioned corresponding to a gap between the static contact and the movable contact. The upper and lower ends of the swing rod and the magnet yoke are respectively and rotationally connected with the insulation shielding plate and the supporting seat. The swing rod, the armature, the insulation shielding plate and the supporting seat form a four-bar linkage structure. A torsional spring is arranged between the armature and the supporting seat. According to the invention, the insulation 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 plastic case circuit breaker with strong short-circuit current breaking capacity, belonging to the technical field of emergency protection devices. Background technique [0002] Molded case circuit breakers (MCCB) are important electrical components in industrial and civil low-voltage power distribution equipment. They are mostly used as branch switches in low-voltage power distribution systems to protect power distribution lines from overload and short-circuit faults. Among them, short-circuit fault protection is its most important function. Because the short-circuit current of the line is very large when the short-circuit fault occurs, a large-energy plasma arc will be generated between the moving and static contacts of the circuit breaker when the short-circuit current is interrupted. These technical measures quickly extinguish the arc, the circuit breaker can complete the task of breaking the short-circuit current. [0003] At ...

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 400V, 50kA, and the DC short-circuit current is more difficult to break because there is no zero-crossing process

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