Built-in switch

Abstract

The built-in switch comprises a shell, an electromagnetic operating system and at least one contact unit, the contact unit at least comprises a contact mechanism, the contact mechanism comprises a moving contact assembly and a static contact, the moving contact assembly comprises a contact support and a moving contact, the electromagnetic operating system is in driving connection with the contact support, and the static contact is in driving connection with the moving contact. A contact spring is arranged between the contact support and the moving contact, the moving contact comprises at least two moving contact pieces which are arranged in parallel, one end of each moving contact piece is rotatably connected to the contact support, and the other end of each moving contact piece is provided with a moving contact point used for being matched with the static contact. According to the utility model, the moving contact assembly moves in a rotating manner, so that the use of a contact mechanism with a bridge type double-breakpoint structure is avoided, the cost is reduced, the contact pressure can be ensured through rotation, the requirement on an electromagnetic operating system is reduced, the moving contact assembly and the electromagnetic operating system are prevented from moving along a straight line together, and the size is reduced; and the moving contact comprises at least two parallel moving contact pieces, so that the current bearing capacity is improved.

Description

Technical Field

[0001] The utility model relates to the field of low-voltage electrical appliances, in particular to a built-in switch. Background Art

[0002] The existing prepaid energy meter mainly controls the power consumption of the main line through a built-in relay or an external circuit breaker. Since the current carrying capacity of the built-in relay is low, it is easy to cause failures such as burning or welding, and the external circuit breaker is large in size and short in life. At present, the power consumption of the main line is controlled by configuring a built-in switch in the energy meter.

[0003] In existing built-in switches, the electromagnetic operating system, contact mechanism and terminal blocks are usually arranged in sequence along the same direction, and the moving contact assembly in the contact mechanism moves in a straight line under the drive of the electromagnetic operating system. The contact mechanism usually adopts a bridge-type double-breakpoint structure, which is not only costly, but also requires a large contact pressure and has high requirements for the electromagnetic operating system. In addition, the moving contact in the contact mechanism usually moves in a straight line with the electromagnetic operating system, so that it occupies a large space in the same direction, which is not conducive to reducing the overall volume. Summary of the invention

[0004] The purpose of the utility model is to overcome at least one defect of the prior art and provide a built-in switch.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] The utility model provides a built-in switch, comprising a shell, an electromagnetic operating system and at least one contact unit, wherein the contact unit at least comprises a contact mechanism, the contact mechanism comprises a moving contact assembly and a stationary contact, the moving contact assembly comprises a contact support and a moving contact, the electromagnetic operating system is drivingly connected to the contact support, a contact spring is provided between the contact support and the moving contact, the moving contact comprises at least two moving contact pieces arranged in parallel, one end of each moving contact piece is rotatably connected to the contact support, and the other end of each moving contact piece is provided with a moving contact point for cooperating with the stationary contact.

[0007] Preferably, the moving contact assembly further comprises a positioning shaft, the positioning shaft is rotatably mounted on the contact support, one end of the moving contact is connected to the positioning shaft, and the positioning shaft rotates together with the moving contact.

[0008] Preferably, a shaft sleeve is disposed outside the positioning shaft, and at least a portion of the shaft sleeve is located between the contact spring and the positioning shaft.

[0009] Preferably, the contact support is provided with an accommodating cavity, and the contact spring and one end of the moving contact are coaxially assembled in the accommodating cavity.

[0010] Preferably, the contact spring includes two torsion springs, with a space for accommodating one end of the moving contact left between the two torsion springs, each torsion spring including a twisted portion, the two twisted portions are axially spaced apart, a connecting space is left between the two twisted portions, both ends of each twisted portion extend outward to form a first elastic arm and a second elastic arm, the two first elastic arms extend or are connected in a direction parallel to the axial direction of the twisted portion toward a direction close to the connecting space, and the two second elastic arms extend or are connected in a direction parallel to the axial direction of the twisted portion toward a direction close to the connecting space.

[0011] Preferably, the contact support is provided with a transmission part, the transmission part is located at a side of the contact support away from the moving contact, and the transmission part is drivingly connected to the electromagnetic operating system.

[0012] Preferably, the electromagnetic operating system includes a coil frame and a yoke, a moving iron core is slidably mounted in the middle of the coil frame, the yoke is surrounded and arranged on the outside of the coil frame, a coil is wound around the middle of the coil frame, and the coil is used to drive the moving iron core to move in a straight line so that one end of a push rod connected to the moving iron core passes through the yoke and extends out of the coil frame, and the push rod is provided with a mating part that is linked to the transmission part.

[0013] Preferably, the transmission part is provided with a matching groove which is slidably plugged with the matching part, and the matching groove reserves a space for the matching part to move.

[0014] Preferably, each contact unit further comprises a pair of wiring terminals, each wiring terminal is connected to a conductive plate, and the conductive plate extends into the housing for connection with the moving contact or the stationary contact.

[0015] Preferably, the end of one of the conductive plates is bent and extended to form a stationary contact plate, and a stationary contact point is provided on the plate surface of the stationary contact plate to form a stationary contact head, and the stationary contact point corresponds to the moving contact point.

[0016] Preferably, the contact unit further comprises an arc extinguishing chamber, the arc extinguishing chamber is cooperatively arranged on one side of the contact mechanism, and the stationary contact plate is provided with an arc striking portion extending into the arc extinguishing chamber.

[0017] The utility model has a built-in switch, in which the moving contact assembly moves in a rotational manner, which avoids the use of a contact mechanism with a bridge-type double-breakpoint structure and reduces costs. The contact pressure can be ensured by rotation, which reduces the requirements for the electromagnetic operating system and avoids moving in a straight line together with the electromagnetic operating system, which is conducive to reducing the volume. At the same time, the moving contact is at least two parallel moving contact pieces, which improves the current carrying capacity.

[0018] In addition, the moving contact and the contact spring are coaxially assembled on the positioning shaft, and a shaft sleeve is sleeved on the positioning shaft to prevent the contact spring from locking the positioning shaft, thereby ensuring that the moving contact can drive the positioning shaft to rotate together.

[0019] In addition, the second conductive plate connected to one of the wiring terminals is bent and extended in the housing to form a static contact, which has the advantages of simple structure and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the internal structure of the built-in switch of the utility model;

[0021] Figure 2 It is a structural schematic diagram of the electromagnetic operating system and the moving contact assembly in the utility model;

[0022] Figure 3 This is a front view of the electromagnetic operating system and the moving contact assembly in the utility model;

[0023] Figure 4 It is a cross-sectional view of the electromagnetic operating system and the moving contact assembly in the utility model;

[0024] Figure 5 It is a structural schematic diagram of the moving contact assembly in the utility model;

[0025] Figure 6 It is a cross-sectional view of the movable contact assembly in the utility model;

[0026] Figure 7 It is a schematic diagram of the cooperation between the moving contact and the contact spring in the utility model;

[0027] Figure 8 It is an exploded schematic diagram of the moving contact assembly in the utility model;

[0028] Fig. 9 It is a structural schematic diagram of the contact spring in the utility model;

[0029] Fig.10 It is a schematic diagram of the structure of the contact support in the utility model;

[0030] Fig.11 It is a cross-sectional view of the contact support in the utility model;

[0031] Reference numerals:

[0032] 2-electromagnetic operating system, 21-yoke, 22-coil assembly, 221-coil skeleton, 23-moving assembly, 231-moving iron core, 232-push rod, 2321-clamping part, 233-linkage part, 234-matching part, 235-slot, 3-contact mechanism, 31-contact support, 310-support body, 311-connecting hole, 312-transmission part, 313-accommodating chamber, 314-matching groove, 315-notch, 316-baffle, 32-moving contact, 320-moving contact piece, 321-moving contact point, 33-static contact, 34-positioning shaft, 341-sleeve, 35-contact spring, 350-twisted part, 351-first abutting part, 352-second abutting part, 4-arc extinguishing chamber, 52-transformer, 6-connecting terminal, 71-first conductive plate, 72-second conductive plate. DETAILED DESCRIPTION

[0033] The following is a further description of the specific implementation of the built-in switch of the utility model in combination with the embodiments given in the accompanying drawings. The built-in switch of the utility model is not limited to the description of the following embodiments.

[0034] like Figure 1 As shown, the built-in switch includes a shell, an electromagnetic operating system 2 and at least one contact unit, the electromagnetic operating system 2 is arranged in the shell, each contact unit includes at least a pair of wiring terminals 6 and a contact mechanism 3, the pair of wiring terminals 6 are arranged outside the shell, the contact mechanism 3 is arranged in the shell and connected between the pair of wiring terminals 6 for controlling the main line on and off in each contact unit, the contact mechanism 3 includes a moving contact assembly and a static contact 33 that cooperate with each other, the moving contact assembly includes a contact support 31 and a moving contact 32, wherein the contact support 31 is drivingly connected to the electromagnetic operating system 2, the moving contact 32 is connected to the contact support 31 for cooperating with the static contact 33, a contact spring 35 is arranged between the contact support 31 and the moving contact 32, and the contact spring 35 provides contact pressure for the moving contact 32, and when the number of contact units is two or more, the contact supports 31 of the two contact units can be linked and connected.

[0035] In addition, each contact unit is also equipped with an arc extinguishing chamber 4 and a current sampling device, wherein the arc extinguishing chamber 4 is cooperatively arranged between the contact mechanism 3 and the terminal 6, and the arc extinguishing chamber 4 extinguishes the arc generated by the contact mechanism 3. The current sampling device is connected to the main line for collecting current signals.

[0036] like Figure 2 , 5 As shown in Figures 7 and 8, the improvement of the present application is that the moving contact 32 includes at least two moving contact pieces 320 arranged in parallel, one end of each moving contact piece 320 is rotatably connected to the contact support 31, and the other end of each moving contact piece 320 is provided with a moving contact point 321 for cooperating with the stationary contact 33.

[0037] In this way, the movement mode of the moving contact assembly is rotation, which avoids the use of a bridge-type double-breakpoint structure contact mechanism 3 and reduces costs. The contact pressure can be ensured by rotation, which reduces the requirements for the electromagnetic operating system 2 and avoids moving in a straight line together with the electromagnetic operating system 2, which is conducive to reducing the volume. At the same time, the moving contact 32 is at least two parallel moving contact pieces 320, which improves the current carrying capacity.

[0038] Combination Figure 1-11 A specific embodiment of a built-in switch is provided.

[0039] like Figure 1 As shown, the built-in switch includes a shell (not shown), in which an electromagnetic operating system 2 and at least one contact unit are arranged, each contact unit includes a contact mechanism 3, an arc extinguishing chamber 4 and at least one pair of terminals 6, the contact mechanism 3 includes a moving contact assembly and a stationary contact 33 that cooperate with each other, the electromagnetic operating system 2 drives the moving contact assembly to rotate in the shell, so that the moving contact assembly contacts or disconnects with the stationary contact 33, and the contact mechanism 3 is connected between a pair of terminals 6; the arc extinguishing chamber 4 is arranged on one side of the contact mechanism 3 to extinguish the arc generated by the disconnection of the contact mechanism 3.

[0040] In this embodiment, the electromagnetic operating system 2 can adopt existing technology, that is, Figure 1 , 4 As shown, the electromagnetic operating system 2 generally includes a yoke 21, a coil assembly 22 and a moving assembly 23. The coil assembly 22 includes a coil frame 221 and a coil. The moving assembly 23 includes a moving iron core 231, a push rod 232 and a linkage 233. The coil is wound around the outer side of the middle part of the coil frame 221. The middle part of the coil frame 221 is a hollow cavity. The yoke 21 is surrounded and arranged on the outer side of the coil frame 221. Figure 4In the embodiment, the yoke 21 is a frame structure, the coil frame 221 and the coil are both located in the yoke 21, the moving iron core 231 is made of a magnetic conductive material, and the moving iron core 231 is slidably assembled in the middle of the coil frame 221. Under the cooperation of the yoke 21 and the coil assembly 22, the moving iron core 231 moves in a straight line in the middle of the coil frame 221, that is, the moving iron core 231 moves along the axis direction parallel to the coil assembly 22, and the push rod 232 is made of a non-magnetic conductive material, and one end of the push rod 232 is connected to the moving iron core 23 1, and the other end passes through the yoke 21 and extends out of the coil frame 221 and is connected to the linkage member 233. Preferably, the end of the push rod 232 is provided with a protruding engaging portion 2321, and the linkage member 233 is provided with a slot 235 plugged with the engaging portion 2321. The linkage member 233 is provided with a matching portion 234. In this embodiment, the linkage member 233 can be a plate-like structure or a block-like structure with a certain length, and the matching portion 234 is a convex shaft, and the protruding direction of the convex shaft is perpendicular to the moving track of the push rod 232. Of course, when the length of the push rod 232 is large enough and the number of contact mechanisms 3 driven is small, the linkage member 233 can be omitted, and the matching portion 234 can be provided on the push rod 232.

[0041] In addition, the electromagnetic operating system 2 also includes a magnet, which cooperates with the yoke 21 and the coil assembly 22 respectively, so that the moving iron core 231 can be kept in a closed or open state. When the power is on, the yoke 21 and the coil assembly 22 jointly drive the moving iron core 231 to move to the open or closed state. In this way, the electromagnetic operating system 2 does not need to be in a powered state for a long time. Of course, the electromagnetic operating system 2 can also use existing magnetic holding products.

[0042] In this embodiment, if Figure 1-9 As shown, the contact mechanism 3 includes a moving contact assembly and a stationary contact 33, wherein the moving contact assembly is rotatably assembled in the housing, the moving contact assembly includes a contact support 31 and a moving contact 32, a contact spring 35 is provided between the contact support 31 and the moving contact 32, and the contact spring 35 provides contact pressure for the moving contact 32, and the moving contact 32 includes at least two moving contact pieces 320 arranged in parallel, Figure 2 , 5 In , 7 and 8, the moving contact 32 is composed of two moving contact pieces 320 arranged in parallel, one end of each moving contact piece 320 is rotatably connected to the contact support 31, and the other end of each moving contact piece 320 is provided with a moving contact point 321 for cooperating with the static contact point of the static contact 33. By arranging at least two moving contact pieces 320, the moving contact 32 can increase the current carrying capacity.

[0043] The contact support 31, the moving contact 32 and the contact spring 35 are coaxially rotatably assembled. The contact support 31 can adopt the existing structure, combined with Figure 2 , 3, 5, 6 and 8 provide a structure of a contact support 31 applied to the present embodiment, the contact support 31 comprises a circular shaft-shaped support body 310, a receiving cavity 313 is provided in the middle of the support body 310, the receiving cavity 313 is provided with an opening corresponding to the side of the support body 310, a notch 315 is provided on one edge of the opening, connecting holes 311 penetrating the receiving cavity 313 are provided at both ends of the support body 310, a positioning shaft 34 is provided in the connecting hole 311, so that the positioning shaft 34 passes through the receiving cavity 313, one end of the moving contact 32 is connected to the positioning shaft 34 and the positioning shaft 34 rotates with the moving contact 32, that is, the contact support 31, the moving contact 32 and the contact spring 35 are rotatably connected through the positioning shaft 34, one end of the moving contact 32 and the contact spring 35 are arranged in the receiving cavity 313, a transmission part 312 and a baffle 316 are provided on opposite sides of the rotation center of the support body 310, Fig.10 , 11 In the embodiment, the transmission part 312 is a protruding boss structure, and the number of the transmission parts 312 is two, and they correspond to the opposite ends of the accommodating cavity 313 respectively. The transmission part 312 is provided with a matching groove 314 for linkage connection with the electromagnetic operating system 2. When there are two or more contact mechanisms 3, two adjacent moving contact assemblies are linked and connected through the transmission part 312, and the baffle 316 is connected to the edge of the open side with the notch 315. Fig.10 , 11 In the embodiment, the baffle 316 is formed by extending outward from the edge area of ​​the supporting body 310 , and the middle part of the moving contact 32 extends out from the notch 315 and cooperates with the baffle 316 .

[0044] like Figure 2 , 5 As shown in Figures 7 and 8, the moving contact 32 includes at least two moving contact pieces 320 arranged in parallel. The two moving contact pieces 320 are preferably connected together to ensure consistency of action. One end of each moving contact piece 320 is located in the accommodating cavity 313 and is rotatably connected to the positioning shaft 34, and the other end is provided with a moving contact 321 for cooperating with the static contact of the static contact 33. The moving contact piece 320 is a plate-shaped structure as a whole. A through hole for the positioning shaft 34 to pass through is provided at one end of the moving contact piece 320, and the positioning shaft 34 rotates with the rotation of the moving contact 32. The middle side surface of the moving contact piece 320 protrudes to form a matching area for elastically connecting with the contact spring 35, and the middle side surface of the moving contact piece 320 facing away from the matching area extends from the notch 315 of the accommodating cavity 313 to cooperate with the baffle 316; a moving contact 321 is provided on the side surface of the other end of the moving contact 32, and the moving contact 321 and the matching area are respectively located on opposite sides of the same moving contact piece 320.

[0045] like Figure 4-9As shown, the contact spring 35 includes two torsion springs, each of which includes a twisted portion 350. The two twisted portions 350 are assembled on the positioning shaft 34, and a connecting space for connecting the moving contact 32 is reserved between the two twisted portions 350. One end of each twisted portion 350 extends outward to form a first elastic arm abutting the moving contact 32, and the other end of each twisted portion 350 extends outward to form a second elastic arm abutting the contact support 31. The extension directions of the first elastic arm and the second elastic arm are both parallel to the axial direction of the twisted portion 350. In this embodiment, the first elastic arms of the two torsion springs are connected to form a first abutting portion 351, and the first abutting portion 351 abuts against the matching area of ​​the moving contact 32. The second elastic arms of the two torsion springs are connected to form a second abutting portion 352, and the first abutting portion 351 and the second abutting portion 352 both span the connecting space. Of course, the first elastic arms of the two torsion springs may also extend toward each other, so that the width of the gap left between the ends of the two first elastic arms is smaller than the width of the connecting space, and each first elastic arm abuts against an adjacent moving contact piece 320. Similarly, the second elastic arms of the two torsion springs may also only extend toward each other.

[0046] In addition, if Figure 6 , 8 As shown, a sleeve 341 is sleeved on the outer side of the positioning shaft 34 , and at least part of the sleeve 341 is located between the contact spring 35 and the outer side of the positioning shaft 34 to prevent the contact spring 35 from locking the positioning shaft 34 , so that the positioning shaft 34 cannot rotate together with the moving contact 32 .

[0047] The static contact 33 can adopt the existing technology. The static contact 33 includes a static contact plate, which is fixed in the shell and spaced opposite to the moving contact 32. A static contact is provided on the side of the static contact plate facing the moving contact 32. The number of static contacts can be one. In this case, the static contact is larger in size and contacts with all the moving contacts on the moving contact 32 at the same time. There can also be two or more static contacts for one-to-one correspondence with the moving contact 321. Preferably, one end of the static contact plate is also bent and extended to form an arc-starting portion.

[0048] like Figure 1 As shown, in this embodiment, the wiring terminal 6 of each contact unit is arranged outside the shell, and each wiring terminal 6 is connected to a conductive plate, which extends into the shell for electrically connecting to the moving contact 32 or the static contact 33. One of the wiring terminals 6 is connected to a first conductive plate 71, which extends into the shell for connecting to the moving contact assembly, and the other wiring terminal 6 is connected to a second conductive plate 72, which extends into the shell for connecting to the static contact 33, or the second conductive plate 72 is directly bent and extended in the shell so that the end of the second conductive plate 72 forms a static contact plate, and at least two parallel static contacts are arranged on the side of the static contact plate facing the first conductive plate 71, and each static contact corresponds to a moving contact 321.

[0049] Each contact unit is also equipped with an arc extinguishing chamber 4 and a transformer 52. The arc extinguishing chamber 4 can be arranged on one side of the contact mechanism 3 using existing technology. The arc striking plate of the static contact 33 extends into the arc extinguishing chamber 4 to facilitate arc striking. The transformer 52 can be arranged inside the outer casing or outside the outer casing. It is only necessary to ensure that the main line of each contact unit passes through the center hole of the transformer 52.

[0050] It should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicate directions or positional relationships based on directions or positional relationships shown in the drawings, or directions or positional relationships that are usually placed when in use, and are only for the convenience of description, rather than indicating that the device or element referred to must have a specific direction, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish descriptions, and cannot be understood as indicating relative importance.

[0051] The above contents are further detailed descriptions of the present invention in combination with specific preferred implementations, and the specific implementation of the present invention cannot be considered to be limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A built-in switch, comprising a housing, an electromagnetic operating system (2) and at least one contact unit, wherein the contact unit at least comprises a contact mechanism (3), wherein the contact mechanism (3) comprises a moving contact assembly and a stationary contact (33), wherein the moving contact assembly comprises a contact support (31) and a moving contact (32), wherein the electromagnetic operating system (2) is drivingly connected to the contact support (31), and a contact spring (35) is provided between the contact support (31) and the moving contact (32), wherein: The moving contact (32) comprises at least two moving contact pieces (320) arranged in parallel, one end of each moving contact piece (320) is rotatably connected to the contact support (31), and the other end of each moving contact piece (320) is provided with a moving contact point (321) for cooperating with the stationary contact (33).

2. The built-in switch according to claim 1, characterized in that: The moving contact assembly also includes a positioning shaft (34), which is rotatably mounted on the contact support (31), one end of the moving contact (32) is connected to the positioning shaft (34), and the positioning shaft (34) rotates together with the moving contact (32).

3. The built-in switch according to claim 2, characterized in that: The outer sleeve of the positioning shaft (34) is provided with a shaft sleeve (341), and at least a portion of the shaft sleeve (341) is located between the contact spring (35) and the positioning shaft (34).

4. The built-in switch according to claim 2, characterized in that: The contact support (31) is provided with a receiving cavity (313), and the contact spring (35) and one end of the moving contact (32) are coaxially assembled in the receiving cavity (313).

5. The built-in switch according to any one of claims 1 to 4, characterized in that: The contact spring (35) includes two torsion springs, and a space for accommodating one end of the moving contact (32) is reserved between the two torsion springs. Each torsion spring includes a twisted portion (350), and the two twisted portions (350) are spaced apart along the axial direction. A connection space is reserved between the two twisted portions (350). The two ends of each twisted portion (350) extend outward to form a first elastic arm and a second elastic arm, respectively. The two first elastic arms extend or connect in a direction parallel to the axial direction of the twisted portion (350) toward a direction close to the connection space, and the two second elastic arms extend or connect in a direction parallel to the axial direction of the twisted portion (350) toward a direction close to the connection space.

6. The built-in switch according to claim 1, characterized in that: The contact support (31) is provided with a transmission part (312), the transmission part (312) is located on a side of the contact support (31) away from the moving contact (32), and the transmission part (312) is drivingly connected to the electromagnetic operating system (2).

7. The built-in switch according to claim 6, characterized in that: The electromagnetic operating system (2) comprises a coil frame (221) and a yoke (21), a moving iron core (231) is slidably mounted in the middle of the coil frame (221), the yoke (21) is arranged to surround the outer side of the coil frame (221), a coil is wound in the middle of the coil frame (221), and the coil is used to drive the moving iron core (231) to move in a straight line so that one end of a push rod (232) connected to the moving iron core (231) passes through the yoke (21) and extends out of the coil frame (221), and the push rod (232) is provided with a matching portion (234) that is linked to the transmission portion (312).

8. The built-in switch according to claim 7, characterized in that: The transmission part (312) is provided with a matching groove (314) which is slidably plugged with the matching part (234), and the matching groove (314) reserves a space for the matching part to move.

9. The built-in switch according to claim 1, characterized in that: Each contact unit also includes a pair of wiring terminals (6), each wiring terminal (6) is connected to a conductive plate, and the conductive plate extends into the housing for connection with a moving contact (32) or a stationary contact (33).

10. The built-in switch according to claim 9, characterized in that: The end of one of the conductive plates is bent and extended to form a stationary contact plate, and a stationary contact point is arranged on the plate surface of the stationary contact plate to form a stationary contact head (33), and the stationary contact point corresponds to the moving contact point (321).

11. The built-in switch according to claim 10, characterized in that: The contact unit further comprises an arc extinguishing chamber (4), the arc extinguishing chamber (4) being arranged in cooperation with one side of the contact mechanism (3), and the stationary contact plate being provided with an arc striking portion extending into the arc extinguishing chamber (4).

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