AU2010277675A1

AU2010277675A1 - Electric switchgear having a snap-action drive

Info

Publication number: AU2010277675A1
Application number: AU2010277675A
Authority: AU
Inventors: Gerd Ahlf; Axel Faber; Frank Mantwill; Andreas Schuldt; Jurgen Seibt; Carsten Seybold
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2009-07-31
Filing date: 2010-07-26
Publication date: 2012-02-23
Anticipated expiration: 2030-07-26
Also published as: EP2460167A1; KR101375478B1; WO2011012564A1; KR20120031233A; ES2560286T3; DE102009035855B4; DE102009035855A1; AU2010277675B2; EP2460167B1

Abstract

An electric switchgear (1), in particular a load-break switch, having a switch shaft (2) and a snap-action drive (3) with a spring element (15) that effects a jump-like movement of the switch shaft (2), is to be characterised by a simple design, a low number of components and low space requirements. According to the invention, the snap-action drive (3) comprises to this end an articulated lever (8) having a first arm (9) and a second arm (10), said first arm (9) being connected with the end remote thereof from the second arm (10) to the switch shaft (2) in a rotationally fixed manner and the second arm (10) being fixedly supported with the end remote from the first arm (9) in a rotatable manner, and said second arm (10) comprising two sub-arms (10a, 10b), between which the spring element (15) is mounted.

Description

PCT/EP2010/060771 / 2009P13178WOAU 1 Description Electrical switchgear having a snap-action drive The invention relates to an electrical switchgear, in particular a load disconnector having a snap-action operating mechanism according to the preamble of claim 1. Such a switchgear is known from DE 28 50 761 C3, for example. Electrical switchgear frequently require an indirectly operating mechanism to ensure that switching operations always occur with identical and sufficient speed, irrespective of external influences. This is realized, for example, by means of snap-action operating mechanisms which include a chargeable energy storage device that facilitates rapid switching. This applies in particular to load disconnectors which are used to switch high-voltage circuits in the industrial sector and in marine systems. In marine systems, for example, load disconnectors are employed for DC voltages from 450 V to 900 V and switching currents of up to 400 A. Due to the high switching currents and switching voltages which occur during the switching operations of such a load disconnector, arcs arise which lead to a gradual erosion of the contacts and consequently result in wear in the switching equipment. In order to minimize contact erosion, the resulting arcs must be reduced as far as possible. This can be achieved by short switching times. In order to reduce the switching times of such load disconnectors, the switching kinematics within the load disconnector are provided with snap-action operating mechanisms. Due to the snap-action operating mechanism the speed of the movement PCT/EP2010/060771 / 2009P13178WOAU 2 applied by an operator to a switching element is increased in the region of an operating point. This is usually effected by spring elements in the snap-action operating mechanism. A snap-action operating mechanism for an electrical switchgear having a breaker shaft and known from DE 28 50 761, includes a compression spring whose spring force produces a snap-action movement of the breaker shaft via a transmission element mounted in a rotational manner on the breaker shaft. A tensioning device for the spring is likewise mounted in a rotational manner on the breaker shaft and during its rotary movement, following a free running movement, also rotates the transmission element. Here the transmission element is constructed as a U-shaped driving part in which sits a first and a second spring-type straight pin. The tensioning device includes a conical spring washer and an actuating lever that is connected to the conical spring washer. The actuating lever has a circular recess in which the first spring-type straight pin moves and which makes a connection to the compression spring. During a disconnection operation of the switchgear, the first spring-type straight pin with the U-shaped driving part is driven via the actuating lever and in so doing tensions the spring. After reaching a dead point, the tensioned spring is released and due to the second spring type straight pin, moves in a frictional manner a spring type straight pin located on the breaker shaft so that the breaker shaft is displaced in a rotational manner. Based on this, the object of the present invention is to specify a switchgear having a snap-action operating mechanism that is characterized by a simple construction, a small number of components and a small space requirement PCT/EP2010/060771 / 2009P13178WOAU 3 and consequently is suitable, in particular, for use in mobile systems with restricted space conditions, such as exist in ships, for example. This object is achieved by an electrical switchgear according to claim 1. In each case, advantageous embodiments are the subject matter of the sub-claims. In an inventive switchgear having a breaker shaft and a snap-action operating mechanism with a spring element that produces a snap-action movement of the breaker shaft, the snap-action operating mechanism includes an articulated arm with a first and a second arm, it being possible for the first arm to be connected to the breaker shaft in a torsionally-rigid manner by its end which faces away from the second arm and for the second arm to be supported by its end facing away from the first arm in a rotatable manner in a stationary position with respect to the breaker shaft, and it being possible for the second arm to include two sub-arms between which the spring element is mounted. By rotation of the breaker shaft, the lever can be displaced from a bent position in which the spring element is not tensioned, to an extended position wherein the spring element is put under tension. When the extended position is exceeded the spring element is released and then with a snap action displaces the actuating lever and the breaker shaft connected thereto, thereby effecting a rapid switching operation in the switchgear. Here the articulated lever acts to both tension the spring element and as a transmission element for transmitting the spring force to the breaker shaft. The inventive solution is thus characterized by a small number of components and a small space requirement. The articulated lever is a simply constructed unit, so that the inventive solution is also PCT/EP2010/060771 / 2009P13178WOAU 4 characterized by a simple construction. At the same time, an additional advantage is that the snap-action operating mechanism acts in both switching directions, that is to say both for a disconnection operation as well as for a closing operation. Components can likewise be saved in this way. Furthermore, the snap-action operating mechanism can be operated from a plurality of sides, which increases the flexibility with respect to the installation site of the switchgear and its operation. Preferentially, a retainer is constructed for the spring element at both sub-arms. The spring element can thus be reliably held in a correct position between the two sub arms. According to an advantageous embodiment, the spring element includes one or more compression springs, since compression springs are characterized by a comparatively high fault tolerance. To further increase the fault tolerance, the spring element can also contain two concentrically-disposed compression springs. The function of the switchgear can therefore be maintained even in the event of failure of one of the two springs. The concentric arrangement also results in a uniform spring loading and a small space requirement. Particularly good compactness and shock resistance of the switchgear as well as mechanical stability of the snap action operating mechanism is possible in that the switchgear has a baseplate in or on which the breaker shaft and the second arm of the articulated lever are supported in a rotational manner.

PCT/EP2010/060771 / 2009P13178WOAU 5 Advantageously, for manual operation the switchgear includes an operator control element which can be manually actuated and a mechanism for translating a movement of the operator control element into a rotational movement of the breaker shaft. According to a particularly advantageous embodiment, the operator control element includes an operating lever that is connected in a torsionally-rigid manner to a rotatable disk which controls one end of a first actuating lever, the other end of said actuating lever controlling in turn a second actuating lever that is connected in a torsionally rigid manner to the breaker shaft. The invention and further advantageous embodiments of the invention as featured in the sub-claims are explained in detail below with the aid of exemplary embodiments in the figures, wherein: FIG 1 shows a side view of a part-sectional drawing of an inventive electric switchgear, FIG 2 shows a detailed representation of the snap-action operating mechanism of FIG 1 in a first end position, FIG 3 shows a detailed representation of the snap-action operating mechanism of the switchgear of FIG 1 in a mid-position, and FIG 4 shows a detailed representation of the snap-action operating mechanism of the switchgear of FIG 1 in a second end position.

PCT/EP2010/060771 / 2009P13178WOAU 6 A switchgear in the form of a load disconnector 1, shown only indicatively in FIG 1, includes a breaker shaft 2, a snap-action operating mechanism 3 for the breaker shaft 2 and a manual operator control element in the form of a stirrup-operated mechanism 4. Cam-operated switching elements are usually used as switchgear units in load disconnectors. For voltages above 24 V, cam-operated switching elements are fitted with arcing chambers to ensure quenching of the arc. The load disconnector 1 therefore has cam-operated switching elements and arcing chambers - not illustrated here. Furthermore, the breaker shaft 2 has cams - not illustrated here - for actuating the cam-operated switching elements. The breaker shaft 2 is supported in a rotational manner on a baseplate 5 of the load disconnector 1 via a shaft extension. The cam-operated switching elements, the arcing chambers as well as the electrical connection components (not illustrated) are attached to the baseplate 5. The stirrup-operated mechanism 4 involves a manual drive, that is to say operation is manual, for example via an operator control lever 6 and not via additional drive units. An actuating mechanism 7 is used to translate a movement of an operator control lever 6 of the stirrup operated mechanism 4 into a rotational movement of the breaker shaft 2. Moreover, the operator control lever 6 is connected in a torsionally-rigid manner to a rotatable disk 20 by which one end of a first actuating lever 21 is controlled, the other end of said actuating lever in turn controlling a second actuating lever 22 which is connected in a torsionally-rigid manner to the breaker shaft 2. To guide the second actuating lever 22, the first actuating PCT/EP2010/060771 / 2009P13178WOAU 7 lever 21 has a slot 23 which guides a bolt 24 located on the second actuating lever 22. When the operator control lever 6 is actuated, the disk 20 is rotated and as a result the first actuating lever 21 is driven vertically downwards in an essentially translatory movement. Due to this movement the bolt 24 is forced into the upper end position of the slot 23 and carried along in a frictional manner by the first actuating lever 21. The bolt 24 then drives the second actuating lever 22 so that the latter rotates the breaker shaft 2. As is illustrated in detail in FIGS 2 - 4, the snap-action operating mechanism 3 includes an articulated lever 8 having a first arm 9 and a second arm 10 connected together via an articulated joint 11. The first arm 9 is connected in a torsionally-rigid manner to the breaker shaft at its end remote from the second arm 10 or articulated joint 11. At its end remote from the first arm 9 or articulated joint 11, the second arm 10 is supported in a rotatable manner in a retainer 13 by a bolt 14. The retainer 13 is permanently screwed to the baseplate 5. The second arm 10 is therefore permanently supported with respect to the breaker shaft 2. The second arm 10 includes two sub-arms 10a, 10b between which a spring element 15 is located. The spring element 15 contains two concentrically-arranged cylindrical compression springs 15a, 15b whose longitudinal axis runs in the direction of the longitudinal axis of the second arm 10. At its end facing the respective springs 15a, 15b, each of the sub-arms 10a, 10b has a retainer 12 for the springs ' PCT/EP2010/060771 / 2009P13178WOAU 8 15a, 15b. This retainer 12 includes a flat supporting surface 16 for the end faces of the springs 15a, 15b, and elevated sections 17, 18. The supporting surface 16 is externally limited by a ring-shaped elevation 17 against which the outer compression spring 15a rests and is consequently permanently retained in the correct position. On the other hand, the supporting surface 16 is limited radially inwards by a cylindrical elevation 18 against which the inner compression spring 15b rests and is therefore likewise permanently retained in the correct position. As has been shown, in the majority of cases these measures are adequate for the correct positioning and control of the position of the springs. In an alternative embodiment - not shown in detail - to guide the springs a bolt can be located centrally inside the springs 15a, 15b. Advantageously, the head of the bolt then lies in a bush which, in the region of the spring supporting surface 16 of the first sub-arm 10a facing the articulated joint 11, is screwed to this sub-arm 10a. A gap by which the bolt can be fixed in position with the aid of a retaining washer is then preferably located in the region of the spring supporting surface 16 of the sub-arm 10b that faces away from the articulated joint 11. The articulated lever 8 and the second actuating lever 22, both of which are connected to the breaker shaft 2 in a torsionally-rigid manner, can be constructed as separate levers. However, in order to reduce the number of components and the space requirement, the two levers 8, 22 - as shown in FIGS 1 - 4 - form a linear double lever, that is to say the second actuating lever 22 and the first arm 9 of the articulated lever 8 are interconnected in line, it PCT/EP2010/060771 / 2009P13178WOAU 9 being possible for the breaker shaft 2 to be located between the two levers. The articulated lever 8 can be displaced from a first end position in which it is bent as shown in FIG 2, via an extended position shown in FIG 3, to a second end position in which it is likewise bent as shown in FIG 4, and vice versa. The location of the two end positions shown in FIGS 2 and 4 can be realized by stops (not shown in detail) which are placed on the breaker shaft 2. In this case the lengths of the first arm 9, the lengths of the first and second sub-arms 10a, 10b, the design of the springs 15a, 15b and the distance between the breaker shaft 2 and the bolt 14 are matched to each other so that in the extended position of the articulated lever 8 shown in FIG 3 there is sufficient space for the compression springs 15a, 15b between the first sub-arm 10a and the second sub-arm 10b when in the compressed state. The slotted hole 23 in the first actuating lever 21 prevents snatching of the first actuating lever 21 and of the operator control element 6 when the snap-action operating mechanism makes the through-connection. Following such a through-connection, the operator control lever 6 of the stirrup-operated mechanism 4 is then manually placed into its respective end position by an operator. The mode of operation of the snap-action operating mechanism 3 is explained below with the aid of FIGS 2 - 4: PCT/EP2010/060771 / 2009P13178WOAU 10 FIG 2 shows the breaker shaft 2 in a first switch position, for example a closed position of the switchgear 1. Here the articulated lever 8 is in a first end position. The two arms 9, 10 of the articulated lever 8 are bent towards each other. If an operator manually moves the operator control lever 6, the breaker shaft 2 is rotated counterclockwise via the first actuating lever 21 and the second actuating lever 22 and at the same time the articulated lever 8 is moved from its end position shown in FIG 2 to an extended position shown in FIG 3, in which the articulated lever 8 is fully extended. During this movement, the springs 15a 15b are compressed or tensioned. In this case the retainer 13 acts as an abutment for the second arm 10 of the articulated lever 8 when the springs 15a, 15b are compressed. When the operator control lever 6 is released before the extended position is reached, the springs 15a, 15b force the articulated lever 8 and therefore also the breaker shaft 2 clockwise into the starting position again as shown in FIG 2. When the extended position is exceeded, the springs 15a, 15b are untensioned and move the articulated lever 8 and with it also the breaker shaft 2 counterclockwise in a snap-action manner up to the end position shown in FIG 4, thereby producing a rapid switching operation at the cam operated switching elements of the switchgear 1. In this case the spring force is designed so that it achieves the necessary actuating force for switching the contacts of the switchgear 1.

PCT/EP2010/060771 / 2009P13178WOAU 11 In the same way, a closing operation of the switchgear is possible by displacement of the articulated lever in the reverse direction, that is to say from the end position shown in FIG 4 to the end position shown in FIG 2. As is apparent, only very few different components are required for the snap-action operating mechanism 3. The snap-action operating mechanism 3 has a very simple construction and in combination with a stirrup-operated mechanism in particular is characterized by high reliability and shock resistance and at the same time excellent compactness and small space requirement. There is also a great advantage in that instead of being located above the baseplate 5, the stirrup-operated mechanism 4 can also be located below the baseplate 5, it then being possible for the first actuating lever 21 to be coupled to the second actuating lever 22 from below. This gives high flexibility with regard to the installation site and the operation of the switchgear, which is a great advantage when used in particular in mobile systems such as ships, for example.

Claims

1. An electrical switchgear (1), in particular a load disconnector having a breaker shaft (2) and a snap-action operating mechanism (3) with a spring element (15) which produces a snap-action type movement of the breaker shaft (2), characterized in that the snap-action operating mechanism (3) contains an articulated lever (8) with a first and a second arm (9, 10), it being possible for the first arm (9) to be connected to the breaker shaft (2) in a torsionally rigid manner by its end which faces away from the second arm (10) and for the second arm (10) to be supported in a rotatable manner by its end facing away from the first arm (9) in a stationary position with respect to the breaker shaft (2), and it being possible for the second arm (10) to include two sub-arms (10a, 10b) between which the spring element (15) is mounted.

2. The electrical switchgear (1) as claimed in claim 1, characterized in that a retainer (12) for the spring element (15) is constructed at the two sub-arms (10a, 10b).

3. The electrical switchgear (1) as claimed in one of the preceding claims, characterized in that the spring element (15) contains one or a plurality of compression springs (15a and 15b).

4. The electrical switchgear (1) as claimed in one of the preceding claims, characterized in that the spring element (15) contains two concentrically-disposed compression springs (15a, 15b). PCT/EP2010/060771 / 2009P13178WOAU 13

5. The electrical switchgear (1) as claimed in one of the preceding claims, characterized by a baseplate (6) in or on which the breaker shaft (2) and the second arm (10) of the articulated lever (8) are supported in a rotatable manner.

6. The electrical switchgear (1) as claimed in one of the preceding claims, characterized by a manually-operated operator control element and a mechanism (7) for translating a movement of the operator control element (6) into a rotational movement of the breaker shaft (2).

7. The electrical switchgear (1) as claimed in claim 6, characterized in that the operator control element contains an operator control lever (6) that is connected to a rotatable disk (20) in a torsionally-rigid manner, said disk controlling one end of a first actuating lever(21), whose other end controls a second actuating lever (22) which is connected to the breaker shaft (2) in a torsionally-rigid manner.

8. The electrical switchgear (1) as claimed in claim 7, characterized in that the first actuating lever (21) has a slot (23) for controlling the second actuating lever (22).