EP0815572B1 - On-load tap changer of a step switch - Google Patents

Abstract

PCT No. PCT/EP96/00400 Sec. 371 Date Mar. 25, 1997 Sec. 102(e) Date Mar. 25, 1997 PCT Filed Jan. 31, 1996 PCT Pub. No. WO96/30922 PCT Pub. Date Oct. 3, 1996An on-load tap changer of a step switch has a force-storage unit which has a charging slide continuously movable by a bidirectionally rotatable drive shaft and an output part that when tripped suddenly follows the movement of the charging slide and rotates a switching shaft. Respective switches for each phase are each actuatable by respective actuating elements that coact with edges of respective concentric cams rotatable by the switching shaft. An axially movable switching unit is mounted on the switching shaft and the switching unit carries cam disks for actuating the switches, each cam disk being subdivided into an upper and a lower subdisk with different shapes. The switching unit is movable in a direction dependent on the rotation direction of the drive shaft into an upper or a lower position. In the upper position of the switching unit all of the lower cam subdisks and in the lower position of the switching unit all of the upper cam subdisks engage the actuating elements to actuate the respective switches.

Description

The invention relates to a diverter switch of a tap changer according to the preamble of first claim.

Such diverter switches are known from DE-OS 42 31 353. Two vacuum interrupters, hereinafter referred to as VAC, are provided for each phase; These VAC and mechanical switch contacts are actuated by a switch shaft that can be rotated in both directions and is quickly rotated after a force accumulator is triggered. In order to actuate the VAC, a cam is fixedly arranged on the control shaft, which has a control cam on its face for each VAC, in which a role is positively guided, which acts on the actuating lever of the assigned VAC.
The mechanical contacts are switched by a switching segment, which is also rotated by the drive shaft and which switches between fixed contacts arranged on the circumference of the diverter switch.
With this diverter switch, the cams for actuating the two VACs and the switching segment for actuating the mechanical contacts are moved from one end position to the other and back again, regardless of the respective direction of movement of the tap changer; this means that the contacts which closed last when moving, ie rotating the selector shaft in one direction, opened first when moving back, ie rotating the selector shaft in the other direction, and vice versa.

Such a known diverter switch is therefore not suitable for realizing an asymmetrical circuit in which the same contact is always the first to be switched electrically or moved mechanically, regardless of the switching direction.
Such an unbalanced circuit is described, for example, in the unpublished DE-OS 44 07 945 and in a modified form with double-pole switching especially for diverter switches in the - also unpublished DE-OS 44 41 082.

FIG. 4 shows the last-mentioned asymmetrical circuit with double-pole switching, in which, regardless of the switching direction, the same actuation sequence, i.e. sequence switching means to be moved or actuated is present.

WO 89/08924 already has a special one for thyristor switches Spring jump drive described, which is independent of its drive direction always in one Should trigger direction, i.e. has only one output direction.

This is one way to implement basically asymmetrical circuits; of the described spring force accumulator is complicated in structure, required by the large number the necessary locking and coupling elements take up a lot of space and is for the rest combined actuation of VAC as electrical switching elements on the one hand and mechanical contacts, on the other hand, in a predetermined actuation sequence suitable.

The object of the invention is therefore a diverter switch of the type described above specify, which can be driven in a simple manner with one in both directions of rotation Switching shaft allows the implementation of an asymmetrical circuit, such that The same VAC and mechanical actuation sequence regardless of the direction of rotation Switching elements should be accessible.

This object is achieved by a diverter switch with the features of the first claim.
The subclaims contain particularly advantageous developments of the invention.

The main advantage of the invention lies in the fact that in that a conventional Energy storage device, which has an elevator carriage and an output part, as it does described for example in DE-PS 28 06 282, can be used. Doing so from the elevator carriage during the continuous elevator process according to the invention in addition, a direction perpendicular to the elevator direction, in the axial direction of the control shaft acting further movement of a coupling member to be explained in more detail. According to the invention, for each switching element to be actuated, both VAC and mechanical contacts, different for each direction of movement of the drive shaft Partial cams with each other on an axially displaceable on the selector shaft arranged switch insert attached; by the axial movement of the Coupling member can be provided for the respective direction of movement of the drive shaft Partial cams also axially displaced and thus with the corresponding Switching elements for actuating the VAC as well as the mechanical contacts are brought into or out of engagement depending on the direction of rotation.

Fig. 1

zeigt einen erfindungsgemäßen Lastumschalter in seitlicher Schnittdarstellung

Fig. 2

zeigt eben diesen Lastumschalter im Querschnitt in der Ebene A-A

Fig. 3

zeigt einen Kraftspeicher mit einem erfindungsgemäßen Koppelelement allein in perspektivischer Darstellung

Fig. 4

zeigt eine mit der Erfindung realisierbare an sich bekannte unsymmetrische Schaltung

Fig. 5

zeigt diese Schaltung mit Schaltkontakten, die, wie in Fig. 1 dargestellt, jeweils um einen Drehpunkt gelagert und als Wechsler ausgebildet sind

Fig. 6

zeigt den Schaltablauf der in Fig. 5 dargestellten Schaltung

Fig. 7

zeigt das entsprechende Schaltdiagramm.

The invention will be explained in more detail below by means of drawings.

Fig. 1

shows a diverter switch according to the invention in a lateral sectional view

Fig. 2

shows just this diverter switch in cross section in the plane AA

Fig. 3

shows an energy accumulator with a coupling element according to the invention alone in perspective

Fig. 4

shows an asymmetrical circuit known per se that can be implemented with the invention

Fig. 5

shows this circuit with switch contacts, which, as shown in Fig. 1, each mounted around a pivot point and designed as a changer

Fig. 6

shows the switching sequence of the circuit shown in Fig. 5

Fig. 7

shows the corresponding circuit diagram.

The diverter switch according to the invention consists of a diverter switch housing, here an insulating cylinder 1, in which a central switching shaft 4 is arranged.
The selector shaft 4 is actuated in a manner known per se by an energy store 2. The energy accumulator 2 has an elevator carriage 2.2, which is continuously pulled up by a rotating drive cam 2.1 of a drive shaft, not shown here, and which, when it reaches its end position, abruptly runs after an output part 2.3, which in turn drives the control shaft 4 in a known and not shown manner .
In addition, according to the invention, a contour 2.4, here on both sides, is provided on the side of the elevator carriage 2.2, in each of which a roller 3.3 of a coupling element 3 engages.
The coupling member 3 also consists of two levers 3.1, which are mounted laterally at approximately the level of the energy accumulator 2, and two articulated coupling rods 3.2, which extend vertically in the diverter switch housing parallel to the selector shaft 4 and down on their free The ends are connected to a switching insert 5 which is axially displaceable on the switching shaft 4.
It is of course also possible to provide a contour 2.4 on the side of the elevator carriage 2.2 only on one side and accordingly to also arrange only one coupling element, but the paired arrangement described offers stability advantages.
The contour 2.4 described is designed so that - depending on the direction of movement of the elevator carriage 2.2 of the energy accumulator 2 - by means of the coupling element 3 when the energy accumulator 2 is pulled up, ie before the actual load switchover, the switching insert 5 axially on the control shaft 4 by a certain amount a is moved up or down.
The shift insert 5 axially displaceable on the shift shaft 4 can be rotated together with the latter by the triggered energy store 2; this is possible, for example, by a multi-toothed design of the shift shaft 4, which thereby allows the shift insert 5 to be positively carried along without impairing its axial displaceability. To ensure this mode of operation, a bearing, for example a ball bearing, is provided between the lower part of the coupling element 3 and the switching insert 5, for example a bearing (not shown in more detail in the figures).
Arranged one above the other on the switching insert 5 are two cam disks 6, 7 with end-side switching curves for actuating the two VAC 11, 12, each of which consists of an upper partial cam disk 6.1, 7.1 and a lower partial cam disk 6.2, 7.2 arranged directly one above the other.
On the switching insert 5, two cams 8, 9 for actuating two movable mechanical contacts 13, 14 are also arranged, which will be explained later.
Actuating rollers 11.1, 12.1 are arranged laterally next to the respective cam disks 6, 7, such that, depending on the position of the switching insert 5, the two upper partial cam disks 6.1, 7.1 or the two lower partial cam disks 6.2, 7.2 correspond to the respective actuating rollers 11.1, 12.1. These actuating rollers 11.1, 12.1 act on the respective VAC 11, 12 via angle levers 11.2, 12.2 and actuate them.
In the stationary state of the diverter switch, there is a gap between the actuating rollers 11.1, 12.1 and the associated partial cam disks 6.1, 7.1 and 6.2, 7.2, since the VAC 11, 12 are closed without force from the outside in the stationary state; these are only positively actuated and opened briefly during the load switching by the respective partial cam disc via the respective roller and the respective actuating lever.
This explained gap in the stationary state makes it possible to move the switching insert 5 and thus the cam plates 6, 7 without collisions between them and the actuating rollers 11.1, 12.1.

Similarly, the two further cams 8, 9 for actuating the two movable mechanical contacts 13, 14 are provided on the switching insert 5. The cams 8, 9 are also arranged one above the other
Partial cams 8.1, 8.2; 9.1, 9.2 divided. Depending on the direction of rotation of the selector shaft, either the two upper partial cams 8.1, 9.1 or the two lower partial cams 8.2, 9.2 correspond to laterally arranged first rollers 13.1, 14.1 or second rollers 13.2, 14.2. In Figure 1, the engagement of the two lower cam plates 8.2, 9.2 is shown.
The roles 13.1, 14.1; 13.2, 14.2 are each connected to spring-loaded toggle levers 13.3, 14.3, which act on the rotatably mounted mechanical contacts 13, 14 in such a way that they can be brought into two switching positions beyond a dead center. The first mechanical contact 13 acts as a switching contact SKM and, depending on the position it occupies, connects either the two fixed contacts SKM _A or the two fixed contacts SKM _{B to} one another. The second movable contact 14 acts as a mechanical auxiliary contact HKM and, depending on the position it occupies, connects either the two fixed auxiliary contacts HKM _A or the two fixed auxiliary contacts HKM _{B to} one another. The two movable mechanical contacts 13, 14 are arranged in the same horizontal plane.
The actuation of the corresponding rollers 13.1, 14.1; 13.2, 14.2 and thus the two toggle levers 13.3, 14.3 through the corresponding partial cam disks 8.1, 9.1 and 8.2, 9.2 of the cam disks 8, 9 are again non-positively, ie cam disks 8, 9 and rollers 13.1, 14.1 are in the stationary state; 13.2, 14.2 not in engagement, so that - as has already been described above for the actuation of the VAC - an axial displacement of the switching insert 5 is easily possible before the load switchover, in particular without collision with any actuating elements, here the rollers.

However, there is a significant difference between the actuation of the VAC 11, 12 and the mechanical contacts 13, 14:
Due to their design, the VAC 11, 12 are always closed when stationary, i.e. they have a stable state that sets itself automatically without additional force, due to the vacuum inside and an additional spring.
It follows from this that a single cam disk is sufficient for actuation, ie the temporary switching to the other switching state. As soon as the effect of this cam disc ceases, the VAC automatically returns to the stable, closed switching state.
This is different with the mechanical contacts 13, 14 described. Here, each movable contact 13, 14, which is mounted about a pivot point, due to the respective spring-loaded toggle lever, can be moved over a dead center and assume two stable states. Each movable mechanical contact 13, 14 is accordingly assigned an upper first roller 13.1, 14.1 and a lower second roller 13.2, 14.2, respectively, which allow alternating switching between the two stable switching states.

To make the structure of the diverter switch simple, it is also possible to use the Embodiment separately shown cams 8, 9 into a single Combine cam with only one upper and one lower cam, in such a way that the actuation of both SKM and HKM in each switching direction is only possible by one only partial cam is carried out.

The previous explanations relate only to one phase of a diverter switch according to the invention. In the case of a three-phase diverter switch, the explained mechanical and electrical actuating and switching elements of all three phases are particularly advantageously arranged in a single horizontal plane.
Fig. 2 shows such an arrangement schematically from above.

It can be seen that within the insulating cylinder 1, the selector shaft 4 is arranged with the axially displaceable and rotatable together with it the switching insert 5 which carries the cams 6, 7, 8, 9 with the respective partial cams.
It can also be seen that centrally around these cams for each phase the two VACs, one acting as an electrical switching contact SKV and the other as an electrical auxiliary contact HKV according to the circuit shown in FIG. 4, and the mechanical contacts for double-pole interruption, whereby one acts as a mechanical switch contact SKM and the other as a mechanical auxiliary contact HKM.
The areas in which the switching and actuating means of a phase are located are identified by areas delimited by arrows in FIG. 2.

Of course, an additional arrangement of known main contacts for continuous current carrying, ie to relieve the switching contacts in stationary operation, is also possible. Circuits of this type extended by permanent main contacts are known. Since the
Permanent main contacts are opened first and closed last, regardless of the switching direction during load switching, and they can be actuated in a manner known per se by means of a contour or cam disc which is firmly connected to the switching shaft 4. An axial shift depending on the switching direction is not necessary. In the exemplary embodiment explained above, however, such permanent main contacts have been deliberately omitted.

Overall, the invention allows a simple implementation of asymmetrical circuits, ie a simple implementation of the same sequence of actuation of electrical and mechanical switching elements in a diverter switch regardless of its switching direction, which alternates due to the force accumulator that can be opened and released in two directions.
The movement required for the shift-direction-dependent shift according to the invention is generated in a simple manner during the continuous movement of the elevator carriage of a force accumulator known per se, ie before the actual switching process begins. All that is required is the additional contour described on the side of the elevator carriage; Except for this easily realizable change, the known energy stores can be used in unchanged form, which offers further advantages.

It is understood that the number and shape of the cams and the actuating and Switching elements, namely both the electrical and the mechanical switching elements, are adaptable to the circuit to be implemented in each case and the invention does not apply to that explained embodiment with two VAC per phase and two double-pole mechanical Switch contacts per phase is limited.

Claims (9)

1. Load diverter switch of a tap-changing switch and consisting of a force storage device (2), which comprises a tension carriage (2.2) continuously movable by a drive shaft rotatable in both directions and a drive output part which after its release rapidly follows the movement of the tensioning carriage (2.2), consisting furthermore of a switch shaft (4) which is rotatable by the released drive output part and consisting furthermore of switching means for each phase, which are actuable by actuating elements which in turn correspond with concentric cam discs (8, 9) of end face outline and rotatable by the switch shaft (4), characterised thereby, that an axially displaceable switch insert (5) is arranged on the switch shaft (4), that the switch insert (5) carries the cam discs (6, 7, 8, 9) for the actuation of the switching means, that each cam disc (6, 7, 8, 9) is subdivided into an upper and lower part cam disc (6.1, 7.1, 8.1, 9.1; 6.2, 7.2, 8.2, 9.2) with outlines differing one among the other and that the switch insert (5) is movable into an upper or lower operative setting directionally dependent on the direction of rotation of the drive shaft in such a manner that the actuating elements (11.1, 11.2; 12.1, 12.2; 13.1, 13.2, 13.3; 14.1, 14.2, 14.3) for the actuation of the switching means correspond with all lower part cam discs (6.2, 7.2, 8.2, 9.2) for the upper operative setting of the switch insert (5) and with all upper part cam discs (6.1, 7.1, 8.1, 9.1) for the lower operative setting of the switch insert (5).
2. Load diverter switch according to claim 1, characterised thereby, that the switch insert (5) is shape-lockingly connected by means of a coupling member (3) with an outline (2.4) at the tensioning carriage (2.2) of the force storage device (2) in such a manner that, on the movement of the tensining carriage (2.2), the switch insert (5) is axially displaceable upwardly or downwardly directionally dependent on this movement and movable into an upper or lower operative setting.
3. Load diverter switch according to claim 1 or 2, characterised thereby, that the switching means consist of at least two vacuum switching tubes (11, 12) and at least two mechanical contacts (13, 14) for each phase.
4. Load diverter switch according to claim 3, characterised thereby, that each actuating element for the actuation of the vacuum switches (11, 12) consists of a fastening roller (11.1, 12.1), which correspnds force-lockingly with the respective part cam disc (6.1, 6.2; 7.1, 7.2), and an angle lever (11.2, 12.2) connected therewith.
5. Load diverter switch according to claim 3 or 4, characterised thereby, that each actuating element for the actuation of the mechanical contacts (13, 14) consists of a first and a second roller (13.1, 13.2; 14.1, 14.2), which corresponds force-lockingly with the respective part cam disc, as well as of a spring-loaded toggle lever (13.3, 14.3) in such a manner that the respective mechanical contact (13, 14) is switchable to and fro between two stationary states according to whether a pressure is exerted on the respective first roller (13.1, 14.1) or on the respective second roller (13.2, 14.2).
6. Load diverter switch according to claim 5, characterised thereby, that all first rollers (13.1, 14.1) on the one hand and all second rollers (13.2, 14.2) on the other hand correspond with the same part cam disc each time.
7. Load diverter switch according to one of the claims 3 to 6, characterised thereby, that the mechanical contacts (13, 14) are constructed as double-pole switch contacts.
8. Load diverter switch according to one of the claims 3 to 7, characterised thereby, that additional in themselves known continuous main contacts are provided, which are actuable directly by the switch shaft (4) and in the stationary state take over the continuous current conduction.
9. Load diverter switch according to one of the claims 3 to 8, characterised thereby, that the further cam discs (8, 9) for the actuation of the mechanical contacts (13, 14) are combined into a single cam disc which is subdivided into an upper and lower part cam disc with outlines differing one among the other.

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