VACUUM SWITCH INCLUDING AN INSULATING BODY
HAVING A NUMBER OF TRANSPARENT PORTIONS
MADE OF A SINGLE CRYSTAL ALUMINA
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. Patent Application Serial
No. 13/195,070, filed August 1, 0 1, entitled "Vacuum Switch Including A
Insulating Body Having A Number Of Transparent Portions Made Of A Single
Crystal Alumina," which is hereby incorporated by reference herein.
BACKGROUND
Field
The disclosed concept pertains to vacuum switching apparatus such as,
for example, vacuum switches including a vacuum envelope such as, for example,
vacuum interrupters.
Background Information
Vacuum interrupters include separable main contacts disposed within
an insulated and hermetically sealed vacuum chamber. The vacuum chamber
typically includes, for example and without limitation, a number of sections of
ceramics (e.g., without limitation, a number of tubular ceramic portions) for electrical
insulation capped by a number of end members (e.g., without limitation, metal
components, such as metal end plates; end caps; seal cups) to form an envelope n
which a partial vacuum may be drawn. The example ceramic section is typically
cylindrical; however, other suitable cross-sectional shapes may be used. Two end
members are typically employed. Where there are multiple ceramic sections, an
internal center shield may be disposed between the example ceramic sections.
Typically, the number of sections of ceramics for electrical insulation
are a number of solid opaque structures.
U.S. Patent No. 4,408,107 discloses a vacuum envelope including a
housing made of non-magnetic metallic material with end plates fabricated from
insulating material in the form of a ceramic or crystallized glass.
U.S. Patent No. 4,249,050 discloses a vacuum switch comprising a
vacuum vessel defined by an insulating cylinder, which is preferably made of a
transparent material such as glass, and end plates. A cylindrical member may b
constructed by a metal cylinder which is provided with a glass window at a portion
corresponding to a gap between shields to permit direct observation of the interior of
the vacuum vessel.
U.S. Patent Application Pub. No. 2007/0278187 discloses a vacuum
bottle attached to a housing to form a switch or interrupter assembly. The vacuum
bottle contains a contact. An actuating element connects to an actuating mechanism
for either a switch or interrupter. An indicator for the contact is attached to an
insulated rod of the actuating mechanism. The indicator has a red portion (for
indicating the contact is closed) and a green portion (for indicating the contact is
open). A viewing window extends through the housing so that, when the actuating
mechanism opens or closes the contact, the red portion or green portion of the
indicator is aligned with the viewing window and shows the position of the contact.
U.S. Patent Application Pub. No. 2007/0295694 discloses a vacuum
bottle with a viewing window that is mounted in series with a circuit breaker within a
porcelain casing. A rigid tube and a elastomer casing are arranged to define an
observation window that is at least translucent, and through which the open or closed
posit ion of switch contacts can be seen. The rigid tube is made by molding a plastics
material that is transparent or at least translucent. The plastics material may be a
transparent thermoplastic polymer such as safety glass.
There is room for improvement n electrical switching apparatus, such
as vacuum switches.
There is also room for improvement i vacuum interrupters.
SUMMARY
These needs and others are met by embodiments of the disclosed
concept in which a vacuum switch comprises a number of transparent portions such
as, for example and without limitation, window(s), region(s), body or bodies present
in an insulating body. As a result, all of the insulating body or a portion of the
insulat ing body is made from a transparent material made of a single crystal alumina
(AI2O3) for viewing a fixed contact assembly and a movable contact assembly within
a vacuum envelope.
accordance with embodiments of the disclosed concept, a vacuum
switch comprises: a vacuum envelope: a fixed contact assembly partially within the
vacuum envelope; and a movable contact assembly partially within the vacuum
envelope and movable between a closed position in electrical contact with the fixed
contact assembly and an open position spaced apart from the fixed contact assembly;
wherein the vacuum envelope comprises a insulating body comprising a number of
transparent portions made of a single crystal alumina (ANO. for viewing the fixed
contact assembly and the movable contact assembly within the vacuum envelope.
The number of transparent portions may be a number of sapphire
members.
The insulating body may further comprise a number of openings; and
each of the number of sapphire members may b brazed to the insulating body at a
corresponding one of the number of openings.
The insulating body may be made of the single crystal alumina
(AI2O3); and the number of transparent portions may b all of the insulating body.
The insulating body may be in the form of a solid cylinder made of the
single crystal alumina (AI2O3) .
The number of transparent portions may be a number of transparent
windows.
The number of transparent portions may be a number of transparent
regions.
The number of transparent portions may be all of the insulating body.
The insulating body may further comprise a number of openings; and
each of the number of transparent portions may be brazed to the insulating body at a
corresponding one of the number of openings.
The insulating body may be metalized at a number of edges; each of
the number of edges may be defined by a corresponding one of the number of
openings; each of the number of transparent portions may be metalized at a peripheral
edge corresponding to one of the metalized number of edges of the insulating body;
and the metalized peripheral edge may be brazed to a corresponding one of the
metalized number of edges of the insulating body.
BR1EF DESCRIPTION OF THE DRAWINGS
A full understanding of the disclosed concept can be gained from the
following description of the preferred embodiments when read in conjunction with the
accompanying drawings which:
Figure 1 is a partially exploded isometric view of a vacuum switch in an
open position i accordance with embodiments of the disclosed concept.
Figure 2 is an isometric view of the vacuum switch of Figure 1 in a
closed position.
Figure 3 is an isometric view of a vacuum switch in an open position in
accordance with another embodiment of the disclosed concept.
Figure 4 is an isometric view of the vacuum switch of Figure 3 in a
closed position.
Figure 5 is an isometric view of a vacuum switch i a closed position n
accordance with another embodiment of the disclosed concept.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As employed herein, the term "number" shall mean one or an integer
greater than one (i.e., a plurality).
As employed herein, the statement that two or more parts are
"connected" or "coupled" together shall mean that the parts are joined together either
directly or joined through one or more intermediate parts. Further, as employed
herein, the statement that two or more parts are "attached" shall mean that the parts
are joined together directly.
As employed herein, the term "vacuum envelope" means an envelope
employing a partial vacuum therein.
As employed herein, the term "partial vacuum" means a space (e.g.,
within a vacuum envelope) partially exhausted (e.g., to the highest degree practicable;
to a relatively high degree; to a degree suitable for use n a vacuum switching
apparatus application) by a suitable mechanism (e.g., without limitation, an air pump;
a vacuum furnace).
The disclosed concept is described n association with vacuum
interrupters, although the disclosed concept is applicable to a wide range of vacuum
switches.
The disclosed concept enables the separable contacts of a vacuum
interrupter to be seen in an open or closed position by employing a number of
transparent portions as part of or as an insulating body.
Although glass windows are known, glass is not as robust as ceramic,
polycrystaline alumina, single crystal alumina or sapphire, and will break easier.
Over time, because glass is not as dense as ceramic, polycrystaline alumina, single
crystal alumina or sapphire, the glass will allow hydrogen to permeate through the
glass and cause a vacuum switch to lose the quality of its partial vacuum. Ceramic,
polycrystaline alumina, single crystal alumina or sapphire provide a good quality
partial vacuum virtually forever. A o, attaching glass to ceramic will present
problems since the dielectric strength of glass is not as good a the dielectric strength
of ceramic, polycrystaline alumina, single crystal alumina or sapphire.
Referring to Figures 1 and 2, a vacuum switch, such as a vacuum
interrupter 2, is shown. The vacuum switch 2 includes a vacuum envelope 4, a fixed
contact assembly 6 partially within the vacuum envelope 4, and a movable contact
assembly 7 partially within the vacuum envelope 4 and movable between a closed
position (Figure 2) in electrical contact with the fixed contact assembly 6 and a open
position (Figure 1) spaced apart from the fixed contact assembly 6. The vacuum
envelope 4 is an insulating body including a number of transparent portions 8 (e.g.,
without limitation, two transparent portions 8 are shown in Figures 1 and 2 ) made of a
single crystal alumina (AI2O3) (e.g., sapphire) for viewing the fixed contact assembly
6 and the movable contact assembly 7 within the vacuum envelope 4.
The insulating body 5 of the vacuum envelope 4 may be made of
polycrystaline alumina (AI2O3) .
The number of transparent portions 8 may be a number of sapphire
members.
As show n in Figures 1 and 2, the transparent portions 8 are example
transparent sapphire members (e.g., disks) brazed into the insulating body 5 f the
vacuum envelope 4. This provides a number of viewing windows 10 for viewing the
posit ion of separable contacts 12 formed by the fixed contact assembly 6 and the
movable contact assembly 7 in either the closed position (Figure 2 ) or the open
position (Figure 1). Although example transparent sapphire disks are shown, the
transparent portions 8 may have, for example and without limitation, any suitable
shape, such as a rectangular shape and/or a curved surface for cosmetic reasons.
The insulating body 5 of the vacuum envelope 4 includes a number of
openings 14. Each of the number of transparent portions 8 (e.g., number of sapphire
members) is brazed to the insulating body 5 at a corresponding one of the number of
openings 14.
The number of transparent portions 8 may be a number of transparent
windows.
The insulating body 5 of the vacuum envelope 4 may be metal ized at a
number of edges 16. Each of the number f edges 16 may be defined by a
corresponding one of the number of openings 14. Each of the number of transparent
portions 8 may be metalized at a peripheral edge 18 corresponding to one of the
metalized number of edges 6 of the insulating body. The metalized peripheral edge
18 may be brazed to a corresponding one of the metalized number of edges 16 of the
insulating body 5.
During manufacture of the vacuum interrupter 2, interfacing regions
(e.g., 16,18) of the vacuum envelope 4 are first metalized and then are brazed. The
insulating body 5 is a cylinder 20 metalized at the interface areas, which are the
number of edges 16. The number of transparent portions 8 (e.g., the number of
transparent windows) are also metalized at the interface areas, which are the
peripheral edges 18. The number of transparent windows and the cylinder 20 are
brazed at the metalized areas. A pair of end members 22,24 are coupled at the ends of
the cylinder 20 to complete the vacuum envelope 4.
n the disclosed embodiments, a vacuum is achieved internally with,
for example, a vacuum furnace (not shown). The air is removed internally within the
vacuum furnace and then the cylinder 20 and the number of transparent portions 8 are
brazed together at the end of the vacuum cycle. The end result is a vacuum inside of
the vacuum interrupter 2.
Referring to Figures 3 and 4, another vacuum switch, such as vacuum
interrupter 30, is shown. The vacuum interrupter 30 is similar to the vacuum interrupter
2 of Figure 1except that a number of transparent portions (e.g., without limitation, one
transparent portion 32 is shown in Figures 3 and 4 ) is a number of transparent regions
34, and an insulating body o a vacuum envelope of the example vacuum interrupter
30 is formed by a first upper (with respect to Figure 3) cylinder 3 made of
polycrystalme alumina (AI2O3), the central transparent region 34 made of single
crystal alumina (AI2O3) (e.g., sapphire), and a second lower (with respect to Figure 3)
cylinder 38 made of polycrystalme alumina (AI2O3) . A pair of end members 40,42
are coupled at the ends of the respective cylinders 36,38 to complete the vacuum
envelope.
Figure 5 shows another vacuum switch, such as vacuum interrupter 50, in
a closed position. Here, the vacuum envelope 52 is an insulating body 54 that is a
solid cylinder made f sapphire. For example and without limitation, a sapphire is a
gemstone variety of the mineral corundum, an aluminium oxide (AI2O3) . In this
example, a number f transparent portions 56 is all of the insulating body 54. A pair
of end members 58,60 are coupled at the ends of the insulating body 54 to complete
the vacuum envelope.
While specific embodiments of the disclosed concept have been
described in detail, it will be appreciated by those skilled in the art that various
modifications and alternatives to those details could be developed in light of the
overall teachings of the disclosure. Accordingly, the particular arrangements
disclosed are meant to be illustrative only and not limiting as to the scope of the
disclosed concept which is to be given the full breadth of the claims appended and
any and all equivalents thereof.
What is Claimed is:
1. A vacuum switch (2;30;50) comprising :
a vacuum envelope (4);
a fixed contact assembly (6) partially within said vacuum
envelope; and
a movable contact assembly (7) partially within said vacuum
envelope and movable between a closed position in electrical contact with the fixed
contact assembly and an open position spaced apart from the fixed contact assembly;
wherein said vacuum envelope comprises an insulating body
(5) comprising a number of transparent portions (8) made of a single crystal alumina
(AI2O3) for viewing said fixed contact assembly and said movable contact assembly
within said vacuum envelope.
2. The vacuum switch (2;30) of Claim wherein the insulating
body further comprises a cylinder (20) made of polycrystaline alumina (AI2O3) .
3. The vacuum switch (2;30;50) of Claim 1wherein said number
of transparent portions is a number of sapphire members (8;32;56).
4. The vacuum switch (2) of Claim 3 wherein the insulating body
(5) further comprises a number of openings (14); and wherein each of said number of
sapphire members is brazed to the insulating body a a corresponding one of the
number of openings.
5. The vacuum switch (50) of Claim 1wherein the insulating
body (54) is made of the single crystal alumina (AI2O3); and wherein said number of
transparent portions (56) is all of the insulating body.
6. The vacuum switch (50) of Claim 5 wherein the insulating
body (54) is in the form of a solid cylinder (54) made of the single crystal alumina
7. The vacuum switch (2) of Claim 1wherein said number of
transparent portions (8) is a number of transparent windows.
8. The vacuum switch (30) of Claim 1wherein said number of
transparent portions (32) is a number of transparent regions.
9. The vacuum switch (50) of Claim wherein said number of
transparent portions (56) is all of the insulating body (54).
0. The vacuum switch (2) of Claim 1wherein the insulating body
further comprises a number of openings (14); and wherein each of said number of
transparent portions is brazed to the insulating body at a corresponding one of the
number of openings.
11. The vacuum switch (2) of Claim 10 wherein the insulating
body is metal ized at a number of edges (16); wherein each of said number of edges is
defined by a corresponding one of the number of openings; wherein each of said
number of transparent portions is metal ized at a peripheral edge (18) corresponding to
one of the metal ized number of edges of the insulating body; and wherein the
metal ized peripheral edge is brazed to a corresponding one of the metal ized number
of edges of the insulating body.
12. The vacuum switch (2;30;50) of Claim 1wherein the vacuum
switch is a vacuum interrupter (2;30;50).
13. The vacuum switch (2:30:50) of Claim 1wherein the single
crystal alumina (AI2O3) is sapphire.
14. The vacuum switch (2) of Claim 1wherein said number of
transparent portions is a plurality of transparent portions (8).
15. The vacuum switch (2) of Claim 1wherein said vacuum
envelope further comprises a plurality of end members (22,24) coupled to the
insulating body.