Circuit breaker

Abstract

A circuit breaker for a double-break mechanism includes a current interrupting section having a contact mechanism. The contact mechanism includes first and second fixed contactors arranged in parallel and having fixed contacts, and a bridging movable contactor having an arm with movable contacts opposing the fixed contacts. A magnetic plate may be interposed in a middle region between two pairs of the fixed and movable contacts extending along a path of switching movement of the movable contactor. Partition walls formed of organic polymer material may be provided to stand along the path of the movable contactor. The partition walls sandwich each pair of the fixed contact and the movable contact to form a narrow gap arc extinguishing space between the partition walls.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a contact mechanism of a current interrupting section in Example 1 according to the invention;

FIG. 2 shows movements of the arcs generated between fixed and movable contacts in the event of current interruption in the structure of FIG. 1;

FIG. 3 is a perspective view of a current interrupting section in Example 2 according to the invention;

FIG. 4 shows movements of the arcs generated between the fixed and movable contacts in the event of current interruption and illustrates a function of the narrow gap partition wall assembly of FIG. 3;

FIGS. 5( a) and 5(b) illustrate a structure and a function of the essential parts of the current interrupting section in Example 3 according to the invention, in which FIG. 5(a) is a sectional view of the narrow gap partition wall assembly and FIG. 5(b) shows movements of the arcs generated between the fixed and movable contacts in the event of current interruption;

FIG. 6 is a perspective view of a current interrupting section in Example 4 according to the invention;

FIGS. 7( a) and 7(b) illustrate a structure and a function of the essential parts of the current interrupting section in Example 5 according to the invention, in which FIG. 7(a) is a sectional view of the narrow gap partition wall assembly and FIG. 7(b) shows movements of the arcs generated between the fixed and movable contacts in the event of current interruption;

FIG. 8 is a side sectional view of a double-break type circuit breaker;

FIG. 9 is a perspective view showing a prior art structure of a current interrupting section of FIG. 8;

FIG. 10 shows movements of an arc generated between the fixed and movable contacts upon opening operation in the current interrupting section of FIG. 9; and

FIGS. 11( a) to 11(c) schematically show movements of the arc generated between the fixed and movable contacts in FIG. 10, in which FIG. 11(a) shows a state immediately after the beginning of opening operation, FIG. 11(b) shows a state after the arcs moved away from each other due to a repulsive electromagnetic force between the arcs, and FIG. 11(c) shows the fixed and movable contacts with a configuration of unbalanced dissipation.

Claims

1. A circuit breaker for a double-break mechanism, comprising: a current interrupting section having a contact mechanism, said contact mechanism comprising first and second fixed contactors arranged in parallel and having fixed contacts, and a bridging movable contactor having an arm with movable contacts opposing the fixed contacts, anda magnetic plate interposed in a middle region between two pairs of the fixed and movable contacts extending along a path of switching movement of the movable contactor.

2. A circuit breaker according to claim 1, wherein said magnetic plate is arranged to shield magnetic fields formed by arcs between the movable contacts and the fixed contacts.

3. A circuit breaker for a double-break mechanism, comprising, a current interrupting section having a contact mechanism, said contact mechanism comprising first and second fixed contactors arranged in parallel and having fixed contacts, and a bridging movable contactor having an arm with movable contacts opposing the fixed contacts, andpartition walls formed of organic polymer material and provided to stand along a path of switching movement of the movable contactor, said partition walls sandwiching each pair of the fixed contact and the movable contact to form a narrow arc extinguishing space between the partition walls.

4. A circuit breaker according to claim 3, wherein said partition walls comprise outer partition walls formed outside the fixed contacts of the first and second fixed contactors and the movable contacts, and an inner partition wall situated between two pairs of the fixed contacts and the movable contacts.

5. A circuit beaker according to claim 4, wherein the outer partition walls are composed of an organic polymer material that generates a greater amount of evaporating gas due to heat of arcing, and the inner partition wall is composed of an organic polymer material that generates an evaporating gas less than that formed by the outer partition walls.

6. A circuit beaker according to claim 4, wherein the outer partition walls have a thickness greater than that of the inner partition wall.

7. A circuit beaker according to claim 4, wherein a distance between the pair of fixed and movable contacts and the outer partition wall is smaller than a distance between the pair of fixed and movable contacts and the inner partition wall provided.