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EP-4738411-A1 - ELECTRIC SWITCH

EP4738411A1EP 4738411 A1EP4738411 A1EP 4738411A1EP-4738411-A1

Abstract

An electric switch comprising a frame (2), a first stationary contact (41), a rotating contact (8) and a plurality of arc extinguisher members. The plurality of arc extinguisher members has a guide protrusion system adapted to guide an electric arc (77) generated during an opening event of the electric switch to a tortuous path in which the electric arc (77) advances in the plurality of arc extinguisher members in a lateral direction parallel to a rotation axis of the rotating contact (8) thereby lengthening the electric arc. The guide protrusion system comprises a plurality of guide protrusions each protruding from a body part of the corresponding arc extinguisher member towards an adjacent arc extinguisher member and providing the shortest route for the electric arc (77) between the two arc extinguisher members.

Inventors

  • LEHTIMÄKI, Jarmo
  • Mäki, Markus

Assignees

  • ABB SCHWEIZ AG

Dates

Publication Date
20260506
Application Date
20241029

Claims (14)

  1. An electric switch comprising: a frame (2); a first stationary contact (41) stationarily fixed to the frame (2); a roll element (6) adapted to rotate relative to the frame (2) around a rotation axis (16) between a first position and second position; a rotating contact (8) stationarily fixed to the roll element (6), and comprising a first contact portion (81) such that in the first position of the roll element (6) the first contact portion (81) is electrically conductively connected to the first stationary contact (41), and in the second position of the roll element (6) the rotating contact (8) is disconnected from the first stationary contact (41); and a plurality of arc extinguisher members for extinguishing an electric arc (77) generated during an opening event between the first stationary contact (41) and the first contact portion (81) of the rotating contact (8), wherein the plurality of arc extinguisher members is located adjacent a path of the first contact portion (81), and wherein each of the plurality of arc extinguisher members comprises a body part made of electrically conducting material, characterized in that the plurality of arc extinguisher members has a guide protrusion system adapted to guide the electric arc (77) to a tortuous path in which the electric arc (77) advances in the plurality of arc extinguisher members in a lateral direction parallel to the rotation axis (16) thereby lengthening the electric arc, wherein the guide protrusion system comprises a plurality of guide protrusions each protruding from a body part of the corresponding arc extinguisher member towards an adjacent arc extinguisher member and providing the shortest route for the electric arc (77) between the two arc extinguisher members.
  2. The electric switch according to claim 1, wherein the guide protrusion system is located farther from the rotation axis (16) than the first contact portion (81) of the rotating contact (8).
  3. The electric switch according to claim 1 or 2, wherein the guide protrusion system is an integral part of the plurality of arc extinguisher members.
  4. The electric switch according to any one of the preceding claims, wherein the plurality of arc extinguisher members is made of sheet metal.
  5. The electric switch according to claim 4, wherein the guide protrusion system is made by a forming process through mechanical deformation.
  6. The electric switch according to any one of the preceding claims, wherein each guide protrusion protrudes from the body part of the corresponding arc extinguisher member in a direction perpendicular to a plane defined by the body part.
  7. The electric switch according to any one of the preceding claims, wherein the guide protrusion system comprises a plurality of guide protrusions on one side of a centre plane perpendicular to the rotation axis (16), and a plurality of guide protrusions on the other side of the centre plane such that the centre plane passes through an arc section (417) of the first stationary contact (41), wherein the arc section (417) is a section from which the electric arc (77) is adapted to transfer to the plurality of arc extinguisher members during the opening event.
  8. The electric switch according to any one of the preceding claims, wherein each of the plurality of guide protrusions protrude from the body part of the corresponding arc extinguisher member at least 0.4mm in a direction perpendicular to a plane defined by the body part.
  9. The electric switch according to any one of the preceding claims, wherein each of the plurality of guide protrusions is a closed protrusion.
  10. The electric switch according to any one of the preceding claims, wherein for each of the plurality of guide protrusions, on a plane defined by the body part of the arc extinguisher member from which the guide protrusion protrudes from, a surface area of a projection of the guide protrusion is greater than or equal to 2% of a surface area of a projection of the arc extinguisher member.
  11. The electric switch according to any one of the preceding claims, wherein for each of the plurality of guide protrusions, on a plane defined by the body part of the arc extinguisher member from which the guide protrusion protrudes from, a surface area of a projection of the guide protrusion is greater than or equal to 5% of a surface area of a projection of an outer section of the arc extinguisher member, wherein the outer section of the arc extinguisher member is located radially outwards relative to the rotating contact (8).
  12. The electric switch according to any one of the preceding claims, wherein the electric switch has a guide wall system adapted to guide a gas flow generated by the electric arc (77) during the opening event in order to increase probability that the electric arc (77) advances through the guide protrusion system.
  13. The electric switch according to claim 12, wherein the guide wall system comprises a plurality of intermediate guide wall segments (22) each located between two successive arc extinguisher members and adapted to obstruct a radially outwards directed gas flow between the successive arc extinguisher members in a location laterally spaced apart from a desired arc position while allowing the radially outwards directed gas flow adjacent the desired arc position, wherein the desired arc position is a position in which the guide protrusion system is adapted to provide the shortest route between the successive arc extinguisher members.
  14. The electric switch according to claim 12 or 13, wherein the guide wall system is an integral part of the frame (2).

Description

FIELD OF THE INVENTION The present invention relates to an electric switch. BACKGROUND OF THE INVENTION An electric switch is a device adapted to open and close an electric circuit it is connected to. When an electric circuit is opened by an electric switch, an electric arc whose temperature is thousands of degrees may occur in the electric switch. An electric arc includes ionized gas, which contains a large number of free electrons. Such a gas plasma is electrically conductive. An electric arc delays transfer of an electric switch from a conducting state to a non-conducting state. Further, an electric arc is often harmful for an electric switch and for an electric assembly comprising the electric switch. It is known in the art to use arc extinguisher members such as arc extinguisher plates for reducing duration of electric arcs in electric switches. Examples of known electric switches provided with arc extinguisher plates are described in publications EP 3457423 A1, CN113593996A and WO2018086350A1. BRIEF DESCRIPTION OF THE INVENTION An object of the present invention is to provide an electric switch which has an improved structure regarding electric arc extinguishing. The objects of the invention are achieved by an electric switch which is characterized by what is stated in the independent claim. The preferred embodiments of the invention are disclosed in the dependent claims. The invention is based on the idea of providing arc extinguisher members of an electric switch with a guide protrusion system adapted to guide an electric arc generated during an opening event of the electric switch to a tortuous path in which the electric arc advances in the arc extinguisher members in a lateral direction parallel to a rotation axis of a rotating contact of the electric switch thereby lengthening the electric arc. The guide protrusion system comprises a plurality of guide protrusions each protruding from a body part of the corresponding arc extinguisher member towards an adjacent arc extinguisher member and providing the shortest route for the electric arc between the two arc extinguisher members. Locations of the guide protrusions alternate from one lateral side to the other in order to form the tortuous or meandering path for the electric arc. An advantage of the electric switch of the invention is that the electric arc is not only longer but it also advances in the arc extinguisher members in the lateral direction thereby further improving cooling of the electric arc. BRIEF DESCRIPTION OF THE DRAWINGS In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which Figure 1 is a side view of an electric switch according to an embodiment of the invention;Figure 2 shows part of the components of the electric switch of Figure 1 and an electric arc generated during an opening event of the electric switch;Figure 3 shows a first stationary contact and a plurality of arc extinguisher members of the electric switch of Figure 1 from a direction oblique relative to a rotation axis of a roll element of the electric switch;Figure 4 shows a first stationary contact and a plurality of arc extinguisher members of an electric switch according to an alternative embodiment of the invention;Figure 5 shows a route of an electric arc through the plurality of arc extinguisher members shown in Figure 4;Figure 6 shows a first arc extinguisher member of the electric switch of Figure 1;Figure 7 shows a second arc extinguisher member of the electric switch of Figure 1;Figure 8 shows the first arc extinguisher member of Figure 6 from a direction perpendicular to a plane defined by a body part of the first arc extinguisher member, and a cross-section of the first arc extinguisher member along line A-A;Figure 9 shows a first modification of the first arc extinguisher member;Figure 10 shows a first modification of the second arc extinguisher member;Figure 11 shows a route of an electric arc through a plurality of arc extinguisher members comprising the first modifications of the first and second arc extinguisher members shown in Figures 9 and 10;Figure 12 shows a route of an electric arc through a plurality of arc extinguisher members comprising the first modifications of the second arc extinguisher member shown in Figure 10 and intermediate arc extinguisher members;Figure 13 shows a second modification of the first arc extinguisher member;Figure 14 shows a third modification of the first arc extinguisher member;Figure 15 shows a fourth modification of the first arc extinguisher member;Figure 16 shows part of components of an electric switch according to a further embodiment comprising a guide wall system; andFigure 17 is a partial side view of the components shown in Figure 16. DETAILED DESCRIPTION OF THE INVENTION Figure 1 is a side view of an electric switch according to an embodiment of the invention. The electric switch comprises a frame 2, a first stati