WO2013044990A1

WO2013044990A1 - Actuating device for a current switching device

Info

Publication number: WO2013044990A1
Application number: PCT/EP2011/067180
Authority: WO
Inventors: Carlo Boffelli
Original assignee: Abb Technology Ag
Priority date: 2011-09-30
Filing date: 2011-09-30
Publication date: 2013-04-04

Abstract

An actuating device (1) for a current switching device (2) comprises displacing means (20) for displacing a movable contact (6) of said current switching device (2) between a separation position (7), in which said movable contact (6) is separated from a fixed contact (5) of said current switching device (2), and a contact position (10), in which said movable contact (6) is in contact with said fixed contact (5), the actuating device (1) further comprising shifting means (50) configured so as to enable said displacing means (20) to move said movable contact (6) in said separation position (7) and in said contact position (10) in an alternate way upon respective one-way-driving-forces (26, 27) pointing to a same driving direction (40).

Description

Actuating device for a current switching device

The present invention relates to an actuating device for a current switching device, such as a vacuum interrupter of a circuit breaker. The actuating device of the invention enables the driving operations of the vacuum interrupter to be simplified, thus implying an overall improvement on the circuit closing and opening operations of a switchgear apparatus in which the switching device is included.

It is known in the art a circuit breaker having a pole assembly and provided with a vacuum interrupter for each phase of the pole assembly, the vacuum interrupter comprising a fixed contact and a movable contact. The movable contact is movable between a first position, in which it is coupled with the fixed contact, and a second position, in which it is separated from the fixed contact, thereby realizing the closing and opening operations of the circuit breaker. An actuating device is provided for driving the movable contact. The actuating device comprises an articulated lever mechanism pivotally connected to a stem protruding from the movable contact and comprising a connecting-rod which can be moved by a driving unit or actuator, such as a mechanical actuator, magnetic actuator, hydraulic actuator or an electric motor. In particular, the connecting-rod is moved by a driving shaft of the actuator.

The driving shaft must be able to rotate by a precise set angle both in a clockwise direction and in a counterclockwise direction in order to move, through the lever mechanism, the movable contact in the first position and in the second position respectively, thus closing or opening the circuit. In other words if the actuator will be the electric motor it must be equipped with a suitable control unit for precisely controlling the rotation direction and angular rotation of the driving shaft.

If, instead of the electric motor, a mechanical actuator, magnetic actuator or hydraulic actuator is used, the latters must be of the double-acting type, in order to be able to move the lever mechanism in two opposite directions for opening or closing the electrical circuit. This implies a more structurally complicated actuator; for the hydraulic one for example the circuit will have suitable pump means and electrovalves for a proper and precise functioning in the two opposite directions.

The known actuating device combined with the electric motor or with the hydraulic actuator as above discussed result to be a rather structurally complicated, expensive and bulky technical solution.

It would be desirable to overcome all the above mentioned drawbacks in order to simplify the closing and opening operations of the vacuum interrupter.

This is achieved by an actuating device as defined in the appended claims and described hereinafter in details.

The present disclosure encompasses also a vacuum interrupter provided with said actuating device, a switching device, in particular a circuit-breaker, including one or more of said vacuum interrupters, and a switchgear apparatus, equivalently called with the term panel or cabinet or switchboard, including said switching device as well.

Characteristics and advantages of the present disclosure will result from the description and from claims.

The present disclosure can be better understood and implemented with reference to the attached drawings that illustrate some embodiments thereof by way of non-limiting example, in which:

Figure 1 is a side view of a switching device;

Figure 2 shows schematically a vacuum interrupter provided with an actuating device according to the invention, which are included in the switching device of Figure 1;

Figure 3 is a perspective cutaway view of the vacuum interrupter and the actuating device, where some portions have been removed for making internal parts visible;

Figure 4 is an exploded view of the actuating device of the invention and of the schematic vacuum interrupter; Figure 5 is an exploded view of some components of the actuating device according to the invention;

Figures 6 to 11 shows the actuating device in different functioning steps;

Figure 12 schematically shows a possible configuration in which the actuating device is operated by a cam member rotating only in a preset rotation direction.

It should be noted that in the detailed description that follows, in order to clearly and concisely disclose the present invention, the drawings may not necessarily be to scale and certain features of the disclosure may be shown in somewhat schematic form.

With reference to the attached Figures, an actuating device 1 is described which is suitable for actuating a current switching device. In particular, in the following description and in a non-limitative way, the current switching device is a vacuum interrupter 2 of a circuit breaker 3. In other words, reference is made to a vacuum circuit breaker 3. However, it is understood that the actuating device 1 can also be adapted and used in connection with other types of current switching devices, such as disconnectors, contactors etc .

In particular, but in a non-limitative way, the actuating device 1 here disclosed is intended to be included in a medium voltage switchgear apparatus, where, for the purposes of the present application, the term medium voltage refers to applications in the range from lkV up to some tens of kV, e.g. 36 kV.

In the following description it should be considered that the circuit breaker 3 referred to comprises a pole assembly having one or more phases, where for each phase there is provided a vacuum interrupter 2 provided with a respective actuating device 1 according to the invention.

Each vacuum interrupter 2, shown in schematic form in the attached Figures, comprises an ampoule 4 housing a fixed contact 5, which is arranged in a stationary position, and a movable contact 6 which is movable between a separation position 7, shown in Figures 2, 3, 4, 6, 12, in which it is separated from the fixed contact 5 for opening an electrical circuit, and a contact position 10 shown in Figures 7 to 11, in which the movable contact 6 is in contact with the fixed contact 5 thus closing the electrical circuit. The movable contact 6 is provided with a stem 8 which protrudes outside the ampoule 4 through a suitable opening of a cap 9 of the vacuum interrupter 2.

The actuating device 1 comprises displacing means 20 which are suitable for displacing the movable contact 6 between the separation position 7 and the contact position 10.

The displacing means 20 comprise first biasing means 21 for urging the movable contact 6 in the contact position 10, and second biasing means 22 for urging the movable contact 6 in the separation position 7. The first and second biasing means comprise, in particular but in a non-limitative way, a first spring 21 and a second spring 22 respectively. The first 21 and second 22 springs, in particular, are compression type springs; the first spring 21 has an elastic stiffness greater than the second spring 22 for the reasons that will be described later on.

The displacing means 20 comprise a movable abutting member 23 which is rotatable around a longitudinal axis 30 of the actuating device 1. The movable abutting member 23, during functioning, is linearly movable in a reciprocating way along the longitudinal axis 30 in a direction towards and away from the fixed contact 5. In other words, the movable abutting member 23 is movable along the longitudinal axis 30 in both directions .

The displacing means 20 further comprise a pushing member 24 intended to receive driving forces 26, 27 for example by a manually operated driving lever, or by an operating motor unit 25, schematically shown in a possible version in Figure 12, in order to drive the movable contact 6.

The actuating device 1, as it will better result later on, is configured for operating with driving forces which are always oriented in a same one-way direction, either for displacing the movable contact 6 to the contact position 10 or for displacing the movable contact 6 to the separation position 7.

In particular, the driving forces for closing and opening the vacuum interrupter 2 comprise a first one-way pushing force 26 and a second one-way pushing force 27 respectively which act on the pushing member 24 by pointing towards the movable contact 6 along a driving direction 40 parallel to the longitudinal axis 30. This is achieved owing to shifting means 50 included in the actuating device 1 which will be described later on.

The displacing means 20 further comprise a connecting element 28, better shown in Figure 4, suitable for being firmly connected to the stem 8 of the movable contact 6. The connecting element 28 has an oblong cylindrical shaped portion 32 and is provided with an abutment flange 29 which is shaped so as to receive the action of the first 21 and second 22 springs.

In particular, the first spring 21 is placed around the cylindrical shaped portion 32 and is interposed between the movable abutting member 23 and the abutment flange 29, whereas the second spring 22 is intended to be interposed between the abutment flange 29 and a stationary abutting disc element 31 which is applied to the cap 9.

The actuating device 1, as above mentioned, comprises shifting means 50, better shown in Figures 4 and 5, which are configured so as to enable the displacing means 20 to move the movable contact 6 in the separation position 7 and in the contact position 10 in an alternate way upon the first oneway-pushing-force 26 and the second one-way-pushing-force 27 respectively .

With reference to Figure 5, the shifting means 50 comprise cam-pointed-ribs 54 provided on the pushing member 24 for exerting a pushing action on the movable abutting member 23. The cam-pointed-ribs 54 are longitudinally arranged along the pushing member 24 and are distributed around the longitudinal axis 30.

The shifting means 50 comprise abutting protrusions 52 which are circularly distributed on the movable abutting member 23. The abutting protrusions 52 protrude radially from the movable abutting member 23 outwardly with respect to the longitudinal axis 30. The abutting protrusions 52 comprise follower surfaces 53 arranged in a tilted position with respect to the longitudinal axis 30. The follower surfaces 53 act for transforming a pushing action by the cam-pointed-ribs 54 in a rotation motion of the movable abutting member 23 by a set angular step around the longitudinal axis 30.

The shifting means 50 further comprise a stationary guiding- stopping-member 51 which houses and slidingly guides the pushing member 24. The stationary guiding-stopping-member 51 is configured for selectively stopping the movement of the movable abutting member 23 away from the fixed contact 5 to a long-stroke position (shown in Figure 6) and to a short- stroke position (shown in Figure 9), in correspondence of which the separation position 7 and the contact position 10 of the movable contact 6 are achieved respectively.

On the stationary guiding-stopping-member 51 there is provided a resting portion 55 shaped for selectively receiving the abutting protrusions 52 in the long-stroke position and in the short-stroke position.

In particular, the resting portion comprises a sawtoothed resting crown 55 including a plurality of circularly distributed trough zones 56 on which the abutting protrusions 52 may rest at said short-stroke position. Each trough zone 56 is delimited by a first surface, extending parallel to the longitudinal axis 30, and a second surface which is tilted with respect to the first surface and is shaped for matching with a respective follower surface 53 of the movable abutting member 23. The resting portion 55 includes longitudinal groves 57 distributed in an alternated way with the trough zones 56, in which the abutting protrusions 52 are received at the long-stroke position. The longitudinal groves 57 guide the sliding movement of the above described cam-pointed-ribs 54 and prevent rotation of the pushing element 24 around the longitudinal axis 30.

With reference to Figures 6 to 11 functioning of the actuating device is described in the following.

In Figure 6 the movable contact 6 is in the separation position 7 and the movable abutting member 23 is in the long- stroke position. In such a position the second spring 22 urges the abutment flange 29 in a direction away from the fixed contact 5. At the same time, the first spring 21 keeps the movable abutting member 23 against the pushing member 24. In particular, one or more abutting protrusions 52 are housed in the longitudinal grooves 57 and rests against the cam- pointed-ribs 54.

With reference to Figure 7, when closing of the circuit is required, a first pushing force 26 is exerted on the pushing member 24 so as to push the movable abutting member 23 towards the abutting disc element 31. The pressure on the movable abutting member 23 is transmitted, through the first spring 21, on the abutment flange 29. As the first spring 21 is stiffer than the second spring 22, the latter is compressed first thus allowing advancement of the connecting element 28, and thus of the movable contact 6, towards the fixed contact 5. As the pushing member 24 proceeds, disengaging of the abutting protrusions 52 from the longitudinal grooves 57 is obtained as shown in Figure 8. It should be noted that during such a disengaging step the second spring 22 is substantially in a loaded status and the first spring 21 is at least partially compressed for allowing movement of the movable abutting member 23 while the abutment flange 29, and thus the movable contact 6, are stationary in the contact position 7. In other words, the first spring 21 is yielded so as to enable an extra-displacement of the movable abutting member 23 while the second spring 22 is in the loaded status and the movable contact 6 is stationary. Owing to such an extra-displacement the abutting protrusions 52 disengage from the longitudinal grooves 57 and, owing to the shape of the cam pointed ribs 54 and of the follower surfaces 53, the movable abutting member 23 is rotated around the longitudinal axis 30 by a suitable angle so that the abutting protrusions 52 can be received in the trough zones 56 at the short-stroke-position, as shown in Figure 9. When opening of the circuit is required, a second pushing force 27 can be exerted, as shown in Figure 10, on the pushing member 24 so as to displace the movable abutting member 23 towards the abutting disc element 31, thus disengaging the abutting protrusion 52 from the trough zones 56. During this further disengaging step, the first spring 21 is compressed while the abutment flange 29 and the movable contact 6 are stationary. Analogously to what above described, the follower surfaces 53, in contact with the cam-pointed ribs 54, slide relative to the latter and make the movable abutting member 23 rotate by a further suitable angle around the longitudinal axis 30. In this way, the abutting protrusions 52 get again arranged in correspondence of the longitudinal grooves 57, as shown in Figure 11. When the pushing member 24 is released, the action of the first spring 21 and of the second spring 22 puts the actuating device 1 again in the configuration in Figure 6, with the movable contact 6 in the separation position 7.

The actuating device 1 according to the invention above discussed fully achieves the intended aims of providing a technical solution which enables to noticeably simplify the closing and opening operations of the vacuum interrupter.

The actuating device 1, owing to its structural configuration, may operated by any desired operating unit which is able to exert a pushing action on the pushing member 24 in the driving direction 40. Therefore, double-acting operating units are avoided.

For example, a simple electric motor which rotates a cam element 25 only in a set rotation direction 34 as schematically shown in Figure 12 can be coupled with the actuating device 1. The cam element 25, by simply rotating only in a preset direction, exerts, through a possible hinged intermediate lever 33, pushing driving forces all oriented in the same driving direction 40 which open and close the vacuum interrupter 2 in an alternate way. Differently from the prior art actuating devices, owing to the actuating device 1 according to the invention there is no need for expensive control units for the electric motor. Instead of the rotating electric motor, also other different units may be provided for operating the actuating device 1, such units being structurally simplified compared with the complicated double- acting hydraulics actuators which are required for the articulated lever mechanism of the prior art.

The actuating device 1 is susceptible of modifications or variations all within the scope of the inventive concept and any details may be replaced with technically equivalent elements .

Claims

1. Actuating device for a current switching device (2), comprising displacing means (20) for displacing a movable contact (6) of said current switching device (2) between a separation position (7), in which said movable contact (6) is separated from a fixed contact (5) of said current switching device (2), and a contact position (10), in which said movable contact (6) is in contact with said fixed contact (5), characterized in that it further comprises shifting means (50) configured so as to enable said displacing means (20) to move said movable contact (6) in said separation position (7) and in said contact position (10) in an alternate way upon respective one-way-driving-forces (26, 27) pointing to a same driving direction (40) .

2. Actuating device according to claim 1, wherein said shifting means (50) are configured to cooperate with said displacing means (20) for arranging said movable contact (6) in said contact position (10) and in said separation position (7) upon a first pushing force (26) and a second pushing force (27) respectively which are equally oriented in said driving direction (40) .

3. Actuating device according to claim 1 or 2, wherein said displacing means comprises first biasing means (21) for urging said movable contact (6) in said contact position (10) and second biasing means (22) for urging said movable contact (6) in said separation position (7) .

4. Actuating device according to claim 3, wherein said displacing means (20) comprise:

— a movable abutting member (23) which is rotatable around a longitudinal axis (30) and reciprocatable along said longitudinal axis (30),

— a pushing member (24) intended to receive said oneway-driving forces (26, 27) for moving said movable abutting member (23),

— and a connecting element (28) suitable for being connected to a stem (8) of said movable contact (6) protruding outwardly of said current switching device (2), said connecting element (28) being provided with an abutment flange (29) shaped for receiving the action of said first (21) and second (22) biasing means.

5. Actuating device according to claim 4, wherein said shifting means (50) comprise a stationary guiding- stopping-member (51) arranged for selectively stopping the movement of said movable abutting member (23) away from said fixed contact (5) to a long- stroke position and to a short-stroke position respectively, in correspondence of which said separation position (7) and said contact position (10) of said movable contact (6) are achieved.

6. Actuating device according to claim 4 or 5, wherein said first (21) and second (22) biasing means comprise a first spring (21) and a second spring (22) respectively, said first spring (21) being interposed between said abutment flange (29) and said movable abutting member (23), and said second spring (22) being interposed between said abutment flange (29) and a cap (9) of said current switching device (2) through which said stem (8) comes out therefrom.

7. Actuating device according to one or more of preceding claims, wherein said shifting means (50) further comprise:

— abutting protrusions (52) which are circularly distributed on said movable abutting member (23) and protrude therefrom radially and outwardly with respect to said longitudinal axis (30),

— cam-pointed-ribs (54) longitudinally obtained on said pushing member (24), distributed around said longitudinal axis (30) and shaped for exerting a pushing action on said abutting protrusions (52), — and a resting portion (55) obtained on said guiding-stopping-member (51) and shaped for selectively receiving said abutting protrusions (52) in said long-stroke position and in said short-stroke position.

8. Actuating device according to 7, wherein said abutting protrusions (52) comprise follower surfaces (53) arranged in a tilted position with respect to said longitudinal axis (30) for transforming a pushing action by said cam-pointed-ribs (54) in a rotation motion of said movable abutting member (23) by a set angular step around said longitudinal axis (30) .

9. Actuating device according to 8, wherein said resting portion comprises a saw-toothed resting crown (55) including a plurality of circularly distributed trough zones (56) on which said abutting protrusions (52) may rest at said short-stroke position, each trough zone (56) being delimited by a first surface, extending parallel to said longitudinal axis (30), and a second surface which is tilted with respect to said first surface and is shaped for matching with a respective follower surface (53) .

10. Actuating device according to claim 9, wherein said resting portion (55) includes longitudinal groves

(57) distributed in an alternated way with said trough zones (56), in which said abutting protrusions

(52) are received at said long-stroke position, said longitudinal groves (57) guiding the sliding movement of said cam-pointed-ribs (54) and preventing rotation of said pushing element (24) around said longitudinal axis (30).

11. Actuating device according to one or more of preceding claims, wherein said first spring (21) and said second spring (22) are of compression type, said first spring (21) having an elastic stiffness greater than said second spring (22) .

12. Actuating device according to claim 11 as appended to claim 10, wherein said second spring (22) is configured to substantially yield to a loaded status earlier than said first spring (21) thus enabling said connecting element (28) to move said movable contact (6) in said contact position (10), said first spring (21) being yieldable for enabling an extra- displacement of said movable abutting member (23), while said second spring (22) is in said loaded status and while said movable contact (6) is stationary in said contact position (10), in order to allow engagement of said abutting protrusions (52) with said trough zones (56) at said short-stroke- position and disengagement of said abutting protrusions (52) from said trough zones (56) with subsequent introduction within said longitudinal grooves (57) in said long-stroke-position.

13. Actuating device according to one or more of the preceding claims, further comprising a stationary abutting element (31) which is fixable to said cap (9) for restingly receiving said second spring (22), an opening being obtained on said stationary abutting element (31) through which said stem (8) is slidable, said guiding-stopping member (51) being connected to said stationary abutting element (31) and housing said displacing means (20) and said shifting means (50) .

14. Current switching device comprising an actuating device (1) according to any one of the preceding claims .

15. Current switching device according to claim 14, wherein said current switching device is a circuit breaker ( 3 ) .

16. Current switching device according to claim 15, wherein circuit breaker is a vacuum circuit breaker (3) .

Switchgear apparatus comprising a current switching device (3) according to any one of claims 14 to 16.