US3418439A

US3418439A - High-voltage electric circuit breaker

Info

Publication number: US3418439A
Application number: US499205A
Authority: US
Inventors: Edward J Casey; Milton L Heintz
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1965-10-21
Filing date: 1965-10-21
Publication date: 1968-12-24
Anticipated expiration: 1985-12-24
Also published as: GB1131520A; JPS4321211B1; DE1640182A1; ES332238A1; CH448214A; FR1499529A

Description

Dec. 24, 1968 E. J. CASEY ET AL 3,418,439

HIGH-VOLTAGE ELECTRIC CIRCUIT BREAKER Filed Oct. 21, 1965 3 Sheets-Sheet 1 F/g. Z.

44 INVENTORS. M 7061 EDWARD J. CASEY,

MILTON L.HE//vrz BY Wm M ATTORNEY Dec. 24, 1968 E. J. CASEY ETAL HIGH-VOLTAGE ELECTRIC CIRCUIT BREAKER HE/NTZ,

5 Sheets-Sheet 2 INVENTORS. EDWARD J. CASEY MILTON L Filed Oct. 21, 1965 A 7' TORNE Y Dec. 24, 1968 E. J. CASEY ET AL HIGH-VOLTAGE ELECTRIC CIRCUIT BREAKER 3 Sheets-Sheet 5 Filed Oct. 21, 1965 m M J R M L 7 0 VON T R r wAm WA w 0 4 EM qr g United States Patent Ofice Patented Dec. 24, 1968 3,418,439 HIGH-VOLTAGE ELECTRIC CIRCUIT BREAKER Edward J. Casey, Media, and Milton L. Heintz, Newtown Square, Pa., assignors to General Electric Company, a corporation of New York Filed Oct. 21, 1965, Ser. No. 499,205 Claims. (Cl. 200-144) ABSTRACT OF THE DISCLOSURE Vacuum-type circuit breaker comprising a high voltage metal housing mounted on a vertically-extending insulating support. First and second vacuum interrupters are mounted at one side of the housing and third and fourth interrupters at the opposite side. First and second horizontally-extending hollow insulators on opposite sides of the housing respectively mount the first and fourth interrupters, whereas the second and third interrupters are mounted directly on the housing in offset, laterally-spaced relationship to the first and second insulators, respectively. The interrupters are electrically connected in such a manner that current flows successively through the first, second, third and fourth interrupters.

This invention relates to a high voltage electric circuit breaker and relates more particularly to a high voltage electric circuit breaker that comprises a plurality of enclosed interrupter units electrically connected together in series. In a preferred embodiment of the invention, the interrupter units are vacuum-type circuit interrupters, each comprising a sealed envelope and relatively movable contacts located therein.

In the usual circuit breaker of this type, the seriesconnected interrupter units are mounted in aligned relationship to form an assembly, and an insulating housing of tubular form is provided about the assembly to provide a weather-proof enclosure. The individual interrupter units are usually operated by one or more movable operating rods extending longitudinally of the assembly. These operating rods are typically located in the cylindrical space between the interrupter assembly and the insulating enclosure. A disadvantage of such an arrangement is that the enclosure diameter must be relatively large in order to accommodate both the interrupter assembly and the operating rods, and such large diameter insulating enclosures are quite expensive.

An object of the present invention is to arrange the interrupter units in such a manner that inexpensive insulating enclosures of a relatively small diameter can be used for enclosing the interrupter units and the operating rods.

Another object is to provide a high voltage circuit breaker that lends itself to being constructed of modular units which can be quickly assembled and which can be used in varying numbers to provide circuit breakers of different voltage ratings.

Another object is to construct the circuit breaker in such a manner that individual interrupter units can be easily inspected and replaced, if necessary, without disturbing the remaining interrupter units.

In carrying out our invention in one form, we provide a high voltage electric circuit breaker that comprises a metal housing normally at a high voltage and an insulating support on which the metal housing is mounted. First and second circuit interrupters are located at one side of the housing, and third and fourth circuit interrupters are located at another side of the housing. A first generally horizontally-extending hollow insulator is mounted on the housing at said one side, and a second generally horizontally-extending hollow insulator is mounted on the housing at said other side. Means is provided for mounting the first circuit interrupter on one of the hollow insulators and the fourth circuit interrupter on the other of the hollow insulators. Additional means is provided for mounting the second and third interrupters on the metal housing in offset laterally-spaced relationship to said hollow insulators. The four interrupters are electrically connected in series so that current can flow successively through the first, second, third and fourth interrupters. A pair of generally horizontally extending operating rods for the first and fourth interrupters, respectively, are provided, and these operating rods extend from their respective interrupters through the hollow insulators into the interior of the metal housing. Additional operating rods are provided for the second and third interrupters, respectively, and these operating rods extend from their respective interrupters into the interior of the metal housing. Located inside the metal housing and mechanically coupled to these operating rods is operating means for producing substantially simultaneous operation of the operating rods.

For a better understanding of our invention, reference may be had to the following description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side elevational View, partially schematic, of a circuit breaker embodying one form of my invention.

FIG. 2 is a plan view of the circuit breaker of FIG. 1. Certain portions of the circuit breaker of FIG. 1 have been removed for clarification.

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2. The circuit breaker is shown in a closed position.

FIG. 4 is a schematic view of the circuit breaker of FIG. 3, the parts in FIG. 4 being shown in an open position.

FIG. 5 is a sectional view along the line 55 of FIG. 3.

FIG. 6 is a schematic illustration of a modified form of the invention.

FIG. 7 is an enlarged detail view of a portion of FIG. 3.

Referring now to FIG. 1, the circuit breaker shown therein comprises a metal housing 11 that is normally at a high voltage with respect to ground. This housing 11 is mounted on a cylindrical column 12, preferably of porcelain, which electrically isolates the metal housing 11 from ground. The lower end of the insulating support column 12 is suitably mounted on a conventional metal framework 13, which is at ground potential.

The metal housing 11 serves as a support on which the interrupting units of the circuit breaker are mounted. These interrupting units can best be seen in FIG. 3, where four interrupting

units

21, 22, 22a and 21a are shown. In a preferred form of the invention, all of these interrupter units are substantially identical. These interrupting units can be of a conventional construction, but to facilitate an understanding of the invention a detailed description of one of them is presented hereinafter. The first and

second interrupting units

21 and 22 are located at one side of the metal housing 11, and the third and fourth interrupting units 22a and 2111 are located at an opposite side of the housing. All the interrupting units are electrically connected together in series, as will soon be described.

The interrupting units at the right-hand side of the housing 11 are mounted on the housing in the same manner as those on the left-hand side of the housing. Accordingly, the mounting of only the right-hand interrupting units will be described in detail. Corresponding parts at the left-hand side of the housing 11 are assigned corresponding reference numerals except with the suflix a.

Each interrupting unit is preferably a vacuum-type circuit interrupter and can be of any suitable conventional design. For a more specific showing of an interrupter suitable for use in the disclosed circuit breaker, reference may be had to U.S. Patent 3,163,734 to Lee, assigned to the assignee of the present invention. Generally speaking, each of the interrupters comprises a highly-evacuated sealed envelope 30 in which a pair of separable butt-

type contacts

31 and 32 are mounted. The contacts have been suitably processed to free them of sorbed gases and contaminants that decompose in the presence of an arc to form permanent gases. The envelope 30 comprises a tubular housing 33 of insulating material and a pair of

end caps

34 and 35 closing off the ends of the tubular housing and suitably sealed thereto. The right-hand contact 31 (of interrupter 21) is a stationary contact that is supported on the inner end of a conductive rod 36. The conductive rod 36 projects. in sealed relationship through the right-hand end of the envelope and is rigidly attached to the end cap 34 by welding.

The other contact 32 of the circuit interrupter 21 is a movable contact brazed to the inner end of a contactactuating rod 38, referred to hereinafter as the movable contact rod. This movable contact rod 38 is mounted for substantially straight line movement along its longitudinal axis and projects freely through an opening in the lefthand end cap 35. A flexible metallic bellows 40 is interposed between the left-hand end cap 35 and the contact rod 38 to provide a seal about the contact rod that allows for longitudinal movement thereof without impairing the vacuum inside the envelope 10.

Opening of the circuit interrupter 21 is eflected by applying a force to the contact rod 38 to drive the movable contact 32 to the left out of engagement with the other contact 31. Initial separation of the contacts establishes a circuit interrupting are between the contacts, and this are will persist until about the time a natural current zero is reached. The are will then vanish and be prevented from reigniting by the high dielectric strength of the vacuum, thus completing the circuit-interrupting operation.

Closing of the interrupter 21 is eflected by driving the left-hand contact 32 to the right from its open position of FIG. 4 into engagement with the other contact 31, thus reestablishing the power circuit through the interrupter.

The actuating means for effecting opening and closing movement of the contact rod 38 will soon be described in detail, but first a description will be given of the structure that is relied upon for supporting each of the interrupters and for carrying current to and from the interrupters.

For supporting the interrupter 21, a horizontallyextending hollow cylinder 44 of an insulating material such as porcelain, is provided. At its left-hand end, the insulating cylinder 44 is suitably secured to the metal housing 11; and at its right-hand end, the cylinder 44 carries metallic structure 4 6 that is secured to the lefthand end plate 35 of the interrupter 21. For securing the insulating cylinder 44 to the housing 11, a plurality of tie rods 47 of a suitable insulating material are provided inside the cylinder 44. These tie rods 47 are clamped at their left-hand end to a wall of the metal housing 11. The right-hand end of each tie rod is threaded, and a nut 48 mounted thereon clamps a metal plate 50 against the right-hand end of the insulator 44. A suitable stop nut 49 on each tie rod 47 limits the force applied by the nut 48. When the nuts 48 are tightened to their normal position shown, the tie rods 47 are loaded in tension and the tubular insulator 44 is loaded in compression. This preloading of the insulator '44 in compression maintains the insulator in compression even when heavy tensile or bending loads are applied thereto, thus improving the insulators ability to withstand such loads without damage. Accordingly, the tie rods are referred to hereinafter as reinforcing means for the insulator 44.

The structure g at the end of insulator 44 is a box-like casing that has spaced-apart end walls 50 and 52 and an integrally formed body 53 connecting these end walls. The body 53 has inspection openings therein that are normally closed by removable covers 54 suitably attached to the body 53. The right hand end wall 52 is attached to the end plate 35 of the vacuum interrupter by series of studs. As may be seen in the enlarged view of FIG. 7, these studs 56 are integral with the end plate 35 of the interrupter, and nuts 57 on the studs, acting through suitable Belleville washers 58, clamp the end plate 35 to the end wall 52.

For providing a weather-proof enclosure about the vacuum interrupter 21, a hollow porcelain cylinder 60 is provided. This cylinder 60 surrounds the envelope 30 of the interrupter and is suitably joined to the end wall 52 at its left hand end. At the right hand end of the insulating cylinder 68, there is an end plate 62 that is suitably joined to the insulating cylinder 60. This end plate 62 serves as one terminal of the circuit breaker assembly.

For carrying current to and from circuit interrupter 21 a pair of flexible metallic braids 64 and 65 are provided at opposite ends of the interrupter. Braid 64 is suitably attached at its respective opposite ends to terminal plate 62 and the stationary contact rod 36. The other braid 65 is suitably attached at its respective opposite ends to the movable contact rod 38 and the body 53 of the metal casing Q. Thus current through the first interrupter 21 follows a path extending successively through

parts

62, 64, 36, 31, 32, 38, 65, and 53.

The upper circuit interrupter is vertically spaced from the hollow insulator 44 and is mounted directly on the wall of metallic housing 11. In this connection, the upper interrupter 22 has studs 56 integral with its left-hand end cap through which the end cap is clamped to the wall of housing 11. Suitable nuts on the studs 86 act through Belleville washers to perform the clamping action, in the same general manner as depicted in FIG. 7.

For providing a weather-proof enclosure about the interrupter 22, a porcelain cylinder is provided. This porcelain cylinder 70 is suitably joined at its left-hand end to the metal housing 11. At the right-hand end of the porcelain cylinder 70, there is an end plate 72 suitably joined thereto.

For carrying current to and from the upper interrupter 22, a pair of flexible metallic braids 74 and 76 are provided at its respective opposite ends. The braid 74 is suitably joined at its respective ends to the end plates 72 and the stationary contact rod 36. The other braid 76 is suitably joined at its respective opposite ends to the movable contact rod 38 of interrupter 22 and the identical movable contact rod 38 of interrupter 22a. Thus, current through the interrupter 22 follows a path through

parts

72, 74, 36, 38 and 76.

For carrying current between the

interrupters

21 and 22, a conductive strap 80 of a high conductivity metal is suitably attached at its respective opposite ends to the parts 72 and 53. It will be apparent that conductive strap 80 connects the

interrupters

21 and 22 in series. It will also be apparent that the braid 76 in metal housing 11 connects the series-connected

interrupters

21, 22 at the right hand side of the metal housing 11 in series with the

seriesconnected interrupters

21a, 22a at the left-hand side of the metal housing 11. Thus, all the interrupters are electrically connected together in series.

The metal housing 11 is electrically connected to the end plates 35 of the two

interrupters

22 and 22a, and these end plates 35 are electrically connected to the movable contacts 38 of their respective interrupters by suitable means (not shown). Thus, when the circuit breaker is closed, the

metal housing 11 is at line potential. When the circuit breaker is open, the metal housing 11 is at approximately mid-potential with respect to the two terminals of the circuit breaker, as will soon be explained.

During a circuit breaker-opening operation, the four circuit interrupters are caused to open substantially simultaneously; and durng a circuit breaker closing operation, the four interrupters are caused to close substantially simultaneously. For producing this simultaneous operation of the four interrupters, a contact-operating linkage 9g is disposed inside the metal housing 11, as shown in FIG. 3.

This contact-operating linkage comprises a verticallymovable actuating rod 92 that is biased in an upward contact-opening direction by a heavy compression spring 93 at the top of housing 11 (FIG. 3). When the circuit breaker is in its closed position, this actuating rod 92 is held in its depressed position shown in FIG. 3 by a trip latch 94 that acts on a latch roller 95 connected to the actuating rod 92. When this trip latch 94 is released, the opening spring 93 is free to expand, thereby driving the actuating rod 92 in an upward opening direction. For transmitting this upward opening movement of actuating rod 92 to the movable contact rods 38 of the individual interrupters, four bell cranks 100 are provided. These four bell cranks 100 are respectively coupled to the movable contact rods 38 of the four interrupters; and all the bell cranks are coupled to the common actuating rod 92. Each bell crank 100 is connected to the actuating rod 92 through a link 102 that is pivotally connected at one end to the bell crank and is pivotally connected at its other end to the actuating rod. The pivots at the respective ends of the link 102 are designated 104 and 106. Each bell crank 100 is mounted for pivotal movement about a stationary pivot 108 carried by a suitable bracket on the metal housing 11. The coupling between the bell crank 100 and the movable contact rod 38 is through a pivot 109 that is slidably mounted on a drive rod 110 connected to the movable contact rod.

The drive rods 110' are directly connected to the movable contact rods 38 of the

upper interrupters

22 and 22a. But for each of the

lower interrupters

21 and 21a, there is an insulating intermediate rod 111 disposed between the movable contact rod 38 and its drive rod 110. Each of these insulating intermediate rods 111 is rigidly connected to the movable contact rod 3 8 and extends through one of the hollow supporting insulators 44 into the interior of metal housing 11.

When the common actuating rod 92 is driven upwardly from its position of FIG. 3 by the opening spring 93, as above described, the bell cranks 100 to the right of the vertical actuating rod 92 are pivoted in a clockwise direction and the bell cranks 100 to the left of the vertical actuating rod 92 are pivoted in a counterclockwise direction. In response to such pivotal motion of hell cranks 100, the pivots 109 on the bell cranks move from their illustrated position of FIG. 3 toward the center of housing 12. After a predetermined amount of such movement, each pivot 109 engages a stop 112 on the associated drive rod 110' and drives the rod 110 in a contact-opening direction. More specifically, the movable contact rods 38 of

interrupters

21 and 22 are driven to the left, and the movable contact rods 38 of

interrupters

21a and 22a are driven to the right. The stops 112, which are preferably nuts threaded on rods 110, are so adjusted that they are engaged by their respective pivots 109 substantially simultaneously, thereby causing the contacts of the four interrupters to separate substantially simultaneously during a circuit breaker opening operation. FIG. 4 illustrates the interrupters and their operating linkage at the end of an opening operation.

For smoothly terminating the opening operation without significant rebound, a suitable dashpot schematically shown at 113 is provided at the top of housing 12 adjacent the opening spring 39. The dashpot comprises a movable plunger 114, the upward movement of which is opposed by liquid in the dashpot. The plunger 114 is engaged by a cap 116 on the actuating rod 92 after the rod 92 has moved through a predetermined portion of the opening stroke, and thereafter retards further upward movement of actuating rod 92.

Closing of the circuit breaker is elfected by driving the vertically-extending common actuating rod 92 in a downward direction from its open position of FIG. 4. The force for such a closing opera-tion is derived from a suitable operating mechanism (not shown) coupled to the lower end of common actuating rod 92. Such downward closing motion of the actuating rod 92 pivots the right-hand bell cranks in a counterclockwise direction and the lefthand bell cranks in a clockwise direction. Each of these bell cranks acts through its associated wipe spring to drive the movable contact rod 38 in a closing direction. After this closing action has continued sulficiently to cause contact-engagement, the bell cranks 100 continue their closing motion, compressing the wipe springs 115 and developing a clearance space between the pivots 109 and their respective stops 115. When such closing action is terminated, the parts have been restored to their position of FIG. 3.

To insure that the contacts of all four interrupters engage simultaneously during a closing operation, suitable adjusting means (not shown in detail) is provided between each bell crank 100 and its associated link 102. Each of these adjusting means preferably comprises an eccentric portion on pivot 104 that fits in the pivot-receiving opening of link 102. The eccentric portion can be rotatably adjusted with respect to the remainder of the pivot 104 to provide for slight changes in the angular position of the bell crank 100 without changing the position of link 102.

The downward closing force exerted on the actuating rod 92, in addition to closing the interrupters, recharges the opening spring 93, thereby preparing it for another opening operation. At the end of the downward closing travel of actuating rod 92, the trip latch 94 moves into its latching position behind the latch roller 95, thereby latching the circuit breaker in its closed position.

The

latching mechanism

94, 95 can be of any suitable conventional type and is therefore shown in schematic form only. In the illustrated embodiment, it comprises a latch member 94 that is pivotally mounted on a stationary pivot 120 and a reset spring 121 that biases the latch member toward its latched position. For tripping the latch, a long insulating rod 24 coupled to the latch member 94 is provided. When a downward tripping force is applied to this rod 124, the latch member 94 is pivoted clockwise about pivot 120 to release the latch roller 95 and permit the opening spring 93 to drive the actuating rod 92 upwardly. The latch-actuating rod 124 extends through the hollow insulator 12 and is adapted to receive a tripping signal at its lower end.

As pointed out hereinabove, one of the objects of my invention has been to arrange the interrupters in such a manner that inexpensive insulating enclosures of relatively small diameter can be used for enclosing the interrupting units and the operating rods. I have been able to achieve this objective, partially because none of the insulating

enclosures

60, 60a, 70, 70a, 44, 44a is required to accommodate both an interrupter and operating rods located outside the periphery of the interrupter. In this respect, note that the insulating

enclosures

60, 60a, 70, and 70a are called upon merely to enclose the interrupters. There are no rods extending alongside the interrupters that must also be accommodated. Note that the

enclosures

44 and 44a are called upon merely to enclose the operating rods 111 and no interrupters.

I have been able to obviate operating rods running alongside the interrupters by reason of the staggered or offset relationship of the interrupters at a given side of the housing. With this staggered relationship present, an extension (111) of a centrally-located movable contact rod 38 can be run directly from the

interrupter

21 or 21a to the contact-operating linkage 90 without interference from the

other interrupters

22 or 22a.

It is to be noted that the only ones of the porcelain enclosures that carry appreciable bending loads are the

enclosures

44 and 44a. I am able to provide internally located reinforcing rods 47 for these particular enclosures without requiring a large diameter porcelain to accommodate these rods because there are no interrupters inside these particular insulators. With only the operating rods 111 extending therethrough, there is ample space in a

small diameter enclosure

44 or 44a to accommodate the reinforcing rods 47 and certain other structure (soon to be described).

For distributing the total voltage approximately equally between the individual breaks of a multi-break interrupter, it is conventional to provide capacitors of suitable values in parallel with the breaks. These capacitors can be of any suitable conventional design, but I prefer to construct each capacitor as an assembly of stacked ceramic elements, as shown and claimed in application S.N. 323,414,

, Mankotf et al., filed Nov. 13, 1963, now Patent No. 3,325,-

708, :and assigned to the assignee of the present invention. The capacitor assembly shunting the lower interrupter 21 is located in a tubular enclosure 130, preferably of porcelain. This enclosure is attached by suitable brackets 131 and 132 at its opposite ends to the end plates 62 and 72 of the

enclosures

60 and 70. These brackets 131, 132 also serve :as conductors which electrically connect the capacitor assembly at its opposite ends to the plates 62 and 72, thereby connecting it in parallel with interrupter 21.

The capacitor assembly shunting the upper interrupter 22 is mounted inside the porcelain enclosure 44. This capacitor assembly which is shown schematically at 135, comprises terminal conductors 136 and 137. Terminal conductor 136 is electrically and mechanically connected to end plate 50, and terminal conductor 137 is electrically and mechanically connected to the adjacent wall of housing 11. Because there is no interrupter located inside the enclosure 44, there is ample room available for the capacitor assembly 135437. Locating the capacitor assembly 135437 inside the enclosure 44 eliminates the need for :a separate weatherproof enclosure, such as 130, for this capacitor assembly.

The capacitor assemb ies on the left hand side of the metal housing 12 are mounted and are electrically connected in the power circuit in substantially the same manner as those, described hereinabove, on the right hand side of metal housing 12. The same reference numerals are used for corresponding capacitor parts at the two sides of the metal housing except the suffix a is attached to those at the left hand side. Since the capacitors at the left hand side of the metal housing 12 are substantially the same as those at the right hand side of the metal housing, it will be apparent that when the circuit breaker is open the metal housing is at substantially a mid-potential with respect to the terminals of the circuit breaker.

It will be apparent that my circuit breaker is constructed from identical modules assembled together in a building block type of construction. In this connection, the overall assembly of interrupters at the right hand side of the metal housing 11 is identical to the overall assembly of interrupters at the left-hand side of the metal housing; the four

vacuum interrupters

21, 22, 21a and 22a are identical; the or

enclosures

60, 70, 70a and 60a are identical; each of the subassemblies that comprises an enclosure, such as 60, and a vacuum interrupter, such as 21, mounted therein is identical; and each of the supporting

subassemblies

44, 47 and 44a, 47a is identical. The use of such identical modules facilitates construction of and assembly of the modules by high speed assembly line techniques.

Each module has a predetermined volt-age rating; and within certain practical limits, from these modules a circuit breaker having a voltage rating of any desired value can be built up. The voltage rating of the built-up breaker will be equal to the number of modules multiplied by the voltage rating of each module. For example, if a breaker having a voltage rating of half that depicted in FIG. 1 is desired, the modules at one side of the circuit breaker housing 11 can be omitted. Or if a breaker with a higher voltage rating is desired, one or more additional modules, each comprising an enclosure such :as 60 and a vacuum interrupter such as 21 can be provided. As shown in FIG. 6, these additional modules, designated 60c, can be mounted beneath the

lower assembly

44, 60 in a horizontally extending row comprising two insulators 44c, each identical to the insulator 44 of FIG. 1. It will, of course, be necessary to provide a taller housing 11 and suitable bell cranks inside it to provide for operation of interrupter 60c simultaneously with the other interrupters.

The individual interrupters of my circuit breaker assembly can be readily inspected and replaced, if necessary, without disturbing the remaining interrupting units. In this connection, a pair of covered openings are provided in the metal housing 11. The removable covers for these openings are shown at 141 and 142 in FIG. 1. Suitable inspection holes 143 covered by a transparent material, such as shatter-proof glass, are provided in the covers. These inspection holes line up with the wipe mechanisms 109-112; and through these inspection holes 143, the wipe present in any one of the interrupters can be easily determined. If any adjustment is necessary, the

cover

141 or 142 can be removed, and the adjusment made by suitably adjusting the corresponding stop 112. If it is desired to replace either of the upper interrupters 22; the cover 141 on housing 11 is removed and the associated bell crank is suitably disconnected from its contact rod by removing the stop nut 112. Then, the nuts on studs 56 are removed, and'the interrupter is withdrawn from its enclosure 70th'rough-the outer end of the enclosure, after the cover plate 72 has been suitably removed. If. it is desired to replace either of the lower interrupters 21, the cover 54 on the intermediate casing 53 is first removed. Through the opening in casing 53, the insulating operating rod 111 is disconnected from contact rod 38. Thereafter, the nuts on studs 56 of the interrupter are removed, and the interrupter can then be withdrawn from its

enclosure

60 or 60a through the opposite end of the enclosure. It will be apparent that removal of any one of these interrupters can be effected without disturbing the other interrupters. Similarly, the removed interrupter can be replaced with another interrupter without disturbing the remaining interrupters.

While We have shown and described particular embodiments of our invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from our invention in its broader espect; and We, therefore, intend in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A high voltage electric circuit breaker comprising:

(a) a metal housing normally at a high voltage,

(1)) an insulating support on which said metal housing is mounted,

(c) first and second circuit interrupters located at one side of said housing and third and fourth circuit interru-pters located at another side of said housing,

(d) a first generally horizontally-extending hollow insulator mounted on said housing at said one side and a second generally horizontally-extending hollow insulator mounted on said housing at said other side,

. (e) means for mounting said first circuit interrupter on one of said lhOllOW insulators and said fourth circuit interrupter on the other of said hollow insulators,

('f) means for mounting said second and third interrupters on said housing in offset laterally-spaced relationship to said first and second hollow insulators, respectively,

(g) means for electrically connecting said four interrupters in series so that current can flow successively through said first, second, third and fourth interrupters,

(h) a pair of generally horizontally-extending operating rods for said first and fourth inter upters, respectively; said operating rods extending from their respective interrupters through said hollow insulators into the interior of said metal housing,

(i) additional operating rods for said second and third interrupters, respectively, extending from said second and third interrupters, respectively, into the interior of said metal housing,

(j) and means for producing substantially simultaneous operation of said operating rods comprising an actuating member located inside said metal housing and mechanically coupled to said operating rods.

2. The circuit breaker of claim 1 in which:

(a) said second and third interrupters are disposed in vertically-spaced relationship to said hollow insulators,

(b) said second and third interrupters are generally aligned with each other, and

(c) said first and fourth interrupters are aligned with each other.

3. The circuit breaker of claim 1 in which:

(b) said second and third interrupters are aligned with each other,

(c) said first and fourth interrupters are generally aligned with each other,

(d) said actuating member is movable in a generally vertical direction,

(e) said operating rods are movable in a generally horizontal direction to operate said interrupters, and

(f) said means for producing substantially simultaneous operation of said operating rods comprises coupling means connected between said verticallymovable actuating member and said operating rods for converting the generally vertical movement of said actuating member into generally horizontal movement of said operating rods.

4. A high voltage electric circuit breaker comprising:

(a) a metal housing normally at a high voltage,

(b) a generally vertically-extending insulating support on which said metal housing is mounted,

(-c) first and second circuit interrupters located at one side of said housing and third and fourth circuit interrupters located at another side of said housing,

(d) a first hollow insulator mounted on said housing at said one side and a second hollow insulator mounted on said housing at said other side, said hollow insulators extending transversely of said verticallyextending support,

(e) means for mounting said first circuit interrupter on one of said hollow insulators and said fourth circuit interrupter on the other of said hollow insulators,

(f) means for mounting said second and third interrupters on said housing in offset laterally-spaced relationship to said first and second hollow insulators, respectively,

g) means for electrically connecting said four interrupters in series so that current can flow successively through said first, second, third and fourth interrupters,

(h) a pair of operating rods for said first and fourth interrupters, respectively; said operating rods extending from their respective interrupters through said hollow insulators into the interior of said metal housing,

(j) and means for producing substantially simultaneous operation of said operating rods comprising an actuatgenerally generally ing member located inside said metal housing and mechanically coupled to said operating rods.

5. The circuit breaker of claim 4 in which:

(a) a hollow insulating enclosure is provided about each of said interrupters,

(b) the insulating enclosures for said second and third interrupters are mounted on said metal housing in spaced-apart relationship to said hollow insulators, and

(c) the insulating enclosures for said first and fourth interrupters are mounted on said hollow insulators, respectively.

6. The circuit breaker of claim 4 in combination with:

(a) capacitors respectively connected in parallel with said four interrupters,

(b) means for mounting the capacitor that is in parallel with the second interrupter inside the hollow insulator that mounts said first interrupter, and

(0) means for mounting the capacitor that is in parallel with the third interrupter inside the hollow insulator that mounts said fourth interrupter.

7. The circuit breaker of claim 4 in which said circuit interrupters are vacuum-type interrupters, each comprising a highly evacuated envelope and a pair of relatively movable contacts located inside said envelope, one of said contacts being connected to an associated one of said operating rods.

8, A circuit breaker as set forth in claim 4 and further including reinforcing means comprising tie rods located inside of each of said hollow insulators and extending longitudinally thereof for increasing the load-carrying capacity of said hollow insulator, said interrupters being located outside the interior of said hollow insulators.

9. The circuit breaker of claim 4 in which:

(a) each of said interrupters comprises an envelope having a pair of opposed ends, one of which faces said metal housing and the other of which faces in a generally opposite direction,

(b) interrupter supporting means is provided for supporting each of said interrupters at the end of said envelope facing said metal housing,

(c) aocess openings are provided in said circuit breaker adjacent said internupter supporting means for permitting disassem'bly of said supporting means, and

(d) an opening for each envelope larger than said envelope is present in the circuit breaker adjacent said other end of said envelope through which said interrupter may be removed from said circuit breaker independently of the other interrupters after said supporting means has been disassembled.

10. The circuit breaker of claim 1 in which said second and third interrupters each have one end electrically connected to said metal housing both when the circuit breaker is closed and opened.

References Cited UNITED STATES PATENTS 3,123,698 3/ 1964 Waterton. 3,214,557 10/ 1965 Pflanz. 3,352,988 11/1967 Wachta et al.

FOREIGN PATENTS 1,152,740 8/1963 Germany.

ROBERT S. MACON, Primary Examiner.

US. Cl. X.R. 200l45