High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices – Operating mechanism structure or arrangement
Reexamination Certificate
2001-05-10
2003-09-23
Nguyen, Matthew V. (Department: 2838)
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
Operating mechanism structure or arrangement
Reexamination Certificate
active
06624374
ABSTRACT:
REFERENCE TO RELATED APPLICATIONS
This application is based on Japanese Patent Application No. 2000-315186, filed in Japan on Oct. 16, 2000, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a switching apparatus which employs the interaction of magnetic fields produced by opposing coils having currents flowing through them to generate a drive force which can contact or separate contacts to close or open an electric circuit.
2. Description of the Related Art
FIG. 5
is a schematic elevation of a switching apparatus known to the inventors for multiphase electric power (such as three-phase electric power) which utilizes electromagnetic repulsive forces to carry out switching to open and close an electric circuit.
FIG. 5
shows the switching apparatus in a closed contact state. The switching apparatus of
FIG. 5
includes a separate switching unit
20
for each phase of electric power with respect to which switching is to take place, and the plurality of switching units
20
(three units in this case) form one group. The switching units
20
are connected to a common power supply
30
by contact opening drive current supply lines
33
, which conduct based on a contact opening command
31
from a contact opening command switch, and contact closing drive current supply lines
34
, which conduct based on a contact closing command
32
from a contact closing command switch.
The three switching units
20
are supported by and secured to first through fourth support plates
15
-
18
. The switching units
20
are separated from each other by electrically insulating posts
19
which prevent the occurrence of short circuits between phases.
Each switching unit
20
has a switch portion
3
having a fixed contact
1
and a movable contact
2
which is disposed opposite the fixed contact
1
and can move into and out of contact with the fixed contact
1
. A movable shaft
4
extends from the movable contact
3
, and an operating mechanism
5
is operatively connected to the movable shaft
4
to open and close the switch portion
3
by translating the movable shaft
4
in its axial direction.
The fixed contact
1
of each switch portion
3
is secured to the first support plate
15
through an electrical insulator. The fixed contact
1
and the movable contact
2
are housed in an evacuated bulb
6
in order to effectively extinguish an arc which is generated during contact opening or closing.
Each movable shaft
4
includes a live portion
8
connected to the movable contact
2
and a non-live portion
9
connected to the operating mechanism
5
. The live portion
8
and the non-live portion
9
are connected to each other by an electrically insulating rod
7
which prevents current from flowing from the switch portion
3
to the operating mechanism
5
. A movable electrically conducting connecting terminal
10
is installed on the live portion
8
to permit connection to an external conducting body (not shown).
The operating mechanism
5
includes an electromagnetic repulsion plate
11
secured to the non-live portion
9
of the movable shaft
4
, a contact opening fixed coil
12
which is secured to the second support plate
16
and opposes the upper surface of the electromagnetic repulsion plate
11
, a contact closing fixed coil
13
which is secured to the third support plate
17
and opposes the lower surface of the electromagnetic repulsion plate
11
, and a nonlinear bidirectional biasing spring
14
which is secured to the fourth support plate
18
and the non-live portion
9
of the movable shaft
4
and which maintains an open contact state or a closed contact state of the switch portion
3
. The non-live portion
9
of the movable shaft
4
loosely passes through the second support plate
16
and the third support plate
17
, through the contact opening fixed coil
12
and the contact opening fixed coil
13
which are secured to these support plates, and through the fourth support plate
18
to which the biasing spring
14
is secured so as to be able to translate in its axial direction. As a result, the electromagnetic repulsion plate
11
can reciprocate between the contact opening fixed coil
12
and the contact closing fixed coil
13
. The properties of the biasing spring
14
are such that when the point of connection between the movable shaft
4
and the biasing spring
14
moves past a neutral point of the biasing spring
14
, the direction in which the biasing spring
14
exerts a biasing force is reversed.
Contact opening operation of the switching apparatus of
FIG. 5
is performed in the following manner. When the apparatus is in the closed contact state shown in
FIG. 5
in which the fixed contacts
1
and the movable contacts
2
of the switching portions
3
contact each other, if a contact opening command
31
is provided to the power supply
30
from the contact opening command switch, the power supply
30
causes a pulse current to be supplied to the contact opening fixed coil
12
of the operating mechanism
5
of each switching unit
20
through the contact opening drive current supply lines
33
. This current causes each contact opening fixed coil
12
to generate a magnetic field, and the magnetic field causes an induced current to flow in the corresponding electromagnetic repulsion plate
11
, which is in a position close to and opposite the contact opening fixed coil
12
, so as to generate a magnetic field which is opposite in direction to the magnetic field generated by the contact opening fixed coil
12
. Due to the interaction of the magnetic field which is generated by the induced current flowing in the electromagnetic repulsion plate
11
and the magnetic field generated by the contact opening fixed coil
12
, each electromagnetic repulsion plate
11
receives an electromagnetic repulsive force urging it away from the corresponding contact opening fixed coil
12
.
Due to this electromagnetic repulsive force, each electromagnetic repulsion plate
11
is moved downwards in the figure against the upwards spring force exerted by the biasing spring
14
in the contact closing direction. At the same time, the movable shaft
4
which is secured to the electromagnetic repulsion plate
11
and the movable contact
2
which is secured to the movable shaft
4
also move downward, and the fixed contact
1
and the movable contact
2
are made to separate from each other, whereby each switch portion
3
is opened. During this operating process, the biasing spring
14
which was exerting a biasing force in the contact closing direction inverts its direction of action and generates a biasing force in the contact opening direction when the movable shaft
4
moves downwards past the neutral point of the biasing spring
14
. Accordingly, the open contact state of the fixed contact and the movable contact
2
is maintained by the biasing spring
14
.
When the switching apparatus is in the open contact state, if a contact closing command
32
is input from the contact closing command switch to the power supply
30
, the power supply
30
supplies a pulse current to the contact closing fixed coil
13
of each switching unit
20
through the contact closing drive current supply lines
34
. Due to this current, the contact closing fixed coil
13
generates a magnetic field, which generates an induced current in the electromagnetic repulsion plate
11
which is close to and opposing it. As a result, the electromagnetic repulsion plate
11
generates a magnetic field which is in the opposite direction of that generated by the contact closing fixed coil
13
. Due to the interaction of the magnetic field generated by the contact closing fixed coil
13
and the induced magnetic field generated by the electromagnetic repulsion plate
11
, a repulsive force acts on the electromagnetic repulsion plate
11
urging it away from the contact closing fixed coil
13
, and the electromagnetic repulsion plate
11
moves upward against the force of the biasing spring
14
acting in the contact openin
Akita Hiroyuki
Kishida Yukimori
Koyama Ken-ichi
Ooshige Toyomi
Sasao Hiroyuki
Leydig , Voit & Mayer, Ltd.
Mitsubishi Denki & Kabushiki Kaisha
Nguyen Matthew V.
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