Electrical connector

An electrical connector for use in connecting a male contact to a female contact in an energized high voltage circuit, the electrical connector having a female contact assembly which is movable and is accelerated in response to the generation of arc-quenching gases within the electrical connector to aid in more rapidly closing the connection between the female contact and the male contact, and kinetic energy absorption and dissipation means for gradually absorbing and dissipating at least a portion of the kinetic energy imparted to the female contact assembly as a result of such acceleration thereof, so as to decelerate the female contact assembly and thereby facilitate bringing the female contact assembly to a halt subsequent to closing the connection.

The present invention relates generally to electrical connectors and 
pertains, more specifically, to electrical connectors of the type used in 
making a connection in an energized high voltage circuit of an electrical 
distribution system. 
As set forth in some detail in our earlier U.S. Pat. No. 4,186,985, one of 
the more troublesome situations which arises in the joinder of male and 
female contact elements in an energized high voltage circuit is the large 
amount of arc-quenching gases generated during fault closure and the 
concomitant high gas-generated pressures which must be accommodated by the 
connector. The aforesaid patent traces the development of prior art 
devices which are intended for fault closure and discloses an improvement 
which aids in accommodating fault closure. These prior art devices employ 
a piston-driven movable female contact assembly which is moved toward a 
separable male contact by the arc-quenching gases so as to accelerate 
engagement of the contacts, thus minimizing arcing time. 
It is an object of the present invention to provide an electrical connector 
of the type described; that is, an electrical connector in which one 
contact is moved by arc-quenching gases into accelerated contact with an 
inserted complementary contact, and which will operate effectively at 
higher voltages than earlier such devices. 
Another object of the invention is to provide an electrical connector of 
the type described and in which the movable contact assembly may be 
accelerated to a greater speed and then stopped, subsequent to making 
contact, without a catastrophic failure within the connector. 
Still another object of the invention is to provide an electrical connector 
of the type described and in which the movable contact assembly is 
decelerated by kinetic energy absorption and dissipation means, thereby 
enabling the accommodation of higher arc-quenching gas pressures and 
concomitant higher speeds of movement of the movable contact assembly. 
Yet another object of the invention is to provide an electrical connector 
which employs the proved construction arrangement of previous movable 
contact assembly connectors together with improvements which render the 
electrical connector suitable for use in making fault closure connections 
at significantly higher voltages. 
A further object of the invention is to provide an electrical connector of 
the type described and which includes an external configuration that 
renders the connector compatible with existing high voltage electrical 
distribution systems. 
The above objects, as well as still further objects and advantages, are 
attained by the present invention which may be described briefly as an 
improvement in an electrical connector of the type in which a contact 
element assembly is movable within the electrical connector from a first 
position to a second position to accelerate a first contact element for 
rapid movement toward engagement with a complementary second contact 
element brought toward separable engagement with the first contact element 
within the electrical connector to complete an energized high voltage 
circuit, the improvement comprising kinetic energy absorption and 
dissipation means associated with the electrical connector for gradually 
absorbing and dissipating at least a portion of the kinetic energy 
imparted to the contact element assembly as a result of such acceleration 
as the contact element assembly moves from the first position toward the 
second position so as subsequently to decelerate the contact element 
assembly and thereby facilitate bringing the contact element assembly to a 
halt subsequent to the engagement of the first and second contact elements 
.

Referring now to the drawing, and especially to FIG. 1 thereof, a forward 
portion of a female electrical connector element constructed in accordance 
with the invention and shown in the form of a bushing insert is 
illustrated generally at 10. Bushing insert 10 is for use in separable 
connection with a complementary male connector element, such as a 
connector elbow (not shown), in an energized high voltage circuit of an 
electrical distribution system (also not shown). 
Bushing insert 10 has a housing 12 which includes an outer housing casing 
14 of elastomeric materials having an inner portion 16 of insulating 
elastomeric material and an outer portion 18 of conductive elastomeric 
material molded integral with inner portion 16. Housing 12 further 
includes a rigid, metallic, electrically conductive inner housing member 
20 which extends longitudinally between a forward end 22 and a rearward 
end 24 within casing 14. A threaded aperture 26 at the rearward end 24 
receives a threaded stud 28 which is unitary with one end of a metallic, 
electrically conductive extension 30 which itself is threaded at the other 
end thereof (not shown) for attachment to a high voltage circuit, such as 
at the terminal of a transformer (not shown). A tubular insulating 
nosepiece 32 is threaded into the inner housing member 20 at the forward 
end 22 thereof and projects axially therefrom, in a manner now well-known 
in bushing inserts, and carries an annular detent groove 34 adjacent the 
forward end 36 thereof for engaging a complementary detent in the male 
connector element which will be connected with the bushing insert 10. 
Located within the inner housing member 20 is a carrier member 40 which is 
generally tubular and extends between forward end 42 and rearward end 44, 
corresponding to the forward and rearward ends 22 and 24 of the inner 
housing member 20. A piston 46 is unitary with the carrier member 40 
adjacent rearward end 44 and is received within cylindrical inner surface 
48 of inner housing member 20 for axial sliding movement. A female contact 
element 50 is threaded into the carrier member 40 at the forward end 42 
thereof so as to be integral with the carrier member 40 and movable 
axially with movement of the piston 46 and the carrier member 40. A 
tubular sleeve 52 of relatively soft insulating plastic material is 
secured to the female contact element 50 as by fasteners 54 and extends 
forward beyond the forward end of the female contact element 50 to provide 
a forward tubular portion 56 within which there is seated a first tubular 
guide 60, aligned axially with the female contact element 50, and a second 
tubular guide 62, also sligned axially with the female contact element, 
both guides 60 and 62 being affixed to the tubular portion 56. Guide 60 is 
constructed of a material from which arc-quenching gases will evolve in 
response to an arc being struck between an inserted male contact element 
(not shown) and the female contact element 50, and each guide 60 and 62 
serves to receive and guide a follower (not shown) of arc-quenching 
gas-evolving material which projects from the male contact element and 
precedes the male contact element as contact is made with the female 
contact element 50. Guide 62 provides a sealing arrangement for confining 
the arc-quenching gases as the gases are evolved within bushing insert 10, 
in a manner already known in the art. 
Upon insertion of the male contact element into guides 60 and 62, under 
circumstances where the high voltage circuit is energized, an arc will be 
struck between the male contact element and the female contact element 50 
prior to actual physical contact between those elements. The gas-evolving 
materials present in the male contact element follower and in the guide 60 
will emit arc-quenching gases which will flow rearwardly into a chamber 64 
located adjacent transverse surfaces 66 and 68 of piston 46. The pressure 
built up by gases in chamber 64 will act upon the piston 46 to move the 
piston 46 forward, out of the position shown in FIG. 1, toward the 
position shown in FIG. 2, thereby moving the entire female contact 
assembly 70, which includes carrier member 40, female contact element 50 
and guides 60 and 62, in an axially forward direction. Forward axial 
movement of the female contact assembly 70 will be continued until piston 
46 reaches the position illustrated in FIG. 3, at which position the male 
contact element and the female contact element 50 will be fully engaged 
and the female contact assembly 70 will be stopped. Thus, female contact 
assembly 70 will travel axially, in response to the generation of 
arc-quenching gases, from an initial retracted location, as seen in FIG. 
1, to a final advanced location, as seen in FIG. 3, passing through an 
intermediate location, as depicted in FIG. 2. 
Under fault closing conditions, the arc struck between the male contact 
element and the female contact element very quickly will generate a 
relatively large volume of gases, especially in circuits where the 
voltages can be as high as about 35 kV. In addition, the higher voltages 
will produce an arc of greater axial length, requiring a greater length of 
travel between the retracted location and the advanced location of the 
female contact assembly. Under such circumstances the piston 46, and 
indeed the entire female contact assembly 70, will be accelerated to a 
relatively high speed and will possess a considerable amount of kinetic 
energy during travel from the retracted location to the advanced location. 
In order to enable bushing insert 10 to function appropriately during a 
fault closing condition at such high voltages, without a catastrophic 
failure, the structure of bushing insert 10 must accommodate the high 
speed of the female contact assembly 70, and the concomitant great amount 
of kinetic energy imparted to the female contact assembly 70, in order to 
decelerate and bring the female contact assemby 70 to a halt at the 
advanced location. Thus, bushing insert 10 includes kinetic energy 
absorption and dissipation means for absorbing and dissipating the kinetic 
energy of female contact assembly 70 as the assembly moves toward the 
advanced location. 
Referring now to FIGS. 1 through 4, the kinetic energy absorption and 
dissipation means is constructed as follows. A stop member in the form of 
a ring 72 of relatively hard metal is affixed to the inner housing member 
20 adjacent the forward end 22 by means of a threaded connection at 74. A 
stop shoulder 76 is located on the carrier member 40 at the forward end of 
piston 46. Carrier member 40 has an outer cylindrical surface 78 which is 
spaced radially inwardly from cylindrical inner surface 48 of innser 
housing member 20. When piston 46 is in the position illustrated in FIG. 
1, with the female contact assembly 70, and carrier member 40, in the 
retracted location, stop shoulder 76 is spaced axially rearwardly from 
stop ring 72. Shearable members in the form of shearable rings 80, 82 and 
84 are unitary with carrier member 40 and project radially outwardly 
toward inner housing member 20 to establish shearable means. Primary 
shearable ring 80 is located adjacent the forward end 42 of carrier member 
40 to provide a primary shearable structure while secondary shearable 
rings 82 and 84 are spaced axially from primary shearable ring 80 and from 
one another to provide a secondary shearable structure. Primary shearable 
ring 80 is spaced axially rearwardly from stop ring 72. 
Upon the striking of an arc, and the consequent generation of arc-quenching 
gases, the female contact assembly 70 will be accelerated for rapid 
movement forward from the initial location, depicted in FIG. 1, and over 
the length of travel defined by the axial spacing between primary 
shearable ring 80 and stop ring 72. Such unimpeded acceleration will 
result in high speed travel of the female contact assembly enabling rapid 
closing of the gap between the male contact element and the female contact 
element 50 and consequent reduction of arcing time. Initial contact will 
be made between the male contact element and female contact element 50, 
and the arc will be extinguished, when the female contact assembly 70 is 
in the vicinity of the intermediate location shown in FIG. 2. 
Further forward movement of the female contact assembly 70 will facilitate 
completion of the connection, but need not be as rapid as the initial 
movement necessary to effect direct contact between the male and female 
contact elements. Therefore, deceleration can take place during such 
further forward movement so that the female contact assembly 70 can be 
stopped when the advanced location is reached, as shown in FIG. 3, without 
failure of the bushing insert 10. Deceleration takes place as a result of 
the absorption and dissipation of at least a portion of the kinetic energy 
of the female contact assembly 70 as each of the shearable rings 80, 82 
and 84 is sheared from the carrier member 40. Thus, as primary shearable 
ring 80 moves forward it will be intercepted by ring 72 which is 
stationary and projects into the path of travel of shearable ring 80 so as 
to shear the shearable ring 80 from the carrier member 40. Such shearing 
will absorb and dissipate enough of the kinetic energy of the 
forwardly-moving female contact assembly 70 to be significant in effecting 
some deceleration. A notch 86 is provided at the root 88 of shearable ring 
80 to assure that shearing will take place cleanly and at the root 88. 
Continued forward travel of the female contact assembly 70 will bring 
secondary ring 82 into engagement with sheared primary ring 80 and will 
effect the shearing of secondary ring 82 from the carrier member 40, 
accomplishing further deceleration through the absorption and dissipation 
of more of the kinetic energy imparted to female contact assembly 70. 
Likewise, secondary shearable ring 84 will be engaged with 
previously-sheared ring 82 to further decelerate female contact assembly 
70 so that upon reaching the advanced location shown in FIG. 3, stop 
shoulder 76 will be coupled with stationary ring 72, through the sheared 
rings 80, 82 and 84 as seen in FIG. 4, and piston 46 will be brought to a 
halt, together with the remainder of female contact assembly 70. The 
gradual absorption and dissipation of kinetic energy brought about by the 
serial shearing of rings 80, 82 and 84 serves to decelerate and aid in 
bringing to a stop the female contact assembly 70 without a catastrophic 
failure of the bushing insert 10 so that the completed electrical 
connection will remain intact. The provision of secondary rings 82 and 84 
assures that the greatest portion of the kinetic energy absorbed and 
dissipated by the absorption and dissipation means is absorbed and 
dissipated as the female contact assembly 70 travels from the intermediate 
location to the advanced location so that maximum deceleration takes place 
after contact is made between female contact element 50 and the male 
contact element. 
Under normal circuit closure conditions, when the circuit is energized but 
no fault is present, primary shearable ring 80 will not be sheared from 
carrier member 40 and serves as a stop ring to limit the travel of female 
contact assembly 70 only to that travel which facilitates switching. 
During such travel, arc-quenching gases are contained within the bushing 
insert 10 and seals 90, which are carried by tubular sleeve 52, are 
provided to maintain such containment as the female contact assembly 70 
moves forward. However, under a fault closing condition, seals 90 pass 
beyond the forward end 36 of tubular nosepiece 32 and open a passage 92 to 
vent ports 94 in carrier member 40 to enable the venting of excessive 
arc-quenching gases. Seals 90 provide an important function in that they 
assure that adequate arc-quenching gases will be present for extinguishing 
an arc during disconnection under energized conditions. 
Turning now to FIGS. 5 and 6, a forward portion of another female 
electrical connector element constructed in accordance with the invention 
is shown in the form of a forward portion of bushing insert 110. Bushing 
insert 110 is similar to the above-described bushing insert 10 in that a 
housing 112 includes an outer housing casing 114 with inner and outer 
portions 116 and 118 of insulating and conductive elastomeric materials, 
respectively, and a rigid, metallic inner tubular housing member 120. A 
tubular insulating nosepiece 132 is threaded into housing member 120 and 
has a forward end 136. 
A tubular carrier member 140 includes a piston 146 unitary therewith and 
received within a cylindrical inner surface 148 of the housing member 120. 
A female contact element 150 is threaded into the carrier member 140 so 
that the carrier member 140, the piston 146 and the female contact element 
150 all are parts of an axially movable female contact assembly 170. 
A kinetic energy absorption and dissipation means includes a shearing ring 
172 affixed to the inner housing member 120, as in the earlier-described 
embodiment, and a stop shoulder 176 at the forward end of the piston 146. 
A shearable structure is provided on the outer surface 178 of the carrier 
member 140 and, as before, includes a primary shearable structure in the 
form of a shearable ring 180 located adjacent the forward end of the 
carrier member 140. In this instance, however, a secondary shearable 
structure is in the form of a tapered portion 182 located on the carrier 
member 140 axially between the shearable ring 180 and stop shoulder 176 of 
piston 146. The tapered portion 182 extends from an axially-forward 
smaller radius at 183 rearwardly to an axially-rearward larger radius at 
184. Upon forward axial movement of the female contact assembly 170 from 
the retracted location shown in FIG. 5 to the advanced location 
illustrated in FIG. 6, shearable ring 180 will be engaged by shearing ring 
172 and will be sheared from carrier member 140, with the aid of notch 186 
at root 188, and the tapered portion 182 will be intercepted by the 
sheared ring 180, backed-up by the fixed shearing ring 172, with the 
result that material will be sheared from the carrier member 140, along 
the tapered portion 182, as shown at 189. The gradual increase in the 
energy required to shear material 189 from the carrier member 140 along 
the tapered portion 182 thereof effects deceleration of the female contact 
assembly 170 such that the female contact assembly 170 will be halted 
effectively at the advanced position without failure of the bushing insert 
110. 
Preferably, a slight undercut is provided at 196, between the shearable 
ring 180 and the stop shoulder 176 so as to facilitate the venting of 
excessive arc-quenching gases through vent ports 194 and passage 192 after 
seals 190 pass beyond the forward end 136 of tubular nosepiece 132. 
FIG. 7 illustrates fragmented portions of another bushing insert 210 
constructed in accordance with the invention. The most forward portion of 
bushing insert 210, which is not illustrated in FIG. 7, may be constructed 
essentially the same as the forward portion of the bushing inserts 10 and 
110 described above. The arrangement wherein a housing 212 includes an 
outer housing casing 214 of elastomeric materials and a rigid, metallic, 
electrically conductive inner housing member 220 having a forward end 222 
and a rearward end 224 with a threaded aperture 226 at the rearward end 
224 is the same as that of either bushing insert 10 or bushing insert 110. 
In this instance, however, the threaded stud 228 which is received within 
threaded aperture 226 is a part of a metallic, electrically conductive 
extension 230 which, in addition to providing a further threaded aperture 
232 at the remote end 234 thereof for attachment to a high voltage 
circuit, such as the terminal of a transformer (not shown), includes 
kinetic energy absorption and dissipation means as follows. 
Between the threaded stud 228 and the threaded aperture 232, extension 230 
includes an axially-extending portion in the form of neck 236 provided 
with a predetermined transverse cross-sectional area, as at 238, which 
will enable neck 236 to become permanently deformed through axial 
elongation in response to an axially directed force of sufficient 
magnitude applied to neck 236. As in the earlier-described embodiments, 
bushing insert 210 includes a carrier member 240 having a piston 246 
received within the inner surface 248 of inner housing member 220. The 
carrier member 240 is movable within the inner housing member 220 between 
a retracted location, wherein the piston 246 is at the rearward end 224 of 
the inner housing member 220, and an advanced location, wherein the 
carrier member 240, and the female contact assembly 270 of which carrier 
member 240 is a part, is located adjacent the forward end 222 of the inner 
housing member 220 with a stop shoulder 276 on the piston 246 coupled with 
a stop ring 272 affixed to the inner housing member 220 to confine the 
carrier member 240 within the inner housing member 220. 
Should the kinetic energy of the female contact assembly 270 be great 
enough to cause potential damage to the bushing insert 210 once further 
movement of the female contact assembly 270 within the inner housing 
member 220 is constrained by the aforesaid coupling of the stop shoulder 
276 with the inner housing member 220, at least some of the kinetic energy 
will be absorbed and dissipated by the elongation and permanent 
deformation of neck 236 of extension 230, as shown exaggerated in phantom 
at 280 for illustrative purposes. Thus, the predetermined cross-sectional 
area at 238 is chosen, along with the appropriate axial length of neck 
236, so that enough of the kinetic energy of the female contact assembly 
270 will be absorbed and dissipated upon the impact resulting from the 
coupling of stop shoulder 276 with stop ring 272 to preclude a 
catastrophic failure in the bushing insert 210. 
Turning now to FIG. 8, yet another embodiment of the invention is 
illustrated in the form of bushing insert 310. Bushing insert 310 also is 
similar to the earlier-described embodiments in that a housing 312 
includes an outer housing casing 314 of elastomeric materials and a rigid, 
metallic, electrically conductive inner housing member 320 which extends 
longitudinally between a forward end 322 and a rearward end 324 within 
outer housing casing 314. The construction of inner housing member 320 
differs, however, from that of the corresponding component part of the 
aforesaid embodiments in that a rearward extension 330 is unitary with the 
inner housing member 320 at the rearward end 324. A blind hole 332 is 
located in the extension 330, a portion of which is threaded at 334 for 
attachment to a high voltage circuit. Blind hole 332 extends forward 
beyond the threaded portion 334 to establish a tubular neck 336 in the 
extension 330 between the rearward end 324 of the inner housing member 320 
and the threaded portion 334. Tubular neck 336 is provided with a 
carefully chosen predetermined cross-sectional area, as at 338, along with 
the appropriate axial length, for purposes which will be more fully 
described below. 
Located within the inner housing member 320 is a carrier member 340 having 
a piston 346 movable within the inner housing member 320 such that the 
carrier member 340 will move axially between a retracted location, 
illustrated in full lines, and an advanced location, illustrated in 
phantom, in much the same manner as set forth in connection with the 
above-described embodiments. Carrier member 340 and piston 346 thereof are 
parts of a female contact assembly 370 similar to the corresponding female 
contact assemblies of the above bushing inserts 10, 110 and 210. A stop 
member in the form of stop ring 372 is affixed to the inner housing member 
320 and a stop shoulder 374 is located on piston 346. 
When the female contact assembly 370 moves forward in response to the 
pressure of arc-quenching gases generated upon fault closure, the female 
contact assembly 370 will be accelerated to a high speed and the stop 
shoulder 374 will engage the stop ring 372. In order to decelerate the 
female contact assembly 370 and bring it to a halt without a catastrophic 
failure in the bushing insert, axial forward movement of the female 
contact assembly 370 subsequent to impact resulting from coupling of the 
stop shoulder 374 with stop ring 372 is transmitted to tubular neck 336 of 
rearward extension 330 which will elongate, as shown exaggerated in 
phantom at 380, in response to the axial force exerted over the 
cross-sectional area at 338. The permanent deformation of tubular neck 336 
thus serves to absorb and dissipate a sufficient amount of the kinetic 
energy of female contact assembly 370 to preclude failure of the bushing 
insert 10, as well as failure of the connection, at threaded portion 334, 
with the high voltage circuit. The tubular neck 336 provides the advantage 
of making available higher torsional strength for the predetermined 
cross-sectional area 338 when the bushing insert 10 is assembled with the 
terminal of the high voltage circuit. 
It is noted that the absorption and dissipation of kinetic energy of the 
moving female contact assembly is accomplished in each of the 
above-described embodiments either through means of a material shearing 
arrangement or through means of a material deformation arrangement or a 
combination of both means. Thus, bushing inserts 10 and 110 may include a 
permanently deformable neck 236 in the respective extensions 30 and 130 to 
supplement the material shearing arrangements of those bushing inserts in 
absorbing and dissipating kinetic energy, but need not include such a 
supplementary kinetic energy absorption and dissipation means. On the 
other hand, the permanently deformable neck 236 of bushing insert 210 may 
be employed as the sole kinetic energy absorption and dissipation means in 
bushing insert 210 or may be supplemented by the material shearing means 
disclosed in connection with the description of bushing inserts 10 and 
110. Likewise, the tubular neck 336 of rearward extension 330 in bushing 
insert 310 may serve as the sole means for absorbing and dissipating 
kinetic energy or may be supplemented by the material shearing means 
disclosed in the earlier-described embodiments. 
It is to be understood that the above detailed description of embodiments 
of the invention are provided by way of example only. Various details of 
design and construction may be modified without departing from the true 
spirit and scope of the invention as set forth in the appended claims.