Main contact device of selective protective breaker

Abstract

The invention discloses a main contact device of a selective protective breaker, which is provided with a bridge moving contact, a contact support and a contact spring of a moving contact point, and a fixed contact of a fixed contact point; the contact spring is arranged in the contact support; and one arm of two arms of the contact spring acts on the moving contact, while the other arm is limited to a pin roll arranged on a shell. The moving contact, the contact support and the contact spring are connected in a normally closed contact structural form; and the contact support is provided with a plurality of coupling structures, and the coupling structures parallelly receive the on-off control of an operation structure, an electromagnetic system and a short-circuit connection preventing mechanism of the breaker on the main contact. The main contact device has simple and reasonable structure, small volume and low production cost; and the main contact can be opened by the electromagnetic system when a circuit has a short-circuit fault so as to convert the current onto a branch circuit; and more importantly, the main contact can provide stable and reliable pressure guarantee for the connection of the main contact device.

Description

technical field [0001] The invention relates to a main contact device of a low-voltage circuit breaker, in particular to a main contact device of a selective protection circuit breaker. Background technique [0002] At present, miniature circuit breakers are widely used in terminal power distribution systems. Miniature circuit breakers have two-stage protection for overload long-time delay and short-circuit instantaneous. Leapfrog tripping occurred, resulting in large-scale power outages. Therefore, there is a need for a circuit breaker with selective protection function, which requires that once a short-circuit fault occurs in a line or equipment, only the line where the short-circuit fault occurs will be powered off, while other lines are still powered normally. [0003] In order to realize the selective trip protection function, the selective protection circuit breaker not only adopts the main contact, but also uses the auxiliary contact. On / off must be controlled in pa...

AI Technical Summary

Problems solved by technology

[0005] The following problems generally exist in the main contact device of the selective protection circuit breaker in the prior art: one is that the contact pressure of the contact is unstable, and the reason is that the spring that provides the contact force is heated when the contact is connected, making it elastic The second is that the structure is complex and the volume is large; the third is that there is no mechanism to prevent the return to the on position in the short-circuit state. When the short-circuit current of the electromagnetic mechanism passes through a half-wave zero-crossing moment, it may cause the main contact The head returns from the open position to the unexpected closed position in the short circuit state, causing damage to the main contact; the fourth is the single break point type, the arc is large and extinguished slowly

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