GB2520526A

GB2520526A - Switching gear

Info

Publication number: GB2520526A
Application number: GB1320669.3A
Authority: GB
Inventors: Kunche Sunil Kumar; Mahesh Prabhakar Joshi
Original assignee: Eaton Industries Netherlands BV
Current assignee: Danfoss Power Solutions II BV
Priority date: 2013-11-22
Filing date: 2013-11-22
Publication date: 2015-05-27
Also published as: ZA201603422B; EP3072191A1; GB201320669D0; CN105745800A; WO2015074974A1; AU2014352054A1

Abstract

A switching gear comprises a frame, a main contact block 3 movable between a disconnected position and a connected position and an auxiliary contact block 4 movable parallel to the main contact block between a disconnected position and a connected position. An operating lever 6 has a shaft 11 arranged on which are a main operating element 13 and an auxiliary operating element 12. The elements may be a segment gear and toothed rack or a cam. A main rod system 15 and an auxiliary rod system 14 are connected between the respective operating element and contact block, such that on rotation of the operating lever the main contact block and the auxiliary contact block.

Description

Switching gear The invention relates to switching gear like for medium-voltage applications.

Switching gear is typically arranged in a cabinet. The back-wall of this cabinet is provided with main busbars to which the switching gear needs to connect. This switching gear comprises safety circuitry and actuators to make or break contact between busbars. The switching gear for example provides power to a device, like a pump, electric motor or electric valve, switched from the main busbars via this switching gear and ensures that the power can be switched off and turned on easily. Furthermore, auxiliary contacts are provided which are used for testing purposes.

Such switching gear is typically arranged in drawers in the cabinet. This makes it easy to exchange switching gear, when a malfunction is detected.

For maintenance and problem solving, it is necessary that the switching gear can be tested.

For this purpose, the switching gear has to be disconnected from the busbars, It is also desired that in such a test position the switching gear is still connected to an auxiliary connector such that different components of the switching gear can be tested.

With a typical draw-out switch, the switch is partially pulled out of the cabinet such that the draw-out switch is disconnected from the busbars and the switching gear can be tested. In this test position the switching gear is connected to or still connected to an auxiliary connector for testing the switching gear.

The draw-out switch is pulled out further to trnly disconnect the switching gear. In this position the draw-out switching device can be removed safely Known draw-out switching devices are manually operated to position them in the desired 3 0 position. The position is often indicated by marks arranged on the base frame, It is however difficult to position the switching device accurately in the correct position.

Some known draw-out switching devices are provided with a positioning mechanism in which one has to use a ratchet to rotate a screw spindle, which moves the sub-frame with the switching gear. An indicator is arranged with the positioning mechanism for indicating in which position the draw-out switching device is moved. The use of a ratchet to rotate a screw spindle, takes a relative long time for moving the switching device to the desired position, Another disadvantage is that the draw-out switching gear sticks out of the cabinet, when it is put in the test position or the disconnected position.

1 0 It is an obj ect of the invention to reduce or even remove the above mentioned disadvantages.

This object is achieved with switching gear according to the invention, which switching gear comprising: -a frame; -a main contact block arranged to the frame and linear movable between a disconnected position and a connected position; -an auxiliary contact block arranged to the frame and movable parallel to the main contact block between a disconnected position and a connected position; -an operating lever having a shaft; -a main operating element and an auxiliary operating element arranged on the shaft of the operating lever; and -a main rod system and an auxiliary rod system connected between the respective operating element and contact block, such that on rotation of the operating lever the main contact block and the auxiliary contact block move linearly.

Because the main contact block and the auxiliary contact block are movable arranged to the frame, it is no longer required to move the frame, i,e, pull-out the drawer, to bring the switching gear in a testing position or a disconnected position.

3 0 The main contact block and the auxiliary contact block are moved between their respective positions by rotating the operating lever, The rotation of the shaft will cause the main operating element and the auxiliary operating element to rotate. This rotation will be transferred with the respective rod system to the respective contact block, such that first the auxiliary contact b'ock is moved in the connected position and then the main contact Nock is moved into connection with the busbars.

In a preferred embodiment of the switching gear according to the invention the main operating element and the auxiliary operating element are rotational displaced relative to each other, The rotational displacement of the operating elements ensures, that for example the auxiliary contact block starts to move first upon rotation of the shaft and after further rotating the shaft, the main contact block starts to move, As a result, the auxiliary contact block will be connected first and only after thither rotation of the shaft, the main contact block will be connected, When rotating the shaft in the opposite direction, the main contact block will be disconnected first, after which the auxiliary contact block will be disconnected, In a next prefered embodiment of the switching gear according to the invention at least one of the main operating element and the auxiliary operating element comprise a segment gear arranged to the shaft and a toothed rack arranged to the respective rod system.

When the shaft is rotated, the segment gear will change in angular position, such that the toothed rack can be moved in linear direction, This linear movement will be transferred by the rod system to one of the contact blocks, When two segment gears are arranged on the shaft both the main contact block and the auxiliary contact block can be moved from a disconnected to a connected position. By having an angular displacement between the two segment gears it can be ensured, that upon rotation of the shaft the auxiliary contact block is moved first to put the switching gear in the test position arid afterwards the main contact block can be moved to put the switching gear in the connected position, In another prefered embodiment of the switching gear according to the invention at least one of the main operating element and the auxiliary operating element comprise a cam arranged to the shaft and a cam follower arranged to the respective rod system.

When the cam is rotated by rotation of the shaft, the cam follower will follow the curve of the cam. The change in the radial distance from the shaft to the cam surface will cause the cam follower to move linearly, which linear movement will be transferred by the rod system to the respective contact block.

Two cams can be arranged on the shaft or one cam combined with a segment gear. By choosing an angular displacement between two cams, or between the one cam and a segment gear, one can assure, that first the auxiliary contact block is moved and then the main contact block.

In yet another embodiment of the switching gear according to the invention at least one of the main operating element and the auxiliary operating element comprises a guide groove arranged to the shaft and a follower pin extending in the guide groove, which follower pin is connected to the respective rod system.

A guide groove with follower pin functions similarly as a cam and cam follower, but has the advantage that besides a push force also a pull force can be generated.

In a further embodiment of the switching gear according to the invention at least one of the main rod system and the auxiliary rod system comprises an L-shaped rod element having a hinge point at the knee of the L-shaped rod element to provide movement amplification.

With the L-shaped rod element one can provide a transmission to increase or decrease the movement operation element, such that the stroke of the operating element causes a correct stroke of the respective contact block, Furthermore, the L-shaped rod element can provide a change in direction of the linear movement, depending on the angle between the legs of the L-shaped rod element.

In yet another embodiment of the switching gear according to the invention the rod system comprises at least three rods interconnected by sliding hinge points. By having the sliding directions of both hinge points at different angles, it is possible to change the direction of the linear movement of the operating element.

Still a further embodiment of the switching gear according to the invention comprises driving means, for example an electric motor, for rotating the shaft of the operating lever.

As the movement of the main contact block and the auxiliary contact block can be effected by rotation of the shaft, it can easily be automated by having a drive mems to rotate the shaft.

This enables electric actuation of the operating lever, such that different switching gears can be controlled by for example by a computer.

These and other features of the invention 1l be elucidated in conjunction with the 1 0 accompanying drawings.

Figure 1 shows a schematic perspective view of switch gear according to the invention.

Figure 2 shows a partial perspective view of a first embodiment of the invention.

Figure 3 shows a schematic top view of the first embodiment.

Figure 4 shows a partial perspective view of a second embodiment of the invention.

FigureS shows a schematic top view of the second embodiment.

Figure 6 shows a partial perspective view of a third embodiment of the invention.

Figure 7 shows a schematic top view of the third embodiment.

Figure t shows a draw-out switch 1, which is typically arranged in a cabinet (not shown).

Inside such a cabinet busbars 2 are arranged which provide power for the draw-out switch I. This power is provided to the draw-out switch via the main contact block 3.

3 0 Furthermore, the draw-out switch 1 has an auxiliary contact block 4, which can be brought into contact with contacts 5 arranged in the cabinet, such that different components of the switching gear can be tested.

As described in the preamble, it is required that the switching gear I can be put in a position, in which both the main contact block 3 and auxiliary contact block 4 are disconnected, in a position with only the auxiliary contact block 4 connected and a position in which both contact blocks 3, 4 are connected. According to the invention this is achieved by linear movement of the main contact block 3 and linear movement of the auxiliary block 4. This movement is obtained by rotating the operating lever 6.

Figures 2 and 3 shows a first embodiment of switching gear 10 according to the invention.

The operating lever 6 has a shaft I on which two sector gears 12, 13 are aranged, These sector gears 12, 13 engage on toothed racks 14, 15 respectively.

When the shaft II is rotated, the sector gears 12, 13 will engage on the toothed racks N, 15 and cause the toothed racks 14, 15 to make a linear movement. Because the two sector gears 12, 13 are arranged with a relative angular displacement, the sector gear 13 will engage with the toothed rack 15 later, than the sector gear 12 will engage with the toothed rack 14.

As shown in figure 3, the toothed racks 14, 5 are connected to a respective rod system. The toothed rack 14 is connected to the rod system composed out of the toothed rack 14, sliding hinge point 16, connecting rod 17, sliding hinge point t8, and push rod t9. The toothed rack 15 is to the rod system composed out of the toothed rack 15, sliding hinge point 20, connecting rod 21, sliding hinge point 22, and push rod 23.

These rod systems transfer the linear movement of the two toothed racks 14, 15 to the respective contact block 4 and 5. In figure 3, it is shown, that the sector gear 12 already has engaged to the toothed rack t4, such that the auxiliary contact block 4 is moved into contact with the contacts 5. The sector gear 13 is shown to start to engage the toothed rack 15, such that on further rotation of the shaft II, the main contact block is moved into contact with the busbars 2.

Figures 4, 5 show a second embodiment 30 of the invention, In this embodiment 30, the shaft 31 of the operating lever 6 is provided with two cams 32, 33. These cams 32, 33 shift the cam followers 34, 35 respectively such that a linear movement is obtained. Due to the angular displacement of the cams 32, 33, the cam follower 34 will first be moved. This enables a correct timing of the movements of the main contact block 3 and auxiliary contact block 4 The cam followers 34, 35 push against an L-shaped rod element 38, 39 respectively, which each in turn push against a push rod 40, 41 respectively to push the auxiliary contact block 4 and the main contact block 3 into a connected position. The push rods 40, 41 are urged by springs 36, 37 against the L-shaped rod element 38, 39, such that the contact blocks 3, 4 can also be brought back to the disconnected position.

By varying the length of the legs of the L-shaped rod element 38, 39 one can set the amplification factor between the stroke of the cam followers 34, 35 and the required stroke for the push rods 40, 4] such that the main contact block 3 and auxiliary contact block 4 can be moved fully in contact with the busbars 2 and contacts 5 respectively.

Figure 6 shows a partial perspective view of a third embodiment 50 according to the invention. This embodiment 50 functions similarly as the second embodiment 30.

In the third embodiment 50, the shaft 51 of the operating lever 6 is provided with two discs 52, 53, Each disc 52, 53 is provided on both axial surfaces with a guide groove 54, 55 2 0 respectively.

Two rods 56, 57 are each provided with a fork 58, 59 respectively, which forks 58, 59 have follower pins 60 at the free ends of the forks 58, 59 which extend in the respective grooves 54, 55.

When rotating the shaft 5 t with the operating lever 6, the discs 52, 53 with the guide grooves 54, 55 will rotate causing the rods 56, 57 to move linearly As shown in figure 7, the linear movement of the rods 56, 57 is transferred by an L-shaped rod element 61, 62 to a rod element 63, 64 which is connected to the auxiliary contact block 4 and the main contact block 3 respectively