EP1881510B1 - Vacuum switch tube - Google Patents

Description

The invention relates to a vacuum interrupter for a diverter switch a tap changer, in which all contacts of one phase, which are necessary for switching under load, constitute a structural unit.

Voltage regulation of power transformers must be done without load interruption. Typically, this voltage regulation is done by connecting or disconnecting windings of the transformer. During these switching operations, the load current in the transformer must never be interrupted. Otherwise, damage would occur in the transformer and proper supply of the consumers with electrical energy would no longer be guaranteed.

The uninterrupted switching of transformer windings is therefore usually with tap changers. A diverter switch basically consists of two components: the (actual) diverter switch and the selector. The selector is connected directly to the taps of a transformer fine stage winding and is used for the load-free preselection of the winding tap to be switched to. The uninterrupted switching of the load current itself is done with the diverter switch. For this purpose, the diverter switch on mechanical contacts or vacuum interrupters.

Conventional vacuum interrupters are merely simple on-off switches.

In the EP 0258614B1 discloses a tap changer, which has only a single, specially designed vacuum interrupter for load current switching for each phase. The vacuum interrupter described therein combines all the contacts required for the actual load changeover in a single housing. This makes it possible to prevent the contamination of the dielectric transformer oil, but it has been shown that due to the dependent movement of the upper and lower push rod of the implementation of the principle necessary synchronization is technically difficult to achieve. Even a slight deviation from this synchronization is sufficient so that the switching contacts may stand out from each other and thus cause an unwanted interruption of the circuit. Even without lifting the contacts, a defined contact pressure force must be maintained during the movement of the contacts. Furthermore, in the known vacuum interrupter by the geometric arrangement of the components in the interior at each switching process caused by the resulting arc vapor deposition of the located throughout the interior of the vacuum interrupter components instead. This leads after a variety of switching operations to an undesirable decrease in the insulating capacity of the insulating cylinder and can lead to malfunction. The, for the damage of the components causal, occurring during a switching arc can be further amplified by a bouncing of the switching contacts, that the switching resistor is connected in series with the balancing current.

The object of the invention is therefore to provide, starting from the last-mentioned prior art, a vacuum interrupter of the type described above, which is able to provide a simple mechanical solution for switching under load, which is not technically difficult and to use consuming to realize synchronization and also does not have the other disadvantages mentioned.

This object is achieved by a vacuum interrupter with the features of the first claim. The subclaims relate to particularly advantageous developments of the invention.

Fig. 1

eine erste erfindungsgemäße Ausführungsform einer Vakuumschaltröhre für einen Lastumschalter eines Stufenschalters

Fig. 2 bis 8

den Schaltablauf dieser erfindungsgemäßen Vakuumschaltröhre bei einer Umschaltung des Lastumschalters von der Schaltstellung A auf B

Fig. 9

eine zweite Ausführungsform einer erfindungsgemäßen Vakuumschaltröhre.

The invention will be explained in more detail below by way of example with reference to drawings. Show it:

Fig. 1

a first embodiment of a vacuum interrupter according to the invention for a diverter switch a tap changer

Fig. 2 to 8

the switching sequence of this vacuum interrupter according to the invention in a switching of the diverter switch from the switching position A to B.

Fig. 9

A second embodiment of a vacuum interrupter according to the invention.

Corresponding components are provided in all figures with the same reference numerals.

In the FIG. 1 illustrated vacuum interrupter is surrounded by a rotationally symmetrical isolating cylinder 1, which consists of an electrically non-conductive material is manufactured and protects the inside, under vacuum standing mechanism from external influences and maintains the vacuum. Due to the symmetrical design of the vacuum interrupter, the description summarizes the functions of the individual components, which can be found again in the upper and lower parts. In the upper and lower portions of the insulating cylinder 1, an upper cap 2 formed as a flange is soldered to the insulating cylinder 1, and a lower cap 3 is attached, each having an opening, through each of which an upper plunger 4 and a lower plunger 5 a mechanical, electrical conductive connection between a respective outer switching position A and B and one, located in the interior of the vacuum switching cell, electrically conductive central contact plate 6 produces. The mechanical guidance of the axially displaceable plungers 4 and 5 is, on the one hand, taken over by the respective upper and lower bellows 7 and 8 attached to the caps 2 and 3 and used for permanent vacuumization and, on the other hand, by the respective flanges, which are also designed as flanges. upper and lower resistance contact plungers 9 and 10. The inner diameter of the rotationally symmetrical caps 2 and 3 and the outer diameter of the plunger 4 and 5 are to be dimensioned so that the respective resistance contact plunger 9 and 10 are mounted axially displaceable, contact-locking. By downwardly stepwise enlarged diameter of the plunger 4 and 5 is achieved with the corresponding axial displacement that the respective resistance contact plunger 9 and 10 by the positive engagement of the components of the upper and lower resistance contact plates 11 and 12 solve and contact with each other Move tappets 4 and 5 in the corresponding axial direction. So that this movement in the static state can not take place unintentionally without intentional external force, must be overcome in an axial displacement, the force applied by an upper and lower compression spring 13 and 14 holding force between the caps 2 and 3 and the resistance tappets 9 and 10.

Not necessary for understanding the switching principle components are not shown in the figures of the following schematic diagram for clarity.

In the FIGS. 2 to 8 the circuit diagram of a vacuum interrupter according to the invention in the switching from the position A to B is shown. FIG. 2 shows the switch in the starting position, in which the largest proportion of the load current flows due to the lowest line resistance in the system via the upper plunger 4 on the closed permanent main contact A 15 to the discharge contact 17. A much smaller part of the Due to the higher line resistances, current selects the path via the upper upper tappet 4, which is conductively connected in a contact-connected manner to the middle contact plate 6. A negligible proportion of the load current flows via the conductive connection between the upper tappet 4, the upper resistance contact tappet, in this switching position 9, the upper resistance contact plate 11 and the upper contact resistance 18 toward the discharge contact 17. The lower plunger 5 is so far open in this switching position that due to the positive connection, due to the change in diameter of the lower plunger 5 of the lower resistance contact plunger 10 of the lower resistance contact plate 12 is lifted.

In FIG. 3 As a result, the current is forced to take the less unfavorable path due to the higher line resistances via the contact plate 11, which is conductively connected to the upper plunger 4, to the discharge contact 17. A negligible proportion also has the opportunity to switch to this switch position again FIG. 2 to be selected in more detail via the upper switching resistor 18.

As in FIG. 4 recognizable here is the upper plunger 4 raised by an axial displacement so far from the central contact plate 6, that an electrical separation between the middle contact plate 6 and the upper plunger 4 takes place, but not between the upper resistance contact plunger 9 and the upper resistance contact plate 11. Thus the electrically conductive connection between the middle contact plate 6 and the upper plunger 4 is released and the current forced to take the path over the upper contact resistance 18 to the discharge contact 17.

In the switching position too FIG. 5 the lower plunger 5 is axially displaced in the direction of the central contact plate 6, but no further than is necessary for a conductive connection between the lower resistance contact plunger 10 and the lower resistance contact plate 12. As a result, in this switching position, a short-time circulating current is formed between the switching positions A and B, which is limited by the series-connected upper and lower switching resistors 18 and 19.

In FIG. 6 is achieved by an axial displacement of the upper plunger 4, the conductive connection between the upper resistance contact plunger 9 and the upper resistance contact plate 11. This ends the in FIG. 5 described circuit current and the current is from the Position A commutated to the desired switching position B, since it now only has the ability to flow through the lower resistance switch 19.

As the next switching step, the in FIG. 7 is described, the lower plunger 5 by a corresponding displacement with the central contact plate 6 is a conductive connection. Thus, the current is possible, not only, as in FIG. 6 described to flow over the lower switching resistor 19, but also on the resistance cheaper way of conductive contact between the middle contact plate 6 and the lower plunger. 5

Last, in FIG. 8 illustrated switching step, the permanent main contact B 16 is closed, whereby this assumes the line of the main part of the load current through its most favorable line resistance.

Thus, the switching from the position A to the position B is completed. A changeover from the position B to the position A takes place in chronologically reverse order of the preceding description.

In FIG. 9 a second embodiment of a vacuum interrupter according to the invention is shown, which with the basic structure of in FIG. 1 described vacuum interrupter is identical and fulfills the same technical task. Unlike the in FIG. 1 pointed embodiment, the upper and lower bellows 7 and 8 is mounted in the vacuumized interior of the Isolierzylindergehäuses 1. In the FIG. 1 as a component formed plunger 4 and 5 are in the embodiment to FIG. 9 executed in two parts: namely in the upper and lower push rod 22 and 23 and the upper and lower plunger 4 and 5. The storage and leadership of the plunger 4 and 5 take over the, in comparison to the resistance contact plates 11 and 12 FIG. 1 In order to prevent damage to the components located inside the insulating cylinder 1, optional vapor shields 21 and 22 are mounted around the contact points of the push rods 22 and 23 and the plungers 4 and 5 , The attached between the plungers 4 and 5 and the upper and lower bearing 24 and 25 compression springs 13 and 14 provide for a corresponding axial displacement of the push rods 22 and 23 for the solution of the conductive connection between the respective plungers 4 and 5 and the middle contact plate. 6 At one of the FIGS. 2 to 8 analog switchover of the diverter switch from switch position A to B is at the switching steps where in the, in FIG. 1 a conductive connection between the resistor contact tappets 9 and 10 and the resistance contact plates 11 and 12 shown in the embodiment shown in the embodiment FIG. 9 , a conductive connection between the push rods 22 and 23 and the plungers 4 and 5 necessary.

LIST OF REFERENCE NUMBERS

1

insulating

2

upper cap

3

lower cap

4

upper plunger

5

lower plunger

6

middle contact plate

7

upper bellows

8th

lower bellows

9

Upper resistance contact plunger

10

lower resistance contact plunger

11

- upper resistance contact plate

12

- lower resistance contact plate

13

- upper compression spring

14

- Lower compression spring

15

- Permanent main contact A

16

- permanent main contact B

17

- Discharge contact

18

- upper switching resistance

19

- lower switching resistance

20

- upper steam shield

21

- lower steam screen

22

- upper push rod

23

- lower push rod

24

- upper storage

25

- lower storage

Claims (4)

1. Vacuum switching tube for a load transfer switch of a step switch, wherein all the contacts of a phase which are required for switching under load form a structural unit, wherein on the opposite end sides of the vacuum switching tube a tappet acting as a switching contact is provided in each case co-axially mounted and movable in a mutually independent manner,
   characterised in that
   provided centrally within the vacuum switching tube perpendicular to the direction of movement of the tappets (4, 5) is a central, fixed, electrically conductive contact plate (6),
   that disposed in each case above and below the contact plate (6) and electrically insulated therefrom is an upper, electrically conductive resistor contact plate (11) and a lower, electrically conductive resistor contact plate (12) respectively,
   that an upper resistor contact tappet (9) is guided on the upper tappet (4) and a lower resistor contact tappet (10) is guided on the lower tappet (5), in each case in an axially displaceable and electrically conductive manner,
   that in one end position of the tappets (4, 5), in which they are each pressed into the interior of the vacuum switching tube, they are each electrically connected to the contact plate (6) and the resistor contact tappet (9 or 10) mounted thereon in each case or a push rod (22 or 23) is electrically connected to the corresponding resistor contact plate (11 or 12) or a bearing (24 or 25),
   that in the other end position of the tappets (4, 5) there is no electrical connection to the contact plate (6) and no electrical connection of the respective resistor contact tappets (9 or 10) to the corresponding resistor contact plate (11 or 12),
   and that the resistor contact tappets (9, 10) can be actuated in a temporally offset manner by the respective tappet (4, 5) - on which they are axially mounted - during movement thereof from one end position to the other.
2. Apparatus as claimed in Claim 1, characterised in that the tappets (4, 5) comprise a stepped outer diameter which corresponds at least to the inner diameter of the resistor contact tappets (9, 10) formed as a flange.
3. Apparatus as claimed in Claim 1 or 2, characterised in that one free end of at least one compression spring (13, 14) is supported on the respective resistor contact tappet (9 or 10) and the other free end thereof is supported on the respective cap (2 or 3).
4. Apparatus as claimed in Claim 1, characterised in that one free end of at least one compression spring (13, 14) is supported on the respective tappet (4 or 5) and the other free end thereof is supported on the respective bearing (24 or 25).

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