Technical Field
[0001] The present invention relates to a solid dielectric vacuum switch.
Background Art
[0002] A switch that is mounted on or in a railway car is placed on the roof or under the
floor of the railway car. Dimensions of the switch, particularly their height and
width dimensions are limited in terms of reducing air resistance, height of the car
when passing through tunnels, and space restriction on the roof or under the floor
among others.
[0003] As a down sizable switch, a solid dielectric vacuum switch is known, as described
in Patent Literature 1 and Patent Literature 2.
[0004] A switch described in Patent Literature 1 includes a vacuum interrupter, a movable
actuating shaft, a contact pressure spring mechanism that is disposed near a connection
portion between the movable actuating shaft and a movable conductor, and a conductive
box surrounding the contact pressure spring mechanism and the vacuum interrupter and
the conductive box for relaxing an electric field are molded by an insulator.
[0005] In addition, in a switch described in Patent Literature 2, a ground layer is provided
on the outer periphery of an insulation layer that is provided around the vacuum interrupter.
Citation List
Patent Literature
[0006]
Patent Literature 1: Japanese Patent Application Laid-Open No. 2012-69345
Patent Literature 2: Japanese Patent Application Laid-Open No. 2017-21939
Summary of Invention
Technical Problem
[0007] In the switch described in Patent Literature 1, because an insulation distance is
needed when other components of equipment are placed around the switch, there will
be an increase in the space for installing various components of equipment including
the switch.
[0008] In addition, in the switch described in Patent Literature 2, an insulation distance
to peripheral components of equipment can be reduced because the outer periphery of
the insulation layer is grounded. However, no consideration is taken for an insulated
actuating rod that is coupled to the movable conductor in the vacuum interrupter,
an actuator that is coupled to the insulated actuating rod, and insulation in the
periphery of these components.
[0009] Accordingly, the present invention provides a solid dielectric vacuum switch enabling
it to decrease the insulation distance to peripheral components of equipment and improve
the insulation characteristic. Solution to Problem
[0010] To solve problems noted above, a solid dielectric vacuum switch according to the
present invention includes a vacuum interrupter having a fixed electrode, a movable
electrode, a fixed conductor that is connected to the fixed electrode, and a movable
conductor that is connected to the movable electrode; an insulated actuating rod that
is mechanically connected to the movable conductor; an actuator that actuates the
insulated actuating rod; and a solid insulator covering the vacuum interrupter. A
ground layer covering an outer surface of the solid insulator is provided. A conductive
shield is provided within the solid insulator, the conductive shield covering around
a connection portion between the movable conductor and the insulated actuating rod.
Advantageous Effects of Invention
[0011] According to the present invention, it is possible to decrease the insulation distance
between a vacuum switch and its peripheral components of equipment and to improve
the insulation characteristic of the vacuum switch.
[0012] Problems, configurations, and advantageous effects other than described above will
be made apparent from the following description of embodiments.
Brief Description of Drawings
[0013]
Figure 1 illustrates an example of a train set of railway cars on or in which vacuum
switches as Example 1 are mounted.
Figure 2 illustrates feeding circuits of the railway cars in Figure 1.
Figure 3 illustrates another example of the train set of railway cars on or in which
vacuum switches as Example 1 are mounted.
Figure 4 illustrates feeding circuits of the railway cars in Figure 3.
Figure 5 illustrates an external view of a vacuum switch as Example 1 of the present
invention.
Figure 6 is a cross-sectional view of the vacuum switch of Example 1 when cut along
a longitudinal direction.
Figure 7 illustrates a state in which T-shape cable heads are connected to the vacuum
switch of Example 1.
Figure 8 is a cross-sectional view of a vacuum switch as Example 2 when cut along
a longitudinal direction.
Figure 9 illustrates an external view of a vacuum switch as Example 3.
Figure 10 illustrates an external view of a vacuum switch as Example 4.
Figure 11 illustrates an external view of a vacuum switch as Example 5.
Figure 12 illustrates an external view of a vacuum switch as Example 6.
Description of Embodiments
[0014] A vacuum switch as one embodiment of the present invention is a solid dielectric
vacuum switch with its surface being covered with a ground potential. The vacuum switch
is installed such that its longitudinal direction is parallel to the ground plane,
for example, such that the longitudinal direction is along the traveling direction
of a railway car at the top of the roof or on the floor of the railway car. Bushings
to which cables are connected are disposed in any of upper, lower, left, and right
positions in a direction perpendicular to the longitudinal direction. An actuating
mechanics case is disposed substantially in line with a vacuum interrupter that is
a switch unit. Thereby, it is possible to reduce height and width dimensions of the
switch when installed. Also, because the surface is covered with the ground potential,
it is possible to decrease the insulation distance between the vacuum switch and its
peripheral components of equipment. Consequently, it is possible to reduce the space
where the peripheral components of equipment are installed.
[0015] However, according to the study by the present inventors, when the surface of the
vacuum switch is covered with the ground potential, a high electric field region is
created inside the vacuum switch. Particularly, because the periphery of an insulated
actuating rod is covered with atmospheric air where a breakdown electric field is
low in comparison with solid insulating resin or the like, insulation performance
may deteriorate potentially when a high electric field region is created.
[0016] Therefore, in the vacuum switch as one embodiment of the present invention, a conductive
shield covering around the insulated actuating rod is provided and this conductive
shield is disposed near to the surface ground layer. Thereby, the electric field in
an air space around the insulated actuating rod inside the switch is relaxed and,
consequently, the insulation characteristic of the vacuum switch improves. Moreover,
according to the study by the present inventors, by these surface ground layer and
conductive shield, the effect of relaxing the electric field becomes greater than
when only the conductive shield is provided.
[0017] In the following, embodiments of the present invention will be described by Examples
1 to 6 set forth below and with the aid of the drawings. Note that identical reference
numerals across the drawings denote identical structural elements or structural elements
having a similar function.
<Example 1>
[0018] Railway cars on or in which vacuum switches as Example 1 are mounted is first described
with Figures 1 to 4.
[0019] Figure 1 illustrates an example of a train set of railway cars on or in which vacuum
switches as Example 1 are mounted.
[0020] The train set illustrated in Figure 1 is composed of eight cars (1
st to 8
th cars) . High-voltage pull-through cables RC1, RC2, RC3, RC4, and RC5 are disposed
on the roofs of these cars. High-voltage pull-through cables RC3, RC5 are connected
to pantographs PG1, PG2, respectively. The railway cars receive electric power from
a feeder (not illustrated) and the received electric power is distributed to each
car through the high-voltage pull-through cables R1 to R5.
[0021] The respective cables are connected by straight joints SJ1, SJ2, SJ3, SJ4 positioned
on the roofs between the cars and branched toward a car floor direction by T branch
joints TJ1, TJ2 on the roofs. Here, a T branch joint TJ1 and a straight joint SJ2
are integrated into a vacuum switch which will be described later and a T branch joint
TJ2 and a straight joint SJ4 are also integrated into a vacuum switch.
[0022] Figure 2 illustrates a feeder (feeding) circuit of the railway cars in Figure 1.
[0023] As shown in Figure 2, under the floors (Under Floor) of the second car (2
nd car), fourth car (4
th car), and sixth car (6
th car), power receiving vacuum circuit breakers VCB1, VCB2, VCB3 are provided respectively
and, in addition, main transformers Tr1, Tr2, Tr3 are provided respectively.
[0024] A high-voltage pull-through cable RC1 of the 2
nd car is directly connected to a primary side of a power receiving vacuum circuit breaker
VCB1 and a secondary side of the power receiving vacuum circuit breaker VCB1 is connected
to a primary winding of a main transformer Tr1. A secondary winding of the main transformer
Tr1 supplies power to an electric motor and its tertiary winding supplies power to
auxiliary equipment such as air-conditioners and illumination.
[0025] High-voltage pull-through cables that are branched by T branch joints TJ1, TJ2 of
the fourth car (4
th car) and sixth car (6
th car) are respectively connected to the primary sides of power receiving vacuum circuit
breakers VCB2, VCB3 provided under the floors. The secondary sides of the power receiving
vacuum circuit breakers VCB2, VCB3 are respectively connected to the primary windings
of main transformers Tr2, Tr3. The secondary windings of the main transformers Tr2,
Tr3 supply power to electric motors and their tertiary windings supply power to the
auxiliary equipment.
[0026] Note that power may be supplied to the electric motors and auxiliary equipment via
a power converter from the main transformers.
[0027] As described above, the power receiving vacuum circuit breakers VCB1, VCB2, VCB3
and the main transformers Tr1, Tr2, Tr3 are disposed under the floors and other components
of electric equipment (RC1 to 5, SJ1 to 4, PG1 to 2, TJ1 to 2) are disposed on the
roofs. Because VCB1 to 3 and Tr1 to 3 are disposed under the floors, work on the roofs
for installing, maintaining, and inspecting components of electrical equipment is
reduced. Also, when components of electrical equipment are disposed on the roofs,
space in a height direction is much restricted. Nevertheless, as will be described
later, the dimension of a vacuum switch in a height direction can be decreased according
to Example 1 of the present invention and, therefore, the vacuum switch can be installed
easily on the roofs.
[0028] Figure 3 illustrates another example of the train set of the railway cars on or in
which vacuum switches as Example 1 are mounted. In addition, Figure 4 illustrates
a feeding circuit in the railway cars in Figure 3.
[0029] As shown in Figure 3 and Figure 4, in the present Example, the high-voltage pull-through
cables RC1 to 5, straight joints SJ1 to 4, and T branch joints TJ1 to 2 are installed
under the floors (Under Floor). In addition, some high-voltage cables are led inside
the cars from the pantographs PG1, PG2 and connected to the high-voltage pull-through
cables RC3, RC5, respectively. When components of electrical equipment are installed
under the floors in this way, installation space is much restricted. Nevertheless,
a vacuum switch can be installed easily under the floors according to Example 1 that
will be described later.
[0030] As shown in Figure 2 and Figure 4, in a case where a line-to-ground fault (Fault)
has occurred at the high-voltage pull-through cable RC2 in the third car (3
rd car), a vacuum switch is operated by a command from outside to open the straight
joint SJ2 automatically, thereby disconnecting the main transformer Tr1 and an electric
motor connected thereto that are affected by the line-to-ground fault (Fault) from
the feeding circuit. At this time, the main transformers Tr2, Tr3 that are not affected
by the line-to-ground fault (Fault) remain connected to the feeding circuit and, therefore,
operation of the railway cars can be continued using electric motors that are connected
to these transformers.
[0031] Note that a vacuum switch to be operated, i.e., a straight joint (SJ2 or SJ4) to
be disconnected is selected appropriately depending on the location of the line-to-ground
fault. Thereby, it is possible to' separate high-voltage cables that are healthy from
a high-voltage cable including the fault location automatically.
[0032] Then, a vacuum switch as Example 1 of the present invention is described with Figures
5 to 7. Note that a vacuum switch of the present Example 1 is integrated with a T
branch joint (TJ1 or TJ2) and a straight joint (SJ2 or SJ4) in a case where it is
mounted on or in the railway car.
[0033] Figure 5 illustrates an external view of a vacuum switch as Example 1 of the present
invention. Dashed lines in Figure 5 show an internal structure. Note that Figure 5
is a plan view of the vacuum switch being installed on or in the railway car (the
same is also true for Figures 6 and 7). Therefore, a longitudinal direction of the
vacuum switch is along a longitudinal direction of the railway car.
[0034] As shown in Figure 5, the vacuum switch of the present Example 1 is mounted on or
in the railway car with the vacuum switch being set stationary on a base 81 via stays
83A to 83C.
[0035] Figure 6 is a cross-sectional view of the vacuum switch of Example 1 when cut along
the longitudinal direction. Note that the cutting plane is a plane including the central
axis of a movable electrode 5a and an air insulated actuating rod 20 which will be
described later.
[0036] As shown in Figure 6, the vacuum switch of Example 1 includes a vacuum interrupter
1 comprising a fixed electrode 3a, a movable electrode 5a that comes in or out of
contact with the fixed electrode 3a, an arc shield 6 that covers surrounding of the
fixed electrode 3a and the movable electrode 5a, a ceramic insulating cylinder 7 having
a cylindrical form and forming a part of an outer container that supports the arc
shield 6, and a bellows 2, as main parts.
[0037] The outer container of the vacuum interrupter 1 is comprised of the ceramic insulating
cylinder 7 and end plates covering both ends of the ceramic insulating cylinder 7,
and its inside is maintained in a vacuum state. The fixed electrode 3a is connected
to a fixed conductor 3b and the fixed conductor 3b is extended outside the vacuum
interrupter 1 and electrically connected to a bushing conductor 12A adjacent to the
fixed conductor 3b. The movable electrode 5a is connected to a movable conductor 5b
and the movable conductor 5b is extended outside the vacuum interrupter 1 and electrically
connected to bushing conductors 12B, 12C adjacent to the movable conductor 5b.
[0038] The vacuum interrupter 1, the bushing conductor 12A adjacent to the fixed conductor
3b, and the bushing conductors 12B, 12C adjacent to the movable conductor 5b are molded
and coated with a solid insulator 21 made of epoxy resin or the like. In addition,
the surface of the solid insulator 21 is covered with a ground layer 23. Ground potential
is given to the ground layer 23. Note that the ground layer 23 is formed by metallic
spraying or applying a conductive coating material among others. The outermost ends
of the respective bushing conductors toward external air are not molded with the solid
insulator 21 and a conductor portion is exposed. These outermost ends make up connection
ports 10A, 10B, 10C with T-shape cable heads (Figure 7).
[0039] In a movable side of the vacuum interrupter 1, the bellows 2 is disposed between
the movable conductor 5b and the movable-side end plate. This bellows allows the movable
conductor 5b to move, while maintaining the vacuum state of the vacuum interrupter
1. Also, in the movable side of the vacuum interrupter 1, an electromagnetic actuator
30 that actuates an air insulated actuating rod 20 is provided. A movable side actuating
axis of the electromagnetic actuator 30 is coaxially connected to the air insulated
actuating rod 20 via an actuating link portion 31. The electromagnetic actuator 30,
the actuating link portion 31, and an end portion of the air insulated actuating rod
20 connected to the electromagnetic actuator 30 are stored in a mechanics case 82
that coaxially contacts a substantially cylindrical mold part made by the solid insulator
21. Therefore, in the vacuum switch, the electromagnetic actuator 30 is disposed coaxially
with the air insulated actuating rod 20.
[0040] In the electromagnetic actuator 30, for example, using a device combining a permanent
magnet and an electromagnet with a spring, by turning ON/OFF electric conduction to
a coil forming an electromagnet, a drive force is generated. Note that the structure
of the electromagnetic actuator 30 in the present Example is publicly known and detailed
description of the electromagnetic actuator 30 is omitted.
[0041] Using the electromagnetic actuator 30, by actuating a drive axis of the movable electrode
5a, provided by coupling the air insulated actuating rod 20 and the movable conductor
5b integrally and coaxially with a metallic adapter 24, it is possible to make the
movable electrode 5a come in or out of contact with the fixed electrode 3a while ensuring
a sufficient insulation distance between the vacuum interrupter 1 and the electromagnetic
actuator 30. Moreover, between the movable conductor 5b and the bushing conductors
12B, 12C, there are the metallic adapter 24 and a flexible conductor 27 that electrically
connects the metallic adapter 24 and the bushing conductors, moving with the movable
conductor 5b; thereby, conductivity and movability are ensured.
[0042] Furthermore, in the present Example 1, as shown in Figure 6, within the solid insulator
21, a conductive shield 13 is provided to cover the outer periphery of a connection
portion between an end portion of the air insulated actuating rod 20 toward the movable
conductor 5b and the movable conductor 5b. The conductive shield 13 is electrically
connected with the movable conductor 5b via the bushing conductors 12B, 12C and the
flexible conductor 27. Also, an end portion of the conductive shield 13 toward the
movable conductor 5b is in contact with and electrically connected with the bushing
conductors 12B, 12C adjacent to the movable conductor 5b.
[0043] Within the solid insulator 21, the conductive shield 13 extends from a portion where
it contacts the bushing conductors 12B, 12C adjacent to the movable conductor 5b toward
a direction of the electromagnetic actuator 30. Thereby, the conductive shield 13
covers the periphery of the metallic adapter 24, a housing 25, and a shaft support
26, and the flexible conductor 27, existing around the connection portion between
the air insulated actuating rod 20 and the movable conductor 5b, that is, the periphery
of conductor portions around the connection portion between the air insulated actuating
rod 20 and the movable conductor 5b and, in addition, the periphery of an air-exposed
part of the air insulated actuating rod 20 extending from a connection portion with
the metallic adapter 24 toward the direction of the electromagnetic actuator 30.
[0044] Additionally, the conductive shield 13 is made of a conductive material such as metal
and conductive rubber.
[0045] By this conductive shield 13 and the abovementioned ground layer 23, when high voltage
is applied to the conductive shield 13 via the bushing conductors 12B, 12C, an electric
field concentrates inside the solid insulator 21 between the conductive shield 13
and the ground layer 23 and electric field concentration is relaxed in the air surrounding
the conductor portions around the connection portion between the air insulated actuating
rod 20 and the movable conductor 5b. Moreover, a region where the electric field is
concentrated between the conductive shield 13 and the ground layer 23 and in an end
portion of the conductive shield 13 toward the electromagnetic actuator 30 is covered
with the solid insulator 21 having higher dielectric strength than air. Owing to those
above, the insulation characteristic of the vacuum switch improves even with provision
of the ground layer 23. Therefore, according to the present Example 1, a decrease
in insulation distance to peripheral components of equipment is enabled and the insulation
characteristic of the vacuum switch improves.
[0046] Note that, because the solid insulator inner wall 22 near an end portion of the conductive
shield 13 contacts air, insulation may be weakened potentially in this portion. Therefore,
in the present Example 1, a thickness b of the solid insulator 21 between the solid
insulator inner wall 22 and the conductive shield 13 is made larger than a thickness
a of the solid insulator 21 between the ground layer 23 and the conductive shield
13 (b > a), as indicated in section A circled with a dashed line in Figure 6. Thereby,
within the solid insulator 21, the conductive shield 13 is disposed nearer to the
outer surface of the solid insulator 21, i.e., the ground layer 23 than the solid
insulator inner wall 22. That is, within the solid insulator 21, the conductive shield
13 is disposed far from the solid insulator inner wall 22 or close to the outer surface
of the solid insulator 21 and there can be an increase in the thickness of the solid
insulator 21 between the solid insulator inner wall 22 and the conductive shield 13.
Consequently, field strength at the solid insulator inner wall 22 can be decreased.
Note that the thickness a is set to a dimension to adjust the field strength so that
an electric field between the conductive shield 13 and the ground layer 23 does not
cause deterioration in insulation of the solid insulator 21.
[0047] In addition, in the present Example 1, the end portion of the conductive shield 13
toward the electromagnetic actuator 30 bends toward the ground layer 23 within the
solid insulator 21. This makes the above end portion farther from its adjacent solid
insulator inner wall 22 and, consequently, electric field concentration can be relaxed
at the solid insulator inner wall 22 where electric field concentration is liable
to occur.
[0048] Moreover, the solid insulator inner wall 22 adjacent to the end portion of the conductive
shield 13 has a convex curved inner wall surface facing an air space in the vacuum
switch. More specifically, the solid insulator inner wall 22 has a first cylindrical
inner wall surface with an inner diameter being substantially constant for a section
from a portion adjacent to the connection portion between the air insulated actuating
rod 20 and the movable conductor 5b to a portion adjacent to the end portion of the
conductive shield 13, has the convex curved surface facing the air space for a section
adjacent to the end portion of the conductive shield 13, and has a second cylindrical
inner wall surface with an inner diameter being substantially constant and larger
than the first inner wall surface for a section extending toward the electromagnetic
actuator 30 from the portion adjacent to the end portion of the conductive shield
13. These first inner wall surface, convex curved inner wall surface facing the air
space, and second inner wall surface form a smoothly continuing surface.
[0049] Additionally, the entire thickness of the solid insulator 21 abutting the first inner
wall surface and the entire thickness of the solid insulator abutting the second inner
wall surface are approximately equal; for example, the insulator thickness is set
to a thickness that is the sum of thickness dimensions a and b in section A in Figure
6 plus the thickness of the conductive shield 13 or a thickness that is the sum of
thickness dimensions a and b. Thereby, the mechanical strength and insulation performance
of the vacuum switch improve.
[0050] Additionally, in the present Example 1, in conjunction with the setting of the entire
thickness of the solid insulator 21, the outer surface that contacts external air
of the solid insulator 21, i.e., the outer surface of the ground layer 23 has a first
cylindrical outer surface with an outer diameter being substantially constant for
a section from the portion adjacent to the connection portion between the air insulated
actuating rod 20 and the movable conductor 5b to the portion adjacent to the end portion
of the conductive shield, a convex curved surface facing the external air for a section
adjacent to the end portion of the conductive shield 13, and has a second cylindrical
outer surface with an outer diameter being substantially constant and larger than
the first outer surface for a section extending toward the electromagnetic actuator
30 from the portion adjacent to the end portion of the conductive shield 13. These
first outer surface, convex curbed outer surface facing the external air, second outer
surface form a smoothly continuing surface. That is, the shape of the outer surface
of the solid insulator 21 and the ground layer 23 is similar to the shape of the inner
wall surface of the solid insulator 21.
[0051] By of the above-described shape of the solid insulator inner wall and owing to the
fact that this shape allows for an increase in the thickness of the solid insulator
21 between the solid insulator inner wall 22 and the conductive shield 13 in a portion
adjacent to the end portion of the conductive shield 13 toward the electromagnetic
actuator 30, it is possible to relax electric field concentration at the solid insulator
inner wall 22 adjacent to the end portion of the conductive shield.
[0052] Additionally, as described previously, by setting thickness dimensions a and b of
the solid insulator 21 to be a < b, as indicated in section A in Figure 6, so that
the conductive shield is disposed nearer to the outer surface of the solid insulator
21, heat radiation performance of the vacuum switch improves.
[0053] As shown in Figure 6, in the vacuum switch of the present Example 1, a guide 8 and
a shaft support 26 are provided to restrict the direction of movement of the drive
axis of the movable electrode 5a and enhance smoothness of a sliding motion; the movable
electrode 5a, movable conductor 5b, metallic adapter 24, and air insulated actuating
rod 20 are coaxially assembled on the above drive axis. The guide 8 supports a shaft
of the movable conductor 5b that is constituent of the drive axis of the movable electrode
5a. Also, the shaft support 26 that is held in the housing 25 supports a shaft of
the metallic adapter 24 that is constituent of the drive axis of the movable electrode
5a. In this way, the support of shaft is provided by two components which are the
guide 8 and the support shaft 26. This improves the accuracy of centering of the movable
conductor 5b, metallic adapter 24, and air insulated actuating rod 20 that are assembled
coaxially and, consequently, smoothness of the sliding motion improves. Note that,
in the present Example 1, the guide 8 and the shaft support 26 have a shape in which
a flange is placed on one end of a short tube; however, they may have another shape,
not limited to this shape.
[0054] In the present Example 1, inside the vacuum switch, a space surrounding the air insulated
actuating rod 20 and a space surrounding the connection portion between the air insulated
actuating rod 20 and the movable conductor 5b are filled with air and ambient gas
is atmospheric air; however, there is no limitation to this and such space may be
filled with insulating gas such as dry air and SF6 gas. This contributes to improvement
in the insulation performance of the vacuum switch. Additionally, in this case, using
sealing means such as a sealant, sealing is provided between the opening of the solid
insulator 21 toward the electromagnetic actuator 30 and the opening of the mechanics
case 82 abutting the solid insulator to keep in insulating gas inside the vacuum switch.
[0055] Figure 7 illustrates a state in which T-shape cable heads 40A, 40B, 40C are connected
to the vacuum switch of the present Example 1.
[0056] Conductor portions inside the T-shape cable heads 40A, 40B, 40C that are respectively
connected with the end portions of cables 42A, 42B, 42C are bolted onto the outermost
ends of the bushing conductors 12A, 12B, 12C, respectively. The conductor portions
are stored inside T-shaped insulating resin. A T-shape head has a hollow portion for
mating with a bushing part and bolt fastening of a conductor portion and both ends
of the head are open. An opening for bolt fastening is closed with an insulation plug
(41A, 41B, 41C) and, therefore, a connection portion between each bushing conductor
and each T-shape cable head is covered with an insulator and is not exposed to outside.
[0057] As shown in Figure 7, in the vacuum switch of the present Example 1, the vacuum interrupter
1, air insulated actuating rod 20, and electromagnetic actuator 30 are disposed coaxially
and substantially in line. In addition, the bushing conductors 12A, 12B, 12C protrude
in a direction perpendicular to the longitudinal direction of the vacuum switch, i.e.,
a direction perpendicular to a direction in which the movable electrode 5a, movable
conductor 5b, and air insulated actuating rod 20 moves and in a direction parallel
to the plane on which the vacuum switch is set stationary on the base 81. Thereby,
with the cables connected to the vacuum switch, the electromagnetic actuator 30 and
the T-shape cable heads 40A, 40B, 40C do not interfere with each other and it is possible
to decrease the height and width dimensions of the vacuum switch after cable connection.
[0058] As described previously, according to the present Example 1, the surface of the solid
insulator 21 that molds the constituent parts of the vacuum switch is covered with
the ground layer 23 and the conductive shield 13 is provided within the solid insulator
to cover around the connection portion between the air insulated actuating rod 20
and the movable conductor 5b; thereby, the insulation performance of the vacuum switch
can be improved even with provision of the ground layer 23. In addition, because it
is possible to decrease the height and width dimensions of the vacuum switch after
cable connection, it is possible to increase the degree of freedom of a location where
the vacuum switch is installed on or in the railway cars or the like. In addition,
owing to the fact that the surface of the vacuum switch is covered with the ground
layer 23, it is possible to decrease the insulation distance between the vacuum switch
and its peripheral components of equipment, and therefore, it is possible to decrease
the entire space for installing the vacuum switch together with its peripheral components
of equipment.
<Example 2>
[0059] Figure 8 is a cross-sectional view of a vacuum switch as Example 2 of the present
invention when cut along the longitudinal direction. The following description focuses
on a point that differs from Example 1.
[0060] First, in the case of the present Example 2, as with Example 1, the solid insulator
inner wall 22 has a first cylindrical inner wall surface with an inner diameter being
substantially constant for a section from a portion adjacent to the connection portion
between the air insulated actuating rod 20 and the movable conductor 5b to a portion
adjacent to the end portion of the conductive shield 13, has a convex curved surface
facing the air space for a section adjacent to the end portion of the conductive shield
13, and has a second cylindrical inner wall surface with an inner diameter being substantially
constant and larger than the first inner wall surface for a section extending toward
the electromagnetic actuator 30 from the portion adjacent to the end portion of the
conductive shield 13. These first inner wall surface, convex curved inner wall surface
facing the air space, and second inner wall surface form a smoothly continuing surface.
[0061] In the present Example 2, unlike Example 1, the entire thickness of the solid insulator
21 abutting the second inner wall surface is smaller than the entire thickness of
the solid insulator 21 abutting the first inner wall surface. That is, the entire
thickness of the solid insulator 21 abutting the second inner wall surface is, for
example, set to a thickness that is smaller than a thickness that is the sum of thickness
dimensions a and b in section A in Figure 6 plus the thickness of the conductive shield
13 or a thickness that is the sum of thickness dimensions a and b.
[0062] That is, in the present Example 2, in the solid insulator 21, the thickness of the
solid insulator 21 is decreased for a section going far from a section adjacent to
the end portion of the conductive shield 13, where an electric field easily concentrates,
toward the electromagnetic actuator 30, in other words, a section where field strength
becomes lower than that in the section adjacent to the end portion of the conductive
shield 13. Thereby, the weight of the solid insulator 21 is decreased without affecting
the insulation performance of the vacuum switch, and consequently, it is possible
to make the vacuum switch lighter.
<Example 3>
[0063] Figure 9 illustrates an external view of a vacuum switch as Example 3 of the present
invention. Dashed lines in Figure 9 show an internal structure. Note that Figure 9
is a plan view of the vacuum switch being installed on or in the railway car. Hence,
the longitudinal direction of the vacuum switch is along the longitudinal direction
of the railway car. The following description focuses on a point that differs from
Example 1.
[0064] In the present Example 3, unlike Example 1, only one bushing conductor 12B is provided
adjacently to the movable conductor 5b. That is, in respect of functions as straight
joints and T-shape joints, the vacuum switch of the present Example 3 only has a function
as straight joints for connection of a cable (corresponding to the cable 42A in Figure
7) that is connected to the bushing conductor 12A and a cable (corresponding to the
cable 42B in Figure 7) that is connected to the bushing conductor 12B.
[0065] According to the present Example 3, in a case where there are a location where a
cable branch is present and a location where a cable branch is not present, as in
the railway car, it is possible to improve the insulation performance of the vacuum
switch integrated with a straight joint in the location where a cable branch is not
present and to decrease the insulation distance between the vacuum switch and its
peripheral components of equipment. In addition, it is possible to decrease the height
and width dimensions of the vacuum switch after cable connection.
<Example 4>
[0066] Figure 10 illustrates an external view of a vacuum switch as Example 4 of the present
invention. Dashed lines in Figure 10 show an internal structure. Note that Figure
10 is a plan view of the vacuum switch being installed on or in the railway car. Hence,
the longitudinal direction of the vacuum switch is along the longitudinal direction
of the railway car. The following description focuses on a point that differs from
Example 1.
[0067] In the present Example 4, as with Example 1, two bushing conductors 12B, 12C are
provided adjacently to the movable electrode 5a; whereas, unlike Example 1, two bushing
conductor 12A, 12D are also provided adjacently to the fixed electrode 3a. Thereby,
the vacuum switch of the present Example 3 has a function as straight joints for connection
of a cable (corresponding to the cable 42A in Figure 7) that is connected to the bushing
conductor 12A and a cable (corresponding to the cable 42B in Figure 7) that is connected
to the bushing conductor 12B, a function as T-shape joints for branching of a cable
(corresponding to the cable 42C in Figure 7) that is connected to the bushing conductor
12C in the side of the movable electrode 5a, and a function as T-shape joints for
branching of a cable that is connected to a bushing conductor 12D in the fixed side.
[0068] In the present Example, because cable branching is enabled also in the side of the
fixed electrode 3a in addition to the side of the movable electrode 5a, it is possible
to expand the degree of freedom of circuit configurations of the feeder circuit.
<Example 5>
[0069] Figure 11 illustrates an external view of a vacuum switch as Example 5 of the present
invention. Dashed lines in Figure 11 show an internal structure. Note that Figure
11 is a side view of the vacuum switch being installed on or in the railway car. Note
that the longitudinal direction of the vacuum switch is along the longitudinal direction
of the railway car. The following description focuses on a point that differs from
Example 1.
[0070] In the present Example 5, as shown in Fig. 11, the air insulated actuating rod 20
and the electromagnetic actuator 30 are not disposed coaxially and the air insulated
actuating rod 20 and the movable side actuating axis of the electromagnetic actuator
30 are placed at different heights from the base 81 in a state when the vacuum switch
is installed. The air insulated actuating rod 20 and the movable side actuating axis
of the electromagnetic actuator 30 are connected via a link 84 as well as the actuating
link portion 31. That is, the air insulated actuating rod 20 and the movable side
actuating axis of the electromagnetic actuator 30 are coupled non-coaxially via the
link 84. Thereby, strokes of the electromagnetic actuator can be made different from
strokes of the air insulated actuating rod 20 and the degree of freedom of setting
the strokes of both expands. Consequently, workability of stroke adjustment improves.
In addition, by providing the link 84 with a mechanism acting as a lever, it is possible
to decrease the output of the electromagnetic actuator 30. Thereby, the electromagnetic
actuator 30 can be downsized. Consequently, the electromagnetic actuator 30 can be
stored in the mechanics case 82.
<Example 6>
[0071] Figure 12 illustrates an external view of a vacuum switch as Example 6 of the present
invention. Dashed lines in Figure 12 show an internal structure. Note that Figure
12 is a side view of the vacuum switch installed on the roof of the railway car along
the longitudinal direction. The longitudinal direction of the vacuum switch is along
the longitudinal direction of the railway car. Also, Figure 12 depicts a state when
the T-shape cable heads have been connected to the vacuum switch. The following description
focuses on a point that differs from Example 1.
[0072] As shown in Figure 12, in the present Example 6, the base 81 of the vacuum switch
is installed on the train roof 86. In addition, two bushing conductors 12A, 12 D in
the side of the fixed conductor 3b and a bushing conductor 12C in the side of the
movable conductor 5b are disposed in a direction perpendicular to the longitudinal
direction of the vacuum switch and in a direction perpendicular to the plane of the
base 81. That is, the bushing conductors 12A, 12C, 12D protrude in a direction perpendicular
to the plane on which the vacuum switch is installed. Thereby, the bushing conductor
12A protrudes inside the car under the train roof 86 and the cable that is connected
to the bushing conductor 12A can be wired under the train roof 86.
[0073] Note that, even by organizing the bushing conductors as in the present Example 6
(two in the fixed conductor side and one in the movable conductor side) (one in the
fixed conductor side and two in the movable conductor side in Example 1), the vacuum
switch can have both straight joint and T branch joint functions.
[0074] Note that a place where the base 81 is installed is not limited to on the train roof
86 as in the present Example 6 and may be, inter alia, under the roof, on the floor,
or under the floor of the railway car. In each case, the bushing conductor 12A is
protruded and its cable can be wired in an opposite side to the side where the vacuum
switch is located with respect to the base 81. Consequently, the degree of freedom
of placing the vacuum switch expands.
[0075] Now, the present invention is not limited to Examples described hereinbefore and
various modifications are included therein. For example, the foregoing Examples are
those described in detail to explain the present invention clearly and the invention
is not necessarily limited to those including all components described. In addition,
for a subset of the components of each Example, other components may be added to the
subset or the subset may be removed or replaced by other components.
[0076] For instance, a vacuum switch according to the present invention is applicable to
various types of power receiving and power distribution facilities, not limited to
railway car application. In addition, a vacuum switch according to the present invention
may be installed such that its longitudinal direction is along a direction perpendicular
to a horizontal plane of a site where it is installed.
Reference Signs List
[0077] PG1, PG2: pantographs, RC1, RC2, RC3, RC4, RC5: high-voltage pull-through cable,
SJ1, SJ2, SJ3, SJ4: straight joint, TJ1, TJ2: T branch joint, Tr1, Tr2, Tr3: main
transformer, VCB1, VCB2, VCB3: power receiving vacuum circuit breaker, 1: vacuum interrupter,
2: bellows, 3a: fixed electrode, 3b: fixed conductor, 5a: movable electrode, 5b: moveable
conductor, 6: arc shield, 7: ceramic insulating cylinder, 8: guide, 10A, 10B, 10C,
10D: connection port, 12, 12A, 12B, 12C, 12D: bushing conductor, 13: conductive shield,
20: air insulated actuating rod, 21: solid insulator, 22: solid insulator inner wall,
23: ground layer, 24: metallic adapter, 25: housing, 26: shaft support, 27: flexible
conductor, 30: electromagnetic actuator, 31: actuating link portion, 40A, 40B, 40C,
40D: T-shape cable head, 41A, 41B, 41C, 41D: insulation plug, 42A, 42B, 42C, 42D:
cable, 81: base, 82: mechanics case, 83A, 83B, 83C: stay, 84: link, 86: train roof
1. A solid dielectric vacuum switch comprising:
a vacuum interrupter having a fixed electrode, a movable electrode, a fixed conductor
that is connected to the fixed electrode, and a movable conductor that is connected
to the movable electrode;
an insulated actuating rod that is mechanically connected to the movable conductor;
an actuator that actuates the insulated actuating rod; and
a solid insulator covering the vacuum interrupter, wherein a ground layer covering
an outer surface of the solid insulator is provided; and
a conductive shield is provided within the solid insulator, the conductive shield
covering around a connection portion between the movable conductor and the insulated
actuating rod.
2. The solid dielectric vacuum switch according to claim 1,
wherein the conductive shield is disposed nearer to the ground layer than an inner
wall of the solid insulator.
3. The solid dielectric vacuum switch according to claim 1,
wherein a thickness of the solid insulator between an inner wall of the solid insulator
and the conductive shield is larger than a thickness of the solid insulator between
the ground layer and the conductive shield.
4. The solid dielectric vacuum switch according to any one of claims 1 to 3,
wherein an end portion of the conductive shield bends toward the ground layer.
5. The solid dielectric vacuum switch according to any one of claims 1 to 3,
wherein an inner wall surface of the solid insulator adjacent to an end portion of
the conductive shield has a convex curved surface facing an air space.
6. The solid dielectric vacuum switch according to claim 1,
wherein a thickness of the solid insulator for a section between the end portion of
the conductive shield and the actuator is smaller than a thickness of the solid insulator
for a section between the connection portion between the movable conductor and the
insulated actuating rod and the end portion of the conductive shield, wherein these
sections are contiguous.
7. The solid dielectric vacuum switch according to claim 1, comprising:
a first bushing conductor that is connected to the fixed conductor; and
a second bushing conductor that is connected to the movable conductor,
wherein the first bushing conductor and the second bushing conductor are covered with
the solid insulator.
8. The solid dielectric vacuum switch according to claim 7, comprising a third bushing
conductor that is connected to the fixed conductor or the movable conductor,
wherein the third bushing conductor is covered with the solid insulator.
9. The solid dielectric vacuum switch according to claim 1, comprising a plurality of
bushing conductors, each of which is connected to one of the fixed conductor and the
movable conductor,
wherein the plurality of bushing conductors are covered with the solid insulator;
and
the plurality of bushing conductors are disposed in a direction perpendicular to a
movable direction of the movable electrode, the movable conductor, and the insulated
actuating rod.
10. The solid dielectric vacuum switch according to claim 9,
wherein the movable electrode, the movable conductor, and the insulated actuating
rod are coupled coaxially.
11. The solid dielectric vacuum switch according to claim 1, comprising a plurality of
bushing conductors, each of which is connected to one of the fixed conductor and the
movable conductor,
wherein the plurality of bushing conductors are covered with the solid insulator;
and
the plurality of bushing conductors protrude in a direction parallel to a plane on
which the vacuum switch is installed.
12. The solid dielectric vacuum switch according to claim 1, comprising a plurality of
bushing conductors, each of which is connected to one of the fixed conductor and the
movable conductor,
wherein the plurality of bushing conductors are covered with the solid insulator;
and
the plurality of bushing conductors protrude in a direction perpendicular to a plane
on which the vacuum switch is installed.
13. The solid dielectric vacuum switch according to claim 1,
wherein the insulated actuating rod and a movable side actuating axis of the actuator
are coupled coaxially.
14. The solid dielectric vacuum switch according to claim 1,
wherein the insulated actuating rod and a movable side actuating axis of the actuator
are coupled non-coaxially via a link portion.