EP4641600A1

EP4641600A1 - An electric current knife switch with movable dielectric shield

Info

Publication number: EP4641600A1
Application number: EP24172877.3A
Authority: EP
Inventors: John West; Sachin SHIVARANJAN
Original assignee: ABB Schweiz AG
Current assignee: ABB Schweiz AG
Priority date: 2024-04-26
Filing date: 2024-04-26
Publication date: 2025-10-29

Abstract

The present invention relates to an electric current switch (100, 200) comprising: a movable contact lever (102, 202) comprising a lever main contact area (141, 241); a fixed contact assembly (116, 216) comprising a fixed main contact (152, 252), the contact lever is configured to rotate about the pivot point between the closed position (P1) and an open position (P2), the electric current switch further comprising a movable dielectric shield (160, 260), wherein the movement of the movable dielectric shield is between a covering position (C1) wherein it covers the one of the fixed main contact of the fixed contact assembly or the main contact area of the contact lever, and a second position (C2) where the movable dielectric shield has moved away from the covering position, and the movement of the movable dielectric shield is mechanically coupled to the rotation of the contact lever.

Description

Field of the Invention

The present invention relates to an electric current switch.

Background

Electric knife or blade switching devices are fundamental components in electrical systems, used for connecting and disconnecting electrical circuits. Electric knife switches for medium- and high voltage switchgear are subject to electric arcing during current interruption and contact making events. Suppressing the arcs is important to protect the electric switch itself and electric devices connected to the electric switch.
Electric knife switches are equipped with dielectric shields to protect surrounding components from electric arcs. However, the dielectric shields can compromise the efficiency and safety of the electrical connection. Specifically, the dielectric shields often obstruct the establishment of optimal contact between the switching components, leading to potential dielectric issues. Additionally, these dielectric shields can inadvertently become sites where electric arcs initiate during the switching process, posing significant safety risks and operational inefficiencies.
The limitations of existing solutions highlight a clear need for improvements in managing field control in knife switching devices.

Summary

In view of the above-mentioned and other drawbacks of the prior art, it is an object of the present invention to provide an electric current switch that at least partly alleviates the deficiencies with prior art.
According to a first aspect of the invention, there is provided an electric current switch comprising: a movable contact lever comprising a proximal end and a distal end, the contact lever is rotatable at a pivot point at the distal end, the contact lever comprising a lever main contact area at the proximal end; a fixed contact assembly configured to receive the movable contact lever in a closed position of the contact lever, the fixed contact assembly comprising a fixed main contact, the contact lever is configured to rotate about the pivot point between the closed position and an open position, the electric current switch further comprising a movable dielectric shield configured to cover one of the fixed main contact of the fixed contact assembly or the main contact area of the contact lever, the dielectric shield being movable relative to the one of the fixed main contact of the fixed contact assembly or the main contact area of the contact lever that the movable dielectric shield is configured to cover, wherein the movement of the movable dielectric shield is between a covering position wherein it covers the one of the fixed main contact of the fixed contact assembly or the main contact area of the contact lever, and a second position where the movable dielectric shield has moved away from the covering position, and the movement of the movable dielectric shield is mechanically coupled to the rotation of the contact lever.
The present invention is at least partly based on the realization to couple the motion of the contact lever to the dielectric shield such that the dielectric shield moves when the contact lever moves. In other words, there is a movement in the electric switch given by the contact lever. The inventors realized to utilize this movement by coupling it to the dielectric shield to thereby cause a movement of the dielectric shield. The movement of the contact lever is highly synchronized with the formation of arcs since the contact lever moves between electrically open and electrically closed positions, thus, coupling the motion of the contact lever to the dielectric shield provides for timely moving the dielectric shield in and out of the covering position while ensuring dielectric protection when it is needed the most.
The electric current switch may comprise a housing that provides an assembly base for the electric switch. In such case, the pivot point is preferably fixed in relation to the housing. The contact lever and the fixed contact assembly may be housed inside the housing.
In the closed position of the contact lever, an electric current may pass between the main contact area of the contact lever and the fixed main contact of the fixed contact assembly. In the open position, the contact lever and the fixed contact are not in contact whereby an electric current may not pass between them.
In the closed position, the lever main contact area mates with the fixed main contact.
The electric current switch may further comprise an earth contact configured to receive the contact lever in an earthed position of the contact lever, the contact lever is configured to rotate about the pivot point between the earthed position, the closed position, and the open position. The earth contact may be fixed in relation to the housing. Thus, the contact lever may be moved to three positions, while the earth contact, the fixed contact, and the fixed contact assembly may be fixed in relation to for example a housing. The fixed contact and the earth contact may be stationary with respect to the pivot point when the contact lever moves between the earthed position, the closed position, and the open position.
In one embodiment, the movable dielectric shield may be attached to the contact lever to cover the main contact area of the contact lever in the covering position. In this way, it is ensured that the movement of the dielectric shield is synchronized with the movement of the contact lever. Furthermore, attaching the dielectric shield to the contact lever ensures that the shield is always in the correct position with regards to the contact lever to protect against unintended electrical arcing and to maintain the integrity of the electrical insulation, thereby improving the reliability of the switch's operation under varying electrical loads and conditions.
In one embodiment, the movable dielectric shield may be configured to move along a longitudinal axis of the contact lever. In other words, the dielectric shield may slide along the contact lever to cover the main contact area, or to expose the main contact area.
In one embodiment, the movable dielectric shield may be configured to expose the main contact area when the contact lever moves towards the fixed main contact assembly and to cover the main contact area when the contact lever moves away from the fixed main contact assembly. That is, the dielectric shield is ensured to cover the main contact area of the contact lever as soon as it is not in contact with the fixed main contact, reducing the risk of dielectric issues and improving the reliability of the electric current switch.
In one embodiment, the electric current switch may comprise a position guide fixed in relation to the pivot point, and a roller fixed to the dielectric shield, the roller being arranged to slide against the position guide to move the dielectric shield between the covering position and the second position. A position guide and roller advantageously provide for high precision movement of the dielectric shield. The roller's engagement with the position guide allows for a guided movement that may minimize misalignment and friction, which may lead to a longer lifespan for the electric switch and more reliable operation. Furthermore, the use of a position guide and roller may improve consistency and predictability in positioning of the dielectric shield.
The position guide may fix the sliding dielectric shield to the desired position and hold it in place, for example with a snap-fit or lock pocket in the position guide. The position guide may be attached to an insulating part where the contact lever is attached.
Thus, the movement of the dielectric shield can be activated for instance with a position guide pushing or pulling the dielectric shield to the desired position.
In one embodiment, the electric current switch may comprise a spring configured to bias the roller against the position guide. That is, a spring may be used to assist or position the dielectric shield in the required place depending on desired position with regards to the electric current switch. A spring provides for a simple yet robust way of biasing the roller against the position guide.
In one embodiment, the position guide may comprise a slot for guiding the roller along a curved path. A slot provides for a reliable guiding motion of the roller.
In one embodiment, the movable dielectric shield may be arranged to cover the fixed main contact of the fixed contact assembly in the covering position. In other words, the dielectric shield may equally well be arranged to cover the fixed main contact. In this way, the dielectric shield covers the fixed main contact when the electric current switch is in an open position or during the transition between open and closed positions. This reduces the risk of arc flash or electrical discharge, contributing to safer operation and maintenance of the device.
In one embodiment, the movable dielectric shield may be configured to rotate about a pivot axis. That is, the movement of the dielectric shield is a rotation about a pivot axis which may be fixed in relation to the fixed contact assembly.
In one embodiment, the movable dielectric shield may be configured to expose the fixed main contact when the contact lever moves towards the fixed main contact assembly and to cover the fixed main contact when the contact lever moves away from the fixed main contact assembly. That is, the dielectric shield is ensured to cover the fixed main contact are of the fixed contact assembly as soon as it is not in contact with the contact lever, reducing the risk of dielectric issues and improving the reliability of the electric current switch.
In one embodiment, the electric current switch may comprise an actuator, wherein the movable dielectric shield is connected to the actuator that is coupled to the motion of the contact lever such that a motion of the contact lever causes rotation of the dielectric shield about its pivot axis. The actuator provides for a motion transfer between the contact lever and the movable dielectric shield.
The actuator may be but is not limited to a rotary actuator. The actuator may be adapted to operatively engage with the movable dielectric shield through a transmission link. The transmission link may be structured to transfer motion from the actuator to the movable dielectric shield in engagement with the one of the moving members of the electric current switch to rotate the movable dielectric shield in at least one of a clockwise direction and an anti-clockwise direction between the one or more positions. The transmission link may include a chain drive gear operatively coupled/engaged to the moving member of the electric current switch.
In one embodiment, the actuator may be connected to the dielectric shield by a first link and a second link, the first link being rotationally connected to the second link, a first end of the second link is fixed to the actuator and the rotational connection to the first link is at the second end of the second link and at a first end of the first link, and, a second end of the first link is rotationally connected to the dielectric shield. That is, the transmission link here includes a set of links that provide for reliable mechanical motion transfer.
In one embodiment, the contact lever may comprise a fixed dielectric shield at its proximal end configured to cover the main contact area. Thus, improved protection against arcs is ensured.
In one embodiment, the movable dielectric shield may comprise two parts, one on each side of the fixed main contact, the two parts being separated by a separation distance, wherein a width of the fixed dielectric shield is larger than the separation distance. Thus, since the dielectric shield moves away from the covering position when the contact lever approaches the closed position of the electric current switch, the fixed dielectric shield may be relatively large and has no size constraints with regards to the size of the movable dielectric shield of the fixed contact assembly. Hence, improved dielectric protection and reliability of the electric current switch are provided.
In embodiments, the contact lever may be a knife contact, and the electric current switch may be a knife switch.
In summary, the invention relates to an electric current switch comprising: a movable contact lever comprising a lever main contact area; a fixed contact assembly comprising a fixed main contact, the contact lever is configured to rotate about the pivot point between the closed position and an open position, the electric current switch further comprising a movable dielectric shield, wherein the movement of the movable dielectric shield is between a covering position wherein it covers the one of the fixed main contact of the fixed contact assembly or the main contact area of the contact lever, and a second position where the movable dielectric shield has moved away from the covering position, and the movement of the movable dielectric shield is mechanically coupled to the rotation of the contact lever.
Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled person realizes that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention.

Brief Description of the Drawings

These and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing an example embodiment of the invention, wherein:

Fig. 1 illustrates an example electric current switch according to embodiments of the invention;
Fig. 2 illustrates an example electric current switch according to embodiments of the invention;
Fig. 3 illustrates an example electric current switch according to embodiments of the invention;
Fig. 4 illustrates an example electric current switch in an open position according to embodiments of the invention;
Fig. 5 illustrates an example electric current switch in a closed position according to embodiments of the invention;
Fig. 6 illustrates another perspective view of the example electric current switch shown in fig. 4 and fig. 5; and
Fig. 7 illustrates an example electric current switch according to embodiments of the invention.

Detailed Description of Example Embodiments

In the present detailed description, various embodiments of the present invention are herein described with reference to specific implementations. In describing embodiments, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. While specific exemplary embodiments are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations can be used without parting from the scope of the invention.
Fig. 1 schematically illustrates an electric current switch 100 according to embodiments of the present invention.
The electric current switch 100 comprises a movable contact lever 102 comprising a proximal end 106 and a distal end 108. The contact lever 102 is rotatable at a pivot point 110 at the distal end 108. The contact lever 102 comprises a lever main contact area 141 at the proximal end 106.
The electric current switch 100 further comprises a fixed contact assembly 116 configured to receive the movable contact lever 102 in a closed position P1 of the contact lever 102. That is, in the closed position P1, the main contact area 141 of the contact lever 102 is in contact with a fixed main contact 152 of the fixed contact assembly 116 such that electrical current can conduct between the fixed main contact 152 of the fixed contact assembly 116 and the main contact area 141 of the contact lever 102.
The contact lever 102 can be positioned in an open position P2 where no electric current can flow between the fixed main contact 152 of the fixed contact assembly 116 and the main contact area 141 of the contact lever 102. In the open position P2, the main contact area 141 of the contact lever 102 is not in contact with a fixed main contact 152 of the fixed contact assembly 116.
The contact lever 102 is configured to rotate, see direction arrows 155, 156, about the pivot point 110 between the closed position P1 and the open position P2.
The electric current switch 100 further comprises a movable dielectric shield 160 configured to cover the main contact area 141 of the contact lever 102. The dielectric shield 160 is movable relative the main contact area 141 of the contact lever 102 that it is configured to cover.
The movement of the movable dielectric shield 160 is between a covering position C1 wherein it covers the main contact area 141 of the contact lever 102, and a second position C2 where the movable dielectric shield has moved away from the covering position C1. That is, in the covering position C1, the dielectric shield 160 provides the shielding of the main contact area 141, whereas in the second position C2, the dielectric shield 160 has moved away to thereby expose the main contact area 141.
The movement of the movable dielectric shield 160 is mechanically coupled to the rotation of the contact lever 102 about the pivot point 110. In other words, when the contact lever rotates from the open position P2 to the closed position P1, the movable dielectric shield 160 is caused to move so expose the main contact area 141. Similarly, when the contact lever 102 rotates from the closed position P1 to the open position P2, the movable dielectric shield 160 is caused to move to cover the main contact area 141.
In this example embodiment, the electric current switch 100 further comprises an earth contact 162 which the contact lever 102 reaches in the third position P3, which may be denoted a grounded or earthed position, when the contact lever 102 rotates from the open position P2 to the earthed position P3, the movable dielectric shield 160 is caused to move so expose the main contact area 141. Further, when the contact lever 102 rotates from the earthed position P3 to the open position P2, the movable dielectric shield 160 is caused to move to cover the main contact area 141.
The rotation of the contact lever 102 is in a rotation plane that coincides with the mating fixed main contact 152. In other words, contact lever 102 moves in a single plane between the open position P2 where is it is not connected to the main contact 152 and the closed position P1 where it is connected, in physical contact, with the main contact 152. Moreover, the contact lever 102 moves in the same single plane between the open position P2 where is it is not connected to the earth contact 162 and the earthed position P3 where it is connected, in physical contact, with the earth contact 162.
Note that further contacts may be implemented and that the contacts may have high voltage potential, earth, or floating potential, and the herein shown embodiments serve as examples.
In this embodiment, the movable dielectric shield 160 is attached to the contact lever 102 to cover the main contact area 141 of the contact lever 102 in the covering position C1. The attachment is a sliding attachment which allow the movable dielectric shield 160 to move along a longitudinal axis 167 of the contact lever 102. In other words, when the contact lever 102 is rotated between its positions, the mechanical coupling to the movement of the dielectric shield 160 cause the dielectric shield 160 to slide along the longitudinal axis 167 of the contact lever 102.
The dielectric shield 160 may be a symmetric two part dielectric shield 160 that is fitted around the contact lever 102 to be able to slide on the contact lever 102. There may further be a pin and slot arrangement between the contact lever 102 and the slidable dielectric shield 160 to allow for the sliding motion of the dielectric shield 160.
Fig. 2 illustrates the electric current switch 100 with one possible arrangement for coupling of the motion of the contact lever 102 to the motion of the dielectric shield 160.
In this embodiment, the electric current switch 100 comprises a position guide 170 fixed in relation to the pivot point 110 and a roller 172 fixed to the dielectric shield 160. The roller 172, or equally pin or shaft, is arranged to slide against the position guide 170 to move the dielectric shield 160 between the covering position C1 and the second position C2. The position guide 170 comprises a slot 174 for guiding the roller 172 along a curved path. The slot follows a curved path. The curved path may be elliptic or oval.
When the contact lever 102 rotates from the open position P2 towards the closed position P1, the roller 172 is forced to move in the slot 174 by interaction with the walls of the slot, so that the dielectric shield 160 is moved towards the distal end 108 along the longitudinal axis 167 of the contact lever 102 as indicated by arrow 176.
When the contact lever 102 rotates from the closed position P1 towards the open position P2, the roller 172 is forced to move in the slot 174 by interaction with the walls of the slot 174, so that the dielectric shield 160 is moved towards the proximal end 108 and the main contact area 141 along the longitudinal axis 167 of the contact lever 102 as indicated by arrow 178.
When the contact lever 102 rotates from the open position P2 towards the earth position P3, the roller 172 is forced to move in the slot 174 by interaction with the walls of the slot, so that the dielectric shield 160 is moved towards the distal end 108 along the longitudinal axis 167 of the contact lever 102 as indicated by arrow 180.
The position guide 170 fixes the sliding dielectric shield 160 in the covering position C1 and the exposed second positions C2 and holds it in place. That is, the roller 172 cannot move in the slot unless the contact lever 102 is rotated. The position guide 170 may be attached to an insulating part where the contact lever 102 is attached.
Fig. 3 illustrates the electric current switch 100 with one possible arrangement for coupling of the motion of the contact lever 102 to the motion of the dielectric shield 160. In this embodiment the position guide 170 does not have a slot, but instead has an outer guide surface 182 that follows a curved path. The curved path may be elliptic or oval. The roller 172 slides on the outer guide surface 182 and is mechanically biased to lay against the outer slide surface 182 by a spring 184. One end 184a of the spring 184 is attached at or near the pivot point 110 of the contact lever 102 and the other end 184b of the spring 184 is attached to or near the roller 172.
When the contact lever 102 is in the open position P2, the spring 184 is in an extended state. The roller 172 is on one of the eccentric ends of the elliptic or oval position guide 170. When the contact lever 102 moves towards one of the closed position P1 or the earthed position P3, the roller moves along the curved path of the outer guide surface 182 towards the narrow portion of the ellipse or oval shape of the position guide 170 while being pulled against the outer guide surface 182 by the spring 184. The spring 184 thus pulls the dielectric shield 160 towards the distal end 108 of the contact lever 102 to its second position C2 to thereby expose the main contact area 141.
When the contact lever 102 moves from one of the closed position P2 or the earthed position P3, the roller 172 travels along the curved path 182 under the influence of the spring 184 pulling the roller 172 against the curved path 182, and the dielectric shield back to the covering position C1.
The length of the spring 184 is such that it always pulls the roller 172 towards the guide surface 182 regardless of the position of the contact lever 102, between the closed position P1 and the earth position P3. The spring 184 continuously force the roller to be in contact with the guide surface 182.
Fig. 4 and fig. 5 are illustrate an electric current switch 200 according to an embodiment of the present invention. Fig. 4 illustrates the electric current switch 200 in an open position P2. Fig. 5 illustrates the electric current switch 200 in a closed position P1.
The electric current switch 200 comprises a movable contact lever 202 comprising a proximal end 206 and a distal end 208, the contact lever 202 is rotatable at a pivot point 210 at the distal end, the contact lever comprising a lever main contact area 241 at the proximal end 206. In this embodiment, the lever main contact area 241 is covered by a fixed dielectric shield 242 at its proximal end 206.
The electric current switch 200 comprises a fixed contact assembly 216 configured to receive the movable contact lever 202 in a closed position of the contact lever. The fixed contact assembly 216 comprising a fixed main contact 252.
The contact lever 202 is configured to rotate about the pivot point 210 between the closed position P1 (fig. 4 ) and the open position (fig. 5).
The electric current switch 200 further comprises a movable dielectric shield 260 configured to cover the fixed main contact 252 of the fixed contact assembly 216. The dielectric shield 260 is movable relative the fixed main contact 252 of the fixed contact assembly 216 that the movable dielectric shield 260 is configured to cover. The dielectric shield 260 is configured to rotate about a pivot axis 261.
The movement of the movable dielectric shield 260 by rotation about the pivot axis 261 is between a covering position wherein the movable dielectric shield 260 covers the fixed main contact 252 of the fixed contact assembly 216, as shown in fig. 4, and a second position P2 where the movable dielectric shield 260 has moved away from the covering position such that the fixed main contact 252 is exposed as shown in fig. 5.,The movement of the movable dielectric shield 260 is mechanically coupled to the rotation of the contact lever 202.
The rotation of the contact lever 202 is in a rotation plane that coincides with the mating fixed main contact 252. In other words, contact lever 202 moves in a single plane between an open position where is it is not connected to the main contact 152 and a closed position where it is connected, in physical contact, with the main contact 252.
Fig. 6 illustrates the electric current switch 200 from another view. The movable dielectric shield comprises two parts 260a and 260b, one on each side of the fixed main contact 252. The two parts 260a and 260b are separated by a separation distance d. To achieve good dielectric protection, the dielectric shields should be relatively close to the fixed main contact 252. A width w of the fixed dielectric shield 242 is larger than the separation distance d. This is possible since the movable dielectric shield 262a-b moves away from the fixed main contact 252 when the contact lever 202 approaches the fixed main contact 252.
Fig. 7 is a perspective view of the electric current switch 200. The mechanical coupling between the motion of the contact lever 202 and the dielectric shield 260a-b is realized by an actuator 280.
The actuator may be but not limited to a rotary actuator. The actuator may be adapted to operatively engage with the movable dielectric shield 260a-b through a transmission module. The transmission module may be structured to transfer motion from the actuator 280 to the movable dielectric shield 260a-b in engagement with the one of the moving members of the electric current switch to rotate the movable dielectric shield 260a-b in at least one of a clockwise direction and an anti-clockwise direction between the one or more positions. The transmission module may include a chain drive gear operatively coupled/engaged to the moving member of the electric current switch 200.
In this example, the actuator 280 is a curved element or cam connected to the contact lever 202, such that it moves with the rotation of the contact lever 202.
The movable dielectric shield 260a-b is connected to the actuator 280 which is coupled to the motion of the contact lever 202 such that a motion of the contact lever causes rotation of the dielectric shield 260a-b about its pivot axis 261.
The actuator, or movable cam 280 is connected to the dielectric shield 260a by a first link 282 and a second link 284. The first link 282 is rotationally connected to the second link 284.
A first end 284a of the second link 284 is fixed to the actuator 280 and the rotational connection to the first link 282 is at the second end 284b of the second link 284 and at a first end 282a of the first link 282, and, a second end 282b of the first link 282 is rotationally connected to the dielectric shield 260a,b.
A rod 288 forming a rotation axis for the dielectric shield 260a,b is arranged between the dielectric shield parts 260a and 260b. The actuator 280 rotates when the contact lever 202 rotates to connect the main contact area 241 with the fixed main contact 252. This moves the second link 284 along with the rotation of the contact lever 202. The second end 284b of the second link 284 rotates with respect to the first end 282a of the first link 282 and the second end 282b of the first link 282 rotates the dielectric shield parts 260a,b about the shaft 288. This cause the dielectric shield parts 260a,b to move from the covering position in fig. 7 and 4 to a second position shown in fig. 5 where the fixed man contact 252 is exposed and the contact lever 202 can contact the fixed man contact 252.
The shaft 288 is spring loaded by a spring 290 that is biased to move the dielectric shield 260a-b towards the covering position shown in fig. 7 and 4.
The electric current switch 100 may be a knife switch. Thereby, the contact lever 102 is a knife contact or a blade contact. For example, the contact lever 102 may be bar of copper optionally with a protecting CuW insert as arcing contact area. The contact lever may be about 5 mm to 20 mm thick at the main contact area. The thickness is in the direction perpendicular to the rotation plane of the knife or blade. In one preferred embodiment, the thickness of the knife or blade at the main contact area is about 8 mm.
Even though the invention has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art.
Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

An electric current switch (100, 200) comprising:
a movable contact lever (102, 202) comprising a proximal end (106, 206) and a distal end (108, 208), the contact lever is rotatable at a pivot point (110, 210) at the distal end, the contact lever comprising a lever main contact area (141, 241) at the proximal end;

a fixed contact assembly (116, 216) configured to receive the movable contact lever in a closed position of the contact lever, the fixed contact assembly comprising a fixed main contact (152, 252),

the contact lever is configured to rotate about the pivot point between the closed position (P1) and an open position (P2),

the electric current switch further comprising a movable dielectric shield (160, 260) configured to cover one of the fixed main contact of the fixed contact assembly or the main contact area of the contact lever, the dielectric shield being movable relative the one of the fixed main contact of the fixed contact assembly or the main contact area of the contact lever that the movable dielectric shield is configured to cover,

wherein the movement of the movable dielectric shield is between a covering position (C1) wherein it covers the one of the fixed main contact of the fixed contact assembly or the main contact area of the contact lever, and a second position (C2) where the movable dielectric shield has moved away from the covering position, and the movement of the movable dielectric shield is mechanically coupled to the rotation of the contact lever.
The electric current switch according to claim 1, the movable dielectric shield is attached to the contact lever to cover the main contact area of the contact lever in the covering position.
The electric current switch according to claim 2, the movable dielectric shield is configured to move along a longitudinal axis (167) of the contact lever.
The electric current switch according to any one of claims 2 and 3, the movable dielectric shield is configured to expose the main contact area when the contact lever moves towards the fixed main contact assembly and to cover the main contact area when the contact lever moves away from the fixed main contact assembly.
The electric current switch according to any one of claims 2 to 4, comprising a position guide (170) fixed in relation to the pivot point, and a roller (172) fixed to the dielectric shield, the roller being arranged to slide against the position guide to move the dielectric shield between the covering position and the second position.
The electric current switch according to claim 5, comprising a spring (184) configured to bias the roller against the position guide.
The electric current switch according to any one of claims 5 and 6, the position guide comprising a slot (174) for guiding the roller along a curved path.
The electric current switch according to claim 1, the movable dielectric shield is arranged to cover the fixed main contact of the fixed contact assembly in the covering position.
The electric current switch according to claim 8, the movable dielectric shield is configured to rotate about a pivot axis (261).
The electric current switch according to any one of claims 8 and 9, the movable dielectric shield is configured to expose the fixed main contact when the contact lever moves towards the fixed main contact assembly and to cover the fixed main contact when the contact lever moves away from the fixed main contact assembly.
The electric current switch according to any one of claims 8 to 10, wherein the movable dielectric shield is connected to an actuator (280) coupled to the motion of the contact lever such that a motion of the contact lever causes rotation of the dielectric shield about its pivot axis.
The electric current switch according to claim 11, the actuator being connected to the dielectric shield by a first link (282) and a second link (284), the first link being rotationally connected to the second link, a first end (284a) of the second link is fixed to the actuator and the rotational connection to the first link is at the second end (284b) of the second link and at a first end (282a) of the first link, and, a second end (282b) of the first link is rotationally connected to the dielectric shield.
The electric current switch according to any one of claims 8 to 12, the contact lever comprises a fixed dielectric shield (242) at its proximal end configured to cover the main contact area.
The electric current switch according to claim 13, the movable dielectric shield comprises two parts (260a, 260b), one on each side of the fixed main contact, the two parts being separated by a separation distance (d), wherein a width (w) of the fixed dielectric shield is larger than the separation distance.
The electric current switch according to any one of the preceding claims, wherein the contact lever is a knife contact, and the electric current switch is a knife switch.