U.S. patent number 3,599,134 [Application Number 05/022,477] was granted by the patent office on 1971-08-10 for nonmetallic corrosion-resistant enclosure for electrical apparatus.
This patent grant is currently assigned to Westinghouse Electric Corporation. Invention is credited to Dudley L. Galloway.
United States Patent |
3,599,134 |
Galloway |
August 10, 1971 |
NONMETALLIC CORROSION-RESISTANT ENCLOSURE FOR ELECTRICAL
APPARATUS
Abstract
A nonmetallic corrosion-resistant enclosure for electrical
apparatus comprising an outer housing or casing made from rubber or
plastic material which will not deteriorate or corrode and develop
leaks when exposed for an extensive period of time in a high
moisture content environment.
Inventors: |
Galloway; Dudley L.
(Sharpsville, PA) |
Assignee: |
Westinghouse Electric
Corporation (Pittsburgh, PA)
|
Family
ID: |
21809806 |
Appl.
No.: |
05/022,477 |
Filed: |
March 25, 1970 |
Current U.S.
Class: |
336/230; 220/617;
336/92; 174/50; 336/90 |
Current CPC
Class: |
H01F
27/02 (20130101) |
Current International
Class: |
H01F
27/02 (20060101); H01f 027/02 () |
Field of
Search: |
;336/90,92,94
;174/17R,17LF,50,52R ;220/85TC,67,80 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kozma; Thomas J.
Claims
I claim as my invention:
1. A housing for electrical apparatus comprising a nonmetallic
bottom member, a nonmetallic top member, a nonmetallic body member
extending between said bottom member and said top ember and means
providing a fluidtight and mechanically strong connection between
said body member and said bottom member and between said top member
and said body member to provide a fluidtight enclosure, said means
for providing a connection between said body member and said top
and bottom members comprises a dovetail slot having slanting sides
in said bottom member and said top member with the edges of the
bottom end of said body member sealed to the inside slanting walls
of said dovetail slot in said bottom member with an adhesive and
with the edges of the upper end of said body member sealed to the
inside slanting walls of said dovetail slot in said top member,
said adhesive providing a fluidtight seal between said bottom
member and said body member and between said top member and said
body member and means positioned in said dovetail slots in said
bottom member and said top member to provide mechanical strength
for the joints between said body member and said bottom member and
said top member.
2. The apparatus of claim 1 wherein said means positioned in said
dovetail slots comprises a snapring means.
3. The apparatus of claim 2, wherein said snapring means comprises
an inner ring having a slanted side corresponding to the slanted
side of said dovetail slot and an outer ring having a slanted side
corresponding to another slanted side of said dovetail slot.
4. The apparatus of claim 3 wherein said inner snapring and said
outer snapring have interlocking projections.
5. The apparatus of claim 1 wherein said means position in said
dovetail slots comprises thermosetting resin.
6. The housing as claimed in claim 1 having a core-and-coil
assembly positioned therein with the core-and-coil assembly resting
on said bottom member and a rigid support extending from said core
and attached to said upper member to support said upper member in
fixed relation with respect to said bottom member.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to nonmetallic corrosion-resistant
enclosures for electrical apparatus and more particularly to
housings or casings for distribution transformers installed in
locations where the environment has a high moisture content.
2. Description of Prior Art
In the prior art it has been the practice to provide metallic
housings or casings for transformer apparatus. These casings or
housings are very satisfactory when the apparatus is located in an
area where the environment atmosphere has a low moisture content.
However, the present trend is to install transformers underground
or partially buried. This practice introduces problems, since in
practically all underground or partially buried installations the
surrounding atmosphere has a high moisture content. This moisture
causes the metallic housing or casing to corrode. This corrosion
often develops leaks in the casing or housing. Once a leak develops
in the casing or housing the fluid coolant is lost and the
transformer becomes overheated or develops a short circuit and
destroys its usefulness as a transformer. This invention overcomes
the objection to the prior art metallic housing or casing by
providing a nonmetallic housing or casing which is highly resistant
to corrosion or other effects of moisture. The housing or casing of
the present invention is made completely of insulating
corrosion-resistant material, such as a plastic, for example epoxy,
polyvinyl chloride, rubber, or other suitable plastic material. The
housing or casing of the present invention will not corrode due to
moisture and develop leaks.
SUMMARY OF THE INVENTION
This invention provides a nonmetallic corrosion-resistant housing
or casing for electrical apparatus. The casing comprises cast or
molded bottom and top members. The bottom and top members are cast
or molded from a suitable resin, such as filled epoxy, or any other
castable or moldable insulating material. A body portion connects
to the bottom and top members to provide a container or housing.
This body portion also comprises insulation material, such as
epoxy, polyvinyl chloride, rubber, or other insulating material.
The body portion is attached to the bottom and top members by means
of dovetail slots having slanting sides. The dovetail slots receive
the top and bottom of the body member and locking rings snap into
the dovetail slots to firmly hold the bottom and top of the body
member in the dovetail slots in the bottom and top members. The
bottom edge and top edge of the body members are cemented in the
dovetail slots with a suitable adhesive, such as epoxy or rubber
cement, to provide a fluidtight connection to the bottom and top
members prior to snapping the locking rings in place in the
dovetail slots. The locking rings are made of plastic material,
such as nylon, or other suitable thermoplastic material. The
core-and-coil assembly of the transformer rests on the bottom
member. A rigid post is connected to the core-and-coil assembly.
This rigid post is connected to and supports the top member. This
rigid support, provided by the core-coil assembly and the rigid
post, maintains proper spacing between the bottom member and the
top member and prevents the body member from collapsing or
otherwise deforming. Bushings for bringing the necessary conductors
into the casing or housing are mounted on the top member. A hole
for receiving an eyebolt for lifting the transformer is provided
through the top member and extends into the rigid post. This hole
is normally closed with an insulating plug which is removed for
insertion of the eyebolt when it becomes necessary to lift the
apparatus. A fill plug is provided in the top member for filling
the casing or housing with the required fluid cooling medium.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of one embodiment of a casing or
housing provided by this invention;
FIG. 2 is a side elevational view of a second embodiment; and
FIG. 3 is a detail of the dovetail joint and locking rings for
connecting the body portion of the housing or casing to the bottom
and top portions.
DESCRIPTION OF PREFERRED EMBODIMENTS
Throughout the description which follows, like reference characters
refer to like parts on each of the various figures of the
drawing.
Referring specifically to the drawings, FIG. 1 illustrates a side
elevation view of one embodiment of a casing or housing 10 as
provided by this invention. The casing or housing 10 comprises a
bottom member 12, a top member 14 and a body member 16 connected
between the bottom member 12 and the top member 14. The members 12
and 14 are cast or molded from nonmetallic insulating material such
as filled epoxy resin, polyvinyl chloride, or any other suitable
nonmetallic material that can be readily cast or molded. The body
member 16 extends between the bottom member 12 and the top member
14 and is attached to the bottom member 12 and the top member 14
with a fluidtight and mechanically strong connection. The
embodiment of the casing or housing 10 shown in FIG. 1 has a round
cross section, however, it is understood that the cross section of
the housing or casing 10 may have any convenient configuration such
as elliptical, round, square or rectangular.
The bottom member 12 and the top member 14 are circular in shape
and they each have a dovetail groove 18 formed therein. The body
member 16 is made of nonmetallic electrical insulating material
such as epoxy, polyvinyl chloride, rubber or the like. The body
member 16 may be made of rigid self-supporting material or flexible
sheet material. The body member 16 is attached to the bottom member
12 and the top member 14 by folding the ends of the body member 16
as indicated at 20 and sealing the ends of the body member to the
inside of the dovetail grooves 18 by means of a good cement 19
which will provide a fluidtight seal. For example, the cement 19
may be epoxy sealant or room temperature vulcanizing rubber. This
cement 19 seals the edges of the body member 16 to the inside of
the dovetail grooves 18 to form a fluidtight joint between the body
member 16 and the bottom and top members 12 and 14. After the edges
20 of the upper end and the lower end of the body member 16 have
been sealed to the inside of the dovetail grooves 18 to provide a
fluidtight seal, a pair of lockrings 22 and 24 are forced into the
dovetail grooves 18 to provide a strong mechanical connection
between the body member 16 and the bottom member 12 and the top
member 14.
The sealing rings 22 and 24 may be made of nylon or some other
suitable resilient thermoplastic material. The ring 22 is first
placed in position and then the ring 24 is forced in position as
shown more clearly in the detail in FIG. 3. Because of the slanted
sides of the dovetail slots 18, when the ring 24 is forced into
position, projections 26 on the outer ring 22 mate with projections
28 on the inner ring 24 to form a single interlocked ring which is
tight and cannot be removed once the inner ring 24 has been forced
into place. Any tendency to remove the rings 22 and 24 will force
the material of the body member 16 tightly against the inclined
sides of the dovetail slots 18 and provides a tight seal. The epoxy
or room-temperature-vulcanizable rubber which is used to seal the
edges of the body member 10 in the dovetail grooves 18 of the end
members 12 and 14 provides a fluidtight seal between the body
member 16 and the bottom member 12 and the top member 14, and the
snap-in rings 22 and 24 provide mechanical strength for the joint
between the body member 16 and the bottom member 12 and the top
member 14. In some assemblies, a liquid thermosetting resin or a
puttylike thermosetting resin may be substituted for the locking
rings 22 and 24 to provide mechanical strength for the joint.
In the embodiment shown in FIG. 1, a distribution transformer
comprising a core 30 and a coil 32 is shown positioned in the
housing or casing 10. The core-coil assembly comprising the core 30
and the coil 32 rests on a pad 34 positioned on the bottom member
12 of the casing or housing 10. A rigid support or rod member 36 is
attached to the top of the core 30 by means of a clamp 38. This
clamp 38 may be permanently attached to the core 30 by pressure,
tack welding or any other suitable means. The upper end of the
rigid rod or support member 36 is attached to the underside of the
top member 14 by means of a flange 40 and a pin 42. The rigid
support 36 is strong enough to freely support the top member 14
from the core 30. High-voltage bushings 44 and low-voltage bushings
46, for bringing leads into the housing or casing 10 to connect to
the coil 32, are supported on the top member 14. A threaded hole 48
is provided through the top member and extends into the rigid post
or support rod 36 for insertion of an eyebolt 50 for lifting the
transformer. Normally, the eyebolt will be removed and the threaded
hole 48 closed with an insulating plug and the plug will be removed
when it is desired to insert the eyebolt 50 for lifting the
transformer. A fill hole which is normally closed by an insulating
plug 52 is provided in the top member 14 for filling the
transformer with liquid dielectric.
From the foregoing description, it is seen that the embodiment of
FIG. 1 has provided a nonmetallic casing or housing for a
distribution transformer wherein there are no metallic parts
exposed to ambient atmosphere on the outside of the casing. The
core-and-coil assembly is supported on the bottom member 12 of the
housing 10, and the top member 14 and all of the associated
bushings and other hardware mounted on the top member 14 are
supported from the core by means of a rigid post or support 36
connected between the core 30 and the top member 14 of the casing
or housing 10.
FIG. 2 shows a second embodiment of a nonmetallic casing or housing
for transformer apparatus wherein all of the parts exposed to
ambient atmosphere are made of nonmetallic material. The embodiment
of FIG. 2 comprises a top member 14 similar to that disclosed for
FIG. 1. However, in FIG. 2 a metallic casing comprising sides 60
and a bottom member 62 is attached to the nonmetallic top member
14. In addition to the inner housing or container comprising the
metallic sides 60 and the metallic bottom 62, the inner container
is surrounded by an outer container 62. The outer container 62 is
made from some plastic material such as epoxy, polyvinyl chloride,
rubber or other suitable plastic material. The top member 14 of
this embodiment is also provided with a dovetail slot 18. The upper
edge of the nonmetallic housing member 62 is fastened in the groove
18 by means of an adhesive and a pair of snap-in rings 22 and 24 in
a manner similar to that described for the embodiment of FIG. 1.
This connection provides a fluidtight and mechanically strong
connection between the top member 14 and the outer nonmetallic
housing 62. The embodiment of FIG. 2 in all other respects is
identical to that described hereinbefore for FIG. 1. However, it is
stated hereinbefore that the inner housing comprising a body member
60 having a bottom 62 is made of metal, it is understood that this
body member may also be made of filament-wound glass-epoxy or any
other suitable resinous material. In the embodiment of FIG. 2 the
cross section of the housing or container is round; however, as
specified for FIG. 1, the cross section may assume any desired
shape.
FIG. 2 is an enlarged detail illustrating the dovetail slots 18,
with the edge 20 of the body member 16 sealed to the inside of the
slanted sides of the dovetail slots 18 with a good sealant 19, such
as epoxy, room-temperature-volcanizing rubber. The snap-in rings 22
and 24 are shown in place to provide mechanical strength to the
joint between the body portion 16 of the container and the end
members 12 and 14 of the container or housing.
From the foregoing description taken in connection with the
drawings, it is seen that this invention has provided a
nonmetallic, corrosive-resistant, housing or casing for a
distribution transformer which may be installed in an environment
where the atmosphere contains a large quantity of moisture or other
agents which would cause corrosion of metals. Since the entire
exposed surface of the tank or casing provided by this invention is
made of nonmetallic corrosive-resistant resinous materials, the
housing or casing will resist deterioration because of the moisture
better than the metallic tanks used in the prior art, and will
cause less trouble and outages due to corrosion of the housings or
casings for transformers installed in areas which would normally
subject the metallic prior art housing or casing to rapid
corrosion.
* * * * *