US3236984A

US3236984A - High voltage circuit switching device

Info

Publication number: US3236984A
Application number: US237095A
Authority: US
Inventors: Sigurd I Lindell
Original assignee: S&C Electric Co
Current assignee: S&C Electric Co
Priority date: 1962-11-13
Filing date: 1962-11-13
Publication date: 1966-02-22
Anticipated expiration: 1983-02-22

Description

Feb. 22, 1966 s, l. LINDELL HIGH VOLTAGE CIRCUIT SWITCHING DEVICE 5 Sheets-Sheet 1 Filed Nov. 13, 1962 \754 1 n Uhr 5 l. l 77 767 7M 8 9 8 5 4 6 n 6 m m 6 7 m @vii 4 M 4 i .li i l.-

INVENTOR. SIGURD l. LINDELL Feb. 22, 1966 s. LINDELL.

HIGH VOLTAGE CIRCUIT SWITCHING DEVICE 5 Sheets-Sheet 2 Filed Nov. 13, 1962 ERS Feb. 22, 1966 s. LINDELL HIGH VOLTAGE CIRCUIT SWITCHING DEVICE 5 Sheets-Sheet 5 Filed Nov. 13, 1962 m 0 1 0 1 fr M4 M 7 nd M 6 5 1 1w 641 09m. H\\\\ 37 4 1 m 4.. M A1 United States Patent O 3,236,934 HIGH VULTAGE CIRCUIT SWITCHING DEVICE Sigurd I. Lindeli, Northbrook, Ill., assigner to S le C Electric Company, Chicago, Ill., a corporation of Delaware Filed Nov. 13, 1962, Ser. No. 237,095 35 Claims. (Cl. 20G- 149) This invention relates, generally, to high voltage electric circuit makers and breakers and it has particular relation to such devices provided with are extinguishing means. It constitutes an improvement over the construction shown in application Serial No. 118,967, tiled June 22, 1961, in the name of Henry I. Barta and assigned to the assignee of this application, now Patent No. 3,122,658, issued February 25, 1964.

Among the objects of this invention are: To provide for completing the circuit between a pair of high voltage terminals mounted in insulated spaced relation and `for opening the circuit between these terminals in a new and improved manner; to provide for switching and sectionalizing buried cable single phase circuits carrying loads up to 200 amperes at high voltage through the use of an improved form of bayonet type load interrupter switch construction located within a grounded housing of conducting material below the yground level and operable by a live line tool through an access pipe or tube extending from the housing to and above ground level; to establish a safe disconnecting air gap between line terminals carried on insulating bushing type supports extending through the walls of the grounded metallic housing with the bushings having cab'le terminal portions extending in the directions of the buried cable and 'generally parallel to the surface of the ground; to prevent leakage current from owing over the contact supporting insulating members from one terminal to the other by interposing a grounded support and enclosure member therebetween for mounting the insulating members and providing an enclosure for the bayonet type switch; to employ a bayonet type switching member including conducting members or ferrules with a sleeve of insulating material for overlying one of the ferrules and a follower of insulating arc extinguishing material arranged to cooperate with the sleeve in a unitary assembly for extinguishing an are drawn from the ferrule with the arrangement being such that the unitary assem ly is withdrawable as a unit from the housing carrying the terminals connected to the sections of buried cable; to support the arc extinguishing sleeve slidably on the connecting conductor means between the ferrules and providing for biasing it to overlie one of the ferrules; to employ a spring to provide the biasing action and to arrange for it to react between the insulating sleeve and the other ferrule; to direct gases incident to the drawing of an arc from a terminal in such manner that they flow through the terminal; to arrange the sleeve in such manner that it can move away from the lferrule in the event that a high current arc is struck on movement of the device to closed circuit position thereby reducing the restriction of the arc and valving gas so as to prevent destructive pressures from developing within the slidable sleeve; to provide for resiliently latching the bayonet construction against the upward thrust of the spring acting to bias the sleeve over the fer-rule; to provide for venting the interrupting structure in a direction away from the leakage surfaces of the insulators that support the terminals in order to prevent carbon and other arc products from being deposited on these surfaces; and to provide for application an-d withdrawal of the unitary bayonet type connecting conductor means through the agency of a live line tool operating through the metallic pipe or access tube from the surface of the ground with the construction being such that there is no likelihood that the 3,236,984 Patented Feb. 22, 1966 circuit will be grounded as a result of accidental connection between the access pipe and the bayonet type of connecting conductor means during the application or withdrawal thereof.

In the drawings:

FIGS. 1A and 1B, the latter being placed above the former, show a vertical sectional view through a high voltage circuit switching device constructed in accordance with this invention.

FIG. 2 is a view, in side elevation, of a connecting conductor device of the kind and character shown in FIG. 1A, the construction being shown separately from the housing and the line terminals to be interconnected thereby.

FIG. 3 is a horizontal sectional view taken generally along the line 3-3 of FIG. 1A.

FIG. 4 is a vertical sectional view, similar to FIGS. 1A and 1B, `showing another embodiment of this invention.

FIG. 5 is a view, in side elevation, of the embodiment of the invention as `shown in FIG. 4, the arrangement being here shown at a smaller scale.

FIG. 6 is a top plan view of the construction shown in FIG. 5.

Referring now particularly to FIGS. 1A and 1B of the drawings, with the latter being placed above the former, it will be observed that the reference character 10 designates, generally, a high voltage circuit switching device embodying the present invention. The device 10 is arranged and adapted for controlling the connection between

conductors

11 and 12 of buried cable single phase circuits. Conventional wiped

joints

13 and 14 can be provided for interconnecting the device 10 and the

conductors

11 and 12 which extend generally parallel to ground level indicated at 15 in FIG. 1B. It will lbe understood that the

conductors

11 and 12 are located in suitable lead covered cable constructions which initially may be installed in open trenches and connected to opposite sides of the device 10 which also is initially installed in a suitable opening excavated in the ground. After the installation has been completed, the trenches and the opening are lilled to the ground level indicated at 15. The instal- 4lation may be in a vault or basement with the

conductors

11 and 12 extending into it and the device 10 likely to be submerged in the event of iiood conditions or the like.

For enclosing the live or energized parts of the device 10 a metallic housing, shown generally at 16, is employed. It is formed by a vertically extending metallic cylindrical tube 17 having top |and

bottom plates

18 and 19 secured as by welding to the respective end. An aperture 20 is provided in the top plate 18 and forms an access opening to the interior of the housing 16. yIt registers with an opening through a metallic access pipe or tube 2,1 which extends upwardly from the metall-ic housing 16 to a position at or above ground level 15 as indicated in FIG. 1B. At its lower end the metallic access pipe or tube 21 has a radial flange 22 extending therefrom into overlying `relation with a gasket 23 in order to provide a sealed connection to the upper side of the top plate 18. Bolts 24 extend through the Ailange 22 into the top plate 18 to provide a unitary construction. At its upper end, as shown in FIG. 1B, the metallic access pipe or tube 21 is provided with a radial flange 25 through which socket head bolts 26 extend upwardly for removably mounting a cap `27. A gasket 28 underlies the cap 27 and extends around the periphery of the upper end of the metallic yaccess pipe or tube 21 to provide a sealed connection therebetween when the bolts 26 are tightened. A downwardly extending skirt 29 along the periphery of the cap 27 provides additional weather protection and limits the access to the socket heads of the bolts 26. At the lower end of the metallic yaccess pipe or tube 21 there is provided an insulating sleeve 30 which, as shown in FIG. lA, projects a slight distance below the underside of the top plate 18. The insulating sleeve 31) is provided for the purpose of preventing accidental grounding to the metallic access pipe or tube 21 when bayonet type connecting conductor means, to be described, are inserted in or removed from the metallic housing 16 and for guiding the bayonet type connecting conductor mean-s into operative polsition within the housing 16. Additional insulation is provided by a layer 311 of insulating paint over the inner surface of 4the metallic tube 17 and the inner surfaces of the top and

bottom plates

18 and 19.

vThe bottom plate 19 has a central aperture 33 which, when open or uncovered, facilitates the assembly of the apparatus within the metallic housing 16. A hand cover 34 serves to close the aperture 33. A sealed connection to the housing 16 is provided here by a gasket 35 which is located between the under surface of the bottom plate 19 and the upper surface of the hand cover 34. Bolts 36 hold the hand cover 34 in place and compress the gasket 35. Overlying the upper side of the bottom plate 19 is an insulating plate 37 which prevents direct contact of the arc blast with the bottom plate 19 and hand cover 34 that m-ay -be incident to the opening or closing of the circuit between the

conductors

111 and 12.

The metallic housing 16 is arranged to carry upper land lower insulating bushings that are indicated, generally, at 41 and 42. They extend radially through the vertical wall of the metallic cylindrical tube 17. As shown in FIG. 1A they extend through enlarged openings one of which is indicated at 43. Conductor rods 44 and 45 extend through the insulator bushings 41 and 42 and provide connections to the

conductors

11 and 112 which lare completed by the

wiped joints

13 and 14. Any suitable means can be provided for `stationarily mounting the insulator bushings 41 and 42 in parallel spaced relation one above the other and extending through and having a sealed connection to the Wall of the metallic cylindrical tube 17. For this purpose

synthetic rubber shields

46 and 47 are provided and they are suitably cemented to apertured closure plates one of which is indicated at 48. A gasket 48 is interposed between the inner side of the closure plate 48 'and the bushing 42 to provide a water tight sealed connection therebetween. Suitable reaction clam-p means, shown generally at 50, cooperate with the bushing 42 and closure plate 4-8 to compress the gasket 49 and hold the bushing 42 in position on the metallic housing 16.

At the inner ends of the insulator bushings 41 and 42 the conductor rods 44 and 45 are connected toterminal connectors 51 and 52. In turn, the terminal connectors 51 and 52 are secured by bolts 513 and 54 to upper and lower cylindrical terminals that are shown, generally, `at 55 and 56. The upper and lower

cylindrical terminals

55 and 56 are positioned on the inner ends of the insulator bushings v41 and 42 in coaxial relation and in coaxial relation with the access opening and the metallic pipe or tube v21.

The upper cylindrical terminal 55 includes a sleeve 57 of suitable conducting material such as copper, brass, or aluminum through which the bolts 53 extend for mounting it on the terminal connector 5-1. The sleeve 57 has a thick walled lower end 58 within which a contact sleeve 59 is positioned and rolled into 4good contact engagement. The contact sleeve 519 includes upstanding contact fingers 60 that are urged by a garter spring 61 into contact engagement with the outer surface of a contact portion 62 that is cylindrical in shape and is located on the upper end of an upper ferrule which is indicated, generally, at 63. The upper ferrule 63 forms a part of bayonet type connecting conductor means, indicated generally at 64, -that is shown in detached relation in FIG. 2. The bayonet type connecting conductor means 64 is provided for controlling the connection between the upper and lower

cylindrical terminals

55 and 56. For this purpose it has a conducting rod 65 that is secured to the upper ferrule 63 and extends downwardly therethrough and carries a lower ferrule 66 at its lower end the diameter of which is substantially less than the diameter of the upper ferrule 63 for a purpose that will be apparent presently.

It will be observed that the lower ferrule 66 has contact engagement with contact fingers 67 that are urged by a garter spring 68 into Contact engagement therewith. The Contact ngers 67 extend upwardly from a contact sleeve 69 that is located within a metallic sleeve 70 with the combination being secured by the bolts 54 to the terminal connector 52 at the inner end of the conductor rod 45 that extends through the lower insulator bushing 42. The metallic sleeve 70 has a conical upper surface 71 which reacts as a guide for directing the lower ferrule 66 into Contact engagement with the contact lingers 67. Also the upper end of the metallic sleeve 70 functions as an arcing Contact to which an arc is struck or from which it is drawn when the connecting conducting means 64 is applied or withdrawn respectively. Rivets 72 also extend through the lower end of the metallic sleeve 70 and the Contact sleeve 69 to secure them together.

It is desirable that any arcing between the lower ferrule 66 and the contact fingers 67 or the metallic sleeve 7i) be confined as much as possible. For this purpose an insulating sleeve 74 of arc extinguishing material is slidably mounted on the conducting rod 65 between the upper ferrule 63 and the lower ferrule 66. The insulating sleeve 74 can be formed of a material that evolves an arc extinguishing medium when it is subjected to the heat of an arc. For example, it can be formed of methylmethacrylate resin, liber or like material. In order to cause the insulating sleeve 74 to telescope over the lower ferrule 66 a coil compression spring '75 is employed. The coil compression spring 75 is telescoped within the lower end 76 of the upper ferrule 63 and reacts between this ferrule and the upper end of the insulating sleeve 74 to bias it downwardly in overlying relation to the lower ferrule 66 and to the position shown in FIG. 2 of the drawings. The downward movement of the insulating sleeve 74 is limited by a radially inwardly extending shoulder 77 that is located near the upper end of the insulating sleeve 74. As shown in FIG. 2 the downward movement of the insulating sleeve 74 is arrested when the shoulder 77 engages the upper end of the lower ferrule 66. When this takes place under the infiuence of the coil compression spring 75, no further downward movement of the insulating sleeve 74 is permitted.

It will be understood that, when the connecting conductor means 64 is withdrawn or moved upwardly to open the circuit between the

conductors

11 and 12, the lower ferrule 66 is moved upwardly and out of Contact engagement with the Contact fingers 67 and into the lower end of the insulating sleeve 74. Any arc that is incident to this operation and caused by opening the circuit under load is draw between the lower end of the lower ferrule 66 and the upper ends of the contact fingers 67 initially and finally is drawn from the metallic sleeve 70 as the lower end of the lower ferrule 66 moves upwardly past the arcing shoulder 73 thereon. In order to further conne the arc thus drawn, an insulating follower 78 is secured by a rod 79 to the lower end of the lower ferrule 66. The insulating follower 7S is formed of a suitable arc extinguishing material of the kind and character of which the insulating sleeve 74 is formed. Its internal diameter is about the same as the diameter of the lower ferrule 66 while the internal diameter of the insulating sleeve 74 is large enough to permit the lower ferrule 66 and the insulating follower 7 8 to move into the same. When this takes place the arc drawn from the lower ferrule 66 is conlined between the juxtaposed outer surface of the insulating follower 78 and the inner surface of the insulating sleeve '74. This provides a relatively large area of arc extinguishing material that can be subjected to vthe heat of the arc with a corresponding evolution of arc extinguishing medium. In order to assist the spring 75 in holding the sleeve 74 against the conical surface 71 of the sleeve 70, latch means can be provided in the form of radially inwardly spring biased iingers on the sleeve 70 with radially inwardly extending latching sections, such as provided by contact fingers 67, cooperating with an annular groove in the surface of the sleeve 74 adjacent its lower end.

Since the coil compression spring 75 applies an upward thrust to the connecting conductor means 64, it is desirable to provide a restraining force for the purpose of preventing such movement. For this purpose latch means in the form of a ridge 80 is provided on the upper ferrule 63 at the lower end of `the contact portion 62. The ridge 80 is of suicient diameter to engage the under sides of the convex contact portions 81 of the contact fingers 60. It will be understood that the garter spring 61 exerts sufficient force to hold the convex contact portions 81 in engagement with the upper side of the ridge 80l so that lthe upward movement of the connecting conductor means 64 under the influence of the coil compression spring 75 is prevented.

In the event that it is likely that there will be substantial arcing on withdrawal of the connecting conductor means 64 a condenser, shown generally by broken lines and indicated at 82, can be provided. The condenser 82 can be constructed as disclosed in copending application Serial No. 857,381, filed December 4, 1959, in the name of Sigurd I. Lindell and assigned to the assignee of this application, now abandoned.

As pointed out hereinbefore the diameter of the upper ferrule 63 is substantially greater than the diameter of the lower ferrule 66. Accordingly, the diameter of the opening through the upper cylindrical terminal 55 is correspondingly greater than the opening through the lower cylindrical terminal 56. The reason for this is that the insulating sleeve 74, which has a diameter approximately the same as the diameter of the upper ferrule 63, must be inserted through the upper cylindrical terminal 55. Also it is withdrawn through the upper terminal 55. In order to insure that no arcing takes place between the upper ferrule 63 and the upper terminal 55, the lower end 76 of the upper ferrule 63 has sufficient length to maintain contact engagement with the contact fingers 60 while the lower ferrule 66 is being inserted into or withdrawn from the lower terminal 56.

The downward movement of the connecting conductor means 64 through the

terminals

55 and 56 is limited by a cross pin S4. As shown in FIGS. 1A and 2 the cross pin 84 extends through the contact portion 62 of the upper ferrule 63 and is arranged to engage the upper end of the sleeve 57 which forms a part of the upper cylindrical terminal 55.

Extending upwardly from the upper end of the upper ferrule 63 is a shank 85 the diameter of which is substantially less than the diameter of the contact por-tion 62. The shank 85 is provided with a cross pin 86 which together with the shank 85 is provided to permit application and removal of the bayonet type connecting conductor means 64 to and from the

terminals

55 and 56. The cross pin 86 in the shank 85 is arranged to enter slots 87 located in opposite sides of the lower end of an insulating rod 88 which functions as a live line tool to permit application of the connecting conductor means 64 or its Aremoval with one or both of the

conductors

11 and 12 energized. TheV insulating rod 88 has an axial opening 89 in its lower end into which the shank 85 projects with the ends of the cross pin 86 extending into and held in the slots 87 by a coil compression spring 90 which reacts between the bottom of the axial opening 89 and the upper end of the shank 85. Centering spokes 91 extending radially from the insulating rod 88 serve to guide it in its movement through the insulating sleeve 30 and the metallic access pipe or tube 21. With the cap 27 removed, the insulating rod 88 is inserted into the upper end of the metallic access pipe or tube 21 with the upper end 92 extending well above it in order to permit the lineman to grasp it and manipulate the insulating rod 88 and the bayonet type connecting conductor means 64 attached to the lower end in the manner described.

When the bayonet type connecting conductor means 64 has been removed from the

terminals

55 and 56 by the live line tool in the form of an insulating rod 88, constructed as described, an air gap having a length as indicated at 93 in FIG. 1A is provided between the lower end of the upper terminal 55 and the upper end of the lower terminal 56. Since the removal of the connecting conductor means 64 is accompanied by removal of the insulating sleeve 74 and the insulating follower 78, full dielectric strength of the air gap between the

terminals

55 and 56 can be maintained. As a result the distance between the

terminals

55 and 56 can be reduced and the length of the bayonet type connecting conductor means 64 can be correspondingly reduced. Also the unitary construction and removal of the insulating sleeve 74 and insulating follower 78 facilitates th-e inspection of these parts and replacement thereof, if the same appears to be warranted.

It will be recalled that the metallic housing 16 may be located below ground level 15. In any event it is grounded as indicated diagrammatically at 38. Because of this arrangement leakage current cannot flow between the

terminals

55 and 56 when the bayonet type connecting conductor means 64 is removed.

When the insulating rod 88 is mechanically connected to the shank 85 in the manner described for the purpose of removing the bayonet type connecting conductor means 64, the removal is accomplished by applying an upward pull to the rod 88 to effect a corresponding upward movement of the connecting conductor means 64. During the initial part of this upward movement the spring holds the lower end of the insulating sleeve 74 against the conical upper surface 71 of the metallic sleeve 70. As a result of the continued upward movement of the insulating rod 88, the lower ferrule 66 is withdrawn from the contact lingers 67 and into the lower end of the insulating sleeve 74 past the arcing shoulder 73 on the metallic sleeve 7G. Any arc drawn between the lower ferrule 66 and the contact fingers 67 or the arcing shoulder 73 is drawn into the interior of the insulating sleeve 74. The upward movement of the lower ferrule 66 is accompanied by a corresponding upward movement of the insulating follower 78 so that the arc is confined, as described hereinbefore, between its outer surface and the inner surface of the insulating sleeve 74 and is quickly extinguished. Since the insulating sleeve 74 is held tightly against the conical upper surface 71 of the metallic sleeve 70 during the circuit opening operation by the spring 75 and by latching means when provided, the gases that are generated incident to the drawing and extinguishing of the arc are directed downwardly through the lower terminal 56 and either into the condenser 82, if it is employed, or against the upper side of the insulating plate 37. The spacing to the interior of the metallic housing 16 is such that it is unlikely that the arc will strike to it. The layer 31 of insulating paint also reduces the likelihood of arcing to the housing 16. It will be observed from FIG. 1B that the length of the insulating sleeve 30 within the lower end of the metallic access pipe or tube 21 is such as to completely enclose the upper ferrule 63 at the time that the lower ferrule 66 enters or leaves the upper terminal 55. This arrangement makes certain that there will be no inadvertent grounding of the upper terminal 55 to the metallic access pipe or tube 21 during the application or removal of the connecting conductor means 64.

When the circuit between the

conductors

11 and 12 is closed under load or short circuit conditions, an arc is struck between the lower ferrule 66 and the arcing shoulder 73 on the metallic sleeve 70. The gases evolved from the insulating sleeve 74 as a result of heat from a high current arc then cause the insulating sleeve 74 to move upwardly away from the lower ferrule 66 and the follower 78. As a result there is little, if any, restriction on the flow of gas and the same is valved so that destructive pressures are not generated within the insulating sleeve 74.

The restraining force provided by the interaction between the latch means 80 and the contact fingers 60 is appreciably greater than the upward thrust exerted by the spr-ing 75 on the upper ferrule 63. During the downward or closing movement of the connecting conductor means 64, the lower end of the insulating sleeve 74 abuts the conical upper surface 71 of the metallic sleeve 70 at the time that the lower end 76 of the upper ferrule 63 is making contact with the contact fingers 60 on the upper terminal 55. Preferably the upward thrust exerted by the spring 75 is less than the force exerted by the weight of the bayonet type connecting conductor means 64 plus the weight of the insulating rod 88 and parts associated therewith to the end that the assembly can be inserted with the lower end of the insulating sleeve 74 bearing against the conical upper surface 71 of the metallic sleeve '70 while the connecting conductor means 64 is in the extended position as shown in FIG. 2. With this arrangement there is a substantial air gap between the lower end of the low-er ferrule 66 and the upper end of the lower terminal 56. From this position a sharp downward force can be exerted on the upper end 92 of the insulating rod 88 for the purpose of quickly moving the lower ferrule 66 into contact engagement with the lower terminal 56. Thus, if any arcing takes place between the lower ferrule 66 and the lower terminal 56, it will take place during a minimum of time.

Since the portions of the upper and lower insulating bushings 41 and 42 that extend into the metallic housing 16 are horizontal and out of the direct path of any arc products, there is little likelihood that the exposed surface portions thereof will be contaminated by conducting arc products likely to reduce the insulating properties of these bushings.

While the connecting conductor means 64 has been described as including the conducting rod 65 interconnecting the

ferrules

63 and 66, it will be understood that other means such as the expulsion fuse described in U.S. Patent No. 2,813,952, issued November 19, 1957, in the names of Charles H. Baker and John I. Mikos, can be employed.

FIGS. 4, and 6 show another embodiment of the invention. Here it will be observed that the reference character 100 designates, generally, a high voltage circuit switching device that is arranged to control the connection between conductors 101 and 102 of buried cable single phase circuits that are connected by conventional wiped joints 103 and 104 to the device 100. The conductors 101 and 102 extend generally parallel to each other and are located in spaced relation and generally parallel to ground level indicated at 105. The device 100, as pointed out above for the device 10, can be located in a vault, basement or the like that is subject to flooding and hence needs be completely sealed against the entrance of water.

The high voltage circuit switching device 100 includes a metallic housing, indicated generally at 106, that is formed by a metallic cylindrical tube 107 overlying a cylindrical liner 108 of insulation that may be of ceramic material or organic material with the space 108 therebetween filled with a suitable insulating compound. Metallic top and

bottom plates

109 and 110 are provided at the upper and lower ends of the metallic cylindrical tube. 107 and the cylindrical liner 108 therein. Gaskets 111-111 are interposed between the under and upper sides of the top and

bottom plates

109 and 110 and the upper and lower ends of the tube 107 and liner 108 respectively. Brackets 112-112 extending laterally from the upper and lower ends of the metallic cylindrical tube 107 are arranged to receive bolts 113-113 extending through the top and

bottom plates

109 and 110 to provide a sealed construction for the metallic housing 106 in order to prevent the entrance of moisture into the interior thereof.

The top plate 109 has a centrally located opening 114 for receiving one arm 115 of an upper insulator 116 that may be formed of molded organic insulating material such as a phenolic condensation product. The outer surface of the lower portion of the arm 115 is corrugated in order to increase the leakage distance thereover. A flange 117 is formed integrally with the arm 115 and it overlies the top plate 109 with a gasket 118 located therebetween. Bolts 119 serve to clamp the flange 117 to the top plate 109 and to continue the water tight integrity of the metallic housing 106 at its upper end.

The upper insulator 116 carries an upper terminal that is indicated, generally, at 122. The upper terminal 122 includes a cylindrical base portion 123 that can be molded in the upper insulator 116 or inserted after the molding operation has been completed as may be desired. The cylindrical base portion 123 has a conductor rod 124 extending through another arm of the upper insulator 116. The conductor rod 124 extends through and beyond the arm 125 and is connected by a metallic connector 126 to the conductor 102. Secured to and extending downwardly from the cylindrical base portion 123 of the upper terminal 122 is a metallic sleeve 127. At its lower end it has contact fingers 128 that are urged inwardly by a garter spring 129. The contact fingers 128 are arranged to engage an upper ferrule 130 of bayonet type connecting conductor means, shown generally at 131, which include a conducting rod 132 that is secured to and extends downwardly from the upper ferrule 130.

At its lower end the conducting rod 132 is provided with a lower ferrule 133 that is engaged by contact fingers 134 of a lower terminal which is indicated, generally, at 135. The lower terminal 135 is mounted in one arm 136 of a lower insulator that is indicated, generally, at 137. The lower insulator 137 is formed of molded organic insulating material such as a phenolic condensation product. The outer surface of the upper end of the arm 136 is corrugated in order to increase the leakage distance thereover. The arm 136 extends downwardly through an opening 110 in the bottom plate 110. Also the arm 136 has a flange 138 formed integrally therewith that overlies the bottom plate 110 with a gasket 139 therebetween. Bolts 140 clamp the flange 138 into sealing engagement with the gasket 139 and thereby complete the water tight integrity of the metallic housing 106 at its lower end.

The lower terminal 135 includes a metallic sleeve 141 from which the contact fingers 134 extend upwardly. The metallic sleeve 141 is suitably secured in the arm 136 of the lower insulator 137 and at its lower end it carries a spider 142 to which one end.143 of a conductor rod 144 is connected. The conductor rod 144 extends downwardly and laterally through another arm 145 of the lower insulator 137. The conductor rod 144 extends beyond the outer end of the arm 145 and is secured by a metallic connector 146 to the conductor 101.

It is likely that the bayonet type connecting conductor means 131 will be withdrawn from the high voltage circuit switching device 100 under conditions involving current flow between the conductors 101 and 102. In such case it is necessary to interrupt the current flow and any arc or arcs that may be incident to such current flow. For this purpose an upper liner 148 of organic arc extinguishing material such as methylmethacrylate resin, fiber or the like is located within the metallic sleeve 127 of the upper terminal 122 and is secured as by cement 149 to the cylindrical base portion 123. The upper liner 148 extends downwardly to a position slightly above the lower ends of the contact lingers 128 so that any arc which is drawn between the ferrule 130 and the contact fingers 128 will impinge upon the inner surface of the liner 148 and will evolve an arc extinguishing medium therefrom. Just below the upper ferrule 130 and extending over the upper portion of the conducting rod 132 is a sleeve 150 of arc extinguishing material such as methylmethacrylate resin, fiber or the like. The sleeve 150 functions as a follower to confine the arc between its outer surface and the inner surface of the upper liner 148 when the bayonet type connecting conductor means 131 is withdrawn.

A somewhat similar construction for are extinguishing purposes is provided in connection with the lower terminal 1135. A lower liner 151 of arc extinguishing material is suitably secured in the upper end of the arm 135 of the lower insulator 137. When the ferrule `133 is drawn into the liner 151, the arc formed between the lower ferrule 133 and the contact fingers 134 is confined by the inner surface of the lower liner 151. Attached to the lower end of the lower Ife-rrule 133 is a follower 152 of insulating arc extinguishing material which telescopes with the lower liner 151 on withdrawal of the connecting conductor means 131 for the purpose of further confining the arc drawn lbetween the lower ferrule 133 and the contact fingers l134 and for assisting in extinguishing it.

Secured to and extending upwardly lfrom the upper end of the bayonet type connecting conduct-or means 131 is an insulating pull rod 153. At is upper end it has a head 154 to which a suitable live line tool can be attached yfor withdrawing or applying the connecting conductor means 131.

It will be noted that the upper end of the arm 115 that rforms a part of the upper insulator 116 is provided with a cylindrical extension 155 into which the upper end of the insulating pull rod 153 extends. The inner surface of the cylindrical extension 155 is grooved as indicated at 155 in o-rder to increase the leakage resistance thereover. The cylindric-al extension 155 extends into the lower end of a metallic access pipe or tube 156 which has a radially extending flange 157 `at its lower end that overlies a flange 158 formed integrally with the upper insulator 116. A gasket 159 is provided therebetween and bolts 160 exten-d through the flange 157 into threaded inserts 161 that are molded in the flange 158.

At is upper end the metallic access pipe or `tube 156 is provided with a radially extending flange 162 for receiving a closure cap 163 that may be formed of metal or insulation as may be desired. A gasket 164 is positioned between the underside of the cap 163 and the upper side of the flange 162 and studs 165 extend downwardly from the underside of the cap 163 through the gasket 164 and the fiange 162. Nuts 166 threaded on the studs 165 serve to clamp the cap 163 in sealed position on the upper end of the metallic access pipe or tube 156. A skirt 167 depending from the outer periphery of the cap 163 serves as additional wea-ther protection and limits the access to the nuts 166.

lIf desired, a condenser of the kind and character above referred to, shown by broken lines at 170 in FIG. 4, can be provided in conjunction with the arm 145 of the lower insulator 137 `to cool and condense the are products incident to the drawing of an arc between the lower ferrule 133 and the contact fingers 134. The lower end of the condenser 170 is provided with a sealed end plate 171 so that the entrance of moisture into the interior of the metallic housing 106 is prevented.

The access tube 156, top plate 109, tube 107 and bottom plate 110 are grounded as indicated diagramatically at 172, 173, 174 and 175. With this arrangement leakage current cannot fiow between the upper terminal 122 and lower terminal 135 when the bayonet type connecting conductor means 131 is withdrawn.

When the connecting conduct-or means 131 is withdrawn an air gap having a length as indicated at 176 is 10 providedbetween the lower end of the arm of the upper insulator 116 and the upper end of lthe arm 136 of the lower insulator 137. Since the metallic housing 106 is grounded, yno leakage current can iiow between the

terminals

122 and 135.

While the present invention has been described particularly with reference to underground high voltage conductors the connections to which are controlled by buried switching

devices

10 and 106 with access thereto from above ground, it will be understood that they may be installed at locations where they are more readily accessible. =In such case the lengths of the

access tubes

21 and 156 are correspondingly modified and in some cases replaced by covers. The

switching devices

10 and 106 can be mounted horizontally instead of vertically and access thereto can be arranged from underneath instead of from above.

What is claimed as new is:

1. In an underground high voltage electric power distribution system including a pair of buried insulated conductors having one end of each in close proximity, in combination:

(a) an access tube for extending upwardly from the vicinity of said ends of said conductors to ground level,

(b) -a metallic housing having a sealed connection to .the lower end of said access tube,

(c) upper and lower terminals in said metallic housing in insulated spaced relation and aligned with said access tuibe,

(d) means for connecting said upper and lower terminals to said ends of said buried insulated conductors respectively,

(e) connecting conductor means within said metallic hou-sing detachably interconnecting said upper and lower terminals, and

(f) attachment means at the upper end of said connecting conductor means for receiving an operating member inserted in said access tube from its upper end to apply and remove said connecting conductor ineans through said access turbe.

2. The invention, as set forth in claim 1, wherein:

(a) upper and lower insulators extend through the metallic housing and at their inner ends carry the upper and lower terminals respectively, and

(-b) the means connecting said upper and lower terminals to the respective ends of the buried conductors extend .through said upper and lower insulators and are connected lat their outer ends to said ends of said buried conductors.

3. The invention, as set forth in claim 2, wherein the upper and lower insulators extend horizontally through a vertical wall of t-he metallic housing.

4. The invention, as set forth in claim 2, wherein inner end portions of the upper and lower insulators extend downwardly and upwardly respectively through the top 4and -bottom walls of the metallic housing and the outer end portions of said upper and lower insulators extend laterally away from said inner end portions.

5. The invention, as set forth in claim 4, wherein the access tube has its sealed connection to the metallic housing through the vertically extending portion of the upper' insulator.

6. In an underground high voltage electric power distribution system including a pair of buried insulated conductors having one end of each in close proximity, in combination:

(b) a housing having a sealed connection to the lower end of said access tube,

(c) upper and lower terminals in said housing in insulated spaced relation and aligned with said access tube,

(d) means for electrically connecting said upper and lower terminals to said ends respectively of said buried insulated conductors,

(e) connecting conductor means having electrically connected upper and lower ferrules for detachable engagement respectively with said upper and lower terminals,

(f) attachment means at the upper end of said connecting conductor means for receiving an operating member inserted in said access tube from its upper end to apply and remove said connecting conductor means through said access tube, and

(g) an insulating sleeve slidably mounted on said connecting conductor means and biased for movement over said lower ferrule when said connecting conductor means is removed by said operating member and said lower ferrule is withdrawn from said lower terminal.

7. The invention, as set forth in claim 6, wherein an insulating follower depends from the lower ferrule and the insulating sleeve is telescoped over said insulating follower when the connecting conductor means is removed.

8. The invention, as set forth in claim 6, wherein means stationarily mounted in the housing engage the insulating sleeve on application of the connecting conductor means by the operating member to limit the downward movement of said insulating sleeve to uncover the lower ferrule and permit the same to engage the lower terminal on further downward movement of said connecting conductor means.

9. The invention, as set forth in claim 6, wherein the upper and lower terminals and the upper and lower ferrules are of cylindrical configuration and the upper terminal has an opening capable of receiving the insulating sleeve therethrough.

1f). The invention, as set forth in claim 6, wherein:

(a) a spring reacts between the insulating sleeve and the upper ferrule for biasing the former downwardly, and

(b) shoulder means on said insulating sleeve cooperate with the lower ferrule and limit the downward movement of said insulating sleeve when the connecting conductor means is removed.

11. The invention, as set forth in claim 10, wherein:

(a) means stationarily mounted in the housing engage the insulating sleeve on application of the connecting conductor means by the operating member to limit the downward movement of said insulating sleeve under the influence of the spring to uncover the lower ferrule and permit the same to engage the lower terminal on further downward movement of said connecting conductor means, and

(b) latch means react between the upper terminal and the upper ferrule to limit upward movement of said connecting conductor means under the influence of said spring on removal of the operating member.v

12. The invention, as set forth in claim 6, wherein the relationship between the upper terminal and the upper ferrule is such that contact engagement therebetween is maintained until after the lower ferrule has been moved out of Contact engagement with the lower terminal for a substantial ydistance on removal of the connecting conductor means by the operating member.

13. The invention, as set forth in claim 6, wherein:

(a) the access tube is formed of metal, and

(b) an insulating sleeve is telescoped within the lower end of said access tube for a distance sufiicient to prevent connection of the connecting conductor means to said access tube after the lower ferrule has been moved into the vicinity of the upper terminal on application or removal of said connecting conductor means by the operating member.

14. High voltage switching means comprising, in combination:

(a) a pair of terminals,

(b) means mounting said terminals in insulated spaced relation,

(c) connecting conductor means having electrically connected ferrules detachably engaging said terminals respectively,

(d) insulating sleeve means slidably mounted on said connecting conductor means adjacent one of said terminals and relatively movable with respect to said connecting conductor means toward and away from said one terminal, and

(e) means biasing said insulating sleeve means for relative movement with respect to said connecting conductor means to enclose the one of said ferrules engaging said one terminal when said connecting conductor means is moved to disengage said one ferrule from said one terminal whereby an arc formed between said one terminal and said one ferrule on separation thereof is drawn into said insulating sleeve means.

15. High voltage switching means comprising, in combination:

(a) first and second cylindrical terminals,

(b) means mounting said terminals in coaxial insulated spaced relation,

(c) elongated connecting conductor means having first and second ferrules at its ends movable endwise through said terminals to engage and disengage said first and second ferrules with and from said first and second terminals respectively,

(d) insulating sleeve means slidably mounted on said connecting conductor means between said ferrules adjacent said second cylindrical terminal and relatively movable with respect to said connecting conductor means toward and away from said second cylindrical terminal, and

(e) means biasing said insulating sleeve means for relative movement with respect to said connecting conductor means to enclose said second ferrule when said connecting conductor means is moved to disengage said second ferrule from said second terminal whereby an arc formed therebetween is drawn into said insulating sleeve means.

16. High voltage switching means comprising, in combination:

(a) first and second cylindrical terminals,

(b) means mounting said terminals in coaxial insulated spaced relation,

(d) an insulating sleeve slidably mounted on said connecting conductor means between said ferrules and biased for movement over said second ferrule when said connecting conductor means is withdrawn from said terminals,

(e) said elongated connecting conductor means being insertable through said first cylindrical terminal into said second cylindrical terminal and the movement of said insulating sleeve being arrested to uncover said second ferrule as it is moved into engagement with said second cylindrical terminal, and

(f) an insulating follower extending endwise from and movable with said second ferrule, said insulating sleeve moving over said follower on withdrawal of said elongated connecting conductor means whereby an arc drawn between said second cylindrical terminal and said second ferrule is extended between the juxtaposed surfaces of said insulating sleeve and said follower.

biased for movement over said second ferrule when i said connecting conductor means is withdrawn from said terminals,

(e) said elongated connecting conductor means being insertable and removable through said first cylindrical terminal, and

(f) the opening through said first cylindrical terminal being of sufiicient size to allow the passage of said insulating sleeve therethrough.

18. High voltage switching means comprising, in combination:

(a) first and second cylindrical terminals,

(b) means mounting said terminals in coaxial insulated spaced relation,

(e) a spring reacting between said insulating sleeve and said first ferrule and biasing said insulating sleeve over said second ferrule, and

(f) shoulder means on said insulating sleevecooperating with said second ferrule and limiting the movenient of said insulating sleeve under the action of said spring when said elongated connecting conductor means is withdrawn from said terminals.

19. The invention, as set forth in claim 1S, wherein:

(a) means stationarily mounted with respect to the second cylindrical terminal engage the insulating sleeve on application of the connecting conductor means to the terminals to limit the movement of said insulating sleeve under the influence of the spring and uncover the second ferrule to permit the same to engage said second cylindrical terminal on further movement of said connecting conductor means in a switch closing direction, and

(b) latch means react between the first cylindrical terminal and the first ferrule to limit upward movement of said connecting conductor means under the influence of said spring.

20. High voltage switching means comprising, in combination:

(a) first and second cylindrical terminals,

(b) means mounting said terminals in coaxial insulated spaced relation,

(d) an insulating sleeve slidably mounted on said connecting conductor means between said ferrules aud biased for movement over said second ferrule when said connecting conductor means is withdrawn from said terminals,

(e) the relationship between said first cylindrical terminal and said first ferrule being such that contact engagement therebetween is maintained until after said second ferrule has been moved out of contact engagement with said second cylindrical terminal for a substantial distance on withdrawal of said elongated connecting conductor meansfrom said terminals.

21. Bayonet type conductor means for application to and removal from first and second aligned terminals in insulated spaced relation comprising, in combination:

(a) first and second ferrules for engagement with said terminals respectively,

(b) means electrically interconnecting said ferrules and' mechanically holding them in spaced relation,

(c) arc extinguishing insulating sleeve means slidably mounted on said connecting means between said ferrules adjacent said second ferrule and relatively movable with respect to said connecting means toward and away from telescopic engagement with said second ferrule, and

(d) means biasing said insulating sleeve means for relative movement with respect to said connecting means over said second ferrule to enclose it when said second ferrule is moved out of engagement with said second terminal whereby an arc formed therebetween is drawn into and extinguished by said insulating sleeve means.

22. Bayonet type conductor means for application to and removal from first and second aligned terminals in insulated spaced relation comprising, in combination:

(a) first and second ferrules for engagement with said terminals respectively,

(b) means electrically interconnecting said ferrules and mechanically holding them in spaced relation,

(c) an insulating sleeve slidably mounted on said connecting means between said ferrules and biased for movement over said second ferrule when it is out of engagement with said second terminal, and

(d) an insulating follower extending endwise from and movable with said second ferrule, said insulating sleeve moving over said follower when the second ferrule is out of engagement with said second terminal whereby an arc drawn from said second ferrule is extended between the juxtaposed surfaces of said insulating sleeve and said follower.

23. Bayonet type conductor means for application to and removal from first and second aligned terminals in insulated spaced relation comprising, in combination:

(a) first and second ferrules for engagement with said terminals respectively,

(c) an insulating sleeve slidably mounted on said connecting means between said ferrules and biased for movement over said second ferrule when it is out of engagement with said second terminal,

(d) a spring reacting between said insulating sleeve and said first ferrule and biasing said insulating sleeve over said second ferrule, and

(e) shoulder means on said insulating sleeve cooperating with said second ferrule and limiting the movement of said insulating sleeve under the action of Said spring when said second ferrule is withdrawn from said second terminal.

24. The invention, as set forth in claim 23, wherein the (d) conductors extending from said terminals through said insulators for connection to said pair of conductors, and

(e) bayonet type connecting conductor means insertable and removable through said access opening interconnecting said terminals.

26. The invention, as set forth in claim 25, wherein:

(a) the metallic housing is a tube having its ends closed by metallic plates, and

(b) the access opening is closed by sealing means.

27. The invention, as set forth in claim 26, wherein:

(a) the insulators extend radially through the tubular portion of the metallic housing, and

(b) the access opening is located in one of the end plates.

28. The invention, as set forth in claim 25, wherein insulating means extend through the access opening and act to guide the bayonet type connecting conductor means into engagement with the terminals.

29. High voltage switch means comprising, in combination:

(a) a pair of terminals,

(b) means mounting said terminals in insulated spaced relation,

(c) elongated connecting conductor means having electrically connected contact means at the ends detachably engaging said terminals respectively,

(d) insulating sleeve means slidably mounted on said conductor means adjacent one of said terminals and relatively movable with respect to said conductor means toward and away from said one terminal, and

(e) means biasing said insulating sleeve means for relative movement with respect to said connecting conductor means to enclose said one of said contact means engaging said one terminal when said connecting conductor means is moved to disengage said one contact means from said one terminal whereby an arc formed therebetween is drawn into said insulating sleeve means.

30. The invention, as set forth in claim 29, wherein insulating means extends endwise ofthe one contact means and is enclosed by the insulating sleeve means after the one contact means disengages the one terminal.

31. The invention, as set forth in claim 30, wherein at least one of the insulating means is capable of evolving an arc extinguishing medium when subjected to the heat of the arc drawn on disengagement of the one contact means from the one terminal and said arc is confined between said insulating means.

32. Conductor means for application to and removal from first and second aligned terminal in insulated spaced relation comprising, in combination:

(a) rst and second contact means for engagement with said terminals respectively,

(b) meansv electrically interconnecting said contact means and mechanically holding them in spaced relation,

(c) insulating sleeve means slidably mounted on said connecting means between said contact means adjacent said second contact means and relatively movable with respect to said connecting means into and out of telescopic engagement with said second contact means, and

(d) means biasing said insulating sleeve means for relative movement with respect to said connecting means over said second contact means to enclose it when said second contact means is moved out of engagement with said second terminal whereby the arc formed therebetween is drawn into said insulating sleeve means.

33. The invention, as set forth in claim 32, wherein insulating means is secured to and extends endwise from the second contact means and the insulating sleeve means is relatively movable into telescopic engagement therewith after said second contact means is moved out of engagement with the second terminal.

34. The invention, as set forth in claim 33, wherein the juxtaposed surfaces of the insulating means are capable of having evolved therefrom an arc extinguishing medium when subjected to the heat of the arc drawn on disengagement of the second contact means from the second terminal and said arc is confined between these surfaces.

35. High voltage switching means comprising, in comy bination:

(a) first and second high voltage terminals,

(b) means mounting said terminals in coaxial spaced relation with an air gap therebetween,

(c) elongated connecting conductor means having electrically connected spaced contact means detachably engaging said terminals respectively and endwise axially movable into and out of contact engagement therewith,

(d) insulating arc extinguishing sleeve means slidably mounted on said connecting conductor means adjacent one of said terminals and relatively movable with respect to said connecting conductor means toward and away from said one terminal, and

(e) means biasing said sleeve means for relative telescopic movement with respect to said elongated connecting conductor means over the contact means engageable with said one terminal when said elongated connecting conductor means is axially withdrawn from said terminals together with said sleeve means whereby an arc drawn between said contact means and said one terminal is confined by said sleeve means and said air gap only remains between said terminals after withdrawal of said elongated connecting conductor means and said sleeve means.

References Cited by the Examiner UNITED STATES PATENTS MILTON O. HIRSHFIELD, Primary Examiner.

Claims

1. IN AN UNDERGROUND HIGH VOLTAGE ELECTRIC POWER DISTRIBUTION SYSTEM INCLUDING A PAIR OF BURIED INSULATED CONDUCTORS HAVING ONE END OF EACH IN CLOSE PROXIMITY, IN COMBINATION: (A) AN ACCESS TUBE FOR EXTENDING UPWARDLY FROM THE VICINITY OF SAID ENDS OF SAID CONDUCTORS TO GROUND LEVEL, (B) A METALLIC HOUSING HAVING A SEALED CONNECTION TO THE LOWER END OF SAID ACCESS TUBE, (C) UPPER AND LOWER TERMINALS IN SAID METALLIC HOUSING IN INSULATED SPACED RELATION AND ALIGNED WITH SAID ACCESS TUBE, (D) MEANS FOR CONNECTING SAID UPPER AND LOWER TERMINALS TO SAID ENDS OF SAID BURIED INSULATED CONDUCTORS, RESPECTIVELY, (E) CONNECTING CONDUCTOR MEANS WITHIN SAID METALLIC HOUSING DETACHABLY INTERCONNECTING SAID UPPER AND LOWER TERMINALS, AND