ELECTRICAL CONNECTOR WITH FAULT CLOSURE LOCKOUT

FIELD OF THE INVENTION

[0001] The invention relates generally to an electrical connector for a power distribution system. More specifically, the invention relates to an electrical connector, such as a bushing insert, having a lockout feature that prevents resetting a movable piston-contact element after a fault closure event.

BACKGROUND

[0002] Conventional high voltage electrical connectors, such as bushing inserts, connect such devices as transformers to electrical equipment of a power distribution system. Typically, the electrical connector is connected to another electrical device of the power distribution system, such as a cable connector, with female contacts of the electrical connector mating with male contacts of the cable connector.

[0003] During connection of the electrical connector and cable connector under a load, an arc is struck between the contact elements as they approach one another. The arc formed during loadmake is acceptable since the arc is generally of moderate intensity and is quenched as soon as the contact elements are engaged. However, during fault closure or short circuit conditions, a substantial arc can occur between the contact elements of the connectors, resulting in catastrophic failure of the electrical connector including extensive damage and possible explosion.

[0004] Conventional electrical connectors employ a piston that moves the female contact of the electrical connector into engagement with the male contact of the cable connector during fault conditions, thereby accelerating the engagement of the contacts (hereinafter a "fault closure"), which in turn substantially eliminates any arc formed therebetween. After such a fault closure, the electrical connector is not suitable for further use and must be replaced. More specifically, the substantial arc generated during fault closure damages the female contact of the electrical connector such that the female contact will not perform during a subsequent fault closure. However, linemen in the field sometimes reset the piston in the electrical connector by forcing the piston back into its original position before the fault closure. At this point, the electrical connector appears as if it has not endured a fault closure. During a subsequent fault closure, the female contact of the electrical connector will not

completely engage the male contact of the cable connector, and the fault closure will not be completed.

[0005] Accordingly, a need exists in the art for preventing the resetting of the piston of an electrical connector after a fault closure event.

SUMMARY OF THE INVENTION

[0006] The invention relates to preventing the resetting of a moveable member of an electrical connector after a fault closure. When an electrical connector and a cable connector are engaged together during a fault closure, a piston-contact element with a female contact moves forward within the electrical connector to engage a male contact in the cable connector. The piston-contact element moves forward until a piston contact stop on the piston-contact element engages a stop ring in the electrical connector, which prevents further forward movement of the piston contact element. Additionally, a piston lockout member on the piston-contact element prevents movement of the piston-contact element in the opposite direction, thereby preventing the resetting of the piston-contact element to its original position. More specifically, the piston lockout member of the piston-contact element engages the stop ring in the electrical connector to prevent movement of the piston-contact element to its original position.

[0007] These and other aspects, objects, and features of the invention will become apparent from the following detailed description of the exemplary embodiments, read in conjunction with, and reference to, the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a side elevational view in partial cross section of a bushing insert electrical connector being mated with an elbow electrical connector for a power distribution system according to an exemplary embodiment of the invention.

[0009] Figure 2 is a side elevational view in cross section of the bushing insert electrical connector of Figure 1, including a piston-contact element with a piston lockout member according to an exemplary embodiment of the invention.

[0010] Figure 3 is a side elevational view in cross section of the piston-contact element of

Figure 2 according to an exemplary embodiment of the invention.

[0011] Figure 4 is a side elevational view of a resilient member for releasably retaining the piston-contact element in the inner bore of the bushing insert electrical connector according to an exemplary embodiment of the invention.

[0012] Figure 5 is a side elevational view in cross section of the bushing insert electrical connector of Figure 2, showing the piston-contact element in a position prior to engagement with a piston subassembly angled wall according to an exemplary embodiment of the invention.

[0013] Figure 6 is an enlarged side elevational view in cross section of the bushing insert electrical connector of Figure 2, showing the piston-contact element in a position prior to engagement with the piston subassembly angled wall according to an exemplary embodiment of the invention.

[0014] Figure 7 is a side elevational view in cross section of the bushing insert electrical connector of Figure 2, showing the piston-contact element in engagement position with the piston subassembly angled wall according to an exemplary embodiment of the invention.

[0015] Figure 8 is an enlarged side elevational view in cross section of the bushing insert electrical connector of Figure 2, showing the piston-contact element in engagement with the piston subassembly angled wall according to an exemplary embodiment of the invention.

[0016] Figure 9 is a side elevational view in cross section of the bushing insert electrical connector of Figure 2, showing the piston-contact element in the retracted home position according to an exemplary embodiment of the invention.

[0017] Figure 10 is an enlarged side elevational view in cross section of the bushing insert electrical connector of Figure 2, showing the piston-contact element in the retracted home position according to an exemplary embodiment of the invention.

[0018] Figure 11 is an enlarged side elevational view of the piston-contact element tapered protrusion expanding the resilient member and spacing the resilient member from the element retaining groove according to an exemplary embodiment of the invention.

[0019] Figure 12 is a side elevational view in cross section of the bushing insert electrical connector of Figure 2, showing the piston-contact element in an advanced position according to an exemplary embodiment of the invention.

[0020] Figure 13 is an enlarged side elevational view in cross section of the bushing insert electrical connector of Figure 2, showing the piston-contact element in an advanced position according to an exemplary embodiment of the invention.

[0021] Figures 14A-14D are enlarged side elevational views in cross section of the bushing insert electrical connector of Figure 2, showing the piston-contact element as it moves to the advanced position according to an exemplary embodiment of the invention. [0022] Figure 15 is an enlarged side elevational view in cross section of the bushing insert electrical connector of Figure 2, showing a piston lockout member engaging the resilient member in accordance with an exemplary embodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0023] The following description of exemplary embodiments refers to the attached drawings, in which like numerals indicate like elements throughout the figures. [0024] Referring to Figures 1-15, an electrical connector assembly 10 of a power distribution system includes an electrical connector 12, such as a high- voltage bushing insert, adapted to mate with an electrical device 14, such as an elbow cable connector. As best seen in Figures 2-3, the electrical connector 12 includes a housing 26 with an inner bore 28 for receiving a snuffer tube assembly 16. The snuffer tube assembly has a piston-contact element 18 that engages a contact element 20 of the cable connector 14. The piston-contact element 18 is movable between first and second axially spaced positions within an inner bore 28 of the electrical connector 12. During fault closure, first and second contact portions 22, 24 of the piston-contact element 18 move toward the contact element 20 of the cable connector 14 to accelerate engagement thereof and to quench any arc that may have formed while the two contact elements 22, 24 and the contact element 20 approach engagement. A resilient member 46 restricts movement of the piston-contact element 18. [0025] The housing 26 includes a first open end 30 and a second end 32 opposite the first open end 30. A middle portion 34 is positioned between first and second ends 30, 32. The first end 30 is connected to a cable connector 14 through an opening 36 providing access to the inner bore 28. The middle portion 34 is connected to ground. The second end 32 connects to a bushing well (not shown) as is well known and conventional in the art. First and second ends 30, 32 are generally cylindrical with a slight taper from the middle portion 34 to the respective end of the housing 26. The shape of the first end 30, in particular, is adapted to fit within the cable connector 14, as is best seen in Figure 1. The middle portion 34 is radially wider than the first and second ends 30, 32 and has a transition shoulder 38 between the middle portion 34 and first end 30.

[0026] The housing 26 of the electrical connector 12 is a molded unitary member formed of an insulative body 40 with an outer conductive layer 42 located at the middle portion 34 and with an inner conductive casing 44 defining the inner bore 28. The outer layer 42 can be made of a conductive rubber. The insulative body 40 can be made of an insulating rubber. The inner conductive casing 44 can be made of conductive rubber or nylon (for example, insulative glass filled nylon). Alternatively, a conductive paint or adhesive over the top of the nylon may be used. At least a portion the inner casing 44 includes a piston subassembly 70 having a bore retaining groove 84 therein.

[0027] The snuffer tube assembly 16 is received within housing inner bore 28. As best seen in Figure 3, the snuffer tube assembly 16 generally includes the piston-contact element 18, a resilient member 46 having a slot 48 for permitting expansion and compression of the resilient member 46, and a snuffer tube 50. The piston-contact element 18 can be made of any conductive material, such as metal, and has a first end 58, a second end 60, and a middle portion 59. The piston-contact element 18 has an outer surface 54 having a substantially annularly-shaped and continuous element retaining groove 52 for receiving the resilient member 46.

[0028] As seen in Figures 2 and 3, the snuffer tube 50 is connected to the piston-contact element 18 proximate the first end 58 of the piston-contact element 18, as is well known in the art. As best seen in Figure 2, the snuffer tube 50 includes an outer sleeve 62, which can be made of conductive rubber or nylon. The snuffer tube also includes an inner ablative member 64 for providing extinguishing gases, as is known in the art.

[0029] The piston-contact element first end 58 receives contact 20 of the cable connector 14. The second end 60 also receives contact 20 of the cable connector 14 and acts as a piston. Both first and second ends 58, 60 may include resilient probe fingers 66 and resilient contact fingers 68. Resilient probe fingers 66 facilitate engagement of the contact element 20 of the cable connector 14 and ensure a good connection. Resilient contact fingers 68 facilitate connection with the piston subassembly 70 and also ensure a good connection. The resilient probe and contact fingers 66, 68 are shaped to allow insertion of the piston-contact element 18 into the inner bore 28 in one direction, while preventing its removal. [0030] As best illustrated in Figures 3 and 13, the second end 60 of the piston-contact element 18 includes a stopping member 57 having an annular shoulder 56 for abutting the resilient member 46 and limiting travel of the piston-contact element 18 within inner bore 28 in a direction Dl illustrated in Figures 14A-14B. In an exemplary embodiment, the annular

shoulder prevents the piston-contact element 18 from advancing more than substantially about one inch towards the first end 30 of the electrical connector 12.

[0031] The piston-contact element 18 also includes a lockout member 55. As best illustrated in Figures 13-15, the lockout member 55 includes an annular shoulder 55a for abutting the resilient member 46 and limiting travel of the piston-contact element 18 within the inner bore 28 in a direction D2 illustrated in Figure 15. A height h of the annular shoulder 55a is substantially equal to a height of the annular shoulder 56 of the stopping member 57. The lockout member 55 also includes a substantially inclined wall 55b that facilitates positioning of the resilient member 46 between the annular shoulders 55a, 56 when the piston-contact element 18 advances during a fault closure, thereby locking the piston- contact element 18 in the advanced position, as best seen in Figure 15. A width w between the annular shoulders 55a, 56 is sized to accommodate the resilient member 46. [0032] As illustrated in Figure 4, the resilient member 46 is substantially ring shaped and can be spring biased. The resilient member 46 allows the piston-contact element 18 to be slidably inserted into the inner tube 28 of the electrical connector 12 and releasably retains the piston-contact element 18 with respect to the inner tube 28 such that the piston-contact element 18 cannot be easily removed. Resilient member 46 also allows the piston-contact element 18 to slide with respect to the electrical connector 14 when mating with the cable connector 12 during fault conditions.

[0033] As illustrated in Figures 6, 8, 10, and 13, the piston-contact element retaining groove 52 includes a first side wall 49, a second side wall 51, and an end wall 53 for receiving the resilient member 46. An angled wall 47 extends from the second side wall for facilitating disengagement and spacing of the resilient member 46 from the element retaining groove 52 during fault conditions as seen in Figure 13.

[0034] Figures 6, 8, 10, and 12 also illustrate the middle portion 59 of the piston-contact element 18. The middle portion 59 includes a substantially annularly shaped tapered protrusion 61. The tapered protrusion 61 is located proximate the angled wall 47 and has a tapered back side. The tapered protrusion 61 facilitates disengagement of the resilient member 46 from the element retaining groove 52, as best seen in Figure 1 1, permitting the piston-contact element 18 to be advanced to a second position during fault conditions as seen in Figure 13.

[0035] The second end 32 of the housing 26 includes a bushing well (not shown). A metal (for example, copper) piston subassembly 70 is releasably connected to the bushing

well by any suitable fastening means, preferably by a threadable connection. The piston subassembly is constructed of a metal, such as copper. As shown in Figures 5, 7, 9, and 12, the piston subassembly 70 has a first section 72 and a second section 76. The first section 72 includes a nose cone 74 for mating with the bushing well. The second section 76 has inner and outer surfaces 80, 82. The inner surface 80 defines the perimeter of a substantially U- shaped chamber receiving the piston-contact element 18 of the snuffer tube assembly 16. The piston subassembly 70 and the inner conductive casing 44 are integrally connected, defining an inner surface of the inner bore 28. The piston subassembly 70 may be independently positioned as a separate element adjacent to the inner conductive casing 44 or alternatively the inner conductive casing 44 and the piston subassembly 70 can be one element.

[0036] As best seen in Figure 9, when the piston-contact element 18 is in the fully retracted home position, a space 78 remains between the U-shaped chamber defined by the inner surface 80 of the piston subassembly 70 and the second end 60 of the piston-contact element 18. During fault closure or short circuit conditions, gases are generated which fill the chamber space 78. As the gases occupy the space 78, the pressure within the space 78 increases, generating a force against the second end 60 of the piston-contact element 18. This force is sufficient enough to overcome the force applied to the piston-contact element 18 by the resilient member 46.

[0037] As best seen in Figures 6, 8, 10, and 13, the inner surface 80 of the piston subassembly 70 includes a substantially annularly shaped bore retaining groove 84 having a first side wall 81 , a second side wall 83, and an end wall 85. A substantially angled wall 86 extends from the second side wall 83. The substantially annularly shaped bore retaining groove 84 receives the resilient member 46 located on the piston-contact element 18. The substantially angled wall 86 extends from the inner surface 80 toward the outer surface 82 of the piston subassembly 70. The angled wall 86 facilitates positioning of the piston-contact element 18 in the U-shaped chamber of the piston subassembly 70.

[0038] The angled wall 86 guides the piston-contact element 18 into alignment with the annular bore retaining groove 84. Specifically, as the piston-contact element 18 of the snuffer tube assembly is further inserted into the inner bore 28 of the electrical connector 12, the angled wall 86 compresses the resilient member 46. Subsequently, as the piston-contact element 18 is advanced to a position beyond the tapered edge section 86, the compressive force placed upon the resilient member 46 by the angled wall 86 is removed, and the resilient

member 46 expands. The resilient member 46 expands and snaps into the corresponding bore retaining groove 84 located on the inner surface 80 of the piston subassembly 70, thereby locking the piston-contact element 18 in the home position, as is best seen in Figure 9. [0039] OPERATION

[0040] The electrical connector 12 connects to the cable connector 14. Since the cable connector 14 is well known in the art, it will be described only generally. Cable connector 14 includes an insulative housing 100 with first and second ends 102, 104 and an outer conductive jacket 106, as best seen in Figure 1. The first end 102 includes an opening 108 for receiving the electrical connector 12 into a bushing port 110 of the cable connector 14. Extending through the bushing port 110 is the contact element or conductive probe 20. As best seen in Figures 1 -2, the contact element 20 is received within the inner bore 28 of the electrical connector 12, through the resilient probe fingers 66, upon connection of the electrical connector 12 and the cable connector 14. The contact element 20 includes an insulating ablative member 112 to provide arc quenching gases, as is known in the art. The bushing port 110 is shaped to receive the first end 30 of the electrical connector 12. The cable connector 14 includes a groove 114 that mates with an extended lip 98 of the first end 30 of the electrical connector 12. The second end 104 of the cable connector 14 receives a cable (not shown) that is electrically connected to the contact element 20. Although the cable connector 14 is shown as an elbow or L- shaped connector, the electrical connector 12 can be connected to any type of cable connector known in the art.

[0041 ] Referring to Figures 5-13, during fault closure, by moving from a retracted (home) position to an extended (advanced) position, the snuffer tube assembly 16 accelerates the connection of the piston-contact element 18 of the electrical connector 12 and the contact element 20 of the cable connector 14, thereby quenching the formation of an arc and preventing injury to the operator. During fault closure, as the electrical connector 12 and the cable connector 14 approach one another, with electrical connector 12 being inserted into the bushing port 110 of the cable connector 14, an arc is formed between the piston-contact element 18 and the contact element 20, thus triggering the generation of arc quenching gases from the ablative members 64, 112, as is known in the art.

[0042] During normal operation, piston-contact assembly 18 is in the retracted home position, as best seen in Figures 9-10. During a fault closure, gases are generated. As seen in Figures 12-13, as the electrical connector 12 is advanced further into the bushing port 110 of the cable connector 14, the generated gases from the ablative members 64, 112 fill up space

78 located in a U-shaped chamber of the piston subassembly 70 by passing around the piston- contact assembly or through the interior cavity of the piston-contact element 18. As the gases occupy space 78, the pressure increases, and thus a force acts upon the second end 60 of the piston-contact element 18 and initiates movement by overcoming the force applied by resilient member 46.

[0043] Consequently, the piston-contact element 18 is forced in a direction Dl (Figures 14A- 14D) towards the first end 30 of the electrical connector 12. As the piston-contact element 18 is advanced, the angled wall 47 of the element retaining groove 52 initiates an expansion force against the resilient member 46. The force increases as the piston-contact element 18 is advanced. The force acting upon the resilient member 46 increases until the tapered protrusion 61 is reached, and the expansion force plateaus, as best seen in Figure 11. During this time, the piston-contact element 18 is released from the resilient member 46 and permitted to advance towards the first end 30 of the electrical connector 12 under pressure from the generated gases, thus accelerating the connection of the piston-contact element 18 and the contact element 20. When the piston-contact element 18 is released from the resilient member 46 and permitted to advance towards the first end 30 of the electrical connector 12, the resilient member 46 is located in position A as illustrated in Figure 14A. [0044] As the piston-contact element 18 continues to advance in the direction Dl, the angled wall 55b of the lockout member 55 initiates an expansion force against the resilient member 46. At this point, the resilient member 46 is located substantially in position B as illustrated in Figure 14B. The force increases as the piston-contact element 18 is advanced. The force acting upon the resilient member 46 increases until the resilient member 46 is disposed adjacent to a plateau 55c of the lockout member 55, and the expansion force plateaus. At this point, the resilient member 46 is located substantially in position C as illustrated in Figure 14C.

[0045] The piston-contact element 18 can only be advanced a limited distance. As the piston-contact element 18 continues to advance in the direction Dl, the annular shoulder 56 of the stopping member 57 prevents any further advancement in the direction Dl when engaged by the resilient member 46. At this point, the resilient member 46 is located substantially in position D as illustrated in Figure 14D, which is the extended (advanced) position.

[0046] In an exemplary embodiment, the snuffer tube assembly 16, including the piston- contact element 18, is permitted to travel within the inner bore 28 of the electrical connector 12 substantially about one inch.

[0047] After advancement of the piston-contact element 18, the piston-contact element 18 cannot be reset to the retracted home position. If an operator attempts to move the piston-contact element 18 in the direction D2 illustrated in Figure 15, then the annular shoulder 55a of the lockout member 55 prevents any further advancement in the direction D2 when engaged by resilient member 46. Because the lockout member 55 prevents resetting the piston-contact element 18 to the retracted home position, an operator will not have a false indication that the electrical connector 12 is safe for future connections to the cable connector 14. The protrusion of the snuffer tube assembly 16 from the end 30 of the electrical connector 12 provides a visual indication to an operator that the cable connector 14 should not be connected to the electrical connector 12.

[0048] Under normal operating conditions, that is other than fault conditions, the intensity of the arc during connection of the electrical connector 12 and the cable connector 14 is moderate and thus does not create enough pressure in the piston subassembly 70 chamber space 78 to move the piston-contact element 18. Thus, it is generally only under fault conditions that the piston-contact element 18 moves between the retracted and advanced positions.

[0049] In conclusion, the foregoing exemplary embodiments enable an electrical connector with a fault closure lockout feature. Many other modifications, features, and embodiments will become evident to a person of ordinary skill in the art having the benefit of the present disclosure. It should be appreciated, therefore, that many aspects of the invention were described above by way of example only and are not intended as required or essential elements of the invention unless explicitly stated otherwise. It should also be understood that the invention is not restricted to the illustrated embodiments and that various modifications can be made within the spirit and scope of the following claims.