Electricity: circuit makers and breakers – Liquid contact – Time delay
Patent
1985-08-07
1987-03-24
Macon, Robert S.
Electricity: circuit makers and breakers
Liquid contact
Time delay
200147R, H01H 3320
Patent
active
046527079
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a power switch such as an electromagnetic contactor, and more particularly to an improvement in a commutation electrode thereof.
As shown in FIGS. 1(a) and 1(b), a conventional electromagnetic contactor has a commutation electrode 3 disposed around an end of a movable contact member 5 to which a movable contact 6 is joined. FIGS. 2(a) and 2(b) illustrate a fixed contact member 13 disposed in confronting relation to the movable contact member 5 and an arc rubber 15 attached to the fixed contact member 13. A fixed contact 14 is joined to the fixed contact member 13. The movable contact 6 of the movable contact member 5 is movable into and out of contact with the fixed contact 14.
The movable contact member 5 has an intermediate portion connected to a known electromagnetic drive device. The movable contact 6 is joined to each end of the movable contact member 5, and the fixed contact members 13 are provided respectively for the movable contacts 6.
FIGS. 1(a) and 1(b) are perspective and enlarged fragmentary plan views, respectively, schematically showing the commutation electrode 3, the movable contact member 5, and the movable contact 6. The fixed contact member 13, the fixed contact 14, and the arc runner 15 in FIGS. 1(a) and 1(b) are schematically shown in FIGS. 2(a) and 2(b) at an enlarged scale.
In the conventional electromagnetic contactor having the commutation electrode 3, when the fixed contact 14 and the movable contact 6 are separated, an end of an arc generated between these contacts is transferred from the movable contact 6 to the commutation electrode 3, while the other arc end is transferred from the fixed contact 14 to the arc runner 15. The transferred other end of the arc is moved on the arc runner 15 toward the other end thereof until finally the arc is extinguished between the parallel portion of the arc runner 15 and the commutation electrode 3 confronting the same.
With the commutation electrode 3 in the conventional electromagnetic contactor being shaped as shown in FIGS. 1(a) and 1(b), when an arc leg is produced at a position P as shown in FIGS. 1(a) and 1(b), current components i1, i2 flowing from the commutation electrode 3 into the arc legs are of substantially the same value, and an arc current is equal to the sum i of the current components i1, i2 (i=i1+i2). In FIG. 1(b), the commutation electrode 3 has a prescribed thickness (though it is omitted from illustration in FIG. 1(a)) across its width. In FIG. 1(b), l1, l2 denote the distances from the ends of the commutation electrode 3 to the position P where the arc is produced. Since the force F1 imposed by the current i1 on the arc is larger than the force F2 imposed by the current i2 on the arc, the arc is driven in the direction of the force F which is the combination of the forces F1, F2. Therefore, the arc is brought into direct contact with an arc box of synthetic resin accommodating the commutation electrode 3 and the movable contact member 5, thus leaving great damage on the arc box.
DISCLOSURE OF THE INVENTION
Accordingly, it is an object of the present invention to provide a power switch having a prescribed recess (slit) for preventing an arc box from being damaged.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1(a) and 1(b) are enlarged fragmentary views of a movable contact member and a commutation electrode, the view showing a conventional electromagnetic contactor;
FIGS. 2(a) and 2(b) are enlarged fragmentary views of a fixed contact member and an arc runner of the conventional electromagnetic contactor;
FIG. 3 is a side elevational view, partly in cross section, of an electromagnetic contactor according to an embodiment of the present invention;
FIG. 4 is a fragmentary perspective view of a commutation electrode and a movable contact member of the electromagnetic contactor of the invention;
FIG. 5 is a righthand side elevational view, partly in cross section, of an electromagnetic contactor according to another embodiment of the present invention;
FIG. 6 is an enlarge
REFERENCES:
patent: 4477704 (1984-10-01), Mori et al.
patent: 4521655 (1985-06-01), Okado et al.
Kakizoe Masahiro
Masuda Shigeru
Mori Teijiro
Nishizako Shizutaka
Wada Yuichi
Macon Robert S.
Mitsubishi Denki & Kabushiki Kaisha
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