US3527910A - Polyphase vacuum type circuit breaker - Google Patents

Description

p 1970 w. c. MITCHELL, JR, ETAL 3,

POLYPHASE VACUUM TYPE CIRCUIT BREAKER Filed April 25, 1968 INVENTORJ, WILL/AM C. M/TCHLL,JR., ALEXANDERD. /fL//v,

BY M245 71am ATTORNEY United States Patent Office 3,527,910 Patented Sept. 8, 1970 U.S. Cl. 200-144 9 Claims ABSTRACT OF THE DISCLOSURE A polyphase electric circuit breaker comprising three vacuum interrupters, one for each phase of the circuit breaker. The operating mechanism for the interrupters is contained within a housing having a roof with a central horizontal wall portion and two sloping wall portions at opposite sides of the horizontal Wall portions. Tubular insulators are respectively mounted on said wall portions with their axes in a common plane. The vacuum interrupters are respectively mounted atop said tubular insulators and are operated through linkages respectively extending through the tubular insulators into the housing, where they are coupled to a common rotatably-mounted operating member.

This invention relates to an electric circuit breaker and, more particularly, to a polyphase circuit breaker comprising a plurality of vacuum-type circuit interrupters arranged for actuation by a common operating mechanism.

In U.S. Pat. 3,163,735-Miller, assigned to the assignee of the present invention, there is shown a S-phase circuit breaker comprising three vacuum interrupters actuated by a common operating mechanism. The circuit breaker comprises a grounded metal housing in which the three vacuum interrupters are mounted and high voltage bushings projecting into the housing for carrying current to and from the interrupters. A linkage within the housing transmits operating forces to the vacuum interrupters from a mechanism located externally of the housing. A circuit breaker of this design is satisfactory for relatively low voltage applications, e.g., 15 kV,; but when this design is applied to substantially higher voltages, e.g., 34.5 kv., it becomes unduly large and cumbersome.

An object of our invention is to provide a circuit breaker design suitable for a polyphase vacuum-type circuit breaker, which is exceptionally compact, even when applied to these higher voltages.

Another object is to provide a circuit breaker of this type in which operation of the three interrupters can be effected by a simple mechanism having a common operating element disposed in substantially the same plane as the linkage interconnecting the vacuum interrupters and the common operating member.

For a better understanding of the invention, reference 7 may be had to the following description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a sectional view through a polyphase vacuum circuit breaker embodying one form of my invention.

FIG. 2 is a schematic view of a portion of the circuit breaker of FIG. 1, except showing the parts in the open position.

FIG. 3 is a side elevational view of the circuit breaker of FIG. 1, with portions thereof being removed for clarity.

Referring now to FIG. 1, there is shown a polyphase circuit Ibreaker comprising three vacuum-type circuit interrupters 12a, 12b and 120, one being provided for each phase of the circuit breaker. These circuit interrupters are mounted atop spaced-apart tubular insulators 14a, 14b and 140, respectively. The tubular insulators are, in turn, mounted on the roof of a grounded metal housing 16. The metal housing 16 encloses an operating mechanism 18 that is used for operating the three vacuum interrupters.

The roof of the metal housing comprises a centrallylocated horizontal wall portion 20 and two sloping wall portions 21 and 22 located at opposite sides of the horizontal wall portions. The tubular insulators 14a, 14b, and 14c are respectively mounted on these wall portions 20, 21, 22 in spaced-apart relationship to each other. Each tubular insulator has a central longitudinal axis extending substantially perpendicular to its wall portion, and these axes are disposed in substantially a common reference plane, which is indicated at 23 in FIG. 3. As viewed in FIG. 1, the central longitudinal axes of the tubular insulators 14a and 14c are disposed at approximately 45 degree angles to the central longitudinal axis of the central tubular insulator 14b.

Each vacuum circuit interrupter is of a conventional form and comprises a highly evacuated sealed housing 30 and a pair of separable contacts 31, 32 Within the housing. Upper contact 31 is a stationary contact mounted on a conductive supporting rod 33 extending through the upper end of the sealed housing. Lower contact 32 is a movable contact mounted on a conductive contact rod 34 extending in sealed relationship through the lower end of housing 30. A bellows 35 permits longitudinal movement of operating rod 34 without impairing the vacuum inside envelope 30. An external slide bearing 36 surrounds the operating rod 34 and guides it for vertical movement. Preferably, the sealed housing 30 is encapsulated in a weather proof shell 38 of a suitable insulating material.

As shown in FIG. 1, a suitable metallic adaptor 39 of tubular form is located between the vacuum interrupter and the top of the insulating housing. This adaptor 39 is suitably joined to these parts by means not shown. A flexible metallic braid schematically indicated at 41 provides a suitable electrical connection between adaptor 39 and the contact rod 34.

For imparting operating motion to the movable contacts 32 of the three interrupters, we provide within the metal housing 16 a rotatable member 40 of crank form common to the three interrupters. The common operating crank 40 is fixed to a shaft 44 which is suitably journaled in stationary bearings (not shown). The movable contact rods 34 of the three interrupters are connected to this common operating crank 40 through linkages 42a, 42b and 420, respectively. Each of these linkages comprises a vertical operating rod 46 of insulating material extending through its associated tubular insulator 14a, 1412 or and coupled at its upper end to the contact rod 34 through a suitable wipe mechanism 48. At their lower ends operating rods 46 are pivotally connected to connecting rods 50 by pivots 49a, 49b and 49c respectively. Each connecting rod 50 is pivotally connected at its opposite end to the common crank member 40. These latter pivotal connections are designated 51a, 51b, and 51c, respectively. They are located at equal distances from the axis of shaft 44. A suitable guide link 52 pivotally mounted at one end on the housing 16 and pivotally connected at its other end to the lower end of the operating rod 46 is provided for suitably guiding the lower end of each of the operating rods 46.

The wipe mechanism 48 at the upper end of the operating rod 46 is of a conventional form such as shown for example in US. Pat. 3,180,960Barkan,, assigned to the assignee of the present invention. As such, it comprises a cylindrical driving part 60 and a piston-like driven part 61 mounted therein with a compression spring 62 therebetween. During an opening operation, when driving part 60 is driven downwardly from its illustrated position, a

shoulder at its upper end engages the piston-like driven part 61 after a small amount of downward movement and thereafter moves it downwardly with the driving part. On a closing operation, the driven part 61 moves upwardly with the cylindrical driving part until the contacts 32, 31 engage. The driving part 60 continues moving through a slight amount of additional upward travel, called wipe, during which it further compresses Wipe spring 62. This wipe mechanism serves the conventional function of maintaining a hold-closed force on the rnovable contact despite contact-wear.

Opening of the circuit breaker is effected by means of an opening spring 66 which biases the operating crank 40 in a clockwise direction from its solid-line closed position of FIG. 1 toward its dotted-line open position of FIG. 1. This opening spring 66 is a compression spring which bears at its forward, or left hand, end against a shoulder 69 fixed to a guide rod 67 which is pivotally connected at to a downwardly projective arm on operating member 40. At its rear end the compression spring bears against the stationary stop 68. When the circuit breaker is closed, the crank 40 is latched in its solid line position of FIG. 1, as will soon be described. When the crank is unlatched, opening spring 66 is released, and it responds by driving the crank clockwise into its dottedline open position. Such movement of the crank simultaneously drives the movable contacts 32 of the three vacuum interrupters into their disengaged, open position.

Closing of the circuit breaker is eifected by driving the crank member 40 in a counterclockwise direction from its dotted line position of FIG. 1 into its solid-line position of FIG. 1. FIG. 2 further illustrates the parts in the open position. For etfecting such closing movement, a closing linkage 70 of conventional form is connected to the crank member 40. This closing linkage comprises a pair of toggle links 71 and 72 pivotally joined together at knee 74. One of the toggle links 71 is pivotally connected at its opposite end to the downwardly projecting arm on crank 40 by means of a pivot pin 75. The other toggle link is pivotally connected by pivot pin 76 to the end of a guide link 77. Guide link 77 is pivotally supported at its opposite end on a stationary fulcrum 79. Pivot pin 76 carries a latch roller 80 which cooperates with a suitable trip latch 81 which is arranged to be operated in response to predetermined circuit conditions by means of a conventional tripping solenoid (not shown).

So long as the trip latch remains in its latched position of FIG. 2, toggle 71, 72 is capable of transmitting closing thrust to the operating crank 40. Thus, when the knee 74 is lifted from its position shown in FIG. 2, the toggle 71, 72 is extended and drives the crank 40 in a counterclockwise closing direction about the axis of shaft 44 into its solid line position of FIG. 1.

The lifting of knee 74 is produced by the action of a rotatable main cam 84 cooperating with the usual roller 85 which is mounted at knee 74. When main cam 84 is rotated in a clockwise direction by a suitable closing operator (not shown), it lifts knee 74, thereby extending toggle 71, 72 and closing the circuit breaker. In the 11- lustrated embodiment, the cam is suitably stopped in its position of FIG. 1 to prevent the toggle from collapsing at its knee 74 at the end of a closing stroke.

Tripping open of the circuit breaker is effected by driving trip latch 81 counterclockwise about its stationary pivot against the bias of a suitable reset spring 87. Should the latch 81 be tripped when the circuit breaker is closed, or even during a closing stroke, the pivot 76 will be freed by such tripping action, thus no longer serving as a stationary reaction point for toggle 71, 72. This will render the toggle 71, 72 inoperative to transmit closing thrust to the crank 40'; and, as a result, the opening spring 66 will be free to drive the crank into its dotted line open position of FIG. 1.

The closing operator and the tripping solenoid are disposed behind the plane depicted at FIG. 1. Since these components can be of a conventional form they are not shown in the drawing.

As pointed out hereinabove, the longitudinal axis of the three tubular insulating supports 14a, 14b and 140 are in substantially a common reference plane, which is indicated in FIG. 3 at 23. By disposing these insulators in substantially a comon plane, we are able to considerably simplify the operating mechanism and linkages. In this respect, note that since the operating rods 46 are disposed centrally of the tubular insulators, they too are in substantially the common plane 23, and this locates all of the connecting links 50 in the same comon plane. Since all these connecting links 50 are in a common plane, it is a simple matter to provide a common operating member 40, coupled to the connnecting links, which is located in substantially the same plane. By locating all of these parts in substantially the same plane, we can significantly decrease the elfective depth of the metal housing 16, as indicated at D in FIG. 3. No increased depth is needed to accommodate similar parts which might otherwise have been disposed in otfset relationship from each other.

It is to be further noted that the toggle links 71, 72 and the opening spring 66 are in substantially the same plane as the common operating member 40, thus further contributing to the compactness of the mechanism and the reduced depth of housing 16.

A factor that contributes to the simplicity and compactness of our mechanism is that the tubular insulating housings 14a, 14b and 140 are at an angle with respect to each other. Hence linkages which are disposed centrally of thetubular insulators (e.g., linkages 42a, 42b and 420) can easily be extended past the inner ends of the tubular insulators to a common operating region where they can be connected together, as through the common crank member 40. In other words, the simple linkages 42a, 42b, and 42c converge into a location where they can be conveniently connected together. This convergent relationship is obtained without requiring in the linkage any additional links for changing the direction of motion.

The fact that the axis of the two outer insulating housings 14a and 140 are both disposed at substantially 45 degrees with respect to the axis of center insulating housing .14b enables the linkages 42a, 42b and 42c to be substantially identical to each other and enables rotation of the crank 44 to produce substantially equal motion of the upper ends of the operating rod 46. In this regard, note in FIG. 1 that the angles 7, g and h are equal and, further, that the angles j, k, and l are equal. The angle 1 is the angle between the line of action m for link 50 of linkage 42a (i.e., a line connecting the axes of pivots 49a and 51a) and the radial line between the axis of shaft 44 and the axis of pivot pin 51a. Angles g and h are similar angles in the linkage 42b and 420. The angle 1' is the angle between the line of action m for link 50 of of linkage 42a and the line of action of operating rod 46. Angles k and l are similar angles in linkages 42b and 420. These equal angular relationships and the equal distances between the axis of shaft 44 and the crank pins 51a, 51b, and 510 contribute in an important manner to substantially equal travel being produced at the upper end of each operating rod 46 in response to rotation of the crank 40 through an operating stroke.

For conducting current to and from the lower end of each vacuum interrupter, we provide a terminal conductor located atop its tubular supportive insulator and extending transversely thereof, as best shown in FIG. 3. In FIG. 3, this terminal conductor 90 is also mounted atop a hollow insulating post 92 which, in turn, is supported on the roof of metal housing 16. Within each of the hollow insulating posts and supported on housing 21 is a current sensor (shown diagrammatically at 94) which may be of the type described in an article by Stein on a New Current Sensing Device, appearing in the AIEE Transactions, April 1963, pages 223-228. This current sensor measures the current through conductor 90 and provides an output signal for relaying or metering purposes. As an alternative current sensor, a suitably insulated current transformer, supported on housing 21 where post 92 is located, could be mounted about conductor 90.

In the preferred embodiment illustrated, the vacuum interrupter has its axis disposed colinear to the axis of the tubular insulating support. In those applications where there is a need for reduced height, we can mount the interrupter in a position perpendicular to that shown, i.e., at 90 degrees to the axis of the tubular insulating support. In such case, means such as a bell crank must be provided between rods 46 and 34 for converting the vertical motion of rod 46 to horizontal motion for the contact rod 34.

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 aspects; 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 polyphase electric circuit breaker of the vacuumtype comprising:

(a) a housing having a grounded metal roof comprising a centrally-located substantially horizontal Wall portion and two sloping wall portions at opposite sides of said horizontal wall portion,

(b) three spaced-apart tubular insulators respectively mounted on said wall portions, each having a central longitudinal axis extending transverse to its associated wall portion,

(c) said longitudinal axes being located in substantially a common reference plane,

((1) three vacuum interrupters, one for each phase of said circuit breaker, respectively mounted atop said tubular insulators,

(e) a rotatably-mounted common operating member of crank form located within said housing in a central location directly beneath said horizontal wall portion,

(f) three linkages respectively connected between said vacuum interrupters and said common operating member for transmitting operating motion therebetween, v

(g) said linkages respectively extending through said three tubular insulators.

2. The circuit breaker of claim 1 in which each of said linkages comprises:

(a) an insulating operating rod disposed centrally of its associated insulating housing, and

(b) a connecting link pivotally connected at one end to said operating rod and pivotally connected at its other end to said common operating member.

3. The circuit breaker of claim 2 in which each of said connecting links is so oriented that a line of action connecting the pivot points at its opposite ends is disposed at a predetermined angle with respect to the longitudinal axis of its associated operating rod, which angle is substantially the same in each of said linkages.

4. The circuit breaker of claim 3 in which each of said connecting links is so oriented that said line of action is disposed at a predetermined angle with respect to a reference line between the axis of rotation of said operating member and the pivot point between the connecting link and the operating member, which angle is the same for each of said linkages, said latter pivot points being substantially equidistant from the axis of rotation of said operating member.

5. The polyphase circuit breaker of claim 1 in which said common operating member is mounted for rotational movement in substantially said reference plane.

6. The circuit breaker of claim 5 in which:

(a) the central longitudinal axes of the tubular insulators mounted on said sloping walls are disposed at approximately 45 degrees to the central longitudinal axis of the insulator mounted on said horizontal wall, and

(b) said common operating member is located in the region of said housing where said longitudinal axes substantially intersect.

7. The circuit breaker of claim 5 in combination with a trip-free closing mechanism coupled to said common operating member, said closing mechanism comprising toggle links located in substantially the same plane as said common operating member.

8. The circuit breaker of claim 7 in combination with opening spring means coupled to said operating member, said opening spring means being located on an opposite side of said common operating member from said toggle linllis and in approximately the same plane as said toggle in s.

9. The circuit breaker of claim 1 in combination with three terminal conductors respectively connected to one end of said three interrupters, the terminal conductor associated with a given interrupter being located atop the tubular insulator associated with said interrupter and extending transversely of said insulator, and means sup ported on said housing for sensing the current through said terminal conductor.

References Cited UNITED STATES PATENTS 2,943,163 6/1960 Hay. 3,163,735 12/ 1964 Miller. 3,209,101 9/1965 Peek et al. 3,236,978 2/ 1966 Lester.

3,300,609 1/ 1967 Flurscheim et al 200l45 3,418,439 12/1968 Casey et al. 200-145 XR FOREIGN PATENTS 834,424 8/ 1938 France.

ROBERT S. MACON, Primary Examiner US. Cl. X.R. 200 -153

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