TRANSFER SWI CH OPERATING MECHANISM FOR EFFECTING TAP CHANGES
United States Patent 3806674
A transfer switch including, in addition to main contacts, auxiliary contacts and current-carrying contacts, fixed terminals having current-carrying contact means. Special switching means allow selective interconnection of the fixed current-carrying contacts with current-carrying contact means of the fixed terminals. The movable main contacts, the movable auxiliary contacts, and the aforementioned special switching means are all operated by cam means, or a cam disc.
US Patent References:
REGULATING TRANSFORMER TAP-CHANGER SWITCH
Bleibtreu et al. - January 1972 - 3632908
Transfer switch for tap-changing transformers convertible for adaptation to a wide range of currents
Schunda - December 1967 - 3360618
REGULATING TRANSFORMER TAP-CHANGER SWITCH
Bleibtreu et al. - January 1972 - 3632908
Transfer switch for tap-changing transformers convertible for adaptation to a wide range of currents
Schunda - December 1967 - 3360618
Application Number:
05/341310
Publication Date:
04/23/1974
Filing Date:
03/14/1973
View Patent Images:
Export Citation:
Assignee:
Machinenfabrik, Reinhausen Gebruder Scheubeck K. G. (Regensburg, JA)
Primary Class:
Other Classes:
200/17R, 200/11TC
International Classes:
H01H9/00; H01H3/32
Field of Search:
200/11TC,18,17R,153G,153H,153J,153P,153PA,153R
Primary Examiner:
Scott, James R.
Attorney, Agent or Firm:
Salzer, Erwin
Claims:
I claim as my invention
1. A tap-changing transfer switch for tapped regulating transformers comprising
2. A switch as specified in claim 1 wherein
3. A switch as specified in claim 2 wherein the pivotal supports of said two-armed levers are arranged between said flange portions of said substantially U-shaped terminals.
4. A switch as specified in claim 2 wherein said disc is provided with abutment means for engaging said two-armed levers in the limit positions thereof and with slots for operating said two-armed levers incident to pivotal motions of said disc.
1. A tap-changing transfer switch for tapped regulating transformers comprising
2. A switch as specified in claim 1 wherein
3. A switch as specified in claim 2 wherein the pivotal supports of said two-armed levers are arranged between said flange portions of said substantially U-shaped terminals.
4. A switch as specified in claim 2 wherein said disc is provided with abutment means for engaging said two-armed levers in the limit positions thereof and with slots for operating said two-armed levers incident to pivotal motions of said disc.
Description:
BACKGROUND OF THE INVENTION
Tap-changing regulating transformers, and more particularly such transformers known as Jensen-type transformers, include three units, namely the transformer proper having a tapped winding, selector switches for selecting desired taps of the winding, and transfer switches for transferring the load from one selected tap to another.
The coaction of such units has been amply described in prior patents as, for instance, U.S. Pat. No. 3,176,089 to A. Bleibtreu et al., Mar. 30, 1965 for LOAD TAP CHANGERS FOR TRANSFORMERS, U.S. Pat. No. 3,218,400 to A. Bleibtreu, Nov. 16, 1965 for TRANSFER SWITCHES FOR TAP CHANGING REGULATING TRANSFORMERS HAVING SQUIRREL-CAGE-SHAPED SUPPORT FOR THE FIXED CONTACTS THEREOF, and in U.S. Pat. No. 3,632,908 to A. Bleibtreu et al., Jan. 4, 1972 for REGULATING TRANSFORMER TAP CHANGER SWITCH. Reference may be had to the aforementioned patents in regard to general information of the units of which a Jansen-type regulating transformer is made up, and the mode of operation thereof.
The movable contacts of transfer switches may be operated by various means as, for instance, linkages, or cams. The present invention relates to transfer switches whose movable contacts are operated by cams rather than by linkages or toggles.
Transfer switches include pairs of relatively movable main contacts. In this context the term main contacts is used in reference to contacts which are intended to interconnect, and interconnect, a tap of a tapped transformer winding directly with the terminal of an outgoing line, or load circuit. The term directly as used in this context means without interposition of switching resistors, or switch-over resistors.
Transfer switches further include pairs of relatively movable auxiliary contacts. In this context the term auxiliary contact is used in reference to contacts which are intended to interconnect, and interconnect, a tap of a tapped transformer winding with the terminal of an outgoing line, or load circuit, by the intermediary of switching resistors or switch-over resistors.
A third kind of contacts occurring in transfer switches as well as in many other switches and circuit breakers are current-carrying contacts. Such contacts are designed to carry high load currents with very small losses, but are incapable of opening or closing live circuits. Current-carrying contacts of transfer switches interconnect directly, i.e. without interposition of a resistor, a tap of a tapped transformer winding with the terminal of an outgoing line, or load circuit. Current-carrying contacts provide minimal resistance shunts across pairs of engaging main contacts.
Polyphase transfer switches for Jansen-type transformers including main contacts, auxiliary contacts and current-carrying contacts operated by linkages are shown in U.S. Pat. No. 3,671,687 to A. Bleibtreu, June 20, 1972 for TRANSFER SWITCH FOR TAP-CHANGING REGULATING TRANSFORMERS INCLUDING LOST MOTION INTERCONNECTION DRIVING MECHANISM.
The present invention refers to transfer switches including auxiliary contacts, main contacts and current-carrying contacts, and more particularly transfer switches wherein these contacts are operated by cam means rather than linkages, or toggles, and which are designed to cooperate with tapped polyphase or three-phase transformers. In such transfer switches the fixed contacts are generally arranged at points of a cylindrical surface, and this applies also to transfer switches embodying the present invention.
The principal object of the invention is to provide transfer switches of the above description whose bulk is minimized, i.e. which are extremely compact.
A related object of this invention is to provide transfer switches of the above description allowing to greatly simplify the geometry of their various current-paths.
Still another related object of this invention is to provide transfer switches of the above description whose current-carrying contacts may be, or are, positioned immediately adjacent, or very close, to the main contacts and to the auxiliary contacts.
Other objects of this invention will become apparent as this specification progresses.
SUMMARY OF THE INVENTION
Tap changing transfer switches embodying this invention comprise the following elements:
a. A plurality of pairs of relatively movable auxiliary contacts including fixed auxiliary contacts arranged in a pattern that is a sector of a circle.
b. A plurality of pairs of relatively movable main contacts including fixed main contacts arranged in said pattern of a sector of a circle peripherally outside the region of said sector occupied by said fixed auxiliary contacts.
c. Cam means driven by a shaft arranged in the center of said circle for operating said relatively movable auxiliary contacts and said relatively movable main contacts.
d. Two pairs of fixed current-carrying contacts arranged on another circle of relatively large diameter concentric to said circle, each pair of said two pairs of fixed current-carrying contacts being arranged outside the angular area defined by said center of a circle and said fixed main contacts, and on opposite side of said area.
e. A pair of fixed substantially U-shaped terminals arranged on another circle of relatively small diameter concentric to said circle, each of said pair of fixed terminals being arranged outside the angular area defined by said center of a circle and said fixed main contacts and on opposite sides of said area, and each of said pair of fixed substantially U-shaped terminals supporting a pair of terminal contacts on the flange portions thereof.
f. A pair of contact bridges for selectively connecting one fixed current-carrying contact of said two pairs of fixed current-carrying contacts and one terminal contact of said pair of terminal contacts of said pair of terminals.
g. Operating means including cam means driven by said shaft for operating said pair of contact bridges.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a sector of a three-phase transfer switch embodying this invention which transfer switch includes three sectors as shown in FIG. 1, FIG. 1 being in essence a top plan view of the transfer switch, some of its parts having been removed to better expose other parts thereof; and
FIG. 2 is a vertical section of the structure shown in FIG. 1 taken along II--II of FIG. 1 and being drawn on a smaller scale than FIG. 1.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to the drawings, and more particularly to FIG. 1 thereof, reference characters VS, US and WS have been applied to indicate the three sectors included in a three-phase transformer switch. Sectors VS and WS have been indicated but diagrammatically in FIG. 1, and sector US has been shown in considerable detail. Sectors VS and WS are constructed in the same way as sector US.
The structure of FIG. 1 includes movable main contacts 1, 4 and movable auxiliary contacts 2, 3. The aforementioned movable contacts 1, 2, 3, 4 are operated by cam-controlled rods 9, i.e. these contacts are moved either radially outwardly, or radially inwardly, by means of cam-controlled rods 9. Reference characters 5 and 8 have been applied to indicate fixed main contacts cooperating with movable main contacts 1 and 4, and reference characters 6 and 7 have been applied to indicate fixed auxiliary contacts cooperating with movable auxiliary contacts 2 and 3. The ends of rods 9 remote from contacts 1, 2, 3, 4 are provided with pins engaging slots 10 in cam disk 11. The latter is pivotable by means of shaft 12 arranged in the center thereof. Shaft 12 is adapted to be pivoted by motor means (not shown) selectively either in clockwise direction or in counterclockwise direction. Cam disk 11 pivots jointly with shaft 12 and this causes rods 9 to move contacts 1, 2, 3, 4 radially outwardly and radially inwardly in the required predetermined sequence.
Reference characters D 1 and D 2 have been applied to generally designate current-carrying contact means, i.e. contact means capable of carrying a load current continuously but not capable of performing any switching operations under load. The current-carrying contact means D 1 includes the fixed current-carrying contacts U 1 and W 2 , the fixed current-carrying terminal 14 and the current-carrying bridge 13 which conductively interconnects parts U 1 and 14 in the position of the switch mechanism shown in FIG. 1. In that position movable main contact 1 engages fixed main contact 5 and contacts 2, 3, 4 are out of engagement with contacts 6, 7, 8. The fixed current-carrying contact W 2 pertains in terms of operation to sector WS rather than sector US. The current-carrying contact means D 2 include the fixed current-carrying contacts U 2 , V 1 , the fixed current-carrying terminal 15 and the current-carrying bridge 16 which conductively interconnects parts V 1 and 15 in the position of the switch mechanism shown in FIG. 1. The fixed current-carrying contact V 1 pertains in terms of operation to the sector VS rather than sector US of the polyphase switch mechanism. The fixed current-carrying contacts U 1 , U 2 , V 1 , W 2 are arranged along a circle with drive shaft 12 as its center and having a relatively large radius. The channel-shaped current-carrying terminals 14, 15 are arranged along another circle with drive shaft 12 as its center end having a relatively small radius. The contact bridge 13 is adapted to conductively connect selectively either contact U 1 and contact 14 on a flange portion of channel-shaped current-carrying terminal 14, or contact W 2 and contact 142 on a flange portion of channel-shaped current-carrying terminal 14. In a like fashion contact bridge 16 is adapted to conductively connect selectively either contact V 1 and contact 151 on a flange of channel-shaped current-carrying terminal 15, or contact U 2 and contact 152 on a flange of channel-shaped current-carrying terminal contact 15. Current-carrying contact bridge 13 is supported by a two armed lever 17 pivotally supported at 19 by current-carrying terminal 14 and provided with a roller 171 adapted to engage a cam-forming recess or cut-out 21 in cam plate 11. In a like fashion current-carrying contact bridge 16 is supported by a lever 18 having two arms pivotally supported at 20 by current-carrying terminal 15 and provided with a roller 181 adapted to engage a cam-forming recess or cut-out 22 in cam plate 11. Reference numerals 211 and 221 have been applied to indicate short cam sections on cam plate 11 immediately adjacent recesses 21 and 22, respectively. Cam plate 11 may also be provided with cam means 213, 214 to both sides of recess 21 and cam means 223, 224 to both sides of recess 22. The object of these various cam means will become more fully apparent from what follows below.
In FIG. 2 reference character 45 has been applied to indicate supporting insulators which supports current-carrying contacts V 1 , U 2 .
The supporting insulators 45 are on the other hand fixed on a contact supporting segment 31 of insulating material together with terminals 15.
This contact supporting segment 31 supports also the fixed main contacts 5, which are operating together with the movable main contact 1.
The movable main contact 1 is operated by rods 9 and connecting rods 42, said connection rods 42 are hinged together by a bridge 44 which is driven by tension springs 43.
Considering a tap-changing operation starting with the position of the constituent elements of the structure from the positions thereof shown in FIG. 1. Such a tap-changing operation involves a counterclockwise pivotal motion of shaft 12 which is Y-shaped in cross-section and results in a like pivotal motion of cam plate 11. As a result of such a pivotal motion rollers 171, 181 which were heretofore resting against cam surfaces 211, 221 of cam disc 11 are caused to engage recesses 21, 22 of cam disc 11. This causes a pivotal motion of lever 17 about pivot 19 in clockwise direction, and a pivotal motion of lever 18 about pivot 20 in clockwise direction. As a result of that motion of lever 17 contact bridge 13 moves out of engagement with contact surfaces U 1 and 141 into a position intermediate fixed current-carrying contacts U 1 and W 2 . In like fashion the motion of lever 18 moves contact bridge 18 out of engagement with contact surfaces V 1 and 151 into a position intermediate fixed current-carrying contacts V 1 and U 2 . In other words, the current-carrying paths between parts U 1 and 141 and parts V 1 and 151 are eliminated. As the pivotal motion of parts 11 and 12 continues, movable auxiliary contact 2 engages fixed auxiliary contact 6 and the movable main contact parts from fixed main contact 5. Thereafter movable contact 3 moves into engagement with fixed auxiliary contact 7, and shortly thereafter the movable auxiliary contact 2 parts from its cooperating fixed contact 6. As the tap-changing operation further progresses movable main contact 4 engages fixed main contact 8 and movable auxiliary contact 3 parts from fixed auxiliary contact 7. The tap-changing operation is completed when current-carrying bridge 16 is pivoted about pivot 20 into engagement with contact surfaces U 2 and 152. This motion of bridge 16 is caused by engagement of roller 181 and cam surface 222 at the end of the tap-changing operation, immobilizing bridge-supporting lever 18. In a like fashion bridge-supporting lever 17 is pivoted resulting in engagement of current-carrying bridge 13 with contact surfaces W 2 and 142.
It will be understood that like contact motions as those described above occur also in sectors VS and WS of the transfer switch, and that when all parts of the switch mechanism are in their limit positions described above the direction of pivotal motion of shaft 12 and cam plate 11 may be reversed, as a result of which all the parts of the switch mechanism are returned to their initial positions shown in FIG. 1.
The provision of cam surfaces 213, 214, 223, 224 is desirable but optional. The object of these cam surfaces is to initiate by positive action the pivotal motions of bridge-supporting levers 17 and 18. When a tap-changing operation is initiated, i.e. when the pivotal action of cam plate 11 just begins, cam surfaces 213, 214, 223, 224 engage instantly the radially inner ends of levers 17, 18 and thus initiate the pivotal motions thereof about pivots 19 and 20.
It will be apparent from the above that fixed auxiliary contacts 6, 7 cooperating with the movable auxiliary contacts 2, 3 are arranged in a pattern that is a sector of a circle, the center of which is the center of shaft 12. The fixed main contacts 5, 8 cooperating with the movable main contacts 1, 4 are likewise arranged in a pattern which is a sector of a circle, the center of which is the center of shaft 12. Fixed main contacts 5, 8 are arranged peripherally outside the region of the sector of a circle occupied by auxiliary fixed contacts 6, 7. Shaft 12 operates cam means 11, 10 for operating contacts 2, 3, 1, 4. Reference characters U 1 , W 2 have been applied to indicate a first pair of fixed current-carrying contacts arranged on another circle than contacts 5, 6, 7, 8. The circle on which contacts U 1 , W 2 are arranged and the circle on which contacts 5, 6, 7, 8 are arranged are concentric. Reference characters U 2 , V 1 have been applied to indicate a second pair of fixed current-carrying contacts arranged on the same circle as the aforementioned first pair of fixed current-carrying contacts. Contacts U 1 , W 2 and contacts U 2 , V 1 are arranged outside of the angular area defined by the center of the circle on which they are arranged and by fixed main contacts 5, 8. Contacts U 1 , W 2 and contacts U 2 , V 1 are arranged on opposite sides of that area. The pair of fixed terminals 14, 15 is arranged on another circle concentric with the aforementioned circles, but having a relatively small diameter. Each of terminals 14, 15 is arranged outside the angular area defined by the center of shaft 12 and fixed main contacts 5, 8. Fixed terminals 14, 15 are substantially U-shaped, and the flange portions thereof support current-carrying contacts 141, 142 and 151, 152, respectively. The pair of contact bridges 13, 16 are supported by two-armed levers 17, 18 which are pivoted at 19 and 20, respectively. Each contact bridge 13, 16 is formed by a pair of contacts which are biased in opposite directions by interposed helical springs, but maintained in certain limit positions by abutments supported by, or forming part of, levers 17, 18. This has been clearly shown in FIG. 1. Contact bridge 13 can selectively interconnect contacts U 1 and 141 (as shown in FIG. 1), or contacts W 2 and 142. Contact bridge 16 can selectively interconnect contacts V 1 and 151 (as shown in FIG. 1), or contacts U 2 and 152. This depends upon the position of shaft 12 and cam disc 11. Cam disc 11 and the cam-forming slots 21, 22 therein are the means for operating or actuating levers 17, 18 and contact bridges 13, 16.
Tap-changing regulating transformers, and more particularly such transformers known as Jensen-type transformers, include three units, namely the transformer proper having a tapped winding, selector switches for selecting desired taps of the winding, and transfer switches for transferring the load from one selected tap to another.
The coaction of such units has been amply described in prior patents as, for instance, U.S. Pat. No. 3,176,089 to A. Bleibtreu et al., Mar. 30, 1965 for LOAD TAP CHANGERS FOR TRANSFORMERS, U.S. Pat. No. 3,218,400 to A. Bleibtreu, Nov. 16, 1965 for TRANSFER SWITCHES FOR TAP CHANGING REGULATING TRANSFORMERS HAVING SQUIRREL-CAGE-SHAPED SUPPORT FOR THE FIXED CONTACTS THEREOF, and in U.S. Pat. No. 3,632,908 to A. Bleibtreu et al., Jan. 4, 1972 for REGULATING TRANSFORMER TAP CHANGER SWITCH. Reference may be had to the aforementioned patents in regard to general information of the units of which a Jansen-type regulating transformer is made up, and the mode of operation thereof.
The movable contacts of transfer switches may be operated by various means as, for instance, linkages, or cams. The present invention relates to transfer switches whose movable contacts are operated by cams rather than by linkages or toggles.
Transfer switches include pairs of relatively movable main contacts. In this context the term main contacts is used in reference to contacts which are intended to interconnect, and interconnect, a tap of a tapped transformer winding directly with the terminal of an outgoing line, or load circuit. The term directly as used in this context means without interposition of switching resistors, or switch-over resistors.
Transfer switches further include pairs of relatively movable auxiliary contacts. In this context the term auxiliary contact is used in reference to contacts which are intended to interconnect, and interconnect, a tap of a tapped transformer winding with the terminal of an outgoing line, or load circuit, by the intermediary of switching resistors or switch-over resistors.
A third kind of contacts occurring in transfer switches as well as in many other switches and circuit breakers are current-carrying contacts. Such contacts are designed to carry high load currents with very small losses, but are incapable of opening or closing live circuits. Current-carrying contacts of transfer switches interconnect directly, i.e. without interposition of a resistor, a tap of a tapped transformer winding with the terminal of an outgoing line, or load circuit. Current-carrying contacts provide minimal resistance shunts across pairs of engaging main contacts.
Polyphase transfer switches for Jansen-type transformers including main contacts, auxiliary contacts and current-carrying contacts operated by linkages are shown in U.S. Pat. No. 3,671,687 to A. Bleibtreu, June 20, 1972 for TRANSFER SWITCH FOR TAP-CHANGING REGULATING TRANSFORMERS INCLUDING LOST MOTION INTERCONNECTION DRIVING MECHANISM.
The present invention refers to transfer switches including auxiliary contacts, main contacts and current-carrying contacts, and more particularly transfer switches wherein these contacts are operated by cam means rather than linkages, or toggles, and which are designed to cooperate with tapped polyphase or three-phase transformers. In such transfer switches the fixed contacts are generally arranged at points of a cylindrical surface, and this applies also to transfer switches embodying the present invention.
The principal object of the invention is to provide transfer switches of the above description whose bulk is minimized, i.e. which are extremely compact.
A related object of this invention is to provide transfer switches of the above description allowing to greatly simplify the geometry of their various current-paths.
Still another related object of this invention is to provide transfer switches of the above description whose current-carrying contacts may be, or are, positioned immediately adjacent, or very close, to the main contacts and to the auxiliary contacts.
Other objects of this invention will become apparent as this specification progresses.
SUMMARY OF THE INVENTION
Tap changing transfer switches embodying this invention comprise the following elements:
a. A plurality of pairs of relatively movable auxiliary contacts including fixed auxiliary contacts arranged in a pattern that is a sector of a circle.
b. A plurality of pairs of relatively movable main contacts including fixed main contacts arranged in said pattern of a sector of a circle peripherally outside the region of said sector occupied by said fixed auxiliary contacts.
c. Cam means driven by a shaft arranged in the center of said circle for operating said relatively movable auxiliary contacts and said relatively movable main contacts.
d. Two pairs of fixed current-carrying contacts arranged on another circle of relatively large diameter concentric to said circle, each pair of said two pairs of fixed current-carrying contacts being arranged outside the angular area defined by said center of a circle and said fixed main contacts, and on opposite side of said area.
e. A pair of fixed substantially U-shaped terminals arranged on another circle of relatively small diameter concentric to said circle, each of said pair of fixed terminals being arranged outside the angular area defined by said center of a circle and said fixed main contacts and on opposite sides of said area, and each of said pair of fixed substantially U-shaped terminals supporting a pair of terminal contacts on the flange portions thereof.
f. A pair of contact bridges for selectively connecting one fixed current-carrying contact of said two pairs of fixed current-carrying contacts and one terminal contact of said pair of terminal contacts of said pair of terminals.
g. Operating means including cam means driven by said shaft for operating said pair of contact bridges.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a sector of a three-phase transfer switch embodying this invention which transfer switch includes three sectors as shown in FIG. 1, FIG. 1 being in essence a top plan view of the transfer switch, some of its parts having been removed to better expose other parts thereof; and
FIG. 2 is a vertical section of the structure shown in FIG. 1 taken along II--II of FIG. 1 and being drawn on a smaller scale than FIG. 1.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to the drawings, and more particularly to FIG. 1 thereof, reference characters VS, US and WS have been applied to indicate the three sectors included in a three-phase transformer switch. Sectors VS and WS have been indicated but diagrammatically in FIG. 1, and sector US has been shown in considerable detail. Sectors VS and WS are constructed in the same way as sector US.
The structure of FIG. 1 includes movable main contacts 1, 4 and movable auxiliary contacts 2, 3. The aforementioned movable contacts 1, 2, 3, 4 are operated by cam-controlled rods 9, i.e. these contacts are moved either radially outwardly, or radially inwardly, by means of cam-controlled rods 9. Reference characters 5 and 8 have been applied to indicate fixed main contacts cooperating with movable main contacts 1 and 4, and reference characters 6 and 7 have been applied to indicate fixed auxiliary contacts cooperating with movable auxiliary contacts 2 and 3. The ends of rods 9 remote from contacts 1, 2, 3, 4 are provided with pins engaging slots 10 in cam disk 11. The latter is pivotable by means of shaft 12 arranged in the center thereof. Shaft 12 is adapted to be pivoted by motor means (not shown) selectively either in clockwise direction or in counterclockwise direction. Cam disk 11 pivots jointly with shaft 12 and this causes rods 9 to move contacts 1, 2, 3, 4 radially outwardly and radially inwardly in the required predetermined sequence.
Reference characters D 1 and D 2 have been applied to generally designate current-carrying contact means, i.e. contact means capable of carrying a load current continuously but not capable of performing any switching operations under load. The current-carrying contact means D 1 includes the fixed current-carrying contacts U 1 and W 2 , the fixed current-carrying terminal 14 and the current-carrying bridge 13 which conductively interconnects parts U 1 and 14 in the position of the switch mechanism shown in FIG. 1. In that position movable main contact 1 engages fixed main contact 5 and contacts 2, 3, 4 are out of engagement with contacts 6, 7, 8. The fixed current-carrying contact W 2 pertains in terms of operation to sector WS rather than sector US. The current-carrying contact means D 2 include the fixed current-carrying contacts U 2 , V 1 , the fixed current-carrying terminal 15 and the current-carrying bridge 16 which conductively interconnects parts V 1 and 15 in the position of the switch mechanism shown in FIG. 1. The fixed current-carrying contact V 1 pertains in terms of operation to the sector VS rather than sector US of the polyphase switch mechanism. The fixed current-carrying contacts U 1 , U 2 , V 1 , W 2 are arranged along a circle with drive shaft 12 as its center and having a relatively large radius. The channel-shaped current-carrying terminals 14, 15 are arranged along another circle with drive shaft 12 as its center end having a relatively small radius. The contact bridge 13 is adapted to conductively connect selectively either contact U 1 and contact 14 on a flange portion of channel-shaped current-carrying terminal 14, or contact W 2 and contact 142 on a flange portion of channel-shaped current-carrying terminal 14. In a like fashion contact bridge 16 is adapted to conductively connect selectively either contact V 1 and contact 151 on a flange of channel-shaped current-carrying terminal 15, or contact U 2 and contact 152 on a flange of channel-shaped current-carrying terminal contact 15. Current-carrying contact bridge 13 is supported by a two armed lever 17 pivotally supported at 19 by current-carrying terminal 14 and provided with a roller 171 adapted to engage a cam-forming recess or cut-out 21 in cam plate 11. In a like fashion current-carrying contact bridge 16 is supported by a lever 18 having two arms pivotally supported at 20 by current-carrying terminal 15 and provided with a roller 181 adapted to engage a cam-forming recess or cut-out 22 in cam plate 11. Reference numerals 211 and 221 have been applied to indicate short cam sections on cam plate 11 immediately adjacent recesses 21 and 22, respectively. Cam plate 11 may also be provided with cam means 213, 214 to both sides of recess 21 and cam means 223, 224 to both sides of recess 22. The object of these various cam means will become more fully apparent from what follows below.
In FIG. 2 reference character 45 has been applied to indicate supporting insulators which supports current-carrying contacts V 1 , U 2 .
The supporting insulators 45 are on the other hand fixed on a contact supporting segment 31 of insulating material together with terminals 15.
This contact supporting segment 31 supports also the fixed main contacts 5, which are operating together with the movable main contact 1.
The movable main contact 1 is operated by rods 9 and connecting rods 42, said connection rods 42 are hinged together by a bridge 44 which is driven by tension springs 43.
Considering a tap-changing operation starting with the position of the constituent elements of the structure from the positions thereof shown in FIG. 1. Such a tap-changing operation involves a counterclockwise pivotal motion of shaft 12 which is Y-shaped in cross-section and results in a like pivotal motion of cam plate 11. As a result of such a pivotal motion rollers 171, 181 which were heretofore resting against cam surfaces 211, 221 of cam disc 11 are caused to engage recesses 21, 22 of cam disc 11. This causes a pivotal motion of lever 17 about pivot 19 in clockwise direction, and a pivotal motion of lever 18 about pivot 20 in clockwise direction. As a result of that motion of lever 17 contact bridge 13 moves out of engagement with contact surfaces U 1 and 141 into a position intermediate fixed current-carrying contacts U 1 and W 2 . In like fashion the motion of lever 18 moves contact bridge 18 out of engagement with contact surfaces V 1 and 151 into a position intermediate fixed current-carrying contacts V 1 and U 2 . In other words, the current-carrying paths between parts U 1 and 141 and parts V 1 and 151 are eliminated. As the pivotal motion of parts 11 and 12 continues, movable auxiliary contact 2 engages fixed auxiliary contact 6 and the movable main contact parts from fixed main contact 5. Thereafter movable contact 3 moves into engagement with fixed auxiliary contact 7, and shortly thereafter the movable auxiliary contact 2 parts from its cooperating fixed contact 6. As the tap-changing operation further progresses movable main contact 4 engages fixed main contact 8 and movable auxiliary contact 3 parts from fixed auxiliary contact 7. The tap-changing operation is completed when current-carrying bridge 16 is pivoted about pivot 20 into engagement with contact surfaces U 2 and 152. This motion of bridge 16 is caused by engagement of roller 181 and cam surface 222 at the end of the tap-changing operation, immobilizing bridge-supporting lever 18. In a like fashion bridge-supporting lever 17 is pivoted resulting in engagement of current-carrying bridge 13 with contact surfaces W 2 and 142.
It will be understood that like contact motions as those described above occur also in sectors VS and WS of the transfer switch, and that when all parts of the switch mechanism are in their limit positions described above the direction of pivotal motion of shaft 12 and cam plate 11 may be reversed, as a result of which all the parts of the switch mechanism are returned to their initial positions shown in FIG. 1.
The provision of cam surfaces 213, 214, 223, 224 is desirable but optional. The object of these cam surfaces is to initiate by positive action the pivotal motions of bridge-supporting levers 17 and 18. When a tap-changing operation is initiated, i.e. when the pivotal action of cam plate 11 just begins, cam surfaces 213, 214, 223, 224 engage instantly the radially inner ends of levers 17, 18 and thus initiate the pivotal motions thereof about pivots 19 and 20.
It will be apparent from the above that fixed auxiliary contacts 6, 7 cooperating with the movable auxiliary contacts 2, 3 are arranged in a pattern that is a sector of a circle, the center of which is the center of shaft 12. The fixed main contacts 5, 8 cooperating with the movable main contacts 1, 4 are likewise arranged in a pattern which is a sector of a circle, the center of which is the center of shaft 12. Fixed main contacts 5, 8 are arranged peripherally outside the region of the sector of a circle occupied by auxiliary fixed contacts 6, 7. Shaft 12 operates cam means 11, 10 for operating contacts 2, 3, 1, 4. Reference characters U 1 , W 2 have been applied to indicate a first pair of fixed current-carrying contacts arranged on another circle than contacts 5, 6, 7, 8. The circle on which contacts U 1 , W 2 are arranged and the circle on which contacts 5, 6, 7, 8 are arranged are concentric. Reference characters U 2 , V 1 have been applied to indicate a second pair of fixed current-carrying contacts arranged on the same circle as the aforementioned first pair of fixed current-carrying contacts. Contacts U 1 , W 2 and contacts U 2 , V 1 are arranged outside of the angular area defined by the center of the circle on which they are arranged and by fixed main contacts 5, 8. Contacts U 1 , W 2 and contacts U 2 , V 1 are arranged on opposite sides of that area. The pair of fixed terminals 14, 15 is arranged on another circle concentric with the aforementioned circles, but having a relatively small diameter. Each of terminals 14, 15 is arranged outside the angular area defined by the center of shaft 12 and fixed main contacts 5, 8. Fixed terminals 14, 15 are substantially U-shaped, and the flange portions thereof support current-carrying contacts 141, 142 and 151, 152, respectively. The pair of contact bridges 13, 16 are supported by two-armed levers 17, 18 which are pivoted at 19 and 20, respectively. Each contact bridge 13, 16 is formed by a pair of contacts which are biased in opposite directions by interposed helical springs, but maintained in certain limit positions by abutments supported by, or forming part of, levers 17, 18. This has been clearly shown in FIG. 1. Contact bridge 13 can selectively interconnect contacts U 1 and 141 (as shown in FIG. 1), or contacts W 2 and 142. Contact bridge 16 can selectively interconnect contacts V 1 and 151 (as shown in FIG. 1), or contacts U 2 and 152. This depends upon the position of shaft 12 and cam disc 11. Cam disc 11 and the cam-forming slots 21, 22 therein are the means for operating or actuating levers 17, 18 and contact bridges 13, 16.