Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates generally to the
connection and disconnection of high voltage electrical
connector elements in the field and pertains, more
specifically, to an attachment arrangement which assures
the appropriate attachment and securing of a bushing
assembly within an electrical conneckor, and the
subsequent attachment and securing of the electrical
connector to a terminal of a high voltage electrical
apparatus.
In United States patent no. 4,202,591, granted
May 13, 1980, and assigned to the~ assignee hereof, there
is described a high voltage electrical connector of
the type employed to connect a high voltage cable to the
terminal of an electrical apparatus, such as a
transformer, in a power distribution circuit. The
electrical connector is provided with a bushing assembly
which enables a ground connection to be made so as to
ground the terminal without disconnecting the electrical
connector.
It is an object of the present invention to provide
an attachment arrangement which facilitates attachment
and securing of a bushing assembly within an electrical
connector of the type described in the aforesaid patent.
Another object of the present invention is to
provide an attachment arrangement of the type described
and which assures complete and appropriate attachment
and securing of the bushing assembly within the electrical
connector.
Still another object of the invention is to provide
an attachment arrangement which facilitates the appropriate
attachment and securing of the bushing assembly within
the electrical connector in the fiel~.
Yet another object of the invention is to provide
an attachment arrangement of the type described and which
eases attachment and securing of the electrical connector
; to the terminal of a high voltage electrical apparatus
~,
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subsequent to the appropriate attachment and securing
of the bushing assembly within the electrical conductor.
A further object of the invention is to provide an
attachment arrangement of the type described and which
assures the appropriate, proper attachment and securing
of the bushing assembly within the electrical connector
prior to the attachment and securing of the electrical
connector to the terminal.
A still further object of the invention is to
provide an attachment arrangement of the type described
and which is incorporated readily into a bushing assembly
~ fully compatible with present electrical connectors of
the type describedO
Yet a further object of the invention is to provide
an attachment arrangement of the type described and which
is operated easily, in the field, without the necessity
for elaborate and extensive special tools.
The above objects, as well as still further objects
and advantages, are attained by the present invention
which may be described briefly as an attachment arrange-
ment for facilitating attaching and securing a bushing
assembly within an electrical connector of a high voltage
electrical distribution system, the electrical connector
having an axially extending recess including a tapered
portion, a terminal contact affixed to a conductor of
a high voltage cable and including a portion extending
into the recess, the terminal contact having a threaded
aperture placed within the recess and aligned axially
with the tapered portion of the recess, the bushing
assembly including an axially extending tapered body
portion complementary to the tapered portion of the
recess in the electrical connector such that the comple-
mentary tapered portion will be engaged in an appropriate
interference fit, the tapered body portion terminating
at a terminal end, the attachment arrangement comprising:
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a tubular member extending in an axial direction within
the bushing assembly adjacent the terminal end thereof
and having an axially extending internal thread therein;
a coupling member coupled with the tubular member and
projecting axially beyond the terminal end of the
tapered body portion of the bushing assembly, the coupling
member including a first external thread at least a
portion of which is spaced axially away from the tubular
member for engaging the threaded aperture of the terminal
contact, and a second external thread engaged with the
internal thread of the tubular member; wrenching means
associated with the tubular member for enabling rotation
of the tubular member about the axial direction, the
tubular member being so affixed within the bushing
assembly as to assure concomitant rotation of the bushing
assembly in response to said rotation of the tubular
member, minimum torque responsive means for precluding
relative movement between the tubular member and the
coupling member below a predetermined torque exerted by
the tubular member upon the coupling member; and stop
means located such that upon insertion of the bushing
assembly into the recess of the electrical connector
and initial rotation of the bushing assembly, the
coupling member will rotate with the bushing assembly,
and the first external thread of the coupling will be
engaged within the threaded aperture of the terminal
contact prior to the engagement of the complementary
tapered portions in said interference fit, and continued
rotation of the bushing member, as enabled by the
wrenching means, will exceed the predetermined torque
of the minimum torque means to further engage the second
thread within the internal thread of the tubular member
until the complementary tapered portions are engaged
fully in the interference fit and proper electrical
contact is made between the tubular member and the
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terminal contact. The attachment arrangement may
include further minimum torque responsive means
coupling the wrenching means with the tubular member
for precluding relative rotation between the wrenching
means and tubular member unti~ a given tor~ue is ex-
ceeded between the wrenching means and the tubular member,
the given torque being of a value great enough ~o assure
the aforesaid proper electrical contact between the
tubular member and the terminal contact.
The invention will be more fully understood, while
still further objects and advantages will become apparent,
in the following detailed description of an embodiment of
the invention illustrated in the accompanying drawing, in
which:
FIG. 1 is a fragmentary elevational cross-sectional
view of a portion of a bushing assembly carrying an attach-
ment arrangement constructed in accordance with the
invention and showing the bushing assembly about to be
installed within an electrical connector which is to be
connected to a terminal of an electrical apparatus;
FIG. 2 is a fragmentary elevational cross-sectional
view similar to FIG. 1, but with the component parts in
another position;
FIG. 3 is a fragmentary elevational cross-sectional
view similar to FIG. 2, but with the component parts in
still another position;
FIG. 4 is another similar fragmentary elevational
cross-sectional view with the component parts in yet
another position; and
FIG. 5 is still another fragmentary elevational cross-
sectional view showing all of the component parts fully
connected.
Referring now to the drawing, and especially to
FIG. 1 thereof, the component parts depicted are similar
to corresponding component parts illustrated and described
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in the aforementioned patent no. 4,202,591, in that
the component parts include an electrical connector in
the form of a T-shaped receptacle 10, and a terminal 12
of an electrical apparatus (not shown). The receptacle
10 is affixed to the terminus of a high voltage cable,
in the manner illustrated in the aforesaid patent, and an
electrical terminal contact 20 having an integral lug 22
is attached to the conductor of the cable. Lug 22 is to
be connected to the terminal 12 to complete a distribu-
tion circuit.
A composite body 24 surrounds the contact 20 andprovides an axially extending receptacle recess 26
within which terminal 12 is to be received. A second
axially extending recess 28, opposite to first recess
26, is to receive interface bushing assembly 30 which is
constructed to enable direct connection between the terminal
12 and a commonly available electrical connector, such as
an elbow receptacle (not shown).
Bushing assembly 30 includes a generally tubular
housing 34 having a body member 36 of dielectric material,
such as an insulating elastomer, and a central tubular
member 38 of conductive material, such as copper or
aluminum. The upper end of the bushing assembly 30 is
not illustrated, but is essentially the same as that shown
in the aforesaid patent. Suffice it to say that a female
contact assembly is located adjacent the upper end of
the tubular member 38 and includes a female contact ele-
ment which can receive a complementary male contact
element for completing an electrical circuit to tubular
member 38. In the present bushing assembly 3n ~ tubular
member 38 is provided with an extension in the form of
an axially extending tubular extension member 40 of
conductive material~ such as copper or aluminum, affixed
to tubular member 38 by means of a threaded connection
42 at the upper end 44 of tubular extension member 40.
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The lower end 46 of tubular extension member 40 includes
a land 48 for the purposes which will be described in
greater detail below.
A coupling member 50, also constructed of
conductive material such as c~pper or aluminum, is
received within extension member 40, adjacent lower
end 46, and is coupled to extension member 40 by means
of an external thread 5~ which extends axially to upper
end 54 of coupling member 50 and engages a complem.entary
internal thread 56 in extension member 40. A further
external thread 58 extends along the coupling member
50 adjacent the lower end 60 thereof, and stop means in
the form of a collar 62 is located axially between the
external threads 52 and 58.
Prior to the installation of bushing assembly 30
within the recess 28 of receptacle 10, coupling member
50 prQjects beyond the lower end 46 of extension member
40, and the lower end 64 of body member 36 of bushing
assembly 30, with collar 62 spaced axially from lower
ends 46 and 64, as illustrated in FIG. 1. In this
manner, at least a portion of external thread 58 is spaced
far enough downwardly from the tapered portion 66 of the
body member 36 of bushing assembly 30 to enable external
thread 58 to be engaged with a complementary threaded
aperture 68 in lug 22 of contact 20, as seen in FIG. 2,
without resistance which might otherwise occur if the
tapered portion 66 of the body member 36 were to contact
the corresponding.tapered portion 70 of recess 28.
Thus, at least a portion of external thread 58 of coupling
member 50 may be threaded into threaded aperture 68 merely
by turning bushing assembly 30 manually to advance external
thread 58 into threaded aperture 68. Such advancement is
continued until a sufficient axial length of external
thread 58 is engaged within threaded aperture 68 to
provide the holding strength necessary to complete the
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installation of the bushing assembly 30 within the
receptacle 10, as described below, and preferably
until a stop shoulder 72 on collar 62 is seated against
lug 22, as seen in FIG. 3.
Preferably, manual turning of bushing assembly 30
will advance the coupling member 50 into threaded aperture
68 until stop shoulder 72 is seated properly against lug
22. A locking means is provided between the external
thread 52 and the internal thread 56 to lock the coupling
member 50 and the tubular extension member 40 against
movement relative to one another during threading of
the coupling member 50 into the lug 22, at least until
the aforesaid sufficient axial length of thread 58 is
; engaged within threaded aperture 68. The locking means
is in the form of a pellet 74 of synthetic resin material, .
such as nylon, placed within a recess 76 in the wall 78
of coupling member 50 and compressed against internal
thread 56 of tubular extension member 40 to establish a
prevailing torque great enough to preclude the unwanted
relative movement, preferably until stop shoulder 72 is
seated against lug 22. In order to effect continued
rotation of the bushing assembly 30, and preferably after
stop shoulder 72 is seated against lug 22, the prevailing .
~ torque provided by pellet 74 is overcome so that downward
- movement of the tapered body portion 66 into complementary
tapered portion 70 of recess 28 can be continued. Thus,
the pellet 74 provides a locking means which is responsive
to a minimum torque, the minimum torque being of a pre-
determined value which will assure that the coupling
member 50 is sufficiently engaged with lug 22, and
preferably is engaged up to the position where stop
shoulder 72 is seated against the lug 22, before ~ubular
extension member ~0 will move relative to coupling
member 50. Pellet 74 assures that the minimum torque
necessary to engage coupling member 50 sufficiently in
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lug 22 and preferably to seat coupling member 50
properly against lug 22 will be reached before extension
member 40 moves relative to coupling member 50.
Upon proper seating of coupling member 50 within
lug 22, as seen in FIG. 3, further rotation of bushing
assembly 30 will overcome the lock provided by pellet
74 and the tapered body portion 66 of the bushing
assembly 30 will begin to engage complementary tapered
portion 70 of recess 28. Continued downward movement
of the bushing assembly 30 will seat the bushing assembly
30 within the receptacle 10; however, such continued
downward movement will meet with considerable resistance
as a result of the interference fit which must be
established between the complementary tapered portions
66 and 70 in order to attain the desired watertight seal
and dielectric properties along the interface between the
engaged tapered portions. Since the body member 36 of
bushing assembly 30 is constructed of elastomeric
materials, it becomes impractical to grip the bushing
assembly externally to exert the forces necessary to
continue turning the bushing assembly as the resistance
to turning increases with downward movement. The
attachment arrangement of the present invention further
provides an internal wrenching means for facilitating the
continued rotation of the bushing assembly 30, as follows.
Turning now to FIGS. 3 and 4, coupling member 50
has a central bore 80 passing through the coupling
member 50 from end 54 to end 60. A threaded fastener in
the form of a bolt 82 extends axially within the bore 80
and has a head 84 and a thread 86. A pin 90 extends
radially through an aperture 92 in the wall of tubular
member 38 and into a corresponding hole 94 in the head
84 of bolt 82, the pin 90 having a flanged end 96 which
serves to locate the pin 90 radially within aperture 92.
Tubular extension member 40 overlaps the aperture 92
thereby capturing flanged end 96 of pin 90 within aperture
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92. Bolt 82 thus is fixed in the retracted position
illustrated in FIGS. 3 and 4.
A socket 98 in head 84 of bolt 82 provides a
hexagonal wrenching configuration located along the
central axis A of the bushing assembly 30. A tool
100, having a complementary hexagonal driving element
102 is lowered through the tubular member 38, along
axis A, as seen in FIG. 3, and is inserted into socket
98, as seen in FIG. 4. The details of tool 100 are more
fully disclosed in a Canadian,~atent application
entitled ASSEMBLY TOOL FOR ELECTRICAL CONNECTORS, serial
no. , filed of even date herewith, and assigned
to the assignee hereof. For the purposes of the present
disclosure, it is sufficient to understand that rotation
of tool 100 about axis A, once the tool 100 is coupled
with the head 84 of bolt 82, will impart concomitant
rotation to bushing assembly 30 by virtue of the fact
that head 84 is secured to tubular member 38 by pin 90.
Wrenching forces then are applied and transmitted to
move bushing assembly 30 downwardly until the land 48
at th~ lower end 46 of the tubular extension member 40
is seated against lug 22, as shown in FIG. 4, the collar
62 fitting within a corresponding recess 104 at the
lower end 46 of extension member 40. If stop shoulder
72 of collar 62 has not yet been seated properly against
lug 22, downward movement of extension member 40 now
will carry coupling member 50 downwardly to assure proper
seating of the coupling member 50 with lug 22. Once the
land 48 is seated properly, the bushing assembly 30 will
be seated within the receptacle 10 with the appropriate
interference fit and land 48 will assure proper
electrical contact between extension member 40 and lug
22 as well as an appropriate mechanical connection.
It is important that the bushing assembly 30 not
be overtightened; that is, the land 48 must not gaul
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the lug 22 and excessive forces should not be developed
along the interface between the complementary tapered
portions 66 and 70. At the same time, it is important
that at least a minimum torque is applied sufficient to
assure proper seating of bushing assembly 30 within
receptacle 10. In order to preclude the application
of excessive wrenching forces upon the bushing assembly
30, while assuring that the necessary minimum wrenching
forces are applied, the shear strength of pin 90 is chosen
so that pin 90 will shear in response to the application
by tool 100 of a torque in excess of a given value
determined by the minimum torque required for the
appropriate seating o~ bushing assembly 30 within recep- .
tacle 10 and the maximum torque which can be tolerated.
Thus, pin 90 serves as a further minimum torque respon-
sive means which includes securing means for securing the
head 84 of bolt 82 to tubular member 38 for applying
wrenching torque, and the securing means releases in
response to exceeding a given torque to preclude the
application of an excessive torque to the connection
between the bushing assembly 30 and the lug 22 while
assuring that the necessary minimum torque is applied.
Once the pin 90 is sheared, bolt 82 is free to
move axially downwardly within tubular extension member
40 and coupling member 50, until the head 84 of bolt
82 rests upon washers 105 located at the upper end
54 of coupling member 50. It is noted that axially
upward movement of bolt 82 is restricted by a lip 106
which projects radially inwardly to preclude movement
of bolt 82 upwardly into tubular member 38 beyond lip
106. The receptacle 10, with bushing assembly 30 in
place therein, ordinarily will be placed upon terminal
12 with the bolt 82 aligned axially.with a threaded
aperture 108 in terminal 12. Upon freeing of the bolt
82 by shearing of the pin 90, the bolt 82 may be advanced
~7712~
and threaded into the terminal 12, by rotation of tool
100, to complete the connection to the terminal 12, as
shown in FIG~ 5. In the completed connection, bolt 82
clamps lug 22 in place upon the terminal12 and secures
receptacle 10 upon terminal 12 with the appropriate
interference fit at the interface between the recess
26 of the receptacle 10 and the corresponding outer
surface 110 of the terminal 12 and the proper electrical
contact between the lug 22 and the conductor 111 of
terminal 12. It is noted that stop shoulder 72 of
collar 62 is seated against lug 22 to preclude the
projection of end 60 of coupling member 50 downwardly
beyond lug 22 so as to assure proper contact between
lug 22 and conductor 111 of terminal 12. Fragment 112
of sheared pin 90 is retained within aperture 32 in the
wall of tubular member 38 by virtue of flanged end 96
so as to prevent the fragment from dropping freely into
the bushing assembly 30 and possibly causing problems,
such as falling into socket 98 and interfering with the
appropriate engagement of hexagonal element 102 of
tool 100. Likewise, fragment 114 of sheared pin 90 is
confined within hole 94 of bolt head 84, by the wall
of tubular extension member 40. Thus, the location of
fragments 112 and 114 is controlled. Tool 100 then is
withdrawn, as shown.
Thus, the attachment arrangement of the present
invention facilitates the appropriate installation of
the bushing assembly 30 within the receptacle 10 and
then enables connection of the receptacle 10 to the
terminal 12 in simplified operations performed readily
; in the field without complex tools.
It is to be understood that the above detailed
description of an embodiment of the invention is
provided by way of example only. Various details of
design and construction may be modified without departing
.
1~L77~Z9
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from the tru~ spirit and scope of the invention as set
forth in the appended claims.
:
