5

The invention relates to switching devices comprising a housing, a first electrical contact and a second electrical contact. Such switching devices may be used for switching low voltage switching circuits.

10 In a low voltage distribution system switchgear is placed in a cabinet of an encapsulating

housing. The switchgear comprises a switching device. The device is a withdrawable unit housed in a drawer that can be inserted into a rack that is placed in the cabinet. The device comprises a set of first contacts, also referred to as main contacts, and a set of second

contacts, also referred to as auxiliary contacts. Both sets are placed on a backside of the

15 device. The main contacts are for making contact to vertically arranged pairs of distribution

bus bars in the rack. The auxiliary contacts are for making contact to cables of an auxiliary circuit.

The device provides for a number of connection states which are selected by a main

0 disconnect switch and by partially or completely withdrawing the device from the rack. The states are indicated in the table below.

State unit Main Main contacts Auxiliary Test button disconnect contacts light

Connected on Inserted Closed Connected Connected Off

Connected off Inserted Open Connected Connected Off

Test Withdrawn 30 mm Open Disconnected Connectedlll

uminated

Disconnected Withdrawn 45 mm Open Disconnected Disconnected

Off

Removed Removed from the

rack The device is arranged such that a change of state can only be to one or two of the other states corresponding to moving up or down a row in the table. This is arranged for safety reasons.

However, there is a risk that a drawer may be accidentally closed or that it may change from the position in which it is withdrawn by 45 mm to a position in which it is withdrawn by only 30 mm. Such an accidental closure or change of position may for instance occur when someone or something falls against the drawer or leans against it. Such an accidental change in position corresponds to a change in the state and therefore is dangerous. For instance, in case of a change from being withdrawn by 45 mm to 30 mm, the auxiliary circuit is either connected or disconnected.

US20100155214A1 discloses a mechanical control device for electrical switchgear for disconnectors for high- voltage or medium- voltage circuits. According to US20100155214A1 such disconnectors are used to isolate a portion of a live electrical network, such as a high- voltage line, an electrical transformer, or a portion of an electrical substation. The control device comprises a housing in the form of a chassis plate and a motor to drive a toothed driving wheel via gears and torque limiters. The toothed driving wheel always rotates together with a driving disk, which has two U-shaped slots between three teeth on a peripheral edge. The toothed driving wheel and the driving disk are coaxially placed. The control device also comprises a driven disk with two U-shaped slots and 2 end slots and a rotary member with 3 cylindrical rollers.

The driven disk is also coaxially placed with both the toothed driving when and the driving disk. The driven disk is fixed to a transmission shaft that always rotates together with the driven disk. A disconnector is connected to the transmission shaft. The rotational movement of the driving disk is transferred to the driven disk by the cylindrical rollers. In an example, from a position in which the disconnector is open, the driven disk is rotated by the motor. When a first of the three teeth of the driving disk reaches a first of the cylindrical rollers, the rotary members starts to rotate as well and one of the cylindrical rollers enters one of the U- shaped slots of the driving disk. The rotary member rotates around another shaft and the control device is arranged such that at least one cylindrical roller is at least partially in one of the slots of the driven disk. Therefore, as the rotary members starts to rotate, the driven disk starts to rotate as well. As the rotary member starts to rotate, a second cylindrical roller moves into a U-shaped slot of both the driven disk and the driving disk and the first of the three teeth loses contact with the first of the cylindrical rollers. After further rotation the second cylindrical roller moves out of the U-shaped slot of the driving disk a third cylindrical rollers moves into an end slot of the driven disk. The driving disk can now continue to rotate, but the rotational position of the driven disk is fixed. In this rotational position, the disconnector is closed.

The control device handles a disconnector with three switching positions: one in which the disconnector is open, one in which the disconnector is closed and a grounding position. By rotating in the other direction from the position in which the disconnector is open, the grounding position is reached.

This mechanical control device is for high voltage and medium- voltage disconnectors.

Compared to a low- voltage disconnector, it is complex and expensive and still only controls the position of a single disconnector.

It is an object of the invention to provide a switching device that at least partially reduces or obviates these problems.

According to a first embodiment of the invention, there is provided a switching device comprising a housing, a first electrical contact, a second electrical contact; and

a Geneva drive comprising

- a first driven wheel arranged to drive the first electrical contact relative to the housing between a first connected position and a first disconnected position;

a second driven wheel arranged to drive the second electrical contact relative to the housing between a second connected position and a second disconnected position

and a drive wheel comprising a driving pin arranged to alternatingly drive the first driven wheel and the second driven wheel.

Geneva drives are reliable and allow intermittent and alternating drive of the first and second driven wheel. As the rotational motion of the first driven wheel and the second driven wheel is a result of the rotational motion of the drive wheel, the rotational motion of a single wheel, the drive wheel, is alternatingly converted into motion of the first electrical contact and the second electrical contact.

Because the first and the second electrical contact move between the respective first and second connected and disconnected positions relative to the housing, the housing does not need to be moved to obtain different connection states of the switching device. Preferably the first electrical contact is arranged in a first contact module and the first electrical contact is driven by driving the first contact module. Preferably the second electrical contact is arranged in a second contact module and the second electrical contact is driven by driving the second contact module. The first and the second contact modules separate the mechanical system from the electrical system.

According to a second embodiment of the invention, the switching device of the first embodiment comprises:

- first conversion means to convert rotational motion of the first driven wheel to linear motion of the first electrical contact; and

- second conversion means to convert rotational motion of the second driven wheel to linear motion of the second electrical contact.

By converting the rotational motion of the first driven wheel to linear motion, the first contact in the first contact module can be moved between the first connected and the first

disconnected state linearly. Similarly, by converting the rotational motion of the second driven wheel to a linear motion, the second contact in the second contact module can be moved between the second connected and a second disconnected state linearly.

Linear movements for connecting and disconnecting electrical contacts are advantageous as they allow large contact areas to be connected and disconnected. According to a third embodiment of the invention, the switching device of the second embodiment is provided, wherein the first electrical contact is arranged in a first contact module, the first conversion means comprise a first coupler hingeably connected to the first driven wheel and hingeably connected to the first contact module, the first coupler being arranged to exert a pushing and pulling force for driving the first contact module.

As the first coupler can both push and pull the first electrical module, the first coupler suffices to drive the first electrical contact between the connected state and the disconnected state, i.e. only few parts are needed. Because the coupler is hingeably connected to both the driven wheel and the contact module, the direction in which the contact module is moved, can be different from the orientation of the coupler.

Suitable hingeable connections are well known, reliable and easy to design. The person skilled in the art will understand that the hingeable connections here encompass hingeable connections. The hingeable connection may be provided by a pivot.

Preferably, the second electrical contact is arranged in a second contact module and the second conversion means comprise a second coupler hingeably connected to the second driven wheel and hingeably connected to the second contact module, the second coupler being arranged to exert a pushing and pulling force for driving the second contact module.

According to a fourth embodiment of the invention, there is provided for the switching device according to the first, second or third embodiment, wherein the Geneva drive comprises a hard stop for blocking the rotation of the drive wheel in a first direction beyond a first rotational end position.

Because the Geneva drive comprises a hard stop, the transitions between combinations of connection states of the first electrical contact and the second electrical contact are limited. This is because when reaching the hard stop, the drive wheel cannot progress further to reach a next combination of connection states. Instead it can remain in position or be rotated back to positions reached earlier. According to a fifth embodiment of the invention, a switching device according to claim 5 is provided.

Because the Geneva drive comprises a further hard stop blocking the rotation of the drive wheel in the second direction, the drive wheel can only be rotated less than 360 degrees and the number of combination of connection states of the first contact and the second contact is limited.

According to a sixth embodiment of the invention, the switching device according to claim 6 is provided.

The switching device according to this embodiment has the advantage that the first and second electrical contacts provide a way to connect two external circuits with each other. According to a seventh embodiment of the invention, a switching device according to claim 7 is provided.

By rotating through the first recess, the locking member effectively secures the rotational position of the first driven wheel. By securing the rotational position of the first driven wheel when not driven, the connection state of the first electrical contact is secured in either the connected state or the disconnected state. While the connection state of the first electrical contact is secured, the connection state of the second electrical contact may be changed. This may have safety advantages, provide test options or simply different connection states. According to an eighth embodiment of the invention, a switching device according to claim 8 is provided.

By securing the rotational position of the second driven wheel when not driven, the connection state of the second electrical contact is secured in either the connected state or the disconnected state. While the connection state of the second electrical contact is secured, the connection state of the first contact may be changed. This may have safety advantages, provide test options or simply different connection states. In combination this means that the connection state of each of the first contact and the second contact may now be changed while the other connection state of the other contact is locked.

According to a ninth embodiment of the invention, a switching device according to claim 9 is provided.

As the first driven wheel comprises one slot, there are only two possible orientations of the first driven wheel. Similarly there are only two possible orientations of the second driven wheel. Because the rotation of the drive wheel is limited to less than 360 degrees by the presence of the hard stop and the further hard stop, the contact pin does not approach either the first driven wheel or the second driven wheel at a side where there is no slot. In external Geneva wheels slots are in tooth of the driven wheels. By saving slots, tooth are saved.

Therefore lighter driven wheels may be used produced from less material. Preferably, the switching device of the above embodiments is for switching low voltage circuits, i.e. circuits suitable for handling around 1000 V or 1500 V DC.

Examples of embodiments of the invention will now be described with reference to the accompanying schematic drawings. Corresponding reference symbols in the schematic drawings indicate corresponding parts. The schematic drawings are not necessarily to scale and certain features may be exaggerated to better illustrate and explain the present invention. Certain features may not be shown to better illustrate and explain certain aspects of the present invention. Further, the examples are not intended to be exhaustive or otherwise limit or restrict the invention to the precise configurations shown in the drawings and disclosed in the following detailed description.

Figure 1 cabinet for a low voltage distribution system

Figure 2 switching device according to the invention Figure 3 drive wheel of a switching device according to the invention

Figure 4 Geneva drive of a switching device according to the invention corresponding to a connected state of the contact module and a connected state of the auxiliary contact module

Figure 5 Geneva drive of a switching device according to the invention corresponding to a disconnected state of the contact module and a connected state of the auxiliary contact module Figure 6 Geneva drive of a switching device according to the invention corresponding to a disconnected state of the contact module and a disconnected state of the auxiliary contact module

For the purpose of explaining the invention, use is made of an x-direction, a y-direction and a z-direction, which are all perpendicular and chosen in right-handed orientation. A

corresponding Cartesian coordinate system is used as well.

In an example of the invention, the positive z-direction is a vertical upward direction. In the example of the invention, there is an encapsulating housing comprising switchgear for a low voltage distribution system. The encapsulating housing comprises a number of cabinets (1) placed side by side against each other (figure 1). Each cabinet has a front side (parallel to the x-direction) that is accessible for personnel. The cabinets (1) each comprise a main bus bar compartment (2). The main bus bar compartments of neighbouring cabinets are connected by openings (3). Four main bus bars (4) are housed in a main bus bar compartment. The four main bus bars run parallel to the x- direction and are connected to four distribution bus bars per cabinet. The four distribution bus bars are vertically placed (i.e. they run parallel to the z-direction) in an insulated bus bar chamber at the backside of the cabinets. Each of the four distribution bus bars is housed in a separate glass-fibre reinforced polyester bus bar duct running parallel to the z-direction. The four distribution bus bars are each connected to one of the horizontal main bus bars by connection bars.

The cabinets (1) comprise multiple switchgear and control gear compartments aligned to the left walls of the compartments. On the right side of the cabinets (1) is a cable connection compartment (5).

One of the switchgear compartments is occupied by a drawer (6). The drawer (6) forms the housing of a switching device (7) according to the invention (see figure 2). The switching device comprises a contact module (8) with four contacts that are isolated from each other by walls of glass-fibre reinforce polyester. The contact module (8) can be moved along the y- direction to connect (positive y-direction) or disconnect (negative y-direction) the four contacts with the four distribution bus bars.

The switching device also comprises an auxiliary contact module (108) with four auxiliary contacts that are isolated from each other by walls of glass-fibre reinforce polyester. The auxiliary contact module can be moved along the y-direction to connect (positive y-direction) or disconnect (negative y-direction) the four auxiliary contacts with corresponding cables of an auxiliary circuit. The switching device comprises a drive shaft (9) with a helical shape running in an x- direction. The helical shape forms a screw thread that engages with a corresponding structure on a rim (14) of a drive wheel (10) of a Geneva drive. As the skilled person will appreciate, Geneva drives (or mechanisms) are also known as Maltese cross drives (or mechanisms). The drive wheel (figure 3) is mounted on a drive axle (11) running in z-direction. The drive wheel (10) is disk shaped and has 2 major surfaces, a first surface (12) and a second surface each being perpendicular to the z-direction. The first major surface comprises a drive pin (13) that protrudes out of the first surface in positive z-direction. The drive pin is cylindrical and has an axis of symmetry parallel to the axis of symmetry of the drive axle.

At diametrically opposed positions around the drive axle there are a first driven wheel (15) and a second driven wheel (16). The first driven wheel (15) is arranged to rotate around a first driven axle (17), the second driven wheel is arranged to rotate around a second driven axle (18). The first driven axle (17) and the second driven axle (18) each have an axis of symmetry. The axis of symmetry of the drive axle (11) has the same y- coordinate as the axes of symmetry of the first driven axel (17) and the second driven axle (18). The first driven wheel (15) has 5 fold rotational symmetry. The axis of symmetry of the driven wheel (15) is the axis of symmetry of the first driven axle (17). The second driven wheel also has 5 fold rotational symmetry. The axis of symmetry of the second driven wheel (16) is the axis of symmetry of the second driven axle (18). The first driven wheel (15) comprises a U-shaped slot (19) in a first driven tooth (20) and comprises a first locking tooth (21). This is shown in figures 4,5 and 6. The second driven (16) wheel also comprises a U-shaped slot (22) in a second driven tooth (23) and a second locking tooth (24). The first locking tooth (21) and the first driven tooth (20) are arranged such that when the first driven wheel (15) would be rotated in clock- wise direction, the first locking tooth (21) reaches a certain angular position earlier than the first driven tooth (20). The angle between the first locking tooth (21) and the first driven tooth (20) is 72 degrees (corresponding to the 5-fold rotational symmetry). Similarly, the second locking tooth (24) and the second driven tooth (23) are arranged such that when the second driven wheel (16) would be rotated in clock- wise direction, the second locking tooth (24) reaches a certain angular position earlier than the second driven tooth (23). The angle between the second locking tooth (24) and the second driven tooth (23) is 72 degrees (corresponding to the 5-fold rotational symmetry).

The Geneva drive is assembled such that when the drive pin is in the position corresponding to the largest y-coordinate, rotation of the drive wheel in clock wise direction allows the drive pin to enter the second slot and that rotation of the drive wheel in counter clock wise direction allows the drive pin to enter the first slot.

The Geneva drive also comprises a first coupler (36). The first coupler is a bar of rigid material, such as metal and has two ends. On one end, the first coupler is attached to the first driven wheel (15) by a first pivot (25) projecting out of the first surface in z-direction. On the other end the first coupler (36) is attached to the contact module (8) by a second pivot (26) projecting out of the contact module (8) in z-direction.

Similarly, the Geneva drive also comprises a second coupler (27). The second coupler (27) is a bar of rigid material, such as metal and has two ends. On one end, the second coupler (27) is attached to the second driven wheel (16) by a first auxiliary pivot (28) projecting out of the first surface in z-direction. On the other end the second coupler (27) is attached to the second contact module (108) by a second auxiliary pivot (29) projecting out of the second contact module in z-direction. A locking member (31) is arranged for conjoint rotation with the drive wheel. A locking member (31) may be fixed to the drive wheel (10) at the first surface (12) by screws, glue, welding or otherwise. Alternatively, the locking member (31) and the drive wheel (10) are produced as a single part. The locking member (31) comprises a ridge (32) formed as the perimeter of a section of a disk arranged coaxially with the drive wheel (10). The locking member (31) and the ridge (32) both are at a diametrical position relative to the drive pin (13) (see figure 3).

The drive shaft may be rotated by a motor in the drawer or by a manual dial on the front side of the drawer. There may be a gear (30) between the motor or the manual dial and the drive shaft to change the axis of rotation of to compress or expand the angles of rotation.

Different orientations of the drive wheel (10) will now be discussed to explain the use of the switching device (7) (Figure 4, 5 and 6). In a first state of the switching device (7) the contact module (8) is in a first connected position and the auxiliary contact module (108) is in the second connected position, i.e. their y-coordinates have maximum values.

By rotating the drive wheel (10) in clockwise direction (herein also referred to as a first rotational direction), the drive pin (13) enters the U-shaped slot (19) of the first driven tooth (20) (figure 4). As the rotation of the drive wheel (10) continues, the first driven wheel (15) is rotated in counter clockwise direction until the drive pin (13) has left the U-shaped slot (19). While rotating, the first coupler (36) has been moved as well, thereby driving the contact module (8) from the first connected position to the first disconnected position.

During this rotation the locking member immobilized the second driven wheel (16) because the ridge of the locking member (31) engaged with a second recess (33) in the second driven wheel, i.e. the motion of the second driven wheel (16) is positively constrained using geometry. The second recess (33) has the shape of a section of a circle.

The second driven wheel (16) has a further recess (34) similar to the second recess (33) for locking to position of the second driven wheel in another orientation.

Because the second driven wheel (16) is immobilized, the second coupler (27) does not move as well and the auxiliary contact module (108) remains in the second connected position. This state of the switching device (7) (i.e. the state wherein the connection (8) module is in a disconnected position and the auxiliary connection module (108) is a connected position) is herein referred to as a second state.

By rotating the drive wheel (10) further in clockwise direction, the locking member (31) locks orientation of the first driven wheel (15) and drive pin (13) enters the U-shaped slot (22) of the second driven tooth (23). The orientation of the first driven wheel (15) is secured by the ridge (32) of the locking member (31) engaging with a first recess (35) of the first driven wheel (15) , i.e. the motion of the first driven wheel (15) is positively constrained using geometry. The first recess (35) has the shape of a section of a circle.

After entering the U-shaped slot (22) of the second driven tooth (23) the second driven wheel (16) starts to rotate in counter clockwise direction until the drive pin (13) leaves the U-shaped slot (figure 6). During rotation of the second driven wheel (16) the second coupler (27) moves, driving the auxiliary contact module to the second disconnected position. As the orientation of the first driven wheel (15) is immobilized, the first coupler (36) does not move and the contact module remains in first disconnected position.

Herein, the third state of the switching device (7) refers to the state wherein the contact module (8) is in the first disconnected position and the auxiliary contact module (108) is in the second disconnected position. In the third state, the respective y-coordinates of the both the contact module (8) and the auxiliary contact module (108) are at their smallest values.

The Geneva drive comprises two hard stops to limit the states between the described 3 combinations of connection states of the contact module (8) and the auxiliary contact module (108). In this example, the hard stops are formed by protrusions from the second surface of the drive wheel (10).

By rotating the drive wheel (10) further, one of these hard stops is reached. By now rotating back, i.e. in counter clockwise direction (herein also second rotational direction), first the position of the auxiliary contact module (108) changes from the second disconnected position to the second connected position (while the contact module remains in first disconnected position). On rotating further in counter clockwise direction the contact module (8) moves to the first connected position while the auxiliary contact module (108) remains in the second connected position. This corresponds to the first state as described above.

The switching device (7) further comprises a main disconnect and a test button light. The main disconnect is part of an internal electrical circuit connecting the first electrical contact from the contact module (8) with a second electrical contact from the auxiliary contact module (108). The main disconnect is closed in the first state of the switching device and is open in the second and third state. The main disconnect is opened between the first state and the second state. The main disconnect may be driven by the shaft (9). The test light is illuminated only when the switching device is in the third state, otherwise it is off.

The drawer (6) remains in position during the three states of the switching device. However, the drawer (6) can also be removed from the cabinet (1), but only when the switching device is in the third state by use of a locking mechanism attached to the motor or the manual dial.

A second example deviates from the first example in that the first driven wheel (15) only comprises 1 U-shaped slot. Also the second driven wheel (16) comprises 1 U-shaped slot. When the driving pin reaches any of the teeth without a U-shaped slot, the rotation of the drive wheel (10) is blocked, i.e. such a tooth forms a hard stop. Obviously, the first driven wheel (15) and the second driven wheel (16) may not have rotational symmetry in this second example.