AU2015276408B2

AU2015276408B2 - Retraction mechanism

Info

Publication number: AU2015276408B2
Application number: AU2015276408A
Authority: AU
Inventors: Mikel AGRELA GONZALES; Angelo Michele CECCHI; Martin Geelen; Job GREEFHORST; Tim LIE; Pedro ROS-ZUAZUA
Original assignee: Eaton Intelligent Power Ltd
Current assignee: Eaton Intelligent Power Ltd
Priority date: 2014-06-16
Filing date: 2015-06-05
Publication date: 2019-01-17
Anticipated expiration: 2035-06-05
Also published as: EP3155703A1; CN106537704A; GB201410728D0; CN106537704B; BR112016029469A2; WO2015193127A1; AU2015276408A1

Abstract

The invention relates to a retraction mechanism (7) for an electrical contact (9), the retraction mechanism characterized by comprising a drive shaft (20) with an external thread arranged to ratably drive the retraction mechanism, the drive shaft being supported by a frame (6) in a fixed position relative to the frame; a threaded collar (1008) with an internal thread arranged to engage with the outer thread of the drive shaft, the threaded collar being arranged to be moved along the drive shaft by rotation of the drive shaft and means (1000, 1009,1010) to lock the position of the threaded collar with respect to the frame.

Description

The invention relates to a retraction mechanism for an electrical contact.

US20100157512A1 discloses a subunit for connecting supply power to motor control components with moveable electrical contacts. The subunit is comprised in a frame. After the frame is secured into a compartment, the electrical contacts may be advanced to engage supply power buses. For disconnection, the electrical contacts may be retracted and isolated from the buses before the subunit itself is removed from the compartment. The electrical contacts are moved by a linear actuator and a stab assembly mounted on a drive shaft.

The subunit also comprises a set of control power contacts. In one case the position of set of control power contacts is fixed relative to the frame. In another case, they may be moveable in a similar manner to the electrical contacts.

Movement of the electrical contacts triggers an automatic latch such that the frame engages with the compartment. After triggering the automatic latch, the electrical contacts are extended further to finally engage with supply power conductors. When refracting, the electrical contacts are first refracted partly. The automatic latch will release from engagement again when the electrical contacts are retracted further. Only after the automatic latch disengages, the frame may be removed from the compartment.

A shutter or isolator assembly is disposed between the stab assembly and the exterior of the frame. The shutters of the shutter assembly either isolate or expose the electrical contacts form/to the supply power buses. A shutter arm is used to control a shutter indication mechanism that displays via a front panel indicator whether the shutters are open or closed.

A front panel is secured against a periphery of the compartment. The frame includes a number of latching mechanisms on the front panel to lock the frame into place when installed. A door with hinges allows access to components in the subunit when installed in the compartment.

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DE10216594A1 discloses a drawer with a frame provided with a hooked part of a locking mechanism for securing the frame in a reception compartment in a switchgear cabinet. The locking mechanism is operated by 2 operating elements provided on a front panel of the drawer. One of the operating elements also indirectly drives a shutter rod for activating a shutter mechanism of the switchgear cabinet. The shutter rod is driven via a drive shaft between the operating element and the shutter rod. Each operating element drives a hooked part of the locking mechanism. In locked state, the hooked part engages with a lower horizontal rim of an opening in the switchgear cabinet.

A first set of contacts (on the back side of the drawer) and a second set of contacts (on the side of the drawer) are each retractable between a connected position and a disconnected position. This is achieved by a retraction mechanism. The retraction mechanism is operated via a cylinder consisting of a first part and a second part at the front of the drawer. The rotation of the second part of the cylinder is transmitted via teeth to rods of a second part of the retraction mechanism to the second set of contacts. The rotation of the first part of the cylinder is transmitted via teeth to rods of a first part of the retraction mechanism to the first set of contacts.

The second part of the cylinder is operated by a short key. The first part of the cylinder is operated by a long key. When the first part of the cylinder is rotated, the second part is rotated as well.

The locking mechanism prevents access to the cylinder when the frame is not locked into the reception compartment. The long key and the short key must each be inserted against a spring force to prevent accidental operation of the first part of the cylinder and the second part of the cylinder.

The second part of the retraction mechanism locks the locking mechanism in the locked status when the second set of contacts is extended with a protrusion that extends and retracts together with the second set of contacts and engages with an opening in the mechanism that drives the hooked part.

The drawer also comprises a switch for switching on and off electronic components in the drawer. A further locking system locks the retraction mechanism when the electronic components are on line.

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The rods of the first part and require relatively large amount of space to move in. The rods of the second part include a pivoting arm and also require a relatively large amount of space to move in and a relatively large amount of parts.

In addition, two different keys are needed to be able to distinguish between tree states of the retraction mechanism. The three states are:

both the first set of contacts (12) and the second set of contacts (14) are retracted the second set of contacts (14) is extended but the first set of contacts is retracted both the first set of contacts (12) and the second set of contacts (14) are retracted.

A user may by mistake use the wrong key and extend both the first set of contacts and the second set of contacts instead of only extending the second set of contacts. Moreover, by using the long key when both the first set of contacts and the second set of contacts are extended to retract the first set of contacts, the second set of contacts is retracted as well. This option is considered to be less safe and undesirable. Preferably the states can only change from first to second and from second to third and visa versa. Changes between the first state and the third state in either way are undesired.

It is a purpose of the invention to provide an alternative retraction mechanism for an electrical contact wherein the retraction state of the retraction mechanism can be locked.

According to a first embodiment of the invention there is provided a retraction mechanism for an electrical contact, characterized by

- a drive shaft with an external thread arranged to rotatably drive the retraction mechanism, the drive shaft being supported by a frame in a fixed position relative to the frame;

- a threaded collar with an internal thread arranged to engage with the outer thread of the drive shaft, the threaded collar being arranged to be moved along the drive shaft by rotation of the drive shaft; and

- means to lock the position of the threaded collar with respect to the frame.

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Because the drive shaft is supported by the frame in a fixed position relative to the frame and as the internal thread of the collar engages with the external thread of the drive shaft, locking the position of the threaded collar with respect to the frame also locks to orientation of the drive shaft. When the orientation of the drive shaft is locked, the position of the contact, i.e. the retraction state of the contact or the retraction mechanism is locked.

Compared to US20100157512A1 the invention has the advantage that the position of the electrical contact can be locked. By locking the position of the electrical contact the electrical contact cannot inadvertently be moved to for instance a position in between a retracted and extended (or connected and disconnected) position. In addition, locking the position of a contact improves the quality of the contact being less susceptible to vibrations.

With the spindle already present for driving the retraction mechanism, adding a collar requires little space, which is advantageous over DE10216594A1. Moreover, the retraction state of the retraction mechanism is locked without independently of locking of the frame to something else.

According to a second embodiment of the invention there is provided a retraction mechanism according to the first embodiment, wherein the means comprise a locking member comprising an edge arranged such that the movement of the threaded collar along the drive shaft corresponds to a simultaneous travel along the edge and arranged to remain in contact with the threaded collar while the threaded collar travels along the edge, the edge comprising a recess arranged to receive the threaded collar.

Because the edge is arranged to remain in contact with the threaded collar, the recess catches the threaded collar when it reaches the recess while the threaded collar moves along the drive shaft and the edge. When the threaded collar is caught by the recess in the edge, the position along the drive shaft is secured as well. When the position along the drive shaft is secured, the orientation of the drive shaft is secured and the position of the contact is secured.

The skilled person will appreciate that the locking member will move, i.e. shift or rotate, when receiving the threaded collar in the recess because the threaded collar can only move along the spindle.

A locking member with a recessed edge is a relatively simple, cheap and reliable part. It is easy

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PCT/EP2015/062617 to arranged to the edge remains in contact with the threaded collar as well.

According to a third embodiment of the invention there is provided a retraction mechanism according to the second embodiment wherein the means to lock the position of the threaded collar comprise a spring arranged to force the edge of the locking member against the threaded collar.

Springs are relatively reliable and cheap and the application is simple.

Because the edge remains in contact, locking the threaded collar takes place automatically. To move the collar out of the recess against the spring force will require a force to do that. As he will be required to deliver that force, a user will have a clear indication when the retraction mechanism is locked and when he unlocks it.

According to a fourth embodiment of the invention, there is provided a retraction mechanism according to the second or third embodiment, wherein the locking member is arranged to pivot when receiving the threaded collar in the recess.

According to a fifth embodiment of the invention, there is provided a retraction mechanism according to the second, third or fourth embodiment comprising a lever arranged to move the locking member for releasing the threaded collar from the recess.

The lever allows the locking member to be places at a distance from the side of the retraction mechanism where a user operates the retraction mechanism.

According to a sixth embodiment of the invention, there is provided a retraction mechanism according to the fifth embodiment, wherein the locking member comprises a further edge facing the edge, the lever being arranged to move the further edge against the threaded collar, the further edge comprising a further recess arranged for at least partially receiving the threaded collar at a location along the further edge such that releasing the lever while the threaded collar is in the further recess results in the threaded collar being received in the recess.

By providing the further recess for receiving the threaded collar, the user gets an indication when he has reached the position where releasing the lever results in the threaded collar being received

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PCT/EP2015/062617 in the recess.

The further edge may be parallel to the edge. In such a case, if the locking member is pivotable, the further recess may have a slightly different position than the recess.

In a preferable embodiment the edge and the further edge are edges of a slot.

According to a seventh embodiment of the invention, there is provided a retraction mechanism according to any of the preceding claims wherein the drive shaft is arranged to rotably drive the retraction and extension of a further electrical contact and wherein continuous rotation of the drive shaft corresponds to transitions between a first state wherein the electrical contact and the further electrical contact are in a disconnect position, a second state wherein the electrical contact is in a disconnect position and the further electrical contact is in a connect position and a third state wherein the electrical contact and the further electrical contact are both in a connect position.

As the drive shaft cannot skip rotational states, the transitions are limited.

This is advantageous over DE10216594A1, where a mistake by user can make the electrical contact and the further electrical contact to retract or extend simultaneously.

As both the electrical contact and the further electrical contact are rotably driven by the drive shaft, a single drive tool can be used to retract and extend the the electrical contact and the further electrical contact.

It will be clear to the person skilled in the art, that a retracted state can refer to a disconnect or a connect position of a contact, depending on the design. Usually, extended states are used for connect positions.

According to an eight embodiment of the invention, there is provided a retraction mechanism according to the seventh embodiment, wherein the position of the recess corresponds to the position of the threaded collar along the drive shaft when the electrical contact is in the disconnect position and the further electrical contact is in the connect position.

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Limiting the transitions between the retracted and extended state of the electrical contact to those situations wherein the further electrical contact is extended provides additional safety. Because the recess corresponds to the position of the collar when the contact and the further electrical contact are in this state, this state can be locked.

According to an ninth embodiment of the invention, there is provided a switchgear device comprising the retraction mechanism according to any of the preceding embodiments, comprising a switch for switchably connecting the electrical contact to the further electrical contact.

The presence of such a switch increases safety by being able to break the connection between the electrical contact and the further electrical contact when the electrical contact or the further electrical contact is moved to or from a connect position.

According to a tenth embodiment of the invention, there is provided a switchgear device according to the ninth embodiment, comprising a locking mechanism for closing an opening to prevent a drive tool to rotably drive the drive shaft when the switch is in a state wherein the electrical contact is connected to the further electrical contact. The switchgear device according to this embodiment ensures that the electrical contact and the further electrical contact can only be moved when the there is no current flowing over the electrical contact and the further electrical contact. Therefore, the chances on arcs are reduced.

Examples of embodiments 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 in all figures to better illustrate and explain 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 of a low voltage distribution system comprising a drawer with a retraction mechanism according to the invention

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Figure 2 drawer comprising a retraction mechanism according to the invention

Figure 3 schematic overview of the retraction mechanism, locked in the first state

Figure 4 schematic overview of the retraction mechanism, locked in the second state

For the purpose of explaining the invention, use is made of an x-direction, a y-direction and a zdirection, which are all perpendicular and chosen in right-handed orientation. A corresponding Cartesian coordinate system is used as well.

In the following examples of the invention, the positive z-direction is a vertical upward direction, i.e. the negative z-direction is the direction of the force of gravity.

In an example of the invention, there is a housing comprising switchgear for a low voltage distribution system. The 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) framing a retraction mechanism (7) according to the invention (figure 2). In figure 2 parts of the retraction mechanism (7), such as a sliding door (1017) and a switch (2008) are not shown for clearity. The retraction mechanism comprises four contacts (9) fixedly mounted in a first contact housing (8). The four

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PCT/EP2015/062617 contacts (9) are isolated from each other by walls of glass-fibre reinforced polyester. The first contact housing (8) can be extended and retracted along the y-direction thereby extending and retracting the four contacts (9) to connect or disconnect the four contacts (9) with the four distribution bus bars. The connected state of a contact (9) corresponds to the extended state wherein the contact has a maximum value for the y-coordinate. The disconnected state corresponds to the retracted state wherein the contact (9) has a minimum value for the ycoordinate.

The retraction mechanism (7) also comprises a second contact housing (108) with four further electrical contacts (109) that are isolated from each other by walls of glass-fibre reinforced polyester. The second contact housing (108) can be extended and retracted along the y-direction to thereby extending and retracting the four further electrical contacts (109) to connect or disconnect the four further electrical contacts (109) with corresponding cables of an auxiliary circuit.

The drawer (6) comprises a switch (2008) for switchably connecting each of the four contacts (9) to one of the four further electrical contacts (109) over internal cables. Internal here means that the cables run inside the drawer (6).

The extension and retraction motion of the contacts (9) and the further electrical contacts (109) is driven by a threaded drive shaft (20). The threaded drive shaft is cylindrical and has an external thread with a helical shape. The threaded drive shaft (20) extends the y-direction from the front of the drawer (6) to the back of the drawer (6). A gear wheel is concentrically mounted on the threaded drive shaft (20). The gear wheel engages with a further gear wheel to transmit the rotational motion of the threaded drive shaft (20) to a rotational motion of a threaded transmission shaft running in x-direction. The further gear wheel is concentrically fixed to the threaded transmission shaft. The threaded transmission shaft is supported by two bearings in a support frame (14). The positions of the threaded transmission shaft and the two bearings are stationary, the orientation of the threaded transmission shaft changes in use by rotation around an axis in x-direction.

The support frame (14) supports a transport member (11). The first contact housing (8) is fixed to the transport member (11) by screws. The transport member (11) comprises a retraction slot (12) with a part parallel to the threaded transmission shaft and a part at an angle to the threaded

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PCT/EP2015/062617 transmission shaft. The transport member (11) is slidably arranged in the support frame (14) such that it may be moved in y-direction to extend or retract the four contacts (9). The edge of the retraction slot (12) in the transport member (11) engages with a retraction collar arranged around the threaded transmission shaft. The retraction collar comprises an internal thread that engages with the thread of the threaded transmission shaft. The retraction collar therefore moves along the threaded transmission shaft upon rotation of the threaded transmission shaft. When the retraction collar is in use in the part of the retraction slot (12) angled to the threaded transmission shaft, rotation of the threaded transmission shaft and therefore the movement of the retraction collar along the threaded transmission shaft moves the transport member (11), i.e. it either extends the transport member (11) or retracts the transport member (11). When the retraction collar is in the part of the retraction slot (12) parallel to the threaded transmission shaft, rotation of the threaded transmission shaft (and therefore the movement of the retraction collar along the threaded transmission shaft) does not move the transport member (11).

The support frame (14) also supports a further transport member (111). The second contact housing (108) is fixed to the further transport member (111) by screws. The mechanism for extending and retracting the further electrical contacts (109) is similar to that of the contacts (9). The further transport member (111) comprises a further retraction slot (112) with a part parallel to the threaded transmission shaft and a part at an angle to the threaded transmission shaft. The further transport member (111) is slidably arranged in the support frame (14) such that is may be moved in y-direction to extend or retract the four further electrical contacts (109). The edge of the further retraction slot (112) in the transport member (11) engages with a further retraction collar (113) arranged around the threaded transmission shaft. The further retraction collar (113) comprises an internal thread that engages with the thread of the threaded transmission shaft. The further retraction collar (113) therefore moves along the threaded transmission shaft upon rotation of the threaded transmission shaft. When the further retraction collar (113) is in use in the part of the retraction slot (112) angled to the threaded transmission shaft, rotation of the threaded transmission shaft and therefore the movement of the further retraction collar (113) along the threaded transmission shaft moves the further transport member (111), i.e. it either extends the further transport member (111) or retracts the further transport member (111). When the further retraction collar (113) is in the part of the further retraction slot (112) parallel to the threaded transmission shaft, rotation of the threaded transmission shaft and therefore the movement of the retraction collar along the threaded transmission shaft does not move the transport member (11).

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The retraction slot (12), the further retraction slot (112), the retraction collar (13) and the further retraction collar (113) are arranged such that when the retraction collar is in the part of the retraction slot (12) parallel to the threaded transmission shaft, the further retraction collar (113) is in the part of the further retraction slot (112) at an angle to the threaded transmission shaft. In addition, when the retraction collar is in the part of the retraction slot (12) at an angle to the threaded transmission shaft, the further retraction collar (113) is in the part of the further retraction slot (112) parallel to the threaded transmission shaft. This arrangement ensures that upon rotation of the treaded transmission shaft either the four contacts (9) or the four further electrical contacts (109) are moved between extended and retracted positions.

Further, the retraction slot (12), the further retraction slot (112), the retraction collar (13) and the further retraction collar (113) are arranged such the transport member (11) and the further transport member (111) can simultaneously be in an retracted position, corresponding to a first state (figure 3) of the retraction mechanism (7) or can simultaneously be in an extended position corresponding to a third state of the retraction mechanism (7). In a second state (figure 4) the further transport member (111) is in an extended position, whereas the transport member (11) is in a retracted position. As the retraction collar (13) and the further retraction collar (113) move along the threaded transmission shaft linearly, the only possible transitions are from the first state to the second state, from the second state to the third state, from the third state to the second state and from the second state to the first state.

The drawer (6) forms a withdrawable frame for the retraction mechanism (7). The threaded drive shaft (20) is supported by a bearing on each end of the threaded drive shaft (20) (figures 3 and 4). A bearing close to the front side of the drawer (6) is supported by the drawer (6). The position of the threaded drive shaft (20) is stationary with respect to the drawer (6), the orientation of the threaded drive shaft (20) changes in use when the threaded drive shaft (20) rotates around an axis parallel to the y-direction.

A threaded collar (1008) is arranged around the threaded drive shaft (20) between the front side of the drawer (6) and the support frame (14). The threaded collar (1008) has an internal thread engaging with the external thread of the threaded drive shaft (20). The threaded collar (1008) protrudes into a slot (1001) of a locking member (1000).

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The locking member (1000) is a sheet of metal fixed onto an arm of a pivotably arranged locking element (1009). The locking element (1009) is arranged to pivot around a pivot (1019) extending in x-direction. The pivot (1019) is mounted in a sidewall of the drawer (6), the sidewall extending in y-direction.

The slot (1001) comprises an edge (1002). In an orientation of the locking element (1009), the edge (1002) of the slot (1001) is parallel to the direction in which the threaded drive shaft (20) extends, i.e. parallel to the axis around which the treaded drive shaft (20) in use rotates.

A spring is mounted between the bottom of the drawer (6) and the arm of the locking element (1009) in compressed state. The spring therefore pushes the edge (1002) against the threaded collar (1008), in this example in clockwise direction when seen from the positive x-direction.

The edge comprises a first recess (1011), a second recess (1012) and a third recess (1013). Each recess (1011, 1012, 1013) has a shape suitable to receive the threaded collar (1008).

When the threaded collar (1008) reaches a recess, say the first recess (1011) the spring (1010) pushes the arm upward so that it pivots in clockwise direction (when seen from the positive xdirection). When the arm of the locking element (1009) pivots, the locking member (1000) pivots with it. The threaded collar (1008) is received in the first recess (1011).

The first recess (1011) is at a first end of the slot (1001); the third recess (1013) is at a second end of the slot (1001). The first recess (1011) and the third recess (1013) correspond to the first state and the third state of the retraction mechanism (7). The second recess (1012) corresponds to the second state of the retraction mechanism (7) and is situation in between the first recess (1011) and the third recess (1013).

The retraction mechanism (7) further comprises a lever (1014). The lever (1014) is pivotably connected to the locking element (1009) and extends along the sidewall of the drawer (6) to the front of the drawer (6), i.e. it extends in the y-direction. The lever (1014) is slidable in the ydirection. An end of the lever (1014) is curved. The curved end is accessible through the front of the drawer (6) forming a hook so that it may be pulled. The pivotable connection between the lever (1014) and the locking element (1009) is at a smaller y-coordinate and a larger zcoordinate than the pivot (1019) around which the locking element (1009) pivots. By pulling the lever (1014), the locking element (1009) pivots in counter clockwise direction (again seen from

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PCT/EP2015/062617 the positive x-direction), i.e. against the spring force. As the locking element (1009) pivots in counter clockwise direction, the locking member (1000) pivots as well including the slot (1001). If the threaded collar (1008) was received in the first recess (1006), the recess is moved away from the threaded collar (1008) and the threaded collar (1008) can move along the threaded drive shaft (20). The similar effects take place if the threaded collar (1008) was received in either the second recess (1012) or the third recess (1013).

The slot (1002) comprises a further edge (1004) comprising a further recess (1005). The further edge (1004) is parallel to the edge (1002), obviously except at the first recess (1011), the second recess (1012), the third recess (1013) and the further recess (1005). The further recess (1005) is arranged to partially receive the threaded collar (1008). The location of the further recess (1005) is opposite to the second recess (1012).

In use, the lever (1014) may be pulled while the threaded collar (1008) is moved by driving the threaded spindle (20) to rotate. The threaded collar may therefore engage with the further edge (1004) and not with the edge (1002). In such a case the user will be alerted when the second state is reached. This is because the threaded collar (1008) is received in the further recess (1005). By releasing the lever (1014) the locking element (1009) and therefore the locking member (1000) will pivot in clockwise direction (again seen from the positive x-direction) and the threaded collar (1008) will leave the further recess (1005) and be received in the second recess (1012).

The drive shaft (20) can be driven by a user from the front of the drawer (6) by inserting a drive tool (1015) into an end of the drive shaft (20) through an opening in the front of the drawer (6).

The drawer (6) comprises a sliding door (1017) arranged to slide in the x-direction. When the position of the door has a minimum value for the x-coordinate the sliding door (1017) blocks the opening. When the opening is blocked, the drive tool (1015) cannot be used to drive the drive shaft (20).

The switch (2008) comprises a ratable knob arranged on the front of the drawer (6). The ratable knob is mounted on a switching axle extending in the y-direction. The switching axle has a cross section with a square shape.

The sliding door (1017) comprises a recess corresponding to the switching axle. When the

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PCT/EP2015/062617 position of the sliding door (1017) has maximum value for the y-coordinate, the switching axle is received in the recess. The recess engages with the switching axle, preventing the switching axle to rotate, thus locking the state of the switch (2008).

An end of an inner cable (2000) of a Bowden cable (2001) is clamped onto the threaded collar (1008). The Bowden cable (2001) further comprises a hollow outer cable housing (2002). One end of the hollow outer cable housing (2002) is attached to a first cable support (2003) arranged in the drawer (6), the drawer (6) thus functioning as a frame. The other end of the hollow outer cable housing (2002) is attached to a second cable support (2004) near the front of the drawer (6). The position and orientation of the second cable support (2004) are stationary within the drawer (6). Apart of the inner cable (2000) runs from the other end of the hollow outer cable housing (2002) to a pulley (2005) and back to a clamp on the second cable support thereby running in a U-shaped loop. The clamp forms a stationary anchor for the inner cable (2000). The pulley (2005) is mounted on an end of a pivotable arm. The other end of the pivotable arm indicates the state of the retraction mechanism (7) and is visible through a window (2006) in the front of the drawer (6). On the front of the drawer (6) there is a sticker with status indicators at positions corresponding to the position of the other end of the pivotable arm.

A torsion spring forces the pivotable arm to rotate such that the pulley (2005) remains in contact

0 with the inner cable (2000) when the threaded collar (1008) moves towards the first cable support (2003).

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FQLLOWS:1. Retraction mechanism for an electricai contact, the retraction mechanism having a drive shaft with an external thread arranged to rotatably drive the retraction mechanism, the drive shaft being supported by a frame in a fixed position relative to the frame; a threaded collar with an internal thread arranged to engage with the outer thread of the drive shaft, the threaded collar being arranged to be moved along the drive shaft by rotation of the drive shaft; and means to lock the position of the threaded collar with respect to the frame including a locking member having an edge arranged such that the movement of the threaded collar along the drive shaft corresponds to a simultaneous travel along the edge and arranged to remain in contact with the threaded collar while the threaded collar travels along the edge, the edge comprising a recess arranged to receive the threaded collar.
2. Retraction mechanism according to claim 1 wherein the means to lock the position of the threaded collar comprises a spring arranged to force the edge of the locking member against the threaded collar.
3. Retraction mechanism according to claim 2, wherein the locking member is arranged to pivot when receiving the threaded collar in the recess.
4. Retraction mechanism according to claim 2 or claim 3 comprising a lever arranged to move the locking member for releasing the threaded collar from the recess.
5. Retraction mechanism according to claim 4 wherein the locking member comprises a further edge facing the edge, the lever being arranged to 04/12/18

2015276408 04 Dec 2018 move the further edge against the threaded collar, the further edge comprising a further recess arranged for at least partially receiving the threaded collar at a location along the further edge such that releasing the lever while the threaded collar is in the further recess results in the threaded collar being received in the recess.
6. Retraction mechanism according to any one of the preceding claims wherein the drive shaft is arranged to rotably drive the retraction and extension of a further electrical contact and wherein continuous rotation of the drive shaft corresponds to transitions between a first state wherein the electrical contact and the further electrical contact are in a disconnect position, a second state wherein the electrical contact is in a disconnect position and the further electrical contact is in a connect position and a third state wherein the electrical contact and the further electrical contact are both in a connect position.
7. Retraction mechanism according to claim 6 wherein the position of the recess corresponds to the position of the threaded collar along the drive shaft when the electrical contact is in the disconnect position and the further electrical contact is in the connect position.
8. Switchgear device comprising the retraction mechanism according to any one of the preceding claims, comprising a switch for switchably connecting the electrical contact to the further electrical contact.
9. Switchgear device according to claim 8, comprising a locking mechanism for closing an opening to prevent a drive tool to rotably drive the

04/12/18

2015276408 04 Dec 2018 drive shaft when the switch is in a state wherein the electrical contact is connected to the further electrical contact.