Circuit breaker

Details Circuit breaker Circuit breaker

2001-09-27

2003-06-03

Donovan, Lincoln (Department: 2832)

Electricity: magnetically operated switches, magnets, and electr

Electromagnetically actuated switches

With housing or support means

C335S016000, C335S132000, C218S022000

Reexamination Certificate

active

06573815

ABSTRACT:

TECHNICAL FIELD
This invention relates to a circuit breaker in which the circuit breaking is achieved by separating a movable contact of a rotatable movable contact member from a stationary contact of a stationary contact member.
BACKGROUND ART
While circuit connecting or breaking is achieved in a circuit breaker by contacting and separating a movable contact of a movable contact member with respect to a stationary contact of a stationary contact member, an electric arc is generated between the separated movable contact and the stationary contact during the circuit breaking because of a voltage applied to the circuit. Therefore, in the circuit breaking operation, how quickly the arc can be extinguished is an important concern. In a conventional circuit breaker in which the movable contact and the stationary contact are brought into contact or separated by rotating the movable contact member, arc extinguisher plates are disposed in the vicinity of the arc generating position in order to extinguish the arc.
FIGS. 16
a
and
16
b
are views showing the conventional circuit breaker arrangement in which the movable contact member is rotated for circuit interruption,
FIG. 16
a
being a perspective view and
FIG. 16
b
being a cross sectional view taken along the line XVIb—XVIb of
FIG. 16
a
and in a plane perpendicular to the bottom surface of the circuit interrupter. In these figures,
101
is a vessel,
102
is a cover placed over the vessel
101
. The cover
102
does not retain a high pressure within the cover so that the inner gas is permitted to flow outside.
103
is a movable contact member rotatably attached to a mechanism unit
107
and has a movable contact
103
a
,
104
is a stationary contact member secured to the vessel
101
and has a stationary contact
104
a
capable of being contacted by and separated from the movable contact
103
a
,
105
a
and
105
b
are terminals of the stationary contact member
104
,
106
are arc extinguishing plates disposed in the vicinity of the arc generating area and
107
is the mechanism unit for rotating the movable contact member
101
, which mechanism portion includes a handle
107
a
for manual operation.
108
is an exhaust port formed in the cover
102
and
109
is a relay unit for detecting an abnormal current and causes the operation of the mechanism unit
107
.
In the conventional circuit breaker as above described, as shown in
FIGS. 16
a
and
16
b
, the electrical connection between the movable contact
103
a
and the stationary contact
104
a
are established by being brought into contact with each other, so that an electric current flows through the respective terminals
105
a
and
105
b.
On the other hand, in order to interrupt the electric current flowing through the terminals
105
a
and
105
b
, the mechanism unit
107
is operated by the manual operation through the handle
107
a
or by an automatic operation caused by a current higher than the rated current, whereby the operating mechanism unit
107
is operated to rotate the movable contact member
103
to cause the movable contact
103
a
to separate from the stationary contact
104
a
. At this time, an electric arc is generated between the movable contact
103
a
and the stationary contact
104
a
. This arc is elongated by rotational motion of the movable contact member
103
an electromagnetic force generated by the current flowing between the movable contact member
103
and the stationary contact member
104
and, thereafter, the arc is divided and quenched by the arc extinguisher plates
106
extinguished. After this, the movable contact member
103
is held in an open state in which it is separated from the stationary contact
104
.
During the interruption in the conventional circuit breaker, the arc is elongated by the rotational motion of the movable contact member
103
and this elongated arc is divided and quenched by the arc extinguisher plates
106
, so that the interrupting capability is limited by the number of the arc extinguisher plates
106
and the maximum separation distance of the movable contact member
103
or the size of the arc extinguishing chamber.
Also, although an exhaust port
108
is provided at one side within the arc extinguishing chamber in order to exhaust pressurized arc gas generated upon the arc occurrence, since the conventional circuit breaker does not have sufficient gas-tightness of the vessel, the pressurized arc gas (hereinafter referred to as pressurized gas) is exhausted without being utilized in arc extinction through the spaces defined in the mechanism unit and between the relay unit, the vessel, the cover and the like.
Further, while the arc gas contains gases that are effective for the arc extinction, they are not effectively utilized and the arc extinguishing capability is subjected to limitation by the number of the arc extinguishing plates
106
and the maximum separation distance of the movable contact member
103
or the volume of the arc extinguishing chamber.
The present invention has been made to solve the above problem and has as its object the provision of a compact circuit breaker of a high arc extinguishing capability by utilizing a pressurized gas generated upon the arc occurrence.
Another object is to provide a compact circuit breaker of a high arc extinguishing capability by generating and utilizing a gas effective for arc extinction generated upon the arc occurrence and utilizing.
DISCLOSURE OF INVENTION
The circuit breaker according to the present invention comprises a stationary contact member having a stationary contact, a movable contact member having at one end a movable contact capable of contacting with and separating from the stationary contact and having at the other end a rotational center, an arc extinguisher chamber vessel surrounding the stationary contact and the movable contact and defining a pressure accumulating space at one side of an arc generation position at which an electric arc is generated for temporarily storing a pressurized gas pressurized by the arc generated between the stationary and the movable contact upon the current interruption, a main body case including at least one of the arc extinguisher chamber, and an exhaust port disposed at the other end of the arc generation position in the arc extinguisher chamber and the main body case so that the pressurized gas stored within the accumulation space upon the current interruption is exhausted between arc spots formed on the stationary contact and the movable contact.
Also, the arc extinguisher chamber vessel may be constructed in a hexahedron and may have a length c in the direction perpendicular to the plane of rotation of the movable contact, a length b in the direction of initial separation of the movable contact, a length a perpendicular to the b and the c, and may be arranged such that a relation ship a>b>c holds.
Also, of two spaces defined by dividing a space within the arc extinguisher chamber by a plane passing through the centers of the arc spots formed on the movable contact member and the stationary contact member and perpendicular to a plane of rotational movement of the movable contact member, volume of the space provided with the exhaust port may be arranged to be smaller than the volume of the other space.
Also, the exhaust port may be located in the vicinity of the stationary contact or the movable contact upon separation.
Also, a conductor portion for holding the movable contact member may be disposed within the arc extinguisher compartment so that the movable contact member is rotatable and the pressure accumulation space is defined in the vicinity of the conductor portion.
Also, a flow cross-sectional area for the pressurized gas at the position between the stationary contact and the movable contact in a flow path between the stationary contact and the movable contact from the pressure accumulation space may be made smaller than a flow cross-sectional area for the pressurized gas at the position upstream of the flow cross-sectional area between the stationary contact and the movable contac

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