CA1124790A - Tap-changing switching device including vacuum switches - Google Patents
Tap-changing switching device including vacuum switchesInfo
- Publication number
- CA1124790A CA1124790A CA306,804A CA306804A CA1124790A CA 1124790 A CA1124790 A CA 1124790A CA 306804 A CA306804 A CA 306804A CA 1124790 A CA1124790 A CA 1124790A
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- Canada
- Prior art keywords
- pair
- contacts
- tap
- contact
- vacuum
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000004804 winding Methods 0.000 claims abstract description 8
- 230000008093 supporting effect Effects 0.000 claims description 3
- 230000006835 compression Effects 0.000 description 4
- 238000007906 compression Methods 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 2
- 101100000858 Caenorhabditis elegans act-3 gene Proteins 0.000 description 1
- HEFNNWSXXWATRW-UHFFFAOYSA-N Ibuprofen Chemical compound CC(C)CC1=CC=C(C(C)C(O)=O)C=C1 HEFNNWSXXWATRW-UHFFFAOYSA-N 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
- H01H9/0005—Tap change devices
- H01H9/0038—Tap change devices making use of vacuum switches
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F29/00—Variable transformers or inductances not covered by group H01F21/00
- H01F29/02—Variable transformers or inductances not covered by group H01F21/00 with tappings on coil or winding; with provision for rearrangement or interconnection of windings
- H01F29/04—Variable transformers or inductances not covered by group H01F21/00 with tappings on coil or winding; with provision for rearrangement or interconnection of windings having provision for tap-changing without interrupting the load current
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- High-Tension Arc-Extinguishing Switches Without Spraying Means (AREA)
- Rotary Switch, Piano Key Switch, And Lever Switch (AREA)
Abstract
TAP-CHANGING SWITCHING DEVICE INCLUDING VACUUM SWITCHES
Abstract of Disclosure A tap-changing switching device for connecting various taps of a tapped transformer winding to a load. The device is con-spicuous by its simplicity, in particular the absence of any contact-operating linkages. It comprises a system of fixed contacts arranged in a circular pattern and a pair of co-operating movable contacts of which each is connected in series with a vacuum switch. There is a common support for said pair of movable contacts and said vacuum switches of which each is connected in series with one of said movable contacts. The pattern formed by said fixed contacts.
The mechanical and electrical connection between the movable contact and the vacuum switches is effected by a pair of spring-biased rods. Each of the pair of movable contacts is supported on the axially outer end by one of said pair of rods and the movement of this pair of rods is controlled by cam means. The latter are formed by the radially inner sur-faces of the contacts of said system of fixed contacts.
Abstract of Disclosure A tap-changing switching device for connecting various taps of a tapped transformer winding to a load. The device is con-spicuous by its simplicity, in particular the absence of any contact-operating linkages. It comprises a system of fixed contacts arranged in a circular pattern and a pair of co-operating movable contacts of which each is connected in series with a vacuum switch. There is a common support for said pair of movable contacts and said vacuum switches of which each is connected in series with one of said movable contacts. The pattern formed by said fixed contacts.
The mechanical and electrical connection between the movable contact and the vacuum switches is effected by a pair of spring-biased rods. Each of the pair of movable contacts is supported on the axially outer end by one of said pair of rods and the movement of this pair of rods is controlled by cam means. The latter are formed by the radially inner sur-faces of the contacts of said system of fixed contacts.
Description
1~24790 Background of the Invention The closest prior art with which applicant is familiar is disclosed in German Offenlegungsschrift 2 321 369 filed on April 27,1973 under Ser.No. P 23 21 269.6 by Transformatoren Union A.G., Stuttgart, Western Germany, titled '~Load Selector for Tapped Transformers and Chokes1~. Switching devices of the kind dis-closed in the aforementioned publication include vacuum switches which greatly increases their life and their switching performance in relation to tap-changing switches of older design. They are, however, subject to the serious limitations in that they call for complex kinematic means for performing the various operations of the movable contacts, the various operations of the vacuum switches, and the proper coordination of the operation of that of the movable contacts and that of the vacuum switches.
~.
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It is, therefore, the prime object of this invention to pro-vide tap-changing switches which are easier to manufacture, and at lower cost, than those described in the above publication. A
more specific object of the invention is to provide tap-changing switches that have greatly simplified mechanical means for achieving the required sequence of the switching operation in-volved in tap-changes.
Heretofore the operation of the vacuum switches was effected by operating rods which, in turn, were under the control of 10 separate and special cam means. The invention does away with the need of such special cam means for the control of the vacuum switches. It provides single rods of which each controls the operation of a movable contact as well as that of a vacuum switch of the device.
The invention is universally applicable, i.e. to tap-changing switches which are combined with selector switches, and to tap-changing switches as such, i.e. not combined with selector switches.
In the first instance the contacts of the tap-changing switches alternate between two limit positions, while in the second instance, `~ 20 i.e. that of load selectors, the fixed contacts of which each is connected to a tap of a transformer winding, are arranged in a circular pattern - which may encompass a sector of a circle or a full circle - and the movable contacts are pivoted around the center of said circle.
The contacts of switching devices according to this invention and their vacuum switches are intended to be arranged and operated inside of a body of oil. This allows power switching operation or, in other words, performance of switching operations under load. The gas evolution and increase in pressure that occurs inside of a body of oil in which vacuum switches are submersed may be considered as a signal that one of the vacuum switches has become defective. Hence a simple pressure sensor may be used as defect warning means.
11~4790 Summary of the Invention A tap-changing switch according to the present invention includes a plurality of fixed contacts arranged in a circular pattern, each contact of said plurality of contacts being adapted to be connected to a tap of a transformer winding. Such a switch is further provided with a pair of movable contacts each cooperating with said plurality of fixed contacts. Said pair of movable contacts is supported by a support pivotable about the center of said cir-cular pattern formed by said fixed contacts. Said support further supports a pair of vacuum switches including a first vacuum switch and a second vacuum switch each connected in series with one of said pair of movable contacts. A switching resistor supported by said support is connected in series with said first vacuum switch or with said second vacuum switch. A tap-changing switch according to this invention further includes a pair of operating rods having a limited travel, each having an axially outer end and each having an a~ially inner end, each of said pair of operating rods support-ing one of said pair of movable contacts on said axially outer end thereof. One of said pair of operating rods operates said first vacuum switch and the other of said pair of operating rods operates said second vacuum switch with the axially inner end thereof. A tap-changing switch according to this invention further includes a pair of biasing springs. One of said pair of biasing springs biases one of said pair of operating rods to open said first vacuum switch, and the other of said pair of biasing springs biases the other of said pair of operating rods to open said second vacuum switch. A
tap-changing switch according to this invention further includes a plurality of cams each having a contact-control surface engageable by each of said pair of movable contacts. Said contact-control sur-face of each of said plurality of cams includes a center portionrelatively close to said center of said circular pattern and further includes a pair of end portions having a progressively increasing spacing from said center of said circular pattern to compel closing ~124790 of one of said pair of vacuum switches when one of said pair of movable contacts engages said center portion of said contact-control surface, and to allow opening of one of said pair of vacuum switches when one of said pair of movable contacts engages one of said pair of end portions of said contact-control surface.
Brief Description of the Drawings Fig.l is a diagrammatic representation of a load-tap switch according to the present invention, its load being connected to one tap of a transformer winding; and Figs.2-9 are diagrammatic representations of the consecutive t .~ r -3a-1~247gO
switching operations following that of Fig.l until the load is connected from the tap of Fig.l to the next tap.
DescriPtion of Preferred Embodiments Referring now to the drawings, and more particularly to Fig.l thereof, reference numerals 1,2,3 and 4 have been applied to indicate four consecutive fixed or stationary contacts arranged in a circular pattern. Reference numerals 5,6,7 and 8 have been applied to indicate four taps of a transformer winding. Tap 5 is conductively connected to fixed contact 1, tap 6 is conductively 10 connected to fixed contact 2, tap 7 is conductively connected to fixed contact 3, and tap 8 is conductively connected to fixed contact 4. Reference numerals 13 and 14 have been applied to indi-cate a pair of movable contacts supported by a common support 10.
Support 10 is pivotable about the center of the circular pattern formed by fixed contacts 1-4. Support 10 further supports a first vacuum switch 15 and a second vacuum switch 16. vacuum switch 15 is connected in series with movable contact 13 and vacuum switch 16 is connected in series with movable contact 14. Reference numeral 17 has been applied to indicate a switching resistor connected in 20 series with vacuum switch 16 and with contact 14. Resistor 16 may also be connected in series with vacuum switch 15 and contact 13.
Vacuum switches 15,16 may be operated by operating rod9 18 and 19, the travel of which takes place in a direction longitudinally thereof and is limitedO Contact 13 is supported on the radially outer end of rod 18 and contact 14 is supported on the radially outer end of rod 19. The radially inner end of rods 18 and 19 op~rate vacuum switches 15 and 16, i.e.the movable contacts 23 thereof. Movable contacts 23 may be caused to engage fi~ed contacts 24 or to be separated from fixed contacts 24. Reference numerals 30 20 and 21 have been applied to indicate a pair of helical biasing springs. Spring 20 biases rod 18 in contact opening direction and spring 21 biases rod 19 in contact opening direction. Springs 20 and 1~4790 21 further bias pivotable or movable contacts 13,14 into engage-ment with any of the fixed contacts and, as shown in Fig.l, more particularly into engagement with fixed contact 2. The movement of rods 18,19 is controlled by cam means. In the embodiment of the invention shown in Fig.l these cam means are formed by the radially inner surfaces of contacts 1,2,3 and 4. As will be shown below in more detail the above referred-to cam means allow opening by springs 20 of vacuum switch 15 at the end of the en-gagement of one of fixed contacts 1-4 by movable contact 13 and 10 at the beginning of the engagement of another of said fixed con-tacts 1-4 by movable contact 13. In a like fashion the above re-ferred-to cam means allow opening by spring 21 of vacuum switch 16 at the end of the engagement of one of fixed contacts 1-4 by movable contact 14 and at the beginning of the engagement of another of said fixed contacts 1-4 by movable contact 14. To achieve the aforementioned way of controlling the operation of vacuum switches 15 and 16 the end portions of fixed contacts 1-4 are thinner in radial direction than the center portions thereof. Contacts 1-4 and 13,14 as well as vacuum switches 15,16 and support 10 are 20 immersed in a body of oilO Contact 13 and vacuum switch 15 form a first current path to which numeral 11 has been applied. Contact 14, vacuum switch 16 and resistor 17 form a second current path to which numeral 12 has been applied.
In the position of parts shown in Fig~l fixed contact 2 is engaged by both movable contacts 13,14 and both vacuum switches 15, 16 a,re closed. Due to resistor 17 the resistance of current path 12 by far exceeds that of current path 11. ~ence the preponderance of current flow will occur from tap 6 of winding 9 to fixed con-tact 2 and from there over current path 11 to the outgoing line 22 30 which connects the tap-changing switch to any kind of load.
The position of parts shown in Fig.l may be referred-to as statiGnary position because it involves a stationary current flow 1~2~790 from tap 6 to line 22. If it is desired to change from tap 6 to tap 7, support 10 is pivoted in clockwise direction until both contacts 13,14 are in engagement with the cam surface formed by cont,act 3, where contact 3 has its normal thickness, as dis-tinguished from the end regions thereof, where the thickness of contact 3 is decreased. This position of parts may again be re-ferred-to as a stationary position. The intermediate positions of that shown in Fig.l and that shown in Fig.9 may be referred-to as transient position because in these positions the electric parameters of the circuit undergo changes.
Contacts 13 and 14 are preferably in the form of rolls since they have to roll along the cam surfaces formed by fixed contacts 1-4.
IQ the position of parts shown in Fig.l both springs 20 and 21 undergo a maximum compression.
Wh~n support 10 is pivoted in cloc~wise direction, the cam sur-face of contact 2 allows spring 21 to expand which, in turn, allows movable contact 23 of vacuum switch 16 to part from its fi~ed contact 24. That switehing operation of vacuum switch 16 does not involve any power, since the current flowing through current path 12 is minimal due to the presence of resistor 17 therein.
Further clockwise pivotal movement of support 10 and of the parts supported by the latter results in complete disengagement of movable contact 14 from fixed contact 2. This has been shown in Fig.3. Vacuum switch 16 remains open, but has not been required to perform any switching duty.
As shown in Fig.4 contact or roller 13 engages fixed contact 2, spring 20 is compressed and vacuum switch 15 is closed, contact or roller 14 engages fixed contact 3, spring 21 is expanded and allows vacuum switch 16 to remain open though contact 14 engages contact 3O Since vacuum switch 16 is open at this stage, it has not been required to perform any switching operation, but a con-1~2~7~0 ductive connection has been established between contacts 3 and14. The conditions in current branch or current path 11 remain un-changed in the position of parts shown in Fig.4 since contact 13 has only rolled along the cam surface of fixed contact 2 without any expansion of spring 20, i.e. without any movement of rod 18.
Fig.5 shows a step in the operation of the switch mechanism following that shown in Fig.4. As shown in Fig.5 contact or roller ~ has reached a point where contact 3 is sufficiently thick to cause compression of spring 21 and movement of rod 19 to close vacuum switch 16. Hence current path 12 closes a circuit extending from tap 7, across contacts 3 and 14, vacuum switch 16 and resistor 17 to outgoing line 22. On the other hand spring 20 is still compressed, rod 18 is still in its a~ially inner position and vacuum switch 15 is closed. Hence a short-time conductive connection is established between taps 6 and 7 or fixed contacts
~.
~2~7~
It is, therefore, the prime object of this invention to pro-vide tap-changing switches which are easier to manufacture, and at lower cost, than those described in the above publication. A
more specific object of the invention is to provide tap-changing switches that have greatly simplified mechanical means for achieving the required sequence of the switching operation in-volved in tap-changes.
Heretofore the operation of the vacuum switches was effected by operating rods which, in turn, were under the control of 10 separate and special cam means. The invention does away with the need of such special cam means for the control of the vacuum switches. It provides single rods of which each controls the operation of a movable contact as well as that of a vacuum switch of the device.
The invention is universally applicable, i.e. to tap-changing switches which are combined with selector switches, and to tap-changing switches as such, i.e. not combined with selector switches.
In the first instance the contacts of the tap-changing switches alternate between two limit positions, while in the second instance, `~ 20 i.e. that of load selectors, the fixed contacts of which each is connected to a tap of a transformer winding, are arranged in a circular pattern - which may encompass a sector of a circle or a full circle - and the movable contacts are pivoted around the center of said circle.
The contacts of switching devices according to this invention and their vacuum switches are intended to be arranged and operated inside of a body of oil. This allows power switching operation or, in other words, performance of switching operations under load. The gas evolution and increase in pressure that occurs inside of a body of oil in which vacuum switches are submersed may be considered as a signal that one of the vacuum switches has become defective. Hence a simple pressure sensor may be used as defect warning means.
11~4790 Summary of the Invention A tap-changing switch according to the present invention includes a plurality of fixed contacts arranged in a circular pattern, each contact of said plurality of contacts being adapted to be connected to a tap of a transformer winding. Such a switch is further provided with a pair of movable contacts each cooperating with said plurality of fixed contacts. Said pair of movable contacts is supported by a support pivotable about the center of said cir-cular pattern formed by said fixed contacts. Said support further supports a pair of vacuum switches including a first vacuum switch and a second vacuum switch each connected in series with one of said pair of movable contacts. A switching resistor supported by said support is connected in series with said first vacuum switch or with said second vacuum switch. A tap-changing switch according to this invention further includes a pair of operating rods having a limited travel, each having an axially outer end and each having an a~ially inner end, each of said pair of operating rods support-ing one of said pair of movable contacts on said axially outer end thereof. One of said pair of operating rods operates said first vacuum switch and the other of said pair of operating rods operates said second vacuum switch with the axially inner end thereof. A tap-changing switch according to this invention further includes a pair of biasing springs. One of said pair of biasing springs biases one of said pair of operating rods to open said first vacuum switch, and the other of said pair of biasing springs biases the other of said pair of operating rods to open said second vacuum switch. A
tap-changing switch according to this invention further includes a plurality of cams each having a contact-control surface engageable by each of said pair of movable contacts. Said contact-control sur-face of each of said plurality of cams includes a center portionrelatively close to said center of said circular pattern and further includes a pair of end portions having a progressively increasing spacing from said center of said circular pattern to compel closing ~124790 of one of said pair of vacuum switches when one of said pair of movable contacts engages said center portion of said contact-control surface, and to allow opening of one of said pair of vacuum switches when one of said pair of movable contacts engages one of said pair of end portions of said contact-control surface.
Brief Description of the Drawings Fig.l is a diagrammatic representation of a load-tap switch according to the present invention, its load being connected to one tap of a transformer winding; and Figs.2-9 are diagrammatic representations of the consecutive t .~ r -3a-1~247gO
switching operations following that of Fig.l until the load is connected from the tap of Fig.l to the next tap.
DescriPtion of Preferred Embodiments Referring now to the drawings, and more particularly to Fig.l thereof, reference numerals 1,2,3 and 4 have been applied to indicate four consecutive fixed or stationary contacts arranged in a circular pattern. Reference numerals 5,6,7 and 8 have been applied to indicate four taps of a transformer winding. Tap 5 is conductively connected to fixed contact 1, tap 6 is conductively 10 connected to fixed contact 2, tap 7 is conductively connected to fixed contact 3, and tap 8 is conductively connected to fixed contact 4. Reference numerals 13 and 14 have been applied to indi-cate a pair of movable contacts supported by a common support 10.
Support 10 is pivotable about the center of the circular pattern formed by fixed contacts 1-4. Support 10 further supports a first vacuum switch 15 and a second vacuum switch 16. vacuum switch 15 is connected in series with movable contact 13 and vacuum switch 16 is connected in series with movable contact 14. Reference numeral 17 has been applied to indicate a switching resistor connected in 20 series with vacuum switch 16 and with contact 14. Resistor 16 may also be connected in series with vacuum switch 15 and contact 13.
Vacuum switches 15,16 may be operated by operating rod9 18 and 19, the travel of which takes place in a direction longitudinally thereof and is limitedO Contact 13 is supported on the radially outer end of rod 18 and contact 14 is supported on the radially outer end of rod 19. The radially inner end of rods 18 and 19 op~rate vacuum switches 15 and 16, i.e.the movable contacts 23 thereof. Movable contacts 23 may be caused to engage fi~ed contacts 24 or to be separated from fixed contacts 24. Reference numerals 30 20 and 21 have been applied to indicate a pair of helical biasing springs. Spring 20 biases rod 18 in contact opening direction and spring 21 biases rod 19 in contact opening direction. Springs 20 and 1~4790 21 further bias pivotable or movable contacts 13,14 into engage-ment with any of the fixed contacts and, as shown in Fig.l, more particularly into engagement with fixed contact 2. The movement of rods 18,19 is controlled by cam means. In the embodiment of the invention shown in Fig.l these cam means are formed by the radially inner surfaces of contacts 1,2,3 and 4. As will be shown below in more detail the above referred-to cam means allow opening by springs 20 of vacuum switch 15 at the end of the en-gagement of one of fixed contacts 1-4 by movable contact 13 and 10 at the beginning of the engagement of another of said fixed con-tacts 1-4 by movable contact 13. In a like fashion the above re-ferred-to cam means allow opening by spring 21 of vacuum switch 16 at the end of the engagement of one of fixed contacts 1-4 by movable contact 14 and at the beginning of the engagement of another of said fixed contacts 1-4 by movable contact 14. To achieve the aforementioned way of controlling the operation of vacuum switches 15 and 16 the end portions of fixed contacts 1-4 are thinner in radial direction than the center portions thereof. Contacts 1-4 and 13,14 as well as vacuum switches 15,16 and support 10 are 20 immersed in a body of oilO Contact 13 and vacuum switch 15 form a first current path to which numeral 11 has been applied. Contact 14, vacuum switch 16 and resistor 17 form a second current path to which numeral 12 has been applied.
In the position of parts shown in Fig~l fixed contact 2 is engaged by both movable contacts 13,14 and both vacuum switches 15, 16 a,re closed. Due to resistor 17 the resistance of current path 12 by far exceeds that of current path 11. ~ence the preponderance of current flow will occur from tap 6 of winding 9 to fixed con-tact 2 and from there over current path 11 to the outgoing line 22 30 which connects the tap-changing switch to any kind of load.
The position of parts shown in Fig.l may be referred-to as statiGnary position because it involves a stationary current flow 1~2~790 from tap 6 to line 22. If it is desired to change from tap 6 to tap 7, support 10 is pivoted in clockwise direction until both contacts 13,14 are in engagement with the cam surface formed by cont,act 3, where contact 3 has its normal thickness, as dis-tinguished from the end regions thereof, where the thickness of contact 3 is decreased. This position of parts may again be re-ferred-to as a stationary position. The intermediate positions of that shown in Fig.l and that shown in Fig.9 may be referred-to as transient position because in these positions the electric parameters of the circuit undergo changes.
Contacts 13 and 14 are preferably in the form of rolls since they have to roll along the cam surfaces formed by fixed contacts 1-4.
IQ the position of parts shown in Fig.l both springs 20 and 21 undergo a maximum compression.
Wh~n support 10 is pivoted in cloc~wise direction, the cam sur-face of contact 2 allows spring 21 to expand which, in turn, allows movable contact 23 of vacuum switch 16 to part from its fi~ed contact 24. That switehing operation of vacuum switch 16 does not involve any power, since the current flowing through current path 12 is minimal due to the presence of resistor 17 therein.
Further clockwise pivotal movement of support 10 and of the parts supported by the latter results in complete disengagement of movable contact 14 from fixed contact 2. This has been shown in Fig.3. Vacuum switch 16 remains open, but has not been required to perform any switching duty.
As shown in Fig.4 contact or roller 13 engages fixed contact 2, spring 20 is compressed and vacuum switch 15 is closed, contact or roller 14 engages fixed contact 3, spring 21 is expanded and allows vacuum switch 16 to remain open though contact 14 engages contact 3O Since vacuum switch 16 is open at this stage, it has not been required to perform any switching operation, but a con-1~2~7~0 ductive connection has been established between contacts 3 and14. The conditions in current branch or current path 11 remain un-changed in the position of parts shown in Fig.4 since contact 13 has only rolled along the cam surface of fixed contact 2 without any expansion of spring 20, i.e. without any movement of rod 18.
Fig.5 shows a step in the operation of the switch mechanism following that shown in Fig.4. As shown in Fig.5 contact or roller ~ has reached a point where contact 3 is sufficiently thick to cause compression of spring 21 and movement of rod 19 to close vacuum switch 16. Hence current path 12 closes a circuit extending from tap 7, across contacts 3 and 14, vacuum switch 16 and resistor 17 to outgoing line 22. On the other hand spring 20 is still compressed, rod 18 is still in its a~ially inner position and vacuum switch 15 is closed. Hence a short-time conductive connection is established between taps 6 and 7 or fixed contacts
2 and 3. Hence an equalizing current is allowed to flow which is, however, drastically limited by the presence of resistor 17.
According to Fig.6 contact or roller 13 has reached a point where the thickness of fixed contact 2 has decreased, allowing spring 20 to expand, to move rod 18 in a direction longitudinally thereof and to allow vacuum switch 15 to open. However, contacts 2 and 13 have not parted as yet. Since vacuum switch 16 is closed, the vacuum switch 15 has to cope with both the load current and the equalizing current. Arrangements can be made to prevent addition of both currents; but this is not absolutely necessary since vacuum switches are capable of handling large currents.
Referring now to Fig.7, contact 13 has parted from contact 2, thus interrupting current path 11. The load current is furnished only by tap 7 and flows from the latter through parts 3,14,17 to outgoing line 22. The load current is limited by resistor 17.
Figo8 shows the preparation of branch circuit 11 to carry the load current without limitation thereof by current - limiting resistor 17. According to Figo8 fixed contact 3 has been engaged il247~0 by movable contact 13, but spring 20 has not been compressed as yet, rod 18 has not been moved inwardly toward the pivot of support 10, and vacuum switch 15 is still open.
Re~erring now to Fig.9,contact roller 13 has reached a point where the thickness of contact 3 is such as to cause compression of spring 20, inward movement of rod 18 and closing of vacuum switch 15. Now almost all of the load current flows from tap 7 through branch 11 to outgoing line 22. Hence it is not necessary to establish a break in the branch 12.
The same process is repeated when the tap-changing switch is moved one step foreward to fixed contact 4.
However, if the direction of operation of the tap-changing switch is reversed, the above described sequence of steps is also reversed. Assuming the position of parts shown in Fig.9 to be the starting point, then first branch circuit 11 is interrupted by opening of vacuum switch 15, as shown in Fig.8. Then contact 13 parts from contact 3, as shown in Fig.7, which does not involve any power. Thereafter contact or roller 13 engages fixed contact 2 as shown in Fig.6, which is also a switching operation not in-volving any power. Next the position of parts shown in Fig.5 isachieved, wherein taps 6 and 7 are conductively interconnected for a short time, switching resistor 17 being interposed in the current path between said two taps. Continued movement of the pivotable parts of the tap-changing switch in counter-clockwise direction results in opening of vacuum switch 16, as shown iQ Fig.4. There-after contacts 3 and 14 part from each other and vacuum switch 16 opens under the action of spring 21, as shown in Fig.3~ Thereafter pivotable contact 14 engages fixed contact 2 closing the current path 12 between these two contacts. Finally contact or roller 14 reaches the point of increased thickness of contact 2, resulting in inward movement of the former and of rod 19, compression of spring 21 and closing of vacuum switch 160 11~47~
The severity of the switching operations of vacuum switches 15,16 depends upon the direction of operation of the tap-changing switch. But this is of little consequence because of the high interrupting ability of vacuum switches.
It will be apparent from the above that the contact-control surfaces of the cams, i.e. the surfaces which control contacts 13,14, form part of contacts 1-4 and are ju~taposed to the center of contacts 1-4. Contacts 1-4 have substantially the shape of a sector of an annulus. Each sector includes a relatively thick 10 center region and relatively thin end regions. The center region of the contact-control surface of each of the plurality of cams is relatively close to, and the end region of the contact-control surface of each of said plurality of cams are relatively remote from, the center of contacts 1-4 about which support 10 pivots. Hence the regions of the contact-control surfaces relative-ly close to said center effect closing of vacuum switches 15,16 against the bias of springs 20,21 while the end regions of the contact-control surfaces relatively remote from said center allow opening of vacuum switches 15,16 under the action of springs 20 20 and 21.
~' .';
_g_
According to Fig.6 contact or roller 13 has reached a point where the thickness of fixed contact 2 has decreased, allowing spring 20 to expand, to move rod 18 in a direction longitudinally thereof and to allow vacuum switch 15 to open. However, contacts 2 and 13 have not parted as yet. Since vacuum switch 16 is closed, the vacuum switch 15 has to cope with both the load current and the equalizing current. Arrangements can be made to prevent addition of both currents; but this is not absolutely necessary since vacuum switches are capable of handling large currents.
Referring now to Fig.7, contact 13 has parted from contact 2, thus interrupting current path 11. The load current is furnished only by tap 7 and flows from the latter through parts 3,14,17 to outgoing line 22. The load current is limited by resistor 17.
Figo8 shows the preparation of branch circuit 11 to carry the load current without limitation thereof by current - limiting resistor 17. According to Figo8 fixed contact 3 has been engaged il247~0 by movable contact 13, but spring 20 has not been compressed as yet, rod 18 has not been moved inwardly toward the pivot of support 10, and vacuum switch 15 is still open.
Re~erring now to Fig.9,contact roller 13 has reached a point where the thickness of contact 3 is such as to cause compression of spring 20, inward movement of rod 18 and closing of vacuum switch 15. Now almost all of the load current flows from tap 7 through branch 11 to outgoing line 22. Hence it is not necessary to establish a break in the branch 12.
The same process is repeated when the tap-changing switch is moved one step foreward to fixed contact 4.
However, if the direction of operation of the tap-changing switch is reversed, the above described sequence of steps is also reversed. Assuming the position of parts shown in Fig.9 to be the starting point, then first branch circuit 11 is interrupted by opening of vacuum switch 15, as shown in Fig.8. Then contact 13 parts from contact 3, as shown in Fig.7, which does not involve any power. Thereafter contact or roller 13 engages fixed contact 2 as shown in Fig.6, which is also a switching operation not in-volving any power. Next the position of parts shown in Fig.5 isachieved, wherein taps 6 and 7 are conductively interconnected for a short time, switching resistor 17 being interposed in the current path between said two taps. Continued movement of the pivotable parts of the tap-changing switch in counter-clockwise direction results in opening of vacuum switch 16, as shown iQ Fig.4. There-after contacts 3 and 14 part from each other and vacuum switch 16 opens under the action of spring 21, as shown in Fig.3~ Thereafter pivotable contact 14 engages fixed contact 2 closing the current path 12 between these two contacts. Finally contact or roller 14 reaches the point of increased thickness of contact 2, resulting in inward movement of the former and of rod 19, compression of spring 21 and closing of vacuum switch 160 11~47~
The severity of the switching operations of vacuum switches 15,16 depends upon the direction of operation of the tap-changing switch. But this is of little consequence because of the high interrupting ability of vacuum switches.
It will be apparent from the above that the contact-control surfaces of the cams, i.e. the surfaces which control contacts 13,14, form part of contacts 1-4 and are ju~taposed to the center of contacts 1-4. Contacts 1-4 have substantially the shape of a sector of an annulus. Each sector includes a relatively thick 10 center region and relatively thin end regions. The center region of the contact-control surface of each of the plurality of cams is relatively close to, and the end region of the contact-control surface of each of said plurality of cams are relatively remote from, the center of contacts 1-4 about which support 10 pivots. Hence the regions of the contact-control surfaces relative-ly close to said center effect closing of vacuum switches 15,16 against the bias of springs 20,21 while the end regions of the contact-control surfaces relatively remote from said center allow opening of vacuum switches 15,16 under the action of springs 20 20 and 21.
~' .';
_g_
Claims (4)
1. A tap-changing switching device including vacuum switches for connecting a tapped transformer winding to a load comprising in combination (a) a plurality of fixed contacts arranged in a circular pattern, each contact of said plurality of contacts being adapted to be connected to a tap of said transformer winding;
(b) a pair of movable contacts each cooperating with said plurality of fixed contacts;
(c) said pair of movable contacts being supported by a support pivotable about said center of said circular pattern;
(d) said support further supporting a pair of vacuum switches including a first vacuum switch and a second vacuum switch each connected in series with one of said pair of movable contacts;
(e) a switching resistor supported by said support and connected in series with said first vacuum switch or with said second vacuum switch;
(f) a pair of operating rods having a limited travel, each of said pair of operating rods having an axially outer end and an axially inner end,each of said pair of operating rods supporting one of said pair of movable contacts on said axially outer end, said first vacuum switch and said second vacuum switch each being operated by said axially inner end of one of said pair of operating rods;
(g) a pair of biasing springs, each of said pair of biasing springs biasing one of said pair of operating rods to open one of said pair of vacuum switches;
(h) a plurality of cams each having a contact-control surface engageable by each of said pair of movable contacts; and (i) said contact-control surface of each of said plurality of cams including a center portion relatively close to said center of said circular pattern, and further including a pair of end portions having a progressively increasing spacing from said center of said circular pattern, said center portion compelling closing of one of said pair of vacuum switches when one of said pair of movable contacts engages said center portion, and said pair of end portions allowing opening of one of said pair of vacuum switches when one of said pair of movable contacts engages one of said pair of end portions.
(b) a pair of movable contacts each cooperating with said plurality of fixed contacts;
(c) said pair of movable contacts being supported by a support pivotable about said center of said circular pattern;
(d) said support further supporting a pair of vacuum switches including a first vacuum switch and a second vacuum switch each connected in series with one of said pair of movable contacts;
(e) a switching resistor supported by said support and connected in series with said first vacuum switch or with said second vacuum switch;
(f) a pair of operating rods having a limited travel, each of said pair of operating rods having an axially outer end and an axially inner end,each of said pair of operating rods supporting one of said pair of movable contacts on said axially outer end, said first vacuum switch and said second vacuum switch each being operated by said axially inner end of one of said pair of operating rods;
(g) a pair of biasing springs, each of said pair of biasing springs biasing one of said pair of operating rods to open one of said pair of vacuum switches;
(h) a plurality of cams each having a contact-control surface engageable by each of said pair of movable contacts; and (i) said contact-control surface of each of said plurality of cams including a center portion relatively close to said center of said circular pattern, and further including a pair of end portions having a progressively increasing spacing from said center of said circular pattern, said center portion compelling closing of one of said pair of vacuum switches when one of said pair of movable contacts engages said center portion, and said pair of end portions allowing opening of one of said pair of vacuum switches when one of said pair of movable contacts engages one of said pair of end portions.
2. A tap-changing system as specified in claim 1 wherein each of said plurality of fixed contacts has a contact-control surface.
3. A tap-changing system as specified in claim 2 wherein each of said plurality of fixed contacts has substantially the shape of a sector of an annulus including a center region and end regions, and wherein the thickness of said center region exceeds the thickness of said end regions.
4. A tap-changing switching device as specified in claim 3 wherein said system of fixed contacts, said pair of movable contacts and said support are arranged in a body of oil.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2731133.7 | 1977-07-09 | ||
| DE2731133A DE2731133C2 (en) | 1977-07-09 | 1977-07-09 | Step switch for step transformers with a contact system operated under oil |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1124790A true CA1124790A (en) | 1982-06-01 |
Family
ID=6013575
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA306,804A Expired CA1124790A (en) | 1977-07-09 | 1978-07-05 | Tap-changing switching device including vacuum switches |
Country Status (12)
| Country | Link |
|---|---|
| JP (1) | JPS5419119A (en) |
| AT (1) | AT362025B (en) |
| BE (1) | BE868641A (en) |
| CA (1) | CA1124790A (en) |
| DE (1) | DE2731133C2 (en) |
| ES (1) | ES471556A1 (en) |
| FR (1) | FR2397095A1 (en) |
| GB (1) | GB2000911B (en) |
| HU (1) | HU182971B (en) |
| IN (1) | IN148031B (en) |
| NL (1) | NL7807360A (en) |
| SE (1) | SE418126B (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0009287A1 (en) * | 1978-09-18 | 1980-04-02 | ATELIERS DE CONSTRUCTIONS ELECTRIQUES DE CHARLEROI (ACEC) Société Anonyme | Electrical apparatus comprising a series of voltage taps and a tap selector and/or a circuit breaker |
| JPS6179210A (en) * | 1984-09-27 | 1986-04-22 | Toshiba Corp | On-load tap changer |
| GB8607397D0 (en) * | 1986-03-25 | 1986-04-30 | Northern Eng Ind | Arc interrupter |
| DE3833126C2 (en) * | 1988-09-29 | 1995-11-30 | Reinhausen Maschf Scheubeck | Load selector for step transformers |
| CA2140156C (en) * | 1992-07-16 | 1999-01-19 | Dieter Dohnal | Step switch |
| CN1077325C (en) * | 1994-01-27 | 2002-01-02 | 赖茵豪森机械制造公司 | Single pole step-by-step switch with linear operating contact |
| US7982142B2 (en) | 2004-06-30 | 2011-07-19 | Abb Research Ltd. | Diverter switch, a method for operating such a switch and use of such a switch |
| JP5279120B2 (en) * | 2008-10-27 | 2013-09-04 | 株式会社高岳製作所 | Load tap changer |
| CN103177861A (en) * | 2013-04-02 | 2013-06-26 | 江苏硕德开关有限公司 | On-load capacity-adjusting switch high voltage primary loop structure |
| CN104916491B (en) * | 2015-06-30 | 2017-05-17 | 昆山国力电子科技股份有限公司 | Permanent magnet vacuum on-load tap switch |
| CN108899184B (en) * | 2016-02-05 | 2021-07-13 | 浙江宝威电气有限公司 | Transformer on-load capacitance-regulating switch convenient for arc extinguishing |
| CN113192775B (en) * | 2021-04-26 | 2022-11-18 | 国网河南省电力公司超高压公司 | A contact assembly for an on-load voltage regulating switch |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL67667C (en) * | 1946-10-23 | 1951-03-16 | Smit & Willem & Co Nv | |
| FR1453814A (en) * | 1964-11-06 | 1966-07-22 | Telemecanique Electrique | Switching device known as limit switch |
| DE2202186A1 (en) * | 1972-01-15 | 1973-07-26 | Transformatoren Union Ag | MECHANISM FOR LOAD CHANGEOVER OF STEPPED TRANSFORMERS |
| DE2321369A1 (en) * | 1973-04-27 | 1974-11-07 | Transformatoren Union Ag | LOAD SELECTOR FOR TAP-SWITCHES OF TRANSFORMERS AND REACTORS |
-
1977
- 1977-07-09 DE DE2731133A patent/DE2731133C2/en not_active Expired
-
1978
- 1978-05-30 IN IN404/DEL/78A patent/IN148031B/en unknown
- 1978-06-28 FR FR7819367A patent/FR2397095A1/en active Pending
- 1978-06-30 BE BE188991A patent/BE868641A/en not_active IP Right Cessation
- 1978-07-05 CA CA306,804A patent/CA1124790A/en not_active Expired
- 1978-07-06 JP JP8150878A patent/JPS5419119A/en active Granted
- 1978-07-06 AT AT491178A patent/AT362025B/en not_active IP Right Cessation
- 1978-07-06 GB GB7829029A patent/GB2000911B/en not_active Expired
- 1978-07-06 SE SE7807596A patent/SE418126B/en not_active IP Right Cessation
- 1978-07-07 ES ES471556A patent/ES471556A1/en not_active Expired
- 1978-07-07 HU HU78MA3000A patent/HU182971B/en unknown
- 1978-07-07 NL NL7807360A patent/NL7807360A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| SE7807596L (en) | 1979-01-10 |
| IN148031B (en) | 1980-09-27 |
| ATA491178A (en) | 1980-09-15 |
| GB2000911A (en) | 1979-01-17 |
| ES471556A1 (en) | 1979-01-16 |
| DE2731133C2 (en) | 1982-01-07 |
| GB2000911B (en) | 1982-02-17 |
| HU182971B (en) | 1984-03-28 |
| FR2397095A1 (en) | 1979-02-02 |
| SE418126B (en) | 1981-05-04 |
| AT362025B (en) | 1981-04-27 |
| JPS5419119A (en) | 1979-02-13 |
| DE2731133B1 (en) | 1978-12-07 |
| NL7807360A (en) | 1979-01-11 |
| BE868641A (en) | 1978-10-16 |
| JPS6145845B2 (en) | 1986-10-09 |
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| MKEX | Expiry |