High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices – Magnetic blowout
Reexamination Certificate
2000-08-17
2002-04-16
Donovan, Lincoln (Department: 2832)
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
Magnetic blowout
C335S016000, C218S034000
Reexamination Certificate
active
06373014
ABSTRACT:
TECHNICAL FIELD
This invention relates to a current limiting device and a circuit interrupter having a current limiting function.
BACKGROUND ART
FIG. 147
is a perspective view and a partial sectional view showing a conventional circuit interrupter disclosed for example in Japanese Patent Publication No. 1-43973, in which
1130
is a current limiting element portion connected in electrically series to the interrupter portion
1140
by a conductor
1290
,
1001
is a movable member of the current limiting element portion
1130
having a support member
1711
including a movable contact
1002
and a magnetic material,
1005
is a stationary member of the current limiting element portion
1130
and having a stationary contact
1006
, the movable member
1001
and the stationary member
1005
together constituting a contact pair.
1280
is an excitation coil connected in electrically series to the contact pair,
1018
is a movable member contacting pressure spring for generating a suitable contacting pressure in the contact pair.
1015
is a terminal portion,
1045
is a handle,
1721
is a flexible conductor,
1095
is a spring seat,
1110
are exhaust holes,
1135
is a piston, and
1300
is a packing.
FIG. 148
is a right hand side view of FIG.
147
.
During the normal current supplying operation, a current flows through the circuit interrupter from the interrupter portion
1140
, the conductor
1290
, the excitation coil
1280
, the movable member
1001
, the stationary member
1005
and the terminal portion
1015
. When a current of an amount with which the current limiting element portion
1130
is to achieve the current limiting operation flows, the contacts separate due to an electromagnetic repulsive force generated between the movable contact
1002
and the stationary contact
1006
and generate an electric arc. This arc increases the pressure between the contacts, so that the piston
1135
of the movable member
1001
is moved against the force of the spring
1018
. Also, since one portion of the movable member
1001
is a support member
1711
made of a magnetic material, the excitation coil
1280
constituting a coil plunger also provides a force assisting the contact opening. When the movable member
1001
moves in the contact opening direction, the gas on the back side of the movable contact is exhausted through the exhaust holes
1110
, whereby the pressure increased by the arc is also additionally exhausted. The contact open state is maintained until the pressure sufficient to hold the contact in the opened state against the force of the movable contact contacting pressure spring
1018
is not provided
Then, when the current flowing through the current limiting element portion decrease and the arc pressure decreased to a certain value, the movable member
1001
initiates its contact closing operation due to the force of the movable contact contacting pressure spring
1018
. At this time, in order to delay the contact closing process, the exhaust holes
1110
are formed at an acute angle with respect to the contact opening direction, thereby to increase the fluid resistance of the gas to be exhausted. Also, the direction of tilt of the exhaust holes
1110
serves to reduce the fluid resistance of the gas at the time of the contact opening operation. In the current limiting element portion
1130
having such the structure, the fault current flowing through the circuit is limited mainly by an inductance of the excitation coil
1280
and the electrical resistance generated between the contacts
1002
and
1006
. Since the contact pair is positioned within a narrow cylindrical space, the arc pressure generated upon the current limiting operation is increased to increase the resistivity of the arc. Therefore, a high arc voltage necessary for current limiting can be obtained. The current thus current-limited is eventually interrupted by the interrupter portion
1140
connected in series to the current limiting element portion.
FIG. 149
is a partial sectional view showing a conventional three pole current limiting unit disclosed for example in Japanese Patent Publication No. 8-8048, in which a current limiting unit
1200
constitutes a current limiting interrupter (a circuit interrupter with a current limiting function) together with a standard circuit interrupter
1300
which are connected at their housings.
FIG. 151
is a partial sectional view with one portion of the housing side wall removed in order to show the internal structure of the current limiting interrupter. The current limiting unit
1200
contains in the respective inner poles two pairs of contact pairs connected in series as shown in FIG.
152
.
FIG. 153
is an exploded perspective view in which main parts are disassembled in order to show the structure of the two contact pairs shown in FIG.
152
.
In
FIGS. 148
to
153
,
1
a
and
1
b
are first movable member and a second movable member constituted by the movable contacts
1002
a
and
1002
b
and the movable arms
1004
a
and
1004
b
, respectively, and
1005
a
and
1005
b
are first stationary contact and a second stationary contact constituted by the stationary contacts
1006
a
and
1006
b
and the stationary conductors
1007
a
and
1007
b
, respectively. The first movable member
1001
a
and the first stationary member
1005
a
, and the second movable member
1001
b
and the second stationary member
1005
b
constitute contact pairs, respectively.
1015
a
,
1015
b
and
1015
c
are terminal portions disposed at one face of the housing,
1016
a
,
1016
b
and
1016
c
are terminal portions disposed at the opposite face of the housing, the first stationary member
1005
a
being connected to the terminal portion
1016
a
and the second stationary member
1005
b
being connected to the terminal portion
1015
a
through the connecting conductor
1014
, and the first movable member
101
a
and the second movable member
1001
b
are electrically connected by the flexible conductor
1072
to the end portion opposite to the movable contacts
1002
a
and
1002
b.
Therefore, the current path extends from the terminal portion
1016
a
, the stationary conductor
1007
a
, the stationary contact
1006
a
, the movable contact
1002
a
, the movable arm
1004
a
, the flexible conductor
1072
, the movable arm
1004
b
, the movable contact
1002
b
, the stationary contact
1006
b
, the stationary conductor
1007
b
, the connecting conductor
1014
and the terminal portion
1015
a
, and two pairs of contact pairs are electrically connected in series. The two contact pairs are separated and arranged in plane symmetry with respect to a plane of the partition wall
1100
substantially perpendicularly disposed with respect to a plane (the bottom surface of the housing) connecting the terminal portions
1015
a
and
1016
a
disposed at the opposite ends of the housing separated. A rotary shaft
1013
penetrating through the partition wall
1100
rotatably supports the first movable member
1001
a
and the second movable member
1001
b
, and the first movable member
1001
a
and the second movable member
1001
b
are urged toward the first stationary member
1005
a
and the second stationary member
1005
b
, respectively, by means of twist springs
1011
a
and
1011
b
(not shown). At the position opposing to the tip end portion on which the contacts of the above contact pairs are provided, arc extinguishing plates
1019
a
and
1019
b
(not shown) of a horse-shoe shape are provided.
At the time of normal opening and closing as well as overload current interrupting, the standard circuit interrupter
1300
achieves opening and closing operation and the interrupting operation, and the current limiting unit
1200
does not operate. On the other hand, when a large current such as a short circuited current is generated, two contact pairs disposed within the current limiting unit
1200
is rapidly separated against the spring force of the springs
1011
a
and
1011
b
by the electromagnetic repulsive force generated by the parallel and opposite currents flowing through
Fukuya Kazunori
Fushimi Masahiro
Mitsuhashi Takao
Murata Shiro
Takahashi Mitsugu
Donovan Lincoln
Leydig , Voit & Mayer, Ltd.
Mitsubishi Denki & Kabushiki Kaisha
LandOfFree
Current limiting device and circuit interrupter having a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Current limiting device and circuit interrupter having a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Current limiting device and circuit interrupter having a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2888826