US3164703A - Circuit interrupter of the single-bushing type with canted terminal-bushing construction - Google Patents

Description

Jan. 5, 1965 R. E. FRIEDRICH ETAL 3,164,703

CIRCUIT INTERRUPTER OF THE SINGLEBUSHING TYPE WITH CANTED TERMINAL-BUSHING CONSTRUCTION 6 Sheets-Sheet 1 Filed Sept. 15, 1959 r r"| V /Zt Fxg I.

WITNESSES I NVENTORS Robert E. Friedrich, Curl G. Lentjes m 8 George B.Cushinq Jan. 5, 1965 R. E. FRIEDRICH ETAL cmcurr INTERRUPT 3,164,703 ER OF THE SINGLE-BUSHING TYPE WITH CANTED TERMINAL-BUSHING CONSTRUCTION Filed Sept. 15, 1959 6 Sheets-Sheet 2 1965 R. E. FRIEDRICH ETAL 3,164,703

CIRCUIT INTERRUPTER OF THE SINGLE-BUSHING TYPE WITH CANTED TERMINAL-BUSHING CONSTRUCTION Filed Sept. 15, 1959 6 Sheets-Sheet 5 A\\\\\\\\\\\\\\' F i 3(;

1965 R. E. FRIEDRICH ETAL 3,1 4, 03

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CIRCUIT INTERRUPTER OF THE SINGLE- CANTED TERMINAL-BUSHING CONSTRUCTION 6 Sheets-Sheet 6 Filed Sept. 15, 1959 Fig.4.

O I r United States Patent Ofifice 3,154,703 Patented Jan. 5, 1965 CIRCUIT HNTERRUPTER 0F THE SlNG'LEdiUSi-i- ENG TYPE WITH CANTED TERMINAL-BUSHRNG CUNSTRUCTEDN Rohert E. Friedrich, Baldwin, Carl G. Lentjes, Churchiil, and George B. Cashing, Penn Hills, Pa, assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Sept. 15, 1&59, Ser. No. 843,133 '7 (Ilairns. (Cl. Hid-Md) This invention relates to circuit interrupters in general, and, more particularly, to improved mounting constructions and arc-extinguishing arrangements therefor.

As well known by those skilled in the art, in the tanktype oil circuit interrupter a grounded tank is employed with two terminal bushings extending thereinto and supporting at the lower ends thereof arc-extinguishing units bridged by the usual bridging bar. It is, of course, obvious that the terminal bushings, of which there are two for each pole-unit, constitute expensive items of electrical equipment, and it would be of advantage, both as regards space and cost, to eliminate one of the two terminal bushings. The use of terminal bushings, however, extending into a grounded tank, or casing, permits the utilization of inexpensive through-type current transformers. Such through-type, or ring-type current transformers may merely encircle the terminal bushing adjacent the central grounded portion thereof and are, as well known, considerably less expensive than woundtype current transformers, which must be wound with adequate insulation to withstand line-to-ground voltage.

The present invention relates to interrupting apparatus in which only a single terminal bushing is employed, as contrasted to the use of two terminal bushings for tanktype circuit interrupters. Thus, the inexpensive ringtype current transformer may be utilized, and a conventional, stock-item bushing may be used without special construction. Accordingly, the term circuit-interrupter of the single-bushing type means herein a circuit interrupter using only a single terminal bushing, which may be of a conventional standard type.

In United States Patent 2,866,045, issued December 23, 1958, to Winthrop M. Leeds, and assigned to the assignee of the instant application, there is disclosed and described a number of single-bushing circuit-interrupting structures. There is a disadvantage to the amount of space taken up by the particular disposition of the circuit interrupting structure of the Leeds device, and it is a general object of the present invention to retain a number of the advantages of the single-terminal-bushing construction of the interrupting device disclosed in the Leeds patent, yet nevertheless rearranging the disposition of the device to result in a considerable saving of horizontal ground space.

A more specific object of the present invention is the provision of a plurality of compact pole units arranged in a space-saving manner, and adapted for simultaneous operation from a single operating mechanism.

A further object of the present invention is the provision of a singlederminahbustring-type of circuit interrupter, in which preferably the interrupting casing is dis interrupting structure as an internal fault, as contrasted with an external fault.

Yet a further object of the present invention is the pro vision of an improved single-terminalbushing-type of circuit interrupter in which the several interrupting elements thereof are readily adaptable for removal from the circuit-interrupter housing with a minimum of effort.

Yet another object of the present invention is the provision of an improved circuit-interrupting structure in which the arrangement is such as to facilitate the convec-' tion flow of the arc-extinguishing medium to permit its cooling at an upper metallic closure member for the interrupter casing.

Another object of the present invention isthe provision of an improved circuit interrupter of the single-terminalbushing type, in which the operating mechanism is such as to readily adapt the device for multiple-pole operation.

Another object of the invention is the provision of an improved circuit-interrupting structure of the singletcrminal-bushing-type, in which use is made of an effective arc'extinguishing gas having a high dielectric strength, such as sulfur hexafiuoride (SP whereby the distances between internal parts, at opposite potential, may be a minimum, and the terminal-bushing construction is so configured as to result in a considerable horizontal saving of ground space.

Generally, the present invention is concerned with a single-bushing type of circuit interrupter including a grounded mechanism housing supporting both an outwardly extending interrupting means and also a canted terminal bushing. This results in a space-saving arrange ment. In addition, the invention is concerned with a fluid puffer-type interrupter in which a fluid blast is i brought about by relative movement between a piston and a cylinder. Such a self-contained interrupter has particular advantages as applied to the foregoing interrupter construction.

To reflect faults associated with the interrupter as. internal faults, as contrasted with external faults, a .pair of current transformers are mounted upon opposite sides of the grounded mechanism housing and so electrically constructed as to force fiashovers to pass to ground between them.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawings, in which:

FIGURE 1 is an end elevational view of the three-pole circuit-interrupting assemblage with a differential protec-.

tive relay system incorporated in the drawing to illustrate the functioning of the current-transformer arrangement, the contact structure being diagrammatically indicated in the closed-circuit position;

FIG. 2 is a front elevational View of the three-pole FIG. 1 thereof, the reference numeral 1 generally designates a single-bushing-type of circuit interrupter supported upon a grounded metallic framework 2. With reference to FIG. 2, it will be noted that three such single terminal-bushing-types of circuit interrupters may be mounted upon the same grounded frame 2, and a common mechanism compartment 3 may be provided. The mechanism disposed Within the mechanism compartment 3 may be of any conventional type, and, when operated, serves Jr to effect the rotation of a horizontally extending operating rod 4 which interconnects the three pole-units 1.

With reference to FIG. 1, it will be noted that generally each single-terminal-bushing-type of circuit interrupter 1 includes an upstanding insulating interrupter casing 5, a grounded mechanism housing 6, supported by the upstanding framework 2, and a single terminal bushing, generally designated by the reference numeral 7. The terminal bushing 7 may be of a conventional type, such as an oil-filled type, or it may be of the gas-filled type, such as set forth in United States patent application filed December 2, 1959, Serial No. 856,775, by Robert E. Friedrich and James H. Frakes, and assigned to the assignee of the instant application.

Supported upon the mechanism housing 6 and disposed below the interrupter casing is a first current transformer 8, so arranged as to ensure that any faults, or breakdowns occurring along the outer or inner walls of the insulating casing 5 will pass through the first current transformer 8 to ground by way of the framework 2.

A second current transformer 9 is associated with the canted terminal bushing 7 and has the cover plate 10 thereof disposed at such a remote distance from the outer end 11 of the terminal bushing 7, that any breakdown occurring along either the inside or outside surface of the porcelain weatherproof shell 12 will strike to the supporting flange 13 (FIG. 3C) and likewise be carried to ground through the second current transformer 9. As will be more fully brought out hereinafter, it is desired to have any fault condition associated with the circuitinterrupting assemblage 1 sensed as an internal fault condition, as contrasted with an external fault condition. In other words, it is desired to have any fault condition associated with the circuit-interrupting assemblage 1 reflected as an internal fault condition so that the remote circuit interrupters 14, 15 will also open, together with the opening of circuit interrupter 1.

With reference to FIGS. 3B and 30, it will be noted that the mechanism housing 6, at ground potential, is somewhat of an upwardly extending U configuration. The left leg of the U configuration, indicated by the reference numeral 17 (FIG. 38), supports the upstanding insulating casing 5, which is preferably formed from porcelain. The right leg 18 of the generally U-shaped mechanism housing 6 supports the terminal bushing 7 by the mounting flange 13 thereof. Crank means, generally designated by the reference numeral 2t includes a rotatable shaft 21, which extends within the interior of the mechanism housing 6 in a gas-tight manner, and is keyed to an internally disposed crank-arm 22, piv-otally connected at 23 to a pair of operating rods 24. The operating rods 24 are formed of insulating material, and have lower rod-ends 24a of metallic material.

, The rotatable operating shaft 21 may constitute an extension of the rotatable shaft 4 of FIG. 2, which is rotated by the actuation of the mechanism disposed interiorly within the mechanism compartment 3. Thus, clockwise rotation of the operating shaft 21, as viewed in FIG. 3B, effects corresponding clockwise rotative movement of the crank-arm 22, and hence downward opening motion of the pair of insulating operating rods 24. The upper ends of the operating rods 24 have rod-ends 2417 (FIG. 4), which are pivotally connected as at 25 to lugs 26, afiixed diametrically on opposite sides of a movable metallic puffer operating cylinder 27. At the upper end of the puffer cylinder 27 is an inwardly extending flange portion 27a, to which is bolted, by bolts 23, a movable contact support 29. The movable contact support 29 is, in turn, bolted by bolts 30, FIG. 3A, to a movable contact, generally designated by the reference numeral 31. The movable contact 31 includes a plurality of circumferentially spaced flexible spring fingers 32, and a bayonet-type arcing contact 33. The movable fingers 32 and the arcing contact 33 make contacting engagement with a downwardly extending, rod-shaped relatively stationary contact 34. The lower tip portion of the rod-shaped stationary contact 34 is hollowed, as at 34a, to accommodate the upper extremity of the arcing contact 33, as shown in FIG. 3A.

The upper end of the relatively stationary contact 34 is adjustably threadedly secured within a clamp 35, which is bolted as at 36, to an annular mounting plate 37. The mounting plate 37 is secured, by bolts 38, to a mounting flange ring 39, cemented to the upper end of the casing 5. in addition, an upper closure inspection plate 40 is provided, being bolted by bolts 41 to the annular mounting plate 37.

Movable contact support 29 has an upper extension 42, to which is bolted by bolts, no shown, an insulating orifice member 43. The movable contact support 29 also has apertures 44 (FIG. 4) provided therethrough, through which an upward moving blast of gas passes from a compression chamber, generally designated by the reference numeral 45.

The compression chamber 45 is provided by the coaction between the puffer cylinder 27 and a fixed piston 46. It will be obvious, therefore, that relative motion between the operating cylinder 27 and the fixed piston 46 will result in a raising of the pressure within the compression chamber 45 and an ejection of compressed fluid upwardly from the chamber 45, through the apertures 44, and through the orifice opening 47 of the orifice sleeve 43 to effect extinction of the are 19 (FIG. 4) drawn therethrough.

Although FIG. 4 illustrates the fully open circuit position of the interrupter 1, nevertheless, for purposes of illustration, the drawn are 19 has been drawn into the figure, together with arrows 16 indicating the gas blast. Arc extinction quickly follows.

The fixed piston 46 constitutes the upper extremity of an insulating pedestal, generally designated by the reference numeral 48, which is mounted, as at 49 (FIG. 3B), to a lower plate portion 50 of the mechanism housing 6. A removable cover 51 is bolted, by bolts 52, to the same plate portion 513, and permits downward withdrawal of the insulating pedestal 48 for maintenance and service operations, as more fully brought out hereinafter.

Adjacent the lower end of the insulating cylindrical pedestal 48 is a cutout portion 53 which accommodates a tubular conductor 54, having an elbow connection, as at 55, to a horizontally extending tubular conductor 56, which is attached to the lower end 57 of the terminal bushing 7.

Secured, as by a press fit, to the upper end of the tubular conductor 54 is a contact support 58, having integrally formed flexible stationary fingers 59. Contacting, in sliding engagement, with the stationary fingers 59 is a downwardly extending rod-shaped portion 60 of the movable contact structure 31. As shown in FIG. 3A, the contact support 58 is secured, as by stud bolts 61, to the fixed piston 46, the latter constituting an upper closure plate for the tubular pedestal support 48. In addition, one-way acting valves 62 are provided, being spring-biased to their open position, as shown, to permit the ready passage of fluid upwardly from the region 63 (FIG. 3A) interiorly of the pedestal support 48 and into the compression region 45 in the closed-circuit position of the interrupter. However, upon downward opening movement of the operating cylinder 27, the several valves 62 will, of course, close by virtue of the gas pressure present within region 45.

In the closed-circuit position of the interlupter 1, the electrical circuit therethrough includes upper line terminal 64, relatively stationary contact 34, movable contact 31, lower extension 69 of movable contact 31, fingers 59, tubular conductor 54, horizontal conductor 56, and the terminal stud, not shown, extending axially through the terminal bushing 7 to the outer terminal extremity 65 thereof.

To effect the opening operation of the interrupter the 55 mechanism not shown disposed within the mechanism compartment 3 is effective to effect clockwise rotation of the shaft 21 as viewed in FIG. 1. With reference to FIG. 3B, the clockwise rotation of the internally disposed portion of the operating shaft 21 will cause clockwise rotation of the keyed crank-arm 22 to effect thereby downward opening pulling movement of the operating rods 24-. Since the upper ends of the insulating rods 24 are secured to the outer sides of the operating puffer cylinder 2'7, the downward opening movement of the puffer cylinder 2"! will compress gas within the'region 45, closing the valves 62, and forcing the compressed gas upwardly through the orifice opening 47 to effect extinction of the are 19 drawn therethrough, as shown in FIG. 4.

The first downward opening movement of the movable contact structure 31 will effect separation between the relatively movable fingers 32 and the external side 34b of the rod-shaped stationary contact 34. The arcing contact 33 will subsequently separate from the relatively stationary contact 34-, so that no burning occurs upon the finger contacts 32. The are 1% will, therefore, extend between the upper tip extremity of the arcing electrode 3-3 and the annular arc resisting portion 340 of the stationary rod contact 34. Since the gas enclosed within the casing is preferably a highly efficient arc-extinguishing gas having a relatively high dielectric strength, such as sulfur hexafluoride (SP the extinguishing action exerted upon the are if will take place very quickly, and the are 1? will become extinguished.

With reference to FIG. 1, it will be observed that a remote circuit interrupter 14 is connected by a transmission line 65 to the circuit interrupter 1. The remote circuit interrupter 14 includes a pair of stationary contacts 66 bridged by a movable contact 67, biased by gravity to an open position, and retained in the closed position by a latch 68, released by the energization of .a solenoid 69 and associated armature 7%. A current transformer 71 measures the current through the circuit interrupter 14 from the line connection L The secondary winding of the current transformer '71 is connected in parallel with the secondary winding of the current transformer 9 and also with the winding 72 of a differential protective relay, generally designated by the reference numeral 73. When the differential relay '73 becomesenergized and bridges its stationary contacts '74 by the upward movement of a movable bridging contact 75, a tripping circuit is established from the source 76 to effect opening of the circuit interrupter l4, and also energization of winding 77 tripping the circuit interrupter 1 open. More specifically, the rotatable shaft l is diagrammatically represented in FIG. 1. as being biased by a compression spring 78 to an open -circuit position, and latched in the closed-circuit position by a latching device 79, which is pivotally connected to a pair of armatures 8t), 81.

The winding through the differential relay 73 is responsive to the difference of current through the line L, and the current passing through the circuit interrupter l, as well known by those skilled in the art. Similarly, a differential protective relay 82;, having a winding 83, is also responsive to the difference of the current passing through the line L and the current carried by the circuit interrupter 1. Reference may be had to United States patent application, filed March 31, 1958, Serial No. 725,286, new US. Patent 3,632,689, issued May 1, 1962, to Benjamin P. Baker and Robert F, Karlicek, and assigned to the assignee of the instant application, for the general theory and operation of the differential protective relays '73, 82.

it will be noted that any fault current flashing over the inside or outside surface of the porcelain casing S, as

indicated by the fiashover conditions Q5, 95 in P165. 1,

3A and 3B, will flow to ground through the first current ransformer 8. Thus, assuming that the current is flowing in the direction of the line L toward the circuit inter- 5 rupter l, the current transformer 71 will register the fault current, whereas the second current transformer 9, associated with the circuit interrupter 1, will register zero current. Such a condition will cause the operation of the differential relay 73 to complete the tripping circuit 98 to effect opening of the circuit interrupters 1 and 14.

Similarly the current transformer 3 will measure full fault-produced curre t, whereas current transformer 85, associated with remote circuit interrupter 15, will register Zero fault-produced current. As a result, differential relay 82'. will be actuated to trip circuit breakers 1 and 15. Hence all three breakers 1, 14 and 15 open under such an internal fault-condition represented by fiashover 95 or 96.

Likewise, should the current be considered as flowing from the line L through the remote circuit interrupter l5 and toward the circuit interrupter 1, the current transformer winding 85 will measure the fault current, whereas the current transformer 55 will register zero current since the fault current reverses. its direction through the current transformer 8. As a consequence, differential relay 552 will pick up its contacts 85 by the bridging member 87, and complete the tripping circuit 88 to: trip the circuit interrupter f5 open as well as the circuit interrupter 1. in addition, current transformer 9 will register the fault current, whereas current transformer 71 will register zero current. Consequently, dirferential relay 73 will pick up and open circuit interrupters l and 14. As a result, such an internal fault condition or 96 will be sensed as an internal fault condition and will effect tripping of both circuit interrupters 14 and 15 as well as the circuit interrupter 1.

In a similar manner, a breakdown, as at 96, (FIGS. 1 and 3C) over the external surface of the porcelain casing 12 of the terminal bushing 7 will pass to ground through the second current transformer 9, and, by operation of the differential protective relays 73, 82, will insure that breakers 14 and 15 open as Well as. circuit interrupter 1.

From the foregoing description, it will be apparent that the particular disposition of the first and second current transformers 8, 9, associated with the circuit interrupting assemblage 1, is such that any breakdown, or fault condition associated with the circuit interrupter 1 will pass to ground through the current transformers 8, 9 and be sensed as an internal fault condition causing circuit interrupter 1 as well as remote breakers 14, 15 to open. To insure that the fault current passes to ground through the current transformer ii, the latter has an outer, insulat ing peripheral cover 3a, to insure that if the fault strikes the upper side of the current transformer 8, it will pass to ground through the current transformer 8, and not externally thereof.

From the foregoing description of the invention, it will be apparent that there is provided an improved circuitinterrupting structure of the single-terminal-bushing type,

in which considerable ground space is saved by the canted it will be noted that the three poles 1 of the circuit] interrupter are mounted side by side on the grounded structural steel frame 2, that elevates live parts safely above the ground. The pole units 1 are simultaneously operated by a single mechanism disposed within the mechanism compartment 3, which may be of conven--' tional design. Since this mechanism compartment 3 is situated within the supporting framework 2, the overall length and width are held to the minimum necessary to support the pole units.

Each pole unit 1 is comprised of a vertical porcelain column 5 housing the interrupterstructure, and a single, canted bushing '7 of standard external dimensions, and of conventional condenser-type design. It will be noted that the terminals 64, 65 for the circuit interrupter l are provided at the top of the bushing 7 and at the top of the interrupter column 5. All are located in the same horizontal plane at an elevation safely above the work area. The folded configuration of each pole unit 1 avoids an unnecessarily wide, space-wasting span between the terminals 64, 65. Also the adjacent pole units 1 may be spaced as closely as electrical clearances permit, giving a compact overall arrangement.

It will be noted that there is space available for two current transformers in each location, resulting in a total of four current transformers possible per pole unit 1.

It will be noted that the stationary contact 34 is mounted beneath the dome 4i which forms the top of the vertical interrupter column 5. Below it, in this column, is the moving contact structure 31, which comprises an orifice, finger-type main contacts, a bayonettype arcing contact and a putter cylinder 27, supported on a pedestal 48 mounted in the pole-unit base. The moving contact structure 31 is actuated through insulating pull rods 24, connected to lugs 26 on the sides of the puffer cylinder 27 and at the lower ends to two cranks 22 actuated by the circuit-breaker mechanism.

As the breaker opens, downward movement of the pullrods 24 separate, successively, the main contacts and the arcing contacts, and then draws an are 19 within the interrupting orifice 43. Gas, compressed within the cylinder 27 during the opening stroke, is forced through the orifice 43 in a putt to extinguish the are 19. Current is collected from the lower end of the moving contact structure 31 through stationary finger contacts 59, which are, in turn, connected by a tubular conductor 54 to the lower end of the bushing 7.

It is intended, for certain applications, that this poleunit 1 be charged with sulfur hexafiuoride (SP gas, or a similar gas of proven arc-interrupting ability. The unit 1 is essentially gas-tight in construction. Consequently the initial charge of gas should sufiice until maintenance is required after several years of service. The sulfur-hexafluoride gas provides dielectric strength between live parts and ground within the structure, and also serves as the arc-interrupting medium. The drive shaft 4 is sealed at the point where it enters the pressuretype housing 6 with either a conventional O-ring type of seal, or a clamped tubular type seal, such as disclosed in United States Patent 2,889,434, issued June 2, 1959, to Harry J. Lingal and assigned to the assignee of the instant application.

It will be noted that the contact components are readily accessible for servicing and inspection after the gas has been bled out of the pole-unit 1. Removal of the domeshaped cover 40 at the top of the vertical column permits the stationary contact 34 to be extracted. Following this, the moving contacts may either be inspected in place, or taken out by removing the bolts 23 that attach the assembly to the putter cylinder 27. This assembly also includes the sliding contact 60 which connects with the tubular conductor 54 leading to the terminal bushing 7.

. The complete movable contact structure 31 that is supported upon the pedestal 48, excluding the stationary contact 34 supported in the dome 40, may be removed from beneath the pole-unit housing 6. This is a desirable feature because the worker is located close .to ground for his own safety, and the amount of rigging equipment is minimized. The horizontal conductor 56 must be disconnected at the elbow 55 at the contact supporting post 48. Also, the contact ope-rating pull rods 24 must be disconnected from the driving cranks 2 2. For these operations, access is provided through the bottom of the interrupter at the base of the pedestal 48 by removing the cover plate 51 on the bottom of the housing 6. This also provides access to the pedestal mounting flange 49. Removal of bolts 4% in it permits the pedestal 48 and moving contact components 31 to be lowered out of the bottom of the pole-units 1.

The vertical orientation of the interrupter column 5 affords advantages in heat dissipation. Resistance losses cause the conducting parts to heat, and the gas surrounding these parts is, in turn, also heated. However, the tubular construction of the orifice 43, the cylinder 27,;and the supporting pedestal 48 forms a chimney, which carries these hot gases upwardly, by convection, to the dome 4i) at the top of the column 5. The dome 40, being metallic, conducts the heat from these gases outwardly to the surrounding ambient air. In necessary, this feature can be further enhanced by providing a larger dome 4t and equipping it with integral fins.

It is to be observed that check valves 62 have been provided at the bottom of the putter cylinder 27. In addition to permitting the passage of gas for the cooling eflect described, these valves 62 also permit the cylinder 27 to breathe in gas during the closing stroke, which has not been contaminated, or heated by arcing.

The particular circuit-interrupting structure 1, disclosed herein, has the following advantages:

(1) It provides a gas-type of circuit interrupter providing two current transformers or more if required per terminal.

(2) A gas-type circuit interrupter results having current transformers located to provide overlapping differential relay protection.

(3) A gas-type circuit interrupter providing the simplicity of a sealed, self-contained unit.

(4) A gas-type circuit interrupter arranged in a vertical column to enhance heat dissipating ability to provide high continuous current ratings.

(5) A gas-type circuit interrupter having the mechanism located for minimum overall breaker dimensions.

(6) The invention provides a gas-type circuit interrupter designed for ease of inspection and maintenance.

(7) A gas-type of circuit interrupter is obtained having live parts equidistant above ground at the requisite elevation for safety.

(8) The circuit interrupter has pole units 1 of folded configuration to thereby minimize space requirements.

(9) A circuit-interrupting structures results which is simple in construction for economical manufacture.

Although there has been illustrated and described a specific circuit-interrupting structure, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the invention.

We claim as our invention:

1. A circuit interrupter of the single-bushing type including an upstanding insulating cylindrical interrupter housing, a relatively stationary contact disposed interiorly within the upper end of said cylindrical interrupter housing, a longitudinally movable pufier cylinder carrying a movable contact disposed interiorly within said cylindrical interrupter housing, the movable contact being cooperable with the relatively stationary contact to establish an arc, the movement of the putter cylinder forcing fluid under pressure toward the established arc to effect the extinction thereof, a grounded mechanism housing disposed below said upstanding cylindrical interrupter housing and serving to support the same, a canted terminal bushing of conventional type supported by said grounded mechanism housing, the angle between the axial center lines of the interrupter housing and the terminal bushing being less than 180, and a removable cover plate secured to the bottom of the mechanism housing to effect downward withdrawal of the movable puffer cylinder for service and maintenance.

the same, interrupting elements disposed Within said hollow casing for establishing and extinguishing an arc, a canted terminal bushing supported by said grounded support housing, a pair of current transformers, one of said current transformers being disposed below the hollow casing so that any fault to ground over the casing will pass to ground through said one current transformer and the sensed as an internal fault, the other current transformer being mounted upon said grounded support housing in such relation to the protruding end of the terminal bushing that any breakdown over the external end of the terminal bushing will be sensed as an internal fault.

3. The combination in a single-bushing type of circuit interrupter of an upstanding hollow insulating interrupter casing, a grounded support housing disposed below said hollow insulating interrupter casing and serving to support the same, a relatively stationary contact disposed within the upper end of the hollow casing, a movable contact cooperable with the relatively stationary contact to establish an arc, a movable puffer cylinder carrying said movable contact and operable to force a blast of fluid under pressure at the established arc to effect the extinction thereof, a canted terminal bushing supported by said grounded support housing, a pair of current transformers, one of said current transformers being disposed below the hollow casing so that any fault to ground over the casing will pass to ground through said one current transformer and be sensed as an internal fault, the other current transformer being mounted upon said grounded support housing in such relation to the protruding end of the terminal bushing that any breakdown over the external end of the terminal bushing will be sensed as an internal fault.

4. A circuit interrupter of the single-bushing type including an upstanding insulating cylindrical interrupter housing, a relatively stationary contact disposed interiorly Within the upper end of said cylindrical interrupter hous ing, a longitudinally movable puffer cylinder carrying a movable contact disposed interiorly within said cylindrical interrupter housing, the movable contact being cooperable with the relatively stationary contact to establish an arc, the movement of the puffer cylinder forcing fluid under pressure toward the established arc to effect the extinction thereof, a grounded mechanism housing disposed below said upstanding cylindrical interrupter housing and serving to support the same, a canted terminal bushing of conventional type supported by said grounded mechanism housing, and the angle between the axial center lines of the interrupter housing and the terminal bushing being less than 180, crank means disposed within said mechanism housing, and longitudinally extending operating-rod means interconnecting said crank means and said longitudinally movable puffer cylinder, and a removable cover plate secured to the bottom of the mechanism housing to effect downward withdrawal of the movable putter cylinder for service and maintenance.

5. A circuit interrupter of the single-bushing type including an insulating cylindrical interrupter housing, a relatively stationary contact disposed interiorly within the upper end of said cylindrical interrupter housing, a longitudinally movable putter cylinder carrying a movable contact disposed interiorly within said cylindrical interrupter housing, the movable contact being cooper-able with the relatively stationary contact to establish an arc, the movement of the puffer cylinder forcing fluid under pressure toward the established arc to effect the extinction thereof, a grounded mechanism housing disposed below said cylindrical interrupter housing and serving to support the same, a canted terminal bushing of conventional type supported by said grounded mechanism housing and making an angle with the axial center line of the interrupter housing, and a removable cover plate secured to the bottom of the mechanism housing to effect downward withdrawal of the movable puifer cylinder for service and maintenance.

6. The combination in a single-bushing type of circuit interrupter of a hollow insulating interrupter casing, a grounded support housing disposed below said hollow insulating interrupter casing and serving to support the same, interrupting elements disposed within said hollow casing for establishing and extinguishing an arc, a canted terminal bushing supported by said grounded support housing, a pair of current transformers, one of said current transformers being disposed below the hollow casing so that any fault to ground over the casing will pass to ground through said one current trans-former and be sensed as an internal fault, the other current transformer being mounted upon said grounded support housing in such relation to the protruding end of the terminal bushing that any breakdown over the external end of the terminal bushing will be sensed as an internal fault.

7. The combination in a single bushing type of circuit interrupter of a hollow insulating interrupter casing, a grounded support housing disposed below said hollow insulating interrupter casing and serving to support the same, a relatively stationary contact disposed within the upper end of the hollow casing, a movable contact cooperable with the relatively stationary contact to establish an arc, a movable puffer cylinder carrying said movable contact and operable to force a blast of fiuid under pressure at the established arc to effect the extinction thereof, a canted terminal bushing supported by said grounded support housing, a pair of current transformers, one of said current transformers being disposed below the hollow casing so that any fault to ground over the casing will pass to ground through said one current transformer and be sensed as an internal fault, the other current transformer being mounted upon said grounded support housing in such relation to the protruding end of the terminal bushing that any breakdown over the external end of the terminal bushing will be sensed as an internal fault.

References Cited in the file of this patent UNITED STATES PATENTS 2,445,529 Leeds July 20, 1948 2,488,569 Strom Nov. 22, 1949 2,707,740 Zuhlke May 3, 1955 2,709,737 Forwald May 31, 1955 2,766,348 Forwald Oct. 9, 1956 2,804,576 Coggeshall Aug. 27, 1957 2,866,045 Leeds Dec. 23, 1958 2,913,556 Leeds Nov. 17, 1959 2,979,591 Friedrich Apr. 11, 1961 3,114,815 Easley et al Dec. 17, 1963 FOREIGN PATENTS 505,668 Great Britain May 16, 1939 534,936 Great Britain Mar. 24, 1941 535,956 Great Britain Apr. 28, 1941 550,151 Great Britain Dec. 24, 1942 655,585 Germany Jan. 19, 1938

Claims (1)

1. A CIRCUIT INTERRUPTER OF THE SINGLE-BUSHING TYPE INCLUDING AN UPSTANDING INSULATING CYLINDRICAL INTERRUPTER HOUSING, A RELATIVELY STATIONARY CONTACT DISPOSED INTERIORLY WITHIN THE UPPER END OF SAID CYLINDRICAL INTERRUPTER HOUSING, A LONGITUDINALLY MOVABLE PUFFER CYLINDER CARRYING A MOVABLE CONTACT DISPOSED INTERIORLY WITHIN SAID CYLINDRICAL INTERRUPTER HOUSING, THE MOVABLE CONTACT BEING COOPERABLE WITH THE RELATIVELY STATIONARY CONTACT TO ESTABLISH AN ARC, THE MOVEMENT OF THE PUFFER CYLINDER FORCING FLUID UNDER PRESSURE TOWARD THE ESTABLISHED ARC TO EFFECT THE EXTINCTION THEREOF, A GROUNDED MECHANISM HOUSING DISPOSED BELOW SAID UPSTANDING CYLINDRICAL INTERRUPTER HOUSING AND SERVING TO SUPPORT THE SAME, A CANTED TERMINAL BUSHING OF CONVENTIONAL TYPE SUPPORTED BY SAID GROUNDED MECHANISM HOUSING, THE ANGLE BETWEEN THE AXIAL CENTER LINES OF THE INTERRUPTER HOUSING AND THE TERMINAL BUSHING BEING LESS THAN 180*, AND A REMOVABLE COVER PLATE SECURED TO THE BOTTOM OF THE MECHANISM HOUSING TO EFFECT DOWNWARD WITHDRAWAL OF THE MOVABLE PUFFER CYLINDER FOR SERVICE AND MAINTENANCE.

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