CN112802719A

CN112802719A - Current conversion circuit breaker

Info

Publication number: CN112802719A
Application number: CN202110199745.5A
Authority: CN
Inventors: 陈丰飞; 李兴文; 汪倩; 陈思磊; 葛世伟; 高平; 李晓蒙
Original assignee: Xian University of Technology; Xian Jiaotong University; Zhejiang Tengen Electric Co Ltd
Current assignee: Xian University of Technology; Xian Jiaotong University; Zhejiang Tengen Electric Co Ltd
Priority date: 2021-02-22
Filing date: 2021-02-22
Publication date: 2021-05-14

Abstract

The invention discloses a commutation breaker, which comprises a shell, a first terminal, a second terminal, a moving contact, a static contact, a solid-state switch circuit, a conductive piece and a biasing piece, wherein the shell is provided with a first contact and a second contact; the moving contact is rotationally arranged on the shell, and the static contact is arranged on the shell; one end of the solid-state switch circuit is electrically connected with the second terminal and/or the fixed contact, and the other end of the solid-state switch circuit is electrically connected with the conductive piece; the conductive piece is movably arranged relative to the shell, and the motion trail of the conductive piece and the rotation path of the movable contact form an intersection; one end of the biasing member is connected with the conductive member; the rotating process of the moving contact has two stages, wherein in the first stage, the conductive piece is in a moving state, and the conductive piece is electrically connected with the moving contact under the action of the biasing force of the biasing piece, so that the solid-state switching circuit is electrically connected with the moving contact; in the second stage, the conductive piece is in a static state, and the moving contact and the conductive piece have a gap so that the solid-state switch circuit and the moving contact are in an open circuit state; the invention has the characteristic of stable matching of the conductive piece and the moving contact.

Description

Current conversion circuit breaker

Technical Field

The invention relates to a commutation breaker.

Background

A circuit breaker is a kind of protection switch, and is mainly used for protecting a circuit from some fault conditions such as short circuit, overload, etc.

The traditional pure mechanical circuit breaker is broken when some faults occur, electric arcs between a moving contact and a fixed contact are large, and the contacts are easily burnt.

As a relatively emerging solid-state circuit breaker (pure electronics), although the problem of arc generation can be solved, the solid-state circuit breaker has the problems of high energy consumption, large cooling system for heat dissipation of electronic parts and the like, and is not favorable for large-scale popularization and application at present.

With the continuous research of technical personnel in the field of circuit breakers, a mixed circuit breaker is designed, namely, the circuit breaker combining electronics and machinery is designed, and the burning loss of a contact can be greatly reduced by using a mode of mainly using machinery and secondarily using electronics.

For example, CN111799752A discloses a hybrid switch, which includes a mechanical contact part and a solid-state switch circuit part, where the solid-state switch circuit is connected in parallel to a mechanical main circuit (a circuit formed by an incoming line terminal, a fixed contact, a movable contact, and an outgoing line terminal), and the solid-state switch has a trigger switch. When the brake is switched off, the moving contact moves to a certain position to contact the trigger switch, so that the solid-state switch circuit stores energy and is switched on, the current is transferred to the solid-state switch circuit, the current path between the moving contact and the static contact is gradually weakened along with the continuous opening of the moving contact, and the moving contact is completely separated from the conductive part (the current path of the solid-state circuit), namely, the whole breaking process is completed.

When the switch is switched on, the moving contact moves to a certain position to contact the trigger switch, so that the solid-state switch circuit stores energy and is switched on, current can firstly pass through the solid-state switch circuit to form a flow path, and when the moving contact continuously moves to contact the static contact (the moving contact is separated from the trigger switch, and the solid-state circuit is disconnected), the main circuit is communicated, and therefore the whole closing process is completed. By doing so, ablation on the moving contact and the static contact can be greatly reduced.

However, this structure also has a problem that, because the conductive part in this patent is a clip structure (which is stationary with the housing), no matter during the whole switching-on and switching-off process, the moving contact needs to move a long distance in the clip structure, so the friction force is relatively large; if the clamping piece structure is too loose, although the movement of the movable contact is facilitated, the solid-state circuit is likely to be unstable; if the clip is designed too tightly, it will certainly affect the movement of the movable contact.

Disclosure of Invention

The invention mainly aims to provide a commutation breaker with stable conducting effect.

In order to achieve the above object, the present invention provides a commutating circuit breaker, comprising a housing, a first terminal, a second terminal, a movable contact, a fixed contact, a solid-state switching circuit, a conductive member and a biasing member;

the moving contact is rotationally arranged on the shell, and one end of the moving contact is electrically connected with the first terminal;

the static contact is arranged on the shell, and one end of the static contact is electrically connected with the second terminal;

one end of the solid-state switch circuit is electrically connected with the second terminal and/or the fixed contact, and the other end of the solid-state switch circuit is electrically connected with the conductive piece;

the conductive piece is movably arranged relative to the shell, and the motion trail of the conductive piece and the rotation path of the movable contact form an intersection;

one end of the biasing member is connected with the conductive member;

the rotation process of the moving contact has two stages,

in the first stage, the conductive element is in a motion state and is contacted with the moving contact under the action of the biasing force of the biasing element, so that the solid-state switch circuit is electrically connected with the moving contact;

in the second stage, the conductive piece is in a static state, and the moving contact and the conductive piece have a gap so that the solid-state switch circuit and the moving contact are in an open circuit state.

In the process of opening or closing, the rotation of the moving contact is divided into two stages, wherein the first stage is a stage of contacting with the conductive piece, and the second stage is a separation stage when the conductive piece moves to an extreme position (a static state), so that the on-off of the electric connection between the solid-state switch circuit and the moving contact can be ensured. Because the conductive piece is movably arranged, in the first stage, the conductive piece and the moving contact move and are in contact with each other, so that the electric connection stability of the solid-state switch circuit is ensured.

In the prior art, as the conductive component is fixed on the shell, the moving contact is contacted with the shell in the moving process, and the direct friction force generated between the moving contact and the shell is very large. With the above structure of the present invention, during the first phase of the rotation of the movable contact (i.e. during the contact between the movable contact and the conductive member), the conductive member is in a motion state (in motion), so the friction between the movable contact and the conductive member is much smaller than that in the prior art.

The conductive pieces are arranged on the shell in a linear sliding mode.

Wherein, the conductive piece is rotatably arranged on the shell.

The moving contact comprises a contact body and a moving contact positioned at the end part of the contact body, and the conductive piece is positioned between the moving contact and the rotating center of the moving contact; the conductive piece is provided with a contact part contacted with the contact body and used for finishing the action of the first stage.

The moving contact is provided with a contact branch, and the contact branch is positioned between the rotating center of the moving contact and the first terminal; the conductive piece is provided with a contact part contacted with the contact branch to finish the action of the first stage.

The contact device also comprises a conductive piece shell, wherein the conductive piece shell is fixed with the shell, and the part of the conductive piece, which is used for contacting with the moving contact, exceeds the conductive piece shell.

Wherein, the shell of the conductive piece is matched with the shell by a screw or clamped or integrated.

The contact part of the conductive piece, which is used for contacting with the moving contact, is positioned right above or right below the moving contact.

The conductive piece is positioned on the left side and/or the right side of the moving contact, and one side surface of the conductive piece is used for being matched with the contact body to finish the action of the first stage.

The conductive piece is integrally positioned in the upper area or the lower area of the movable contact.

The conductive contact point which completes the first stage action with the moving contact is arranged on the conductive piece.

The contact part is an elastic clamping part which is used for clamping the moving contact to finish the action of the first stage; the clamping force of the elastic clamping part to the movable contact is F1, the force of the movable contact moving in the opposite direction to break away from the elastic clamping part is F2, and F1 is not more than F2.

The contact part is a groove, the moving contact can extend into the groove, and the bottom surface and/or the side surface of the groove are/is used for contacting with the moving contact to finish the action of the first stage.

The side surface of the conductive piece for completing the action in the first stage is provided with a transition surface close to the moving contact, and the transition surface is an inclined surface or a curved surface.

The shell is provided with a limiting structure which limits the conductive piece to be in a static state when moving to a limit position.

The moving contact is provided with an auxiliary contact which is used for contacting with the conductive piece to finish the action of the first stage.

Wherein, the biasing member is one of a spring sheet, a spring and a torsion spring or the combination of any two of the spring sheet, the spring and the torsion spring.

Wherein, the number of the conductive pieces is at least two.

The number of the conducting pieces is at least two, the number of the biasing pieces is the same as that of the conducting pieces, when the moving contact is in a first stage state, all the conducting pieces are in contact with the moving contact, and when the moving contact is in a second stage state, all the conducting pieces have gaps with the moving contact.

Drawings

Fig. 1 is a schematic diagram of a movable contact of a commutating circuit breaker in a second stage according to embodiment 1 of the invention;

fig. 2 is a schematic diagram of a movable contact of a commutating circuit breaker in a first stage according to embodiment 1 of the invention;

fig. 3 is a schematic diagram of a moving contact of a commutating circuit breaker in a closing state according to embodiment 1 of the present invention;

fig. 4 is a schematic structural view of a commutation circulator according to embodiment 1 of the present invention;

fig. 5 is a first modification of the moving contact and the conductive member in embodiment 1 of the present invention;

fig. 6 is a second modification of the conductive device in example 1 of the present invention;

fig. 7 shows a third modification of the conductive member in example 1 of the present invention;

FIG. 8 is a schematic structural view of example 2 of the present invention;

fig. 9 is a schematic diagram of a second stage structure of the movable contact according to embodiment 3 of the present invention;

fig. 10 is a schematic diagram of a second stage structure of the movable contact according to embodiment 4 of the present invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

A commutation breaker comprises a shell, a first terminal, a second terminal, a movable contact, a fixed contact, a solid-state switching circuit, a conductive piece and a biasing piece; the moving contact is rotationally arranged on the shell, and one end of the moving contact is electrically connected with the first terminal; the static contact is arranged on the shell, and one end of the static contact is electrically connected with the second terminal; one end of the solid-state switch circuit is electrically connected with the second terminal and/or the fixed contact, and the other end of the solid-state switch circuit is electrically connected with the conductive piece; the conductive piece is movably arranged relative to the shell, and the motion trail of the conductive piece and the rotation path of the movable contact form an intersection; one end of the biasing member is connected with the conductive member; the rotating process of the moving contact has two stages, wherein in the first stage, the conductive piece is in a motion state and is contacted with the moving contact under the action of the biasing force of the biasing piece, so that the solid-state switch circuit is in an electric connection state with the moving contact; in the second stage, the conductive piece is in a static state, and the moving contact and the conductive piece have a gap so that the solid-state switch circuit and the moving contact are in an open circuit state.

In the process of opening or closing, the rotation of the moving contact is divided into two stages, wherein the first stage is a stage of contacting with the conductive piece, and the second stage is a separation stage when the conductive piece moves to a limit position (a static state), so that the on-off of the electric connection between the solid-state switch circuit and the moving contact can be ensured.

In the prior art, the conductive component is fixed on the shell, so that the movable contact is contacted with the shell when moving, and the direct friction force generated between the movable contact and the shell is very large. With the above structure of the present invention, during the first phase of the rotation of the movable contact (i.e. during the contact between the movable contact and the conductive member), the conductive member is in a motion state (in motion), so the friction between the movable contact and the conductive member is much smaller than that in the prior art.

There are many ways of arranging the conductive elements, and two alternative ways are provided as follows:

mode one, the sliding mode:

in the sliding mode, the conductive member may be arranged in a manner of sliding along a straight line, that is, the contact portion (portion for contacting with the movable contact) of the conductive member is arranged directly above or directly below the movable contact, and the conductive member is connected to a static structure by a biasing member, and the static structure may be, for example, a housing, or a housing of the conductive member;

when the moving contact is changed from the opening state to the closing state, the moving contact is transited from the second stage to the first stage, the moving contact moves gradually to contact with the contact part to enable the biasing part to deform, the conductive part is always contacted with the moving contact under the action of the biasing part, and finally the moving contact reaches the closing position.

When the moving contact is changed from closing to opening, namely the moving contact is changed from a first stage to a second stage, during the first stage, the biasing force of the biasing member drives the conductive member to move along the moving contact. When the conductive piece reaches the limit position (in a static state), the moving contact still continues to move, so that the gap between the moving contact and the conductive piece is gradually enlarged, and finally, the second stage is reached, so that the moving contact and the solid-state switch circuit are sufficiently disconnected.

As another form of the sliding manner, the electric conduction can also be arranged on one side or two sides of the movable contact, and the electric conduction member is connected with a static structure through the biasing member, and the static structure can be a shell or a shell of the electric conduction member;

the face that the electrically conductive piece was used for with the moving contact is a side surface this moment, and when the moving contact was changed by the separating brake towards the combined floodgate, the moving contact passed through to the first stage by the second stage, and the moving contact progressively moves the side surface that contacts to electrically conductive piece and makes the biasing piece deformation, and electrically conductive piece contacts with the moving contact all the time under the effect of biasing piece, and finally the moving contact reaches the combined floodgate position.

Mode two, the rotation mode:

in the rotating mode, the conductive element has a rotation center, and the arrangement mode is that the contact part (the part for contacting with the movable contact) of the conductive element is arranged right above or right below the movable contact, and the conductive element is connected with a static structure through a biasing element, and the static structure can be, for example, a shell and a shell of the conductive element;

The rotating direction of the conductive piece can be consistent with or opposite to that of the movable contact.

As another form of the rotation mode, the electric conduction can also be arranged on one side or two sides of the movable contact, and the electric conduction member is connected with a static structure through the biasing member, and the static structure can be a shell or a shell of the electric conduction member;

The biasing member can be selected from any one or a combination of a pressure spring, a tension spring, a torsion spring and a spring sheet no matter in a sliding mode or a rotating mode, as long as the biasing force can be generated on the conductive member to enable the conductive member and the movable contact to be stably contacted in the first stage.

No matter what type of the conductive piece is adopted, in order to ensure the installation stability of the conductive piece and partial insulation performance, a conductive piece shell can be arranged outside the conductive piece, and as long as a through hole is formed in the conductive piece shell, the contact part of the conductive piece and the movable contact can be exposed.

The conductive piece shell can be arranged in various modes, for example, the conductive piece shell and the shell are directly fastened by screws or fastened in a clamping mode, or a cavity for accommodating the conductive piece is directly arranged on the shell, and the mode of the cavity also belongs to one of the conductive piece shells.

In any way of the conductive member, in order to improve the electrical connection performance between the conductive member and the movable contact, the contact portion (the portion for contacting with the movable contact) of the conductive member may be a conductive contact, and the conductive contact may be made of silver or other known metal or alloy having better electrical conductivity than copper.

No matter what type of the conductive piece is adopted, in order to improve the electricity connection performance between the conductive piece and the moving contact, an auxiliary contact is arranged on the moving contact and used for completing the contact action of the first stage with the conductive piece, and the auxiliary contact can be made of silver or other known metals or alloys with better conductivity than copper.

The mode that the contact part of the conductive piece is arranged right above or below the moving contact is adopted, so that the stability of connection between the contact part and the moving contact is ensured.

The contact part can be elastic clamping part, and elastic clamping part is used for the centre gripping moving contact to accomplish the action of first stage, and the clamping force of elastic clamping part to the moving contact here is F1, and moving contact reverse motion is shaken loose the power of elastic clamping part and is F2, and F1 is not more than F2.

The contact part can be a groove structure, the width dimension of the groove is slightly larger than the width of the moving contact, so that the moving contact can not only be contacted with the bottom surface of the groove, but also be contacted with the side surface of the moving contact and the side wall of the groove.

For the mode that the conductive piece is arranged on the left side and/or the right side of the moving contact, in order to reduce the damping feeling of the matching of the moving contact and the conductive piece, a transition surface is arranged in the area, close to the moving contact, of the side surface of the conductive piece, and the transition surface is an inclined surface or a curved surface; that is, when the moving contact is switched on, the moving contact preferentially contacts the transition surface and then contacts the side surface of the conductive piece.

The following describes the above embodiments with reference to three preferred embodiments.

Example 1:

as shown in fig. 1-4, a commutating circuit breaker comprises a housing 1, a first terminal 2, a second terminal 3, a movable contact 4, a stationary contact 5, a solid-state switching circuit 6, a conductive member 7, and a biasing member 8.

The first terminal 2 is a load terminal, and the load terminal and the movable contact 4 are in an electric connection state, and the electric connection form is many, and the electric connection form can be a flexible connection structure.

The second terminal 3 is a power supply terminal, and the static contact 5 and the power supply terminal are in an electrically connected state, and the electrically connected state has many forms, and can be a busbar connection structure.

The solid-state switch circuit 6 is an IGBT circuit or an IGCT circuit.

The solid-state switch circuit 6 is provided with a trigger switch 9, the trigger switch 9 is positioned in the rotating track of the moving contact 4, and when the moving contact 4 triggers the trigger switch 9, the solid-state switch circuit 6 can store energy and be conducted. The structure of the solid-state switch circuit 6 and the trigger switch 9 is conventional in the art, and therefore, will not be described in detail.

The moving contact 4 includes a moving contact 41 and a contact body 42, the contact body 42 is rotatably disposed on the housing 1 through a rotating shaft, and the switching of the switching-on and switching-off states of the circuit breaker is realized through the rotation of the moving contact 4, which is also the prior art, so that the description is omitted.

One end of the solid-state switching circuit 6 is electrically connected to the second terminal 3, and thus also to the stationary contact 5. It is also possible to use the fixed contact 5 for electrical connection to complete the electrical connection to the second terminal 3.

The other end of the solid-state switching circuit 6 is electrically connected to a conductive member 7.

The housing 1 has a mounting space 10 at a position below the contact body 42, wherein the mounting space 10 acts as an outer shell for the conductor 7. A biasing member 8 is provided between the conductive member 7 and the housing 1, and the conductive member 7 is vertically slidable with respect to the housing 1. The biasing member 8 is here a compression spring, but the biasing member 8 may also take the form of a torsion spring or a leaf spring.

No matter whether the switch is opened or closed, the rotating process of the moving contact 4 has two stages:

in a first stage, in which the movable contact 4 and the conductive member 7 are both in motion, the biasing member 8 provides a biasing force to the conductive member 7, and the conductive member 7 is kept in contact with the movable contact 4 under the action of the biasing force, so that the solid-state switching circuit 6 and the movable contact 4 are in an electrical connection state.

In the second stage, the conductive member 7 is in the limit position (i.e. in the stationary state), and the movable contact 4 and the conductive member 7 have a gap, so that the solid-state switching circuit 6 and the movable contact 4 are in the open circuit state.

The extreme position is defined as the conductor 7 moving to the limit position of the conductor 7 housing 1, so that the conductor 7 is at rest.

In addition to the above structure, the first terminal 2 may be a power supply terminal, and the second terminal 3 may be a load terminal.

As shown in fig. 5, as a modification of the movable contact 4 and the conductive member 7 in embodiment 1, an auxiliary contact 11 is disposed on the movable contact 4, and a conductive contact 12 is disposed on the conductive member 7, where the auxiliary contact 11 and the conductive contact 12 may be silver contacts.

As shown in fig. 6, as a modification of the embodiment 1, as a modification of the conductive member 7 in the embodiment 1, a contact portion between the conductive member 7 and the movable contact 4 is an elastic clamping portion. The elastic clamping part comprises two clamping arms 13 which are oppositely arranged, the movable contact 4 is clamped by the clamping arms 13, the clamping force of the clamping arms 13 is F1, the force of the movable contact 4 moving in the reverse direction to break away from the clamping arms 13 is F2, and F1 is not more than F2.

The depth H of the clamping arm 13 is slightly larger than the height G of the movable contact 4, when the biasing member 8 is not at the compression limit position, the movable contact 4 pushes only part of the clamping arm 13 to move into the clamping arm 13, and only when the biasing member 8 is at the compression limit position, the movable contact 4 can completely enter into the clamping arm 13, so that the design can greatly reduce the friction force between the clamping arm and the movable contact.

As shown in fig. 7, as another variation of embodiment 1, the top of the conductive member 7 is a groove 14, and the width of the groove 14 is slightly larger than the width of the movable contact 4, so that the movable contact 4 can not only contact the bottom surface of the groove 14, but also contact the side surface of the movable contact 4 with the side wall of the groove 14.

In addition, as another modification of embodiment 1, the number of the conductive members 7 may be two, and the number of the same biasing members may be two, and the two conductive members are provided to be movable in the vertical direction by the respective biasing members. In terms of circuitry, both conductive members are connected to the solid state switching circuit.

When the moving contact moves in the first stage, the two conductive pieces are in contact with the moving contact through the action of the biasing piece, and when the moving contact moves in the second stage, gaps are formed between the two conductive pieces and the moving contact.

Example 2:

as shown in fig. 8, embodiment 2 differs from embodiment 1 in that the number of the conductive members 7 in embodiment 2 is two, and the conductive members are provided separately on the lower two sides of the contact body 42, and the adjacent proximal surfaces of the two conductive members 7 are for contact with the contact body 42. The two conducting members 7 are connected to the housing 1 by respective biasing members 8.

When the two conductive members 7 are in the initial position (corresponding to the second stage of the movable contact 4), the gap between the two conductive members is smaller than the width of the contact body 42. When the contact body 42 continues to move to contact the transition surface 15 at the upper part of the conductors 7, the conductors 7 are driven apart by the bevel drive until the contact body 42 completely enters between the conductors 7.

Example 3:

as shown in fig. 9, example 3 differs from practical force 1 in that:

in the embodiment 3, the movable contact 4 has the contact branch 16, and the contact branch 16 and the contact body 42 are just distributed on two sides of the rotation center.

The conductive member 7 is disposed above the contact branch 16, and the contact manner of the conductive member 7 is the same as that of embodiment 1, and therefore, the description thereof is omitted.

The design can lead the conductive piece 7 to be far away from the static contact, and reduce the ablation of the main circuit arc (the arc between the movable contact and the static contact) to the conductive piece.

Example 4:

as shown in fig. 10, embodiment 4 differs from embodiment 1 in that:

the conductive member 7 of embodiment 4 is rotatably connected to the housing 1, and the biasing member 8 may be a torsion spring. The conductive element 7 is also located below the housing 1, and the rotation direction of the conductive element 7 and the rotation direction of the movable contact 4 may be the same or opposite.

It should be noted that the terms "first," "second," "third," and the like in the description and in the claims, and in the drawings, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged under appropriate circumstances in order to facilitate the description of the embodiments of the invention herein.

Claims

1. A commutating circuit breaker, characterized by: the circuit comprises a shell (1), a first terminal (2), a second terminal (3), a moving contact (4), a static contact (5), a solid-state switch circuit (6), a conductive piece (7) and a biasing piece (8);

the moving contact (4) is rotationally arranged on the shell (1), and one end of the moving contact is electrically connected with the first terminal (2);

the static contact (5) is arranged on the shell (1), and one end of the static contact is electrically connected with the second terminal (3);

one end of the solid-state switch circuit (6) is electrically connected with the second terminal (3) and/or the static contact (5), and the other end of the solid-state switch circuit is electrically connected with the conductive piece (7);

the conductive piece (7) is movably arranged relative to the shell (1), and the motion trail of the conductive piece (7) and the rotation path of the movable contact (4) have intersection;

one end of the biasing member (8) is connected with the conductive member (7);

the rotation process of the moving contact (4) has two stages,

in the first stage, the conductive element (7) is in a motion state, and the conductive element (7) is contacted with the moving contact (4) under the action of the biasing force of the biasing element (8) so as to enable the solid-state switch circuit (6) to be in an electric connection state with the moving contact (4);

and in the second stage, the conductive piece (7) is in a static state, and a gap exists between the movable contact (4) and the conductive piece (7), so that the solid-state switch circuit (6) and the movable contact (4) are in an open circuit state.

2. The commutating circuit breaker of claim 1 characterized in that: the conductive piece (7) is arranged on the shell (1) in a linear sliding mode.

3. A commutating circuit breaker according to claim 1 characterized in that: the conductive piece (7) is rotatably arranged on the shell (1).

4. A commutating circuit breaker according to claim 1, 2 or 3 characterized in that: the moving contact (4) comprises a contact body (41) and a moving contact (42) positioned at the end part of the contact body, and the conductive piece (7) is positioned between the moving contact (42) and the rotating center of the moving contact (4); the conductive member (7) has a contact portion contacting the contact body (41) to perform the first stage of operation.

5. A commutating circuit breaker according to claim 1, 2 or 3 characterized in that: the moving contact (4) is provided with a contact branch (16), and the contact branch (16) is positioned between the rotating center of the moving contact (4) and the first terminal (2); the conductive member (7) has a contact portion contacting the contact branch (16) for performing the first stage of operation.

6. The commutating circuit breaker of claim 1 characterized in that: the contact device also comprises a conductive piece shell, the conductive piece shell is fixed with the shell (1), and the part of the conductive piece (7) which is used for being contacted with the moving contact (4) exceeds the conductive piece shell.

7. The commutating circuit breaker of claim 6 wherein: the conductive piece shell and the shell (1) are in screw fit or clamping fit or are integrated.

8. The commutating circuit breaker of claim 1 characterized in that: the contact part of the conductive piece (7) which is used for contacting with the moving contact (4) is positioned right above or right below the moving contact (4).

9. The commutating circuit breaker of claim 8 wherein: the contact part is an elastic clamping part which is used for clamping the moving contact (4) to finish the action of the first stage; the clamping force of the elastic clamping part to the moving contact (4) is F1, the force of the moving contact (4) moving in the opposite direction to break away from the elastic clamping part is F2, and F1 is not more than F2.

10. The commutating circuit breaker of claim 1 characterized in that: the shell (1) is provided with a limiting structure which limits the conductive piece (7) to be in a static state when moving to a limit position.