A Molded Case Circuit Breaker with Strong Capability of Breaking Short-circuit Current

Abstract

Provided is a plastic shell circuit breaker having the high short-circuit current breaking capability. The plastic shell circuit breaker includes a casing, a static contact, a movable contact and an insulation arc extinguishing device, the insulation arc extinguishing device includes a magnet yoke, a support base, a torsion spring, an armature, and an insulation shielding cover having no front wall, the magnet yoke is fixed on the static contact, the support base is fixed at the lower part of the magnet yoke, the top plate of the insulation shielding cover corresponds to the gap between the movable contact and the static contact, the two side walls of the insulation shielding cover are in rotation connection with the support base through a rotating shaft penetrating through the torsion spring, one end of the torsion spring is suspended to the side wall of the insulation shielding cover, the other end of the torsion spring is pressed on the support base, and the armature is fixed to the rear wall of the insulation shielding cover. The insulation shielding cover can rapidly cover the static contact when the circuit breaker breaks the short circuit current, so that the arc between the movable contact and the static contact can be extinguished, in this way, the arc energy amplification time is shortened, the short flashover or no flashover of the circuit breaker is realized, and the short-circuit current breaking capability of the circuit breaker is greatly improved.

Description

technical field [0001] The invention relates to a molded case circuit breaker with strong short-circuit current breaking capacity, belonging to the technical field of switches. Background technique [0002] Molded case circuit breaker (MCCB) is an important electrical component in industrial and civil low-voltage power distribution equipment, and is mostly used as a branch circuit switch for low-voltage power distribution system protection. 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] At present, MCCBs at home and abroad use arc extin...

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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