US3366750A

US3366750A - Switching mechanism for tapped regulating transformers

Info

Publication number: US3366750A
Application number: US396243A
Authority: US
Inventors: Bleibtreu Alexander
Original assignee: Maschinenfabrik Reinhausen Gebrueder Scheubeck GmbH and Co KG
Current assignee: Maschinenfabrik Reinhausen Gebrueder Scheubeck GmbH and Co KG
Priority date: 1963-09-18
Filing date: 1964-09-14
Publication date: 1968-01-30
Anticipated expiration: 1985-01-30
Also published as: FR1405009A; AT243936B; BE653248A; GB1051945A; DE1276191B; NL6410560A; NL123189C; CH413099A

Description

Jan. 30, 1968 A. BLEIBTREU 3,366,750

SWITCHING MECHANISM FOR TAPPED REGULATING TRANSFORMERS Filed Aug. 14, 1964 5 Sheets-Sheet 1 h a/r04 WW k W I W.

' Jan. 30, 1968 A. BLEIBTRE'U 3,366,750

SWITCHING MECHANISM FOR TAPPED REGULATING TRANSFORMERS Filed Aug. 14, 1964 v 5 Sheets-Sheet 2 INVEMOA A. BLEIBTREU Jan.- 30, 1968 5 Sheets-Sheet 3 Filed Aug. 14, 1964 2J 4/ 4 0 4/ 05 a J 1 .w a y I J I! I W I J J J 2/ J H A m. H M m 1 1 Ix w m M 6 1 M V V V I} A l, 4 4 M m A I H 7 i: #0, V .a I w im mm) mm, 6 II I! 1 (111 I A Ii F 4 7 A it n 3 H mw w, M w r m 1 1 1/4 W 3 M F w H. 1 H I z m" 6 I v I I I B a B B 9 w a i i J v mm U fi V W W W n/r01? mm Mbm x) MAM-x Jan. 30, 1968 A. BLEIBTREU SWITCHING MECHANISM FOR TAPPED REGULATING TRANSFORMERS 5 Sheets-Sheet 4 Filed Aug. 14. 1964 Jan. 30, 1968 A T EU I 3,356,750

SWITCHING MECHANISM FOR TAPPED REGULATING TRANSFORMERS Filed Aug. 14, 1964 1 5 Sheets-Sheet 5 Mm WM WW/m M WWW 2W United States Patent ABSTRACT OF THE DISCLOSURE Disclosed is a switching system for tapped high-voltage polyphase regulating transformers of great compactness including transfer switches and selector switches arranged in coaxial relation at predetermined levels, minimizing voltage gradients, insulation requirements, and lengths of current paths.

This invention is concerned with switching systems for tapped regulating transformers, or load tap changers, i.e. with the switching means required for performing tapchanging operations.

It is a general object of this invention to provide improved switching systems for load tap changers.

It is another object of this invention to provide improved switching systems for tapped polyphase transformers, in particular polyphase auto transformers, polyphase delta connected transformers and polyphase center tapped transformers.

Another object of this invention is to provide improved switching systems for tapped high voltage polyphase transformers combining a favorable spatial voltage distribution with great compactness and simple kinematic means for operating the movable contact means of the selector switch provided for selecting the desired transformer taps.

Another object of the invention is to combine the general arrangement of parts disclosed in the copending patent application of Alexander Bleibtreu et al. filed June 19, 1962, Ser. No. 204,029, Load Tap Changers for Transformers, now US. Patent 3,176,089, Mar. 30, 1965 (assigned to the same assignee as the present invention) with an improved selector switch structure and with an improved operating mechanism for the latter.

This invention is more particularly concerned with Jansen type load tap changers. Such load tap changers include ohmic resistors as current-limiting devices to limit the transient currents occurring during tap-changing operations and include fast operating transfer switches for switching or tap-changing operations to be performed under load or even under overload currents. In Jansen" type load tap changers the movable contacts of the transfer switches are generally operated by spring motors and move at high speeds, thus minimizing the times during which the current-limiting switch-over resistors or tapchanging resistors must carry currents. The rapid operation of the transfer switches makes it possible to minimize the size of the aforementioned resistors and to minimize voltage fluctuations resulting from tap changes.

It is another object of this invention to provide improved Jansen type load tap changers for high voltage polyphase transformers.

Summary of the invention Systems embodying this invention include a plurality of stacked transfer switches each including a pair of fixed main contacts, fixed intermediate or auxiliary contacts, and movable contact means sequentially engageable with said pair of fixed main contacts and with said intermediate fixed contacts. A pair of circular slip-ring-like terminals surrounds each of said plurality of transfer switches. Each of said pair of circular terminals is conductively connected to one of said pair of fixed main contacts of one of said plurality of transfer switches. Said pair of circular terminals of each of said plurality of transfer switches is arranged coaxially around a common axis.

Switching systems embodying this invention further include a plurality of switch-over resistor means each operatively related to one of said plurality of transfer switches to limit currents flowing during tap-changing operations thereof. Each of said plurality of resistor means has one end conductively connected to said fixed intermediate contacts of one of said plurality of transfer switches and an opposite end conductively connected to one of said pair of circular terminals of one of said plurality of transfer switches. Each of said plurality of switch-over resistor means is arranged at substantially the same level as one of said plurality of transfer switches.

Switching systems embodying this invention further include a plurality of stacked selector switches each arranged at substantially the same level as one of said plurality of transfer switches. Each of said plurality of selector switches includes a plurality of fixed selector switch contacts arranged in a circular pattern around the aforementioned common axis. Each of said plurality of selector switches further includes a pair of switching bridges hav ing radially outer ends cooperating with said plurality of selector switch contacts thereof and having radially inner ends cooperatively engaging said pair of slip-ring-like circular terminals of one of said plurality of transfer switches.

Switching systems embodying this invention further include a pair of operating rods extending parallel to the aforementioned common axis and angularly displaced degrees. Each of this pair of operating rods projects transversely across one of said pair of switching bridges of each of said plurality of said selector switches.

Switching systems embodying this invention further include means for alternately pivoting each of said pair of operating rods about said common axis in steps having a predetermined angle.

Brief description of drawings showing preferred embodiment of invention FIG. 1 is a diagrammatic representation of the constituent parts pertaining to one single phase of a switching mechanism embodying the present invention;

FIG. 2 is a diagrammatic representation of a tapped three phase auto transformer, this type of transformer being particularly suited to be associated with switching mechanisms embodying the present invention;

FIG. 3 is a diagrammatic representation of a delta connected tapped three phase transformer, this being another type of circuitry particularly suited to be associated with switching mechanisms embodying the present invention;

FIG. 4 is a vertical section of a polyphase switching mechanism embodying the present invention including the gear means for operating the same, the constituent transfer switches of the structure of FIG. 4 being shown in diagrammatic fashion and the constituent selector switches of the structure of FIG. 4 being shown in considerable detail;

FIG. 5 is a top plan view of the structure of FIG. 4 showing the same as it appears upon removal of a cover by which it is normally covered;

FIG. 6 is a vertical longitudinal or radial section of one of the switching bridges comprised in the structure of FIGS. 4 and 5, this section being taken along VI-VI of FIG. 7; and

FIG. 7 is a top plan view of the switching bridge of FIG. 6 and of parts operatively related to the same.

Referring now to the drawings, and more particularly to FIG. 1 thereof, reference character T has been applied to indicate the winding of phase U of a polyphase transformer. Transformer winding T is provided with ten taps designated K, 1, 2, 3 6, 7, 8, 9. Each transformer tap is conductively connected to a corresponding fixed contact 18 in a selector switch generally designated by the reference character 11. Selector switch 11 comprises ten fixed contacts K, 1', 2, 3' 6', 7', 8, 9' which are arranged in a common plane in circular pattern around a center.

Reference numeral 10 has been applied to generally indicate a transfer switch. Transfer switch 10 includes two fixed

circular terminals

14 and 15 arranged in concentric relation to the family of fixed contacts 18 of selector switch 11. Transfer switch 10 further includes a movable reciprocating contact 10d pivoted in the center of

circular terminals

14, 15 and cooperating with

fixed contacts

10a, 10b, 10c. Contacts 10a, 100 are fixed main contacts directly conductively connected to

circular terminals

15 and 14, respectively. Contacts 1012 are fixed intermediate contacts. Each of the two intermediate contacts 10b is conductively connected to one of the

circular terminals

14 and 15, respectively, by the intermediary of one of the two ohmic change-over or tap-changing resistors 12. The structure of FIG. 1 further comprises a pair of

switching bridges

26 and 27, respectively. Switching

bridges

26 and 27 are adapted by means which are described below more in detail to be pivoted about the center of

circular terminals

14 and 15. When pivoted about the above center the radially inner end of switching bridge 26 slides along circular terminal 14, while its radially outer end disengages from one of the fixed contacts 18 of selector switch 11 and engages another such contact. Switching bridge 27 performs in a similar fashion when pivoted about the center of

terminals

14 and 15, i.e. the radially inner end of switching bridge 27 slides along terminal 15, while its radially outer end disengages fixed contact 1' of selector switch 11 and may be moved into engagement with fixed contact 3' thereof.

In the position of the parts shown in FIG. 1 the following circuit is established: Tap 1 of winding T fixed contact 1' of selector switch 11, switching bridge 27, circular terminal 15, fixed contact 10a, movable contact 10d, and point A of the circuit indicated by an arrow. If it is intended to switch from tap 1 to tap 2 switching bridge 26 is pivoted in counter clockwise direction to cause disengagement of the radially outer end thereof from fixed contact K and engagement of the radially outer end thereof with fixed contact 2' of selector switch 11. Now everything is prepared for the intended tap-changing operation. The tap-changing operation proper is performed by pivoting movable contact 10d of transfer switch 10 in clockwise direction from fixed contact 1011 to fixed contact 10c. In the latter position tap 2 is directly connected to point A of the circuit by the following current path tap 2, switching bridge 26, circular terminal 14, fixed contact 10c, movable contact 10d. The latter contact has three intermediate positions when moving in clockwise direction as set forth above. In the first of the intermediate positions movable contact ltld has parted from fixed contact 10a and engages the left fixed contact 10b; thereafter movable contact 19d engages both fixed contacts 10b; and in the last intermediate position movable contact- 10d engages only the right fixed contact 10b without engaging fixed contact ltlc. It will be noted that in the two end positions of movable contact 10d the latter is in engagement with one of the fixed

main contacts

10a or 10c, respectively, and with one of the two fixed intermediary contacts 10b. In the end positions of movable contact 10d neither of the two switch-over resistors or tap changing resistors 12 is included in the circuit, these resistors being then shunted out by movable contact 10d.

When tap 2 is included in the circuit, switching bridge 27 is in its position shown in FIG. 1 and transfer switch 10 is in the limit position opposite to the limit position shown in FIG. 1. If it is now desired to include tap 3 into the circuit, switching bridge 27 is pivoted counter clockwise so that its radially outer end engages the fixed contact 3 of selector switch 11, and thereupon transfer switch 10 is pivoted counter clockwise back to the position shown in FIG. 1.

On the other hand, if it is desired to include tap K into the circuit, i.e. to establish the initial position shown in FIG. 1, switching bridge 26 is pivoted clockwise so that its radially outer end engages again the fixed contact K of selector switch 11, and thereupon transfer switch 10 is pivoted counter clockwise to the position shown in FIG. 1.

In FIGS. 2 and 3 each of the three tapped phase windings T is provided with ten taps of which the first is designated by the reference letter K and the last by the reference numeral 9. Taps 1 to 8 are arranged between tap K and tap 9 of each phase winding T, of the three phases U, V, W.

The switching mechanism of FIGS. 4 and 5 is intended to be operatively associated with three tapped transformer phase windings T as shown in FIGS. 2 and 3, each including ten taps K, 1, 2, 3 '7, 8, 9.

Referring now to FIGS. 4 and 5, the structure shown therein comprises three stacked transfer switches 10, each for switching one phase of a polyphase circuit. Each of the three transfer switches 10 comprises a pair of switchover resistors, or tap-changing resistors 12. Transfer switches 10 may be designed as explained more in detail in connection with FIG. 1. There are various prior art transfer switches which may be used in connection with the arrangement shown in FIGS. 4 and 5, but the most desirable design for the particular purpose in hand is that disclosed in the above referred-to US. patent to Alexander Bleibtreu et al., 3,176,089. Each of the three transfer switches 10 encompasses a region of equal potential and it is necessary, or desirable, to arrange the switchover resistors or tap changing resistors 12 pertaining to each transfer switch 10 at about the same level, and inside of the region of substantially equal potential, of each transfer switch 10. The above referred-to US). Patent 3,176,089 shows a very practical way of arranging the switch-over or tap changing resistors pertaining to a transfer switch at the same level as the other constituent elements of the respective transfer switch and of arranging these resistors in accordance with the voltage distribution prevailing along a stack of transfer switches. In addition thereto, the above application shows in greater detail the structural features of transfer switches intended to actually take the place of transfer switches 10 diagrammatically shown in FIG. 1. Each of the three transfer switches of FIG. 4 is a single-phase transfer switch and the movable contacts of the three transfer switches 10 are coupled for joint operation as, for instance, by means of a common pivotable reciprocating operating shaft (not shown) of insulating material, or at least in part of insulating material.

Reference numeral 11 has been applied in FIG. 4 to indicate three selector switches each for one phase of one of the tapped phase windings T of FIGS. 2. and 3. Each of the three selector switches 11 corresponds to the selector switch 11 of FIGS. 1. The lowest selector switch 11 of FIG. 4 is arranged at substantially the same level as the lowest transfer switch 10, and the highest selector switch 11 is arranged at substantially the same level as the highest transfer switch 10. The intermediate selector switch 11 is arranged atsubstantially the same level as the, intermediate transfer switch 10.

Thethree stacked transfer switches 10 are arranged inside of a cylindrical housing 13 of insulating material. Each transfer switch 10 is associated with a pair of circular terminals or contact rings 14, 15. The three pairs 1 of circular terminals or contact rings -14, 15 are supported by housing 13, each pair being arranged at the same level as one of the transfer switches 10. The stack of transfer switches and the stack of selector switches 11 is supported by a base plate 17. Three insulating bushings 16 project through base plate 17, each for connecting one of transfer switches 10 to an external point of a polyphase circuit.

The fixed contacts K, 1, 2, 3 '7, 8', 9' of each of the three selector switches 11 are supported by a system of vertical rods 18 of insulating material. These rods are arranged in a cylindrical surface coaxial to cylindrical housing 13. The lower ends of insualting rods 18 are secured to the aforementioned base plate 17, whereas their upper ends are secured to a horizontal cover plate 19 extending substantially parallel to base plate 17. Each insulating rod 18 supports three fixed contacts each forming part of one of selector switches 11. Thus the insulating rod 18 to the left of FIG. 4 supports three fixed contacts 2', one being conductively connected to tap 2 of a winding T, of phase U, one being conductively connected to tap 2 of a winding T of phase V and one being conductively connected to tap 2 of winding T,- of phase W. The right of FIG. 4 shows an insulating rod 18 supporting three fixed contacts 3, one being conductively connected to tap 3 of winding T of phase U, one to tap 3 of winding T of phase V and one to tap 3 of winding T of phase W. There is a total of ten vertical angularly spaced insulating rods each supporting three fixed contacts each connected to one of three corresponding taps bearing the same reference character of three different phase windings. Two operating rods or

shafts

20, 21 made wholly, or at least in part, of insulating material extend parallel to the axis of insualting housing 13 and are arranged in the space between housing 13 and the coaxial cylindrical surface defined by insulating rods 18. Shafts or operating

rods

20, 21 are angularly displaced 180 degrees and arranged in a common vertical plane with the vertical axis of housing 13 which is also the common axis of the

annular terminals

14, 15 of the three transfer switches 10. Base plate 17 and cover plate 19 define slots receiving the ends of insulating

shafts

20, 21. Shaft 20 supports on the upper end thereof a geneva gear 22 and shaft 21 supports at the upper end thereof ageneva gear 23. Shaft 20 further supports on the ends thereof a pair of pinions 24 and shaft 21 supports on the ends thereof a pair of pinion 25. Shaft 20 extends transversely across three switching bridges 26 each having a radially inner end slidably engaging one of the three circular terminals or rings 14, and each having a radially outer end cooperating With one of the even numbered fixed contacts K, 2', 4' 6, 8 of one of the three stacked selector switches '11. Shaft 21 supports three switching bridges 27 each having a radially inner end slidably engaging one of the three circular terminals or rings 15, and each having a radially outer end engaging one odd numbered fixed contact 1, 3 7', 9 of one of the three stacked selector switches 11. It will be noted that all of the even numbered fixed contacts and contact K, of each selector switch 11 are arranged in a common plane, and the same applies in regard to the odd numbered contacts thereof. It will also be noted that each pair of switching

bridges

26, 27 is arranged at substantially the same level as, and operatively related to, one of the stacked transfer switches 10. As mentioned above, and as will be more fully apparent from what follows, the radially outer ends of switching bridges 26 cooperate with the even numbered fixed contacts K, 2, 4, 6 and 8 of selector switches 11 and switching bridges 27 cooperate with the odd numbered

fixed contacts

1', 3, 5', 7' and 9 of selector switches 11.

Rotatable main driving gear28 is arranged below cover plate 19 in coaxial relation to terminal rings 14, 15 and provided with a radially outwardly projecting arm 29 supporting a vertical stud or pin-3t for operating geneva gears 22 and 23. Geneva gear 22 is mounted on insulating shaft 20 and provided with four radialslots 31 which are angularly displaced 90 degrees. In like fashion geneva 6 gear 23 is mounted on insulating shaft 21 and provided with four radial slots 32 which are angularly displaced degrees. As gear 28 rotates about the axis of housing 13 operating rod or stud 30 engages alternately one of slots 31 in gear 22 and one of slots 32 in gear 23.

Gear 28 is in meshing engagement with a pinion 33 mounted on shaft 34 supporting worm gear 35 arranged in the head portion 36 of the switching device. Worm gear 35 is in meshing engagement with worm 37 operated by an electric motor drive (not shown). The latter is used to load a spring motor (not shown) for jointly operating with a snap action the three transfer switches 10.

The head portion 36 of the switching device is mounted on the cover 38 of the tank of a polyphase transformer. In other words, the switching device projects into the tank of the transformer which comprises a plurality of tapped phasing windings T, (FIGS. 2 and 3) whose taps are intended to be changed in accordance with varying operating conditions.

Reference numeral 39 has been applied to indicate a pair of gears coaxial to main gear 28, of which one is supported by base plate 17 and the other by cover plate 19. Lower gear 39 is in meshing engagement with

pinions

24, 25 at the lower ends of

shafts

20 and 21, and upper gear 39 is in meshing engagement with the

pinions

24, 25 at the upper ends of

shafts

20 and 21.

Referring now to FIGS. 6 and 7 showing a preferred embodiment of the switching bridges and more particularly of switching bridge 26, it will be apparent that the latter comprises a pair of complementary shells, namely an upper shell 49 and a lower shell 41. The left sides of FIGS. 6 and 7 show one of the insulating rods 18 and one of the fixed contacts 2 of the above switches 11. The shells 4t), 41 engage under pressure the upper and lower rounded side of contact 2. In the same fashion as they engage contacts 2 the shells 40, 41 forming part of contact bridges 26 may engage any of the even numbered fixed contact K, 2, 4, 6' and 8' of each selector switch 11. The shells forming contact bridges 27 are similarly adapted to engage any of the odd numbered

fixed contacts

1, 3, 5, 7 and 9" of each selector switch 11. The radially inner ends of switching bridges 26 engage cooperatively and slide upon circular terminals 14. In the same fashion the radially inner ends of switching bridges 27 engage cooperatively and slide upon circular terminals 15. The constituent metal shells 40, 41 of switching

bridges

26, 27 are held in alignment by vertical rods 42 and spring-biased toward each other and into engagement with their radially outer cooperating fixed contacts and with the radially inner cooperating circular

transfer switch terminals

14, 15. Circular terminals or

terminal contacts

14, 15 are made up of two parts defining an annular recess therebetween. As shown in FIGS. 6 and 7 annular recess 46 receives a ring-shaped plate 45 of insulating material slidably fitted into recess 46, and thus capable of being pivoted, or rotated, about the common axis of housing 13 and of the cylindrical cage formed of insulating rods 18. Ring shaped plate 45 is provided with an integral radially outwardly extending tab-like projection 44 sandwiched between the two shells 40 and 41. Projection 44 is provided with transverse bores for the passage of rods 42 and with transverse bores for the passage of a pair of helical springs 43 Springs 43 bias shells 40, 41 toward each other and into firm engagement with their cooperating contacts at the radially outer ends thereof and into firm engagement with terminals 14 at the radially inner ends thereof. Shells 40, 41 define openings 47 about midway between the ends thereof and insulating shaft 20 projects loosely through openings 47 and is supported in a roller bearing 48 integral with tab-like projection 44 of ring shaped plate 45.

The structure of switching bridges 27 is substantially identical to that of switching bridges 26, except that insulating shaft 21 projects transversely through the former and that the radially inner ends of the former engage circular terminals 15 rather than circular terminals 14.

The operation of the structure of FIGS. 4-7 is as follows.

Operation of

gear drive

37, 35, 34 and 33 causes rotation of main gear 28. Rod 30 on arm 29 of main gear 28 engages and operates one of the geneva gears 22, 23 following each half revolution of main gear 28. Each engagement of rod 30 with one of geneva gears 22, 23 results in a rotation of the latter of 90 degrees. As a re sult of the aforementioned rotation of geneva gears 22, 23,

shafts

20, 21 are sequentially rotated in steps of 90 degrees, i.e.

shafts

20, 21 are alternately rotated in steps of 90 degrees. Rotation of

shafts

20, 21 results in rotation of

pinions

24, 25 meshing with

gears

39, 39. Consequently

shafts

20, 21 are pivoted in steps encompassing equal predetermined angles about the central axis of the composite selector and transfer switch stack. As a result of the pivotal movement of shaft 20, switching bridges 26 engage sequentially the even numbered fixed selector switch contacts K, 2', 4', 6' and 8' of selector switches 11, and as a result of the pivotal movements of shaft 21 switching bridges 27 engage sequentially the odd numbered fixed

selector switch contacts

1', 3', 7 and 9 of selector switches 11. During the aforementioned pivotal motions of shafts 2t), 21 and contact bridges 26, 27 the radially inner ends of the latter remain in engagement with

annular terminals

14, 15 of transfer switches 10. The latter perform all the required load and overload current switching operations. The selector switches 11 do not open current-carrying circuits and do not close such circuits.

It will be apparent from the foregoing that a phase unit in a switching system embodying this invention includes a housing 13 of insulating material which is cylindrical or circular in cross-section (see FIG. 7). A pair of slip-ring-like

fixed contacts

14, 15 is arranged on the outside of housing 13 in parallel planes and coaxial relation to housing 13. A transfer switch and switch-over resistor means 12 are arranged inside housing 13. The transfer switch 10 includes a pair of fixed

main contacts

10a, 10c and fixed auxiliary contacts 1%, 10b arranged in a circular pattern (FIG. 1). Each of said pair of fixed

main contacts

10, 10c is conductively connected with one of said pair of slip-ring-like fixed contacts and fixed auxiiiary contacts 10b, 1012 are arranged between said pair of fixed main contacts 10a, 1017. Each of said switch-over resistor means 12, 12 has one end conductively connected to one of said fixed auxiliary contacts 1%, 10b and an end opposite to said one end conductively connected to one of the slip-ring-like

fixed contacts

14, 15. Transfer switch 10 further includes movable contact means 10d cooperating in a predetermined sequence with said pair of fixed

main contacts

10a, 10c and said fixed auxiliary contacts 10b, 1%.

A phase unit in a switching system embodying this invention includes further a selector switch 11 arranged at substantially the same level as said transfer switch 10. Selector switch 11 includes a first group of circularly arranged spaced fixed contacts 1', 3, 5' positioned at substantially the same level as one of said pair of slipring-like fixed contacts 14, and said selector switch further includes a second group of circularly arranged spaced fixed contacts K, 2', 4' positioned at substantially the same level as the other of said pair of slipring-like

fixed contacts

14, 15. Selector switch 11 further includes a pair of radially extending

contact bridges

26, 27 angularly displaced 180 degrees relative to each other pivotable about the axis of housing 13. Each of said pair of contact bridges 26, 27 has a radially inner end engag ing one of said pair of slip-ring-like

fixed contacts

14, 15. One of said pair of contact bridges 14, 15 has a radially outer end selectively engaging said fixed contacts 1, 3', 5' of said first group of contacts and the other of said pair of contact bridges 14, 15 has a radially outer end selectively engaging said fixed contacts K, 2, 4' of said second group of contacts.

The operating means for selector switch 11 include a

gear mechanism

37, 35, 34, 33, 28, 30, 22, 32, arranged above said first group 1, 3', 5' of fixed contacts and above said second group 2, 4', 6' of fixed contacts of said selector switch. Said operating means further include a pair of operating

rods

20, 21 arranged parallel to the axis of housing 13 and angularly displaced degrees relative to each other. Each of the pair of

rods

20, 21 has an upper end driven by

gear mechanism

37, 35, 34, 33, 28, 3t), 22, 32 around housing 13 and each of the pair of

rods

20, 21 has a lower portion operatively connected to one of contact bridges 26, 27.

Having disclosed a preferred embodiment of the invention, it is desired that the same be not limited to the particular structure disclosed. It will be obvious to any person skilled in the art that many modifications and changes may be made without departing from the broad spirit and scope of this invention. Therefore it is desired that the invention be interpreted as broadly as possible and it be limited only as required by the prior state of the art.

I claim as my invention:

1. A switching system for tapped regulating transform- 5 ers comprising in combination:

(a) a plurality of stacked transfer switches each including a pair of fixed main contacts, fixed intermediate contacts and movable contact means sequentially engageable with said pair of fixed main contacts and with said intermediate fixed contacts, a pair of circular slip-ring-like terminals surrounding each of said plurality of transfer switches, each of said pair of circular terminals being conductively connected to one of said pair of fixed main contacts of one of said plurality of transfer switches, said pair of circular terminals of each of said plurality of transfer switches being arranged coaxially around a common axis;

(b) a plurality of switch-over resistor means each operatively related to one of said plurality of transfer switches to limit currents flowing during tap-changing operations thereof, each of said plurality of resistor means having one end conductively connected to said fixed intermediate contacts of one of said plurality of transfer switches, each of said plurality of resistor means having another end conductively connected to one of said pair of circular terminals of one of said plurality of transfer switches, and each of said plurality of resistors means being arranged at substantially the same level as one of said plurality of transfer switches; and

(c) a plurality of stacked selector switches each arranged at substantially the same level as one of said plurality of transfer switches, each of said plurality of selector switches including a plurality of fixed selector switch contacts arranged in a circular pattern around said common axis, each of said plurality of selector switches further including a pair of switching bridges having radially outer ends cooperating with said plurality of selector switch contacts thereof and having radially inner ends cooperatively engaging said pair of circular terminals of one of said plurality of transfer switches, a pair of operating rods extending parallel to said common axis angularly displaced 180 degrees and each projecting transversely across one of said pair of switching bridges of each of said plurality of selector switches, and means for alternately pivoting each of said pair of operating rods about said common axis in steps having a predetermined angle.

2. A switching system for tapped regulating transformers comprising in combination:

(a) a plurality of stacked transfer switches each including a pair of fixed main contacts, fixed intermediate contacts and movable contact means sequentially movable into engagement with one of said pair of fixed main contacts, into engagement with said intermediate fixed contacts, and into engagement with the other of said pair of fixed main contacts, a pair of circular terminals surrounding each of said plurality of transfer switches, each of said pair of circular terminals being conductively connected to one of said pair of fixed main contacts of one of said plurality of transfer switches, said pair of circular terminals of each of said plurality of transfer switches being arranged coaxially around a common axis;

(b) a plurality of stacked selector switches each arranged at substantially the same level as one of said plurality of transfer switches, each of said plurality of selector switches including a plurality of fixed selector switch contacts arranged in a circular pattern around said common axis, each of said plurality of selector switches further including a pair of switching bridges having radially inner ends cooperatively engaging said pair of circular terminals of one of said plurality of transfer switches;

(c) a plurality of switch-over resistor means each operatively connected to said fixed intermediate contacts of one of said plurality of transfer switches to limit currents flowing during tap-changing operations thereof, each of said switch-over resistor means being arranged at substantially the same level as one of said plurality of transfer switches, and

(d) a pair of shafts extending parallel to said common axis angularly displaced 180 degrees and each projecting transversely across one of said pair of switching bridges of each of said plurality of selector switches, and means for alternately pivoting each of said pair of shafts a predetermined angle about said common axis, said pivoting means including a pair of geneva gears each mounted on one of said pair of shafts, a main gear rotatable about said common axis for operating said pair of geneva gears, a pair of pinions each mounted on one of said pair of shafts, and fixed gear means arranged coaxially to said main gear and meshing with said pair of pinions.

3. A switching system as specified in claim 2 wherein:

(a) each of said pair of circular terminals of each of said plurality of transfer switches defines an annular groove;

(b) each of said plurality of selector switches includes a pair of rings of insulating material each slidably fitted into said annular groove in one ofsaid pair of circular terminals of one of said plurality of transfer switches;

(c) a radial tab-like projection is integral with each of said pair of rings of each of said plurality of selector switches; and

(d) a bearing is provided in said tab-like projection of each of said pair of rings of each of said plurality of selector switches for supporting one of said pair of shafts.

4. A switching system as specified in claim 2 wherein:

(a) each of said pair of switching bridges of each of said plurality of selector switches includes a pair of outer shells bounding an internal space;

(b) spring means inside said internal space biasing said pair of shells toward each other;

(c) a plurality of plate means is guided to turn about said common axis each having a tab-like projection arranged inside said internal space bounded by said pair of shells of each of said pair of switching bridges of each of said plurality of selector switches; and

(d) a bearing in said tab-like projection of each of said plurality of plate means supports one of said pair of shafts.

5. A switching system for tapped regulating transformers comprising in combination:

(a) a plurality of stacked transfer switches each including a pair of fixed main contacts, fixed intermediate contacts and movable contact means sequentially movable from initial engagement with one of said pair of fixed main contacts into engagement with said intermediate fixed contacts and into engagement with the other of said pair of fixed main contacts, a pair of circular terminals surrounding each of said plurality of transfer switches, each of said pair of circular terminals being conductively connected to one of said pair of fixed main contacts of one of said plurality of transfer switches, said pair of circular terminals of each of said plurality of transfer switches being arranged coaxially around a common axis;

(b) a plurality of switch-over resistor means each operatively connected to said fixed intermediate contacts of one of said plurality of transfer switches to limit currents flowing during tap-changing operations thereof, each of said switch-over resistor means being arranged at substantially the same level as one of said plurality of transfer switches; and

(c) a plurality of stacked selector switches each arranged at substantially the same level as one of said plurality of transfer switches, each of said plurality of selector switches including a plurality of fixed selector switch contacts arranged in a circular pattern around said common axis, each of said plurality of selector switches further including a pair of switching bridges having radially outer ends cooperating with said plurality of selector switch contacts thereof and having radially inner ends cooperatively engaging said pair of circular terminals of one of said plurality of transfer switches, a pair of shafts of insulating material parallel to said common axis angularly displaced degrees each projecting transversely across one of said pair of switching bridges of each of said plurality of selector switches, a plurality of arms of insulating material pivotable about said common axis for guiding each of said pair of shafts around said common axis in parallel relation thereto, and gear means for operating said pair of shafts including a main gear rotatable about said common axis, a pair of geneva gears each mounted on one of said pair of shafts and each operated by said main gear, two pairs of pinions each mounted on one of said pair of shafts adjacent the ends thereof, and a pair of spaced fixed gears arranged coaxially to said main gear each in meshing engagement with one of said two pairs of pinions.

6. A switching system for tapped regulating transformers comprising in combination.

(a) a plurality of stacked transfer switches each including a pair of fixed main contacts, fixed intermediate contacts and movable contact means sequentially movable from initial engagement with one of said pair of fixed main contacts into engagement with said intermediate fixed contacts and into engagement with the other of said pair of fixed main contacts, a pair of circular terminals surrounding each of said plurality of transfer switches, each of said pair of circular terminals being conductively connected to one of said pair of fixed main contacts of one of said plurality of transfer switches, said pair of circular terminals of each of said plurality of transfer switches being arranged coaxially around a common axis and said pair of circular terminals of each of said plurality of transfer switches each defining a pair of grooves arranged coaxially around said common axis;

(b) a plurality of switch-over resistor means each operatively connected to said fixed intermediate contacts of one of said plurality of transfer switches to limit the currents flowing during tap-changing operations thereof, each of said switch-over resistor means being arranged at substantially the same level as one of said plurality of transfer switches; and

(c) a plurality of stacked selector switches each arranged at substantially the same level as one of said plurality of transfer switches, each of said plurality of selector switches including a plurality of fixed selector switch contacts arranged in a circular pattern around said common axis, each of said plurality of selector switches further including a pair of insulating rings each having a tab-like radial extension and each having a radially inner edge guided in one of said pair of grooves in one of said pair of circular terminals of one of said plurality of transfer switches, each of said plurality of selector switches further including a pair of switching bridges having radially outer ends cooperating with said plurality of selector switch contacts thereof and having radially inner ends each cooperatively engaging one of said pair of circular terminals of one of said plurality of transfer switches, a pair of shafts extending parallel to said common axis angularly displaced 180 degrees and each projecting transversely across said tab-like projection of one of said pair of insulating rings of each of said plurality of selector switches and extending transversely across one of said pair of switching bridges of each of said plurality of selector switches, and gear means for operating said pair of shafts, said gear means including a main gear rotatable about said common axis, a pair of geneva gears each mounted on one of said pair of shafts and each operated by said main gear, a pair of pinions each mounted on one of said pair of shafts, and fixed gear means arranged coaxially to said main gear in meshing engagement with said pair of pinions.

7. A switching system for tapped regulating transformers comprising in combination:

(a) a plurality of stacked transfer switches each in cluding a pair of fixed main contacts, fixed intermediate contacts and movable contact means sequentially movable from initial engagement with one of said pair of fixed main contacts into engagement with said intermediate fixed contacts and into engagement with the other of said pair of fixed main contacts, a pair of circular terminals surrounding each of said plurality of transfer switches, each of said pair of circular terminals of each of said plurality of transfer switches being conductively connected to one of said pair of fixed main contacts of one of said plurality of transfer switches, said pair of circular terminals of each of said plurality of transfer switches being arranged coaxially around a common axis and each of said pair of circular terminals of each of said plurality of transfer switches defining an annular groove;

(b) a plurality of switch-over resistor means each operatively connected to said fixed intermediate contacts of one of said plurality of transfer switches to limit the currents flowing during tab-changing operations thereof, each of said switch-over resistor means being arranged at substantially the same level as one of said plurality of transfer switches; and

(c) a plurality of selector switches each arranged at substantially the same level as one of said plurality of transfer switches, each of said plurality of selector switches including a plurality of fixed selector switch contacts arranged in a common plane in a circular pattern around said common axis, each of said plurality of selector switches further including a pair of switching bridges having ends adapted to cooperatively engage said fixed selector switch contacts of one of said plurality of selector switches and to cooperatively engage said pair of circular terminals of one of said plurality of transfer switches, each of said pair of switching bridges including a pair of complementary shells bounding an internal space and spring means inside said space biasing said pair of shells toward each other, a plurality of pairs of substantially annular plates of insulating material each engaging with a radially inner edge thereof said annular groove in one of said pair of circular terminals of one of said plurality of transfer switches and each having a tab-like projection extending into said internal space bounded by said pair of complementary shells of each of said pair of switching bridges of each of said plurality of selector switches, a pair of insulating shafts each extending parallel to said common axis arranged in a common plane with said common axis and extending transversely across one of said pair of switching bridges of each of said plurality of selector switches, a bearing in said tab-like projection of each of said substantially annular plates situated inside of one of said pair of complementary shells for rotatably supporting one of said pair of insulating shafts, a pair of geneva gears each fixedly mounted on one of said pair of insulating shafts, a main gear rotatable about said common axis and including pin means alternately engaging one of said pair of geneva gears to alternately pivot one of said pair of insulating shafts, two pairs of pinions, each of said two pairs being mounted on one of said pair of insulating shafts adjacent the ends thereof and a pair of fixed gears arranged in parallel planes having a spacing substantially equal to the length of said pair of insulating shafts, said pair of fixed gears being arranged coaxially to said main gear and each of said pair of fixed gears being in meshing engagement with one of said pair of pinions on one of said pair of insulating shafts.

8. A switching system for tapped regulating transformers comprising in combination:

(a) a plurality of stacked transfer switches each including a pair of fixed main contacts, fixed intermediate contacts and movable contact means sequentially movable from initial engagement with one of said pair of fixed main contacts into engagement with said intermediate fixed contacts and into engagement with the other of said pair of fixed main contacts, a pair of circular terminals surrounding each of said plurality of transfer switches, each of said pair of circular terminals of each of said plurality of transfer switches being conductively connected to one of said pair of fixed main contacts of one of said plurality of transfer switches, said pair of circular terminals of each of said plurality of transfer switches being arranged coaxially around a common axis;

(c) a plurality of selector switches each arranged at substantially the same level as one of said plurality of transfer switches, each of said plurality of selector switches including a plurality of fixed selector switch contacts arranged in a circular pattern around said common axis, a substantially cylindrical cage formed of spaced insulating rods and arranged in coaxial relation to said pair of circular terminals of said plurality of transfer switches supporting said fixed se 7 lector switch contacts of said plurality of selector switches, each of said plurality of selector switches further including a pair of switching bridges, a pair of shafts for operating said pair of switching bridges of each of said plurality of selector switches, said pair of shafts extending parallel to said common axis and being arranged in a common plane with said common axis and each of said pair of shafts projecting transversely across one of said pair of switching bridges of each of said plurality of selector switches, a pair of geneva gears each fixedly mounted on one of said pair of shafts, a main gear rotatable about said common axis and including pin means for alternately operating each of said pair of geneva gears, a pair of pinions each mounted on one of said pair of shafts and a fixed gear coaxial to said main gear and in meshing engagement with said pair of pinions. 9. A tapped polyphase regulating transformer comprising in combination:

(b) a plurality of switch-over resistor means each operatively connected to said fixed intermediate contacts of one of said plurality of transfer switches to limit the currents flowing during tap-changing operations thereof, each of said switch-over resistor means being arranged at substantially the same level as one of said plurality of transfer switches;

(c) a plurality of tapped transformer windings, each of said plurality of tapped transformer windings including a plurality of even numbered taps and a plu rality of odd numbered taps arranged between even numbered taps; and

(d) a plurality of selector switches each arranged at substantially the same level as one of said plurality of transfer switches, each of said plurality of selector switches including a plurality of even numbered fixed selector switch contacts and a plurality of odd numbered fixed selector switch contacts arranged between even numbered selector switch contacts, said plurality of even numbered selector switch conacts of each of said plurality of selector switches being arranged in a first common plane, said plurality of odd numbered contacts of each of said plurality of selector switches being arranged in a second common plane, each of said plurality of even numbered taps of each of said plurality of windings being conductively connected to one of said even numbered fixed selector switch contacts of one of said plurality of selector switches, and each of said plurality of odd numbered taps of each of said plurality of windings being conductively connected to one of said odd numbered fixed selector switch contacts of one of said plurality of selector switches, each of said plurality of selector switches further including a pair of switching bridges having radially outer ends cooperating with said plurality of selector switch contacts thereof and having radially inner ends slidably engaging said pair of circular terminals of one of said plurality of transfer switches, a pair of shafts at least in part of insulating material extending parallel to said comm-on axis and arranged in a common plane with said common axis each projecting transversely across one of said pair of switching bridges of each of said plurality of selector switches, a pair of geneva gears each mounted on one of said pair of shafts, a main gear rotatable about said common axis operating said pair of geneva gears, a pair of pinions each mounted on one of said pair of shafts, and fixed gear means arranged coaxially 14 to said main gear and meshing with said pair of pinions. 10. A tapped polyphase regulating transformer comprising in combination:

(b) a plurality of switch-over resistor means each conductively connected to said fixed intermediate contacts of one of said plurality of transfer switches to limit the currents flowing during movement of said reciprocating contact means of each of said plurality of transfer switches, each of said switch-over resistor means arranged at substantially the same level as one of said plurality of transfer switches;

(c) a plurality of tapped transformer windings, each of said plurality of windings including a plurality of even numbered taps and a plurality of odd numbered taps arranged between even numbered taps; and

(d) a plurality of selector switches each arranged at substantially the same level as one of said plurality of transfer switches, each of said plurality of selector switches including a plurality of even numbered fixed selector switch contacts and a plurality of odd numbered selector switch contacts arranged between even numbered selector switch contacts, each of said plurality of even numbered selector switch contacts of each of said plurality of selector switches being conductively connected to one of said plurality of even numbered taps of said plurality of windings, and each of said plurality of odd numbered selector switch contacts of each of said plurality of selector switches being conductively connected to one of said plurality of odd numbered taps of one of said plurality of windings, said selector switch contacts of each of said plurality of selector switches being arranged in a circular pattern around said common axis, each of said plurality of selector switches further including a pair of switching bridges, a pair of shafts for operating said pair of switching bridges of each of said plurality of selector switches, said pair of shafts extending parallel to said common axis and being arranged in a common vertical plane with said common axis and each of said pair of shafts projecting transversely across one of said pair of switching bridges of each of said plurality of selector switches, gear means including a pair of geneva gears for alternately pivoting each of said pair of shafts about said common axis, pinion means on each of said pair of shafts, and a fixed gear coaxial to said common axis and in meshing engagement with said pinion means.

11. A tapped regulating transformer comprising in combination:

(a) a plurality of stacked transfer switches each including a pair of fixed main contacts, fixed intermediate contacts and movable contact means sequentially movable from initial engagement with one of said pair of fixed main cont-acts into engagement 7 with said intermediate fixed contacts and into engagement with the other of said pair of fixed main 15 Y contacts, a pair of circular terminals surroundin each of said plurality of transfer switches, each of said pair of circular terminals of each of said plurality of transfer switches being conductively connected to one of said pair of fixed main contacts of one of said plurality of transfer switches, said pair of circular terminals of each of said plurality of transfer switches being arranged coaxially around a common axis;

(b) a plurality of switch-over resistor means each conductively connected to said fixed intermediate contacts of one of said plurality of transfer switches to limit the currents flowing during movement of said movable contact means of each of said plurality of transfer switches, each of said switch-over resistor means being arranged at substantially the same level as one of said plurality of transfer switches;

(c) a plurality of tapped transformer windings each including a plurality of even numbered taps and a plurality of odd numbered taps arranged between even numbered taps; and

(d) a plurality of selector switches each arranged at substantially the same level as one of said plurality of transfer switches, each of said plurality of selector switches including a plurality of even numbered fixed selector switch contacts and a plurality of odd numbered selector switch contacts arranged between even numbered selector switch contacts, each of said plurality of even numbered selector switch contacts of each of said plurality of selector switches being conductively connected to one of said plurality of even numbered taps of one of said plurality of windings and each of said plurality of odd numbered selector switch contacts of each of said plurality of selector switches being conductively connected to one of said plurality of odd numbered taps of one of said plurality of windings, said selector switch contacts of each of said plurality of selector switches being arranged in a circular pattern around said common axis, each of said plurality of selector switches further including a pair of switching bridges having ends adapted to cooperatively engage fixed selector switch contacts of one of said plurality of selector switches and to cooperatively engage one of said pair of circular terminals of one of said plurality of transfer switches, a pair of shafts each extending parallel to said common axis and being arranged in a common plane with said common axis each extending transversely across one of said pair of switching bridges of each of said plurality of selector switches, a pair of geneva gears each fixedly mounted on one of said pair of shafts, a main gear rotatable about said common axis and including pin means alternately engaging one of said pair of geneva gears to alternately pivot one of said pair of shafts about the own axis thereof, pinion means on each of said pair of shafts, and a fixed gear arranged in coaxial relation to said main gear and in meshing engagement with said pinion means.

12. A tapped polyphase regulating transformer comprising in combination:

(a) a plurality of stacked transfer switches each including a pair of fixed main contacts, fixed intermediate contacts and movable contact means sequentially movable from initial engagement with one of said pair of fixed main contacts into engagement with said intermediate fixed contacts and into engagement with the other of said pair of fixed main contacts, a pair of circular terminals surrounding each of said plurality of transfer switches, each of said pair of circular terminals of each of said plurality of transfer switches being conductively connected to one of said pair of fixed main contacts of one of said plurality of transfer switches, said pair of circular terminals 1% of each of said plurality of transfer switches being arranged coaxially around a common axis;

(c) a plurality of tapped transformer windings each including a plurality of even numbered taps and a plurality of odd numbered taps arranged between even numbered taps;

(d) a plurality of selector switches each arranged at substantially the same level as one of said plurality of transfer switches, each of said plurality of selector switches including a plurality of even numbered fixed selector switch contacts and a plurality of odd numbered selector switch contacts arranged between even numbered selector switch contacts, each of said plurality of even numbered selector switch contacts of each of said plurality of selector switches being conductively connected to one of said plurality of even numbered taps of one of said plurality of windings, and each of said plurality of odd numbered selector switch contacts of each of said plurality of selector switches being conductively connected to one of said plurality of odd numbered taps of one of said plurality of windings, said selector switch contacts of each of said plurality of selector switches being arranged in a circular pattern around said common axis, each of said plurality of selector switches further including a pair of switching bridges having ends adapted to cooperatively engage fixed selector switch contacts of one of said plurality of selector switches and to cooperatively engage one of said pair of circular terminals of one of said plurality of transfer switches, a pair of shafts of insulating material each .being arranged in a common plane with said common axis and extending parallel to said common axis and transversely across one of said pair of switching bridges of each of said plurality of selector switches, a pair of geneva gears each fixedly mounted on one of said pair of shafts, a main gear rotatable about said common axis and including pin means alternately engaging one of said pair of geneva gears to alternately pivot said pair of shafts, two pairs of pinions, each of said two pairs of pinions being fixedly mounted on one of said pair of shafts adjacent the ends thereof, and a pair of spaced fixed gears arranged in coaxial relation to said main gear, each of said pair of fixed gears being in meshing engagement with one of said pair of pinions on one of said pair of shafts.

13. A tapped polyphase regulating transformer comprising in combination:

(a) a plurality of stacked transfer switches each including a pair of fixed main contacts, fixed intermediate contacts and movable contact means sequentially movable from initial engagement with one of said pair of fixed main contacts into engagement with said intermediate fixed contacts and into engagement with the other of said pair of fixed main contacts, a pair of circular terminals surrounding each of said plurality of transfer switches, each of said pair of circular terminals of each of said plurality of transfer switches being conductively connected to one of said pair of fixed main contacts of one of said plurality of transfer switches, said pair of circular terminals of each of said plurality of transfer switches being arranged coaxially around a common axis, and each of said pair of circular terminals of each of said plurality of transfer switches defining an annular groove;

(d) a plurality of selector switches each arranged at substantially the same level as one of said plurality of transfer switches, each of said plurality of selector switches including a plurality of even numbered fixed selector switch contacts and a plurality of odd numbered fixed selector switch contacts arranged between even numbered selector switch contacts, each of said plurality of even numbered selector switch contacts of each of said plurality of selector switches being conductively connected to one of said plurality of even numbered taps of one of said plurality of windings, and each of said plurality of odd numbered selector switch contacts of each of said plurality of selector switches being conductively connected to one of said odd numbered taps of one of said plurality of windings, said selector switch contacts of each of said plurality of selector switches being arranged in a circular pattern around said common axis, each of said plurality of selector switches further including a pair of switching bridges having ends adapted to cooperatively engage fixed selector switch contacts of one of said plurality of selector switches and to cooperatively engage said pair of circular terminals of one of said plurality of transfer switches, each of said pair of switching bridges including a pair of complementary shells bounding an internal space and spring means inside of said internal space biasing said pair of shells toward each other, a plurality of pairs of substantially annular plates of insulating material each engaging with an axially inner edge thereof said annular groove in one of said pair of circular terminals of one of said plurality of transfer switches, each of said plurality of pairs of annular plates having a pair of tap-like projections extending into said internal space bounded by said pair of complementary shells of one of said pair of switching bridges of each of said plurality of selector switches, a pair of insulating shafts arranged in a common plane with said common axis extending parallel to said common laxis each transversely across one of said pair of switching bridges of each of said plurality of selector switches, a pair of bearings in each of said pair of tap-like projections of said plurality of pairs of annular plates, each of said pair of bearings supporting one of said pair of shafts, a pair of geneva gears each fixedly mounted on one of said pair of shafts, a main gear rotatable about said common axis and including pin means alternately engaging one of said pair of geneva gears to alternately pivot one of said pair of shafts about their own axis thereof, two pairs of pinions, each of said two pairs of pinions being mounted on one of said pair of shafts adjacent the ends thereof, and a pair of fixed gears arranged in coaxial relation to said main gear in parallel planes having a spacing substantially equal to the length of said pair of shafts, each of said pair of gears being in meshing engagement with one of said pair of pinions on one of said pair of shafts.

14. A tapped polyphase regulating transformer comprising in combination:

(a) a plurality of stacked transfer switches each including a pair of fixed main contacts, fixed intermediate contacts and movable contact means sequentially movable from engagement with one of said pair of fixed main contacts into engagement with said intermediate fixed contacts and into engagement with the other of said pair of fixed main contacts, a pair of circular terminals surrounding each of said plurality of transfer switches, each of said pair of circular terminals of each of said plurality of transfer switches being conductively connected to one of said pair of fixed main contacts of one of said plurality of transfer switches, said pair of circular terminals of each of said plurality of transfer switches being arranged coaxially around a common axis;

(d) a plurality of selector switches each arranged at substantially the same level as one of said plurality of transfer switches, each of said plurality of selector switches including a plurality of even numbered fixed selector switch contacts and a plurality of odd numbered selector switch contacts arranged between even numbered selector switch contacts, each of said plurality of even numbered selector switch contacts of each of said plurality of selector switches being conductively connected to one of said plurality of even numbered taps of one of said plurality of windings, and each of said plurality of odd numbered selector switch contacts of each of said plurality of selector switches being conductively connected to one of said plurality of odd numbered taps of one of said plurality of windings, a substantially cylindrical cage formed of spaced insulating rods arranged in coaxial relation to said pair of circular terminals of said plurality of transfer switches supporting said fixed selector switch contacts of said plurality of selector switches, each of said plurality of selector switches further including a pair of switching bridges, a pair of shafts at least in part of insulating material for operating said pair of switching bridges, said pair of shafts being arranged with said common axis in a common plane and extending parallel to said common axis and each of said pair of shafts projecting transversely across one of said pair of switching bridges of each of said plurality of selector switches, gear means including a pair of geneva gears for alternately pivoting each of said pair of shafts a predeter- :mined angle around said common axis in response to operation of said pair of geneva gears, pinion means mounted on each of said pair of shafts, and fixed gear means arranged in coaxial relation to said common axis in mashing engagement with said pin- 1011 means.

15. A switching mechanism for tapped regulating transformers comprising in combination:

(a) a housing of insulating material circular in crosssection;

(b) a pair of slip-ring-like fixed contacts arranged outside said housing in parallel planes and in coaxial relation to said housing;

(c) a transfer switch and switch-over resistor means arranged inside said housing, said transfer switch including a pair of fixed main contacts and fixed auxiliary contacts arranged in a'circular pattern, each of said pair of fixed main contacts being conductively connected with one of said pair of slipring-like fixed contacts and said fixed auxiliary contacts being arranged between said pair of fixed main contacts, each of said switch-over resistor means having one end conductively connected to one of said fixed auxiliary contacts and an end opposite to said one end conductively connected to one of said slipring-like fixed contacts, and said transfer switch further including movable contact means cooperating in a predetermined sequence with said pair of fixed main contacts and said fixed auxiliary contacts;

(d) a selector switch arranged at substantially the same level as said transfer switch, said selector switch including a first group of circularly arranged spaced fixed contacts positioned at substantially the same level as one of said pair of slip-ring-like fixed contacts and said selector switch including a second group of circularly arranged spaced fixed contacts positioned at substantially the same level as the other of said pair of slip-ring-like fixed contacts, and said selector switch further including a pair of radially extending contact bridges angularly displaced 180 degrees relative to each other pivotable about the axis of said housing, each of said pair of contact bridges having a radially inner end engaging one of said pair of slip-ring-like fixed contacts, one of said pair of contact bridges having a radially outer end selectively engaging said fixed contacts of said first group of contacts and the other of said pair of contact bridges having a radially outer end selectively engaging said fixed contacts of said second group of contacts; and

(e) operating means for said selector switch including a gear mechanism arranged above said first group of fixed contacts and above said second group of fixed contacts thereof, said operating means further including a pair of operating rods arranged parallel to the axis of said housing and angularly displaced degrees relative to each other, each of said pair of rods having an upper end driven by said gear mechanism around said housing and each of said pair of rods having a lower portion operatively connected to one of said pair of contact bridges.

References Cited UNITED STATES PATENTS 1,914,907 6/1933 Buchhold et a1. 20011 2,231,627 2/1941 Jansen ZOO-11 3,194,900 7/ 1965 Bleibtreu 2001l 3/ 1965 Bleibtreu et a1. 20018 JOHN F. COUCH, Primary Examiner.

A. D. PELLINEN, Assistant Examiner.