EP3358594A1

EP3358594A1 - Single-stage circuit breaker

Info

Publication number: EP3358594A1
Application number: EP18154732.4A
Authority: EP
Inventors: Chang Chun Hu
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2017-02-04
Filing date: 2018-02-01
Publication date: 2018-08-08
Anticipated expiration: 2038-02-01
Also published as: CN108400072A; EP3358594B1; CN108400072B

Abstract

The present invention provides a single-stage circuit breaker. The single-stage circuit breaker comprises: a first accommodation chamber having a first current path formed therein; a second accommodation chamber having a second current path formed therein; an electromagnetic trip device arranged in the first accommodation chamber; a first contact assembly and a first execution assembly; an arc fault and leakage trip device arranged in the second accommodation chamber; a second contact assembly and a second execution assembly; a circuit board assembly for arc fault handling and leakage protection; and an auxiliary contact assembly arranged inside the second accommodation chamber for effecting safe electrical isolation of the circuit board assembly. The single-stage circuit breaker according to the present invention can make the circuit board assembly obtain a relatively safe electrical isolation so as to effectively improve the safety and reliability of the entire circuit breaker.

Description

Cross-reference to related application

This application claims priority to Chinese Patent Application CN 201710064313.7, filed February 4, 2017 , which is incorporated by reference herein, in the entirety and for all purposes.

Technical Field

The present invention relates to a low-voltage circuit breaker, and in particular to a single-stage circuit breaker.

Background Art

An arc fault detection circuit breaker, referred to as AFDD (arc fault detection device) for short, is also an electric line protection device, and the main function thereof is to detect and identify a dangerous grounding arc fault, a parallel arc fault and a series arc fault, and to drive an action of a device for disconnecting the current in a timely manner, so as to prevent the occurrence of electrical fire. Using embedded system digital circuit control and an original arc characteristics recognition algorithm, the advantages of small size and strong function are achieved, and a leakage current protection function is integrated, so that automatic monitoring and protection of fault arc and leakage current are achieved, effectively guaranteeing the safety of low-voltage power distribution lines and electrical equipment as well as people.
However, the prior art AFDD circuit breaker has the following problem when in use: a PCBA board may be damaged when an over-voltage of the AFDD circuit breaker is greater than 400 v (e.g., in a 500 VDC insulation resistance test). Specifically, because of the circuit connection requirements for a particular market, one end of the PCBA board is directly connected to a left-side terminal so that the PCBA board is always in an energized state, regardless of whether a main loop of the circuit breaker is in a switched-on or switched-off state. Taking the main loop of the circuit breaker in the OFF state as an example, although the movable and stationary contacts are disconnected at this time, the following current loop is still formed in the circuit breaker, that is, a large current of the main loop passes through the left-side terminal, the stationary contact, the conductive wire, the PCBA board and a right-side terminal successively, and once the safety voltage of the PCBA board is exceeded, the safety and reliability thereof becomes greatly compromised.

Summary of the Invention

An object of the present invention is to provide a single-stage circuit breaker, which can make a circuit board assembly obtain a relatively safe electrical isolation so as to effectively improve the safety and reliability of the entire circuit breaker.
The present invention provides a single-stage circuit breaker, comprising a first accommodation chamber having a first current path formed therein; a second accommodation chamber having a second current path formed therein; an electromagnetic trip device arranged in the first accommodation chamber; a first contact assembly and a first execution assembly used for cooperating with the electromagnetic trip device and located in the first accommodation chamber; an arc fault and leakage trip device arranged in the second accommodation chamber; a second contact assembly and a second execution assembly used for cooperating with the arc fault and leakage trip device and located in the second accommodation chamber; a circuit board assembly for arc fault handling and leakage protection; and an auxiliary contact assembly arranged inside the second accommodation chamber for effecting safe electrical isolation of the circuit board assembly.
In a further exemplary embodiment of the single-stage circuit breaker, the circuit board assembly comprises a first circuit board and a second circuit board, wherein the first circuit board is accommodated in the first accommodation chamber, and the second circuit board is accommodated in the second accommodation chamber.
In a yet further exemplary embodiment of the single-stage circuit breaker, one end of the auxiliary contact assembly is electrically connected to the second circuit board, and the other end of the auxiliary contact assembly can be disconnected from or connected to the second contact assembly, so as to make the circuit board assembly obtain a safe electrical isolation.
In a yet further exemplary embodiment of the single-stage circuit breaker, the auxiliary contact assembly comprises a first contact member, with one end thereof being capable of being bent and deformed under a contact pressure of a movable contact in the second contact assembly and forming a reset force; and a second contact member, with one end thereof being electrically connected to the first contact member and the other end thereof being electrically connected to the second circuit board.
In a yet further exemplary embodiment of the single-stage circuit breaker, the movable contact comprises a first arc-shaped contact end portion and a second long strip-shaped contact end portion, wherein the second contact end portion also has a predetermined bending angle, so that the loop current can be switched off or on more safely and reliably, so as to prevent the generation of a poor arc.
In a yet further exemplary embodiment of the single-stage circuit breaker, one end of the first contact member has a bent contact matching portion for engaging with the first contact end portion in a matching manner, in order to enhance the stability of connection and disconnection of the circuit.
In a yet further exemplary embodiment of the single-stage circuit breaker, an N-pole main switch for controlling an N-pole main loop can be formed between a stationary contact and the movable contact in the second contact assembly, and an auxiliary switch for controlling a loop of the circuit board assembly can be formed between the first contact member and the movable contact. The above-mentioned design can effectively prevent the circuit board assembly from always being in an energized state, thereby effectively reducing the risk of damaging the circuit board assembly caused by over-voltage breakdown, and thus improving the safety and reliability of the entire circuit breaker.
In a yet further exemplary embodiment of the single-stage circuit breaker, when the single-stage circuit breaker is switched from an ON state to an OFF state, the N-pole main switch is switched off first, and then the auxiliary switch is switched off; and when the single-stage circuit breaker is switched from the OFF state to the ON state, the auxiliary switch is switched on first, and then the N-pole main switch is switched on, in order to protect the auxiliary contact from being damaged due to large arc ablation, thereby improving the electrical safety.
In a yet further exemplary embodiment of the single-stage circuit breaker, the first contact member is made of an elastic metal wire and the second contact member is made of a conductive wire, and one of end portions of the second contact member is welded or crimped to the first contact member, in order to enhance the stability of an electrical contact between the movable contact and the first contact member.
In a yet further exemplary embodiment of the single-stage circuit breaker, the contact matching portion is substantially U-shaped to further ensure the reliability of the electrical contact.

Brief Description of the Drawings

The present invention is described in detail below in conjunction with the accompanying drawings and particular embodiments. In the accompanying drawings:

Fig. 1 is a schematic diagram of an L-pole structure of a single-stage circuit breaker according to an embodiment of the present invention;
Fig. 2 is a schematic diagram of an N-pole structure of a single-stage circuit breaker according to an embodiment of the present invention;
Fig. 3 is a schematic diagram of the positions where an N-pole main switch K2 and an auxiliary switch K3 are formed in Fig. 2;
Fig. 4 is a schematic circuit diagram of a single-stage circuit breaker according to an embodiment of the present invention;
Fig. 5 is a schematic diagram of a current loop for a circuit board assembly when the N-pole structure of the single-stage circuit breaker in Fig. 2 is accessed from a left-side terminal; and
Fig. 6 is a schematic diagram of the current loop for a circuit board assembly when the N-pole structure of the single-stage circuit breaker in Fig. 2 is accessed from a right-side terminal.

Description of Reference Numerals:

First execution assembly 11
Multi-function button module 12	Second contact end portion 272
Electromagnetic trip device 13	Stationary contact 28
Arc extinguishing device 15	Left-side terminal 29
First contact assembly 16	Right-side terminal 24
Thermal protection and arc fault detection device 17	Driving member 31
Circuit board assembly 18	Operating handle 32
First circuit board 181	L-pole main switch K1
Second circuit board 182	N-pole main switch K2
Second execution assembly 21	Auxiliary switch K3
Arc fault and leakage trip device 23	Auxiliary contact assembly 50
Second contact assembly 26	First contact member 51
Movable contact 27	Second contact member 52
First contact end portion 271	Contact matching portion 511

Detailed Description of the Drawings

In order to more clearly understand the technical features, objectives and effects of the present invention, the particular embodiments of the present invention are described with reference to the accompanying drawings, and in the figures, the same reference numerals denote the same parts. In the accompanying drawings which represent various embodiments, the same last two digits denote structurally identical or structurally similar but functionally identical components.
In order to make the figures concise, the parts relevant to the present invention are merely shown illustratively in the figures, and they do not represent the actual structure as a product. In addition, in order to make the figures concise and easy to be understood, in some figures, there are components of the same structure or function, and only one therein is drawn illustratively or only one therein is marked.
The words "up", "down", "front", "rear", "left", "right", etc. herein are merely used to indicate the positional relationship between related parts, but not to limit their absolute positions.
The words "first", "second", etc. herein are merely used for distinguishing parts from each other rather than representing the degree of importance and order, etc. thereof.
The words "parallel", "vertical", etc. are not strictly mathematical and/or geometrical limitations, and also contain permissible errors that can be understood by a person skilled in the art and are allowable during manufacturing or usage, etc.
A single-stage circuit breaker according to an embodiment of the present invention has a shell, the shell further comprising a first housing, a second housing, and a mounting housing located between the first housing and the second housing. A first accommodation chamber is formed between the first housing and the mounting housing, and a second accommodation chamber is formed between the second housing and the mounting housing. A first current path is formed in the first accommodation chamber. A second current path is formed in the second accommodation chamber.
Further, referring to Figs. 1 and 2, the single-stage circuit breaker further comprises an electromagnetic trip device 13, a first contact assembly 16, a first execution assembly 11, an arc fault and leakage trip device 23, a second contact assembly 26, a second execution assembly 21, a circuit board assembly 18, and an auxiliary contact assembly 50. The first execution assembly 11 and the second execution assembly 21 move simultaneously with an operating handle 32 via a common driving member 31. It is to be understood that the single-stage circuit breaker of the present application also has an arc extinguishing device 15, wherein the arc extinguishing device 15 is accommodated between the electromagnetic protection device 13 and the first contact assembly 16. The single-stage circuit breaker of the present application also has a thermal protection and arc fault detection device 17, wherein the thermal protection and arc fault detection device 17 is arranged near the arc extinguishing device 15 and located in the first accommodation chamber. The single-stage circuit breaker further comprises a multi-function button module 12 arranged at a side portion of the shell for state displaying and function testing of the single-stage circuit breaker.
The first contact assembly 16 and the first execution assembly 11 are used for cooperating with the electromagnetic trip device 13 and located in the first accommodation chamber. The arc fault and leakage trip device 23 is arranged in the second accommodation chamber. The second contact assembly 26 and the second execution assembly 21 are used for cooperating with the arc fault and leakage trip device 23 and located in the second accommodation chamber. The circuit board assembly 18 is used for arc fault handling and leakage protection. The auxiliary contact assembly 50 is arranged inside the second accommodation chamber for effecting safe electrical isolation of the circuit board assembly.
Optionally, the circuit board assembly 18 comprises a first circuit board 181 and a second circuit board 182, wherein the first circuit board 181 is accommodated in the first accommodation chamber, and the second circuit board 182 is accommodated in the second accommodation chamber. As a preferred embodiment, the first circuit board 181 and the second circuit board 182 are arranged in parallel to each other by means of a pin connection and at least partially overlap in a vertical direction. As an optional embodiment, the first circuit board 181 and the second circuit board 182 may be connected together via a flexible board. As another optional embodiment, the first circuit board 181 and the second circuit board 182 may be integrated as a whole.
The first execution assembly 11 and the second execution assembly 21 can be respectively actuated by the action of the handle 32, and then the first contact assembly 16 and the second contact assembly 26 are respectively actuated. With reference to Fig. 5, an L-pole main switch K1 formed between a movable contact and a stationary contact in the first contact assembly 16 serves to control the connection and disconnection of an L-pole main loop. An N-pole main switch K2 formed between a stationary contact 28 and a movable contact 27 in the second contact assembly 26 serves to control the connection and disconnection of an N-pole main loop.
It is to be noted that one end of the auxiliary contact assembly 50 is electrically connected to the second circuit board 182, and the other end of the auxiliary contact assembly 50 can be disconnected from or connected to the second contact assembly 26. With reference to Fig. 4, the presence of the auxiliary contact assembly 50 is equivalent to the addition of an auxiliary switch K3 between the circuit board assembly 18 and a right-side wiring terminal. This allows a current loop on the board assembly 18 to be independent of the L-pole main loop and the N-pole main loop, respectively. When the circuit breaker is in an ON state, the L-pole main switch K1 and the N-pole main switch K2 are in a switched-on state, the auxiliary switch K3 is also in a switched-on state, and the circuit breaker works normally. It is to be noted that when the circuit breaker is in an OFF state, the L-pole main switch K1 and the N-pole main switch K2 are in a switched-off state, and the auxiliary switch K3 is also in a switched-off state, so that the circuit board assembly 18 is electrically isolated dually. Therefore, by controlling the switching on/off of the auxiliary switch K3, the circuit board assembly 18 can be safely electrically isolated and the circuit board assembly 18 can be effectively prevented from being always in an energized state, so as to effectively reduce the risk of damaging the circuit board assembly 18 by over-voltage breakdown, thereby improving the safety and reliability of the entire circuit breaker.
With reference to Figs. 3 and 4, the auxiliary contact assembly 50 comprises a first contact member 51 and a second contact member 52. One end of the first contact member 51 can be bent and deformed under a contact pressure of the movable contact 27 in the second contact assembly 26 and form a reset force. One end of the second contact member 52 is electrically connected to the first contact member 51, and the other end of the second contact member 52 is electrically connected to the second circuit board 182.
It can be seen with reference to Figs. 3 and 4 that an N-pole main switch K2 for controlling an N-pole main loop can be formed between a stationary contact 28 and the movable contact 27 in the second contact assembly 26, and an auxiliary switch K3 for controlling a loop of the circuit board assembly 18 can be formed between the first contact member 51 and the movable contact 27. It is to be noted that, in order to protect the auxiliary contact from being ablated by a large arc, when the circuit breaker is switched from an ON state to an OFF state, the N-pole main switch K2 is switched off first, and then the auxiliary switch K3 is switched off. When the circuit breaker is switched from the OFF state to the ON state, the auxiliary switch K3 is switched on first, and then the N-pole main switch K2 is switched on, thereby improving the electrical safety.
Preferably, the movable contact 27 comprises a first contact end portion 271 and a second contact end portion 272. The first contact end portion 271 is in the shape of a circular arc with a gentle transition. The second contact end portion 272 is in the shape of a long strip, and the second contact end portion 272 also has a predetermined bending angle. The above-mentioned design can make the second contact end portion 272 of the movable contact 27 better match the stationary contact 28, so that the main loop current can be switched off or on safely and reliably to minimize the generation of arcs as much as possible.
There is a contact matching portion 511 at one end of the first contact member 51. The contact matching portion 511 is bent for engaging with the first contact end portion 271 in a matching manner. By designing a contact surface of the first contact end portion 271 to be of a circular arc shape, it is possible to facilitate steady and smooth sliding of the contact matching portion 511 on the first contact end portion 271 to ensure a more stable electrical contact therebetween, so that the loop current can be switched off or on stably and reliably, so as to prevent the generation of a poor arc. As a preferred embodiment, the contact matching portion 511 is substantially U-shaped, and the above-mentioned design can ensure that the contact matching portion 511 has a sufficiently large contact area and contact pressure to make same better come into electrical contact with the first contact end portion 271.
With reference to Figs. 2, 5 and 6, the N-pole structure of the circuit breaker is shown. As an optional exemplary embodiment, the N-pole structure may be accessed from a left-side terminal 29 shown in Fig. 5 (for example, the terminals 2 and 4 in Fig. 4 serve as the left-side terminal). When the circuit breaker is in an ON state, the stationary contact 28 and the movable contact 27 in the second contact assembly 26 are turned off, the auxiliary switch K3 and the N-pole main switch K2 are both in a switched-on state, and the loop current for the circuit board assembly passes through the left-side terminal 29, the stationary contact 28, the movable contact 27, the first contact member 51, the second contact member 52, and the second circuit board 182 successively. Of course, as shown in Fig. 6, the structure may also be accessed selectively from a right-side terminal 24 (for example, the terminals 1 and 3 in Fig. 4 serve as the right-side terminal). In this case, the loop current for the circuit board assembly passes through the right-side terminal 24, the conductive wire, the movable contact 27, the first contact member 51, the second contact member 52 and the second circuit board 182 successively.
Preferably, the first contact member 51 is made of an elastic metal wire. Since the elastic metal wire has an elastic reset force, the first contact member 51 can be bent and deformed after being subjected to a contact force from the movable contact 27, so as to reserve enough elastic force to ensure the stability of an electrical contact between the movable contact 27 and the first contact member 51 when the auxiliary switch K3 is in a switched-on state. The second contact member 52 is made of a conductive wire, and one of end portions of the second contact member 52 is welded or crimped to the first contact member 51.
When the operating handle 32 of the single-stage circuit breaker starts to operate and the circuit breaker is switched from an ON state to an OFF state, the L-pole main switch K1 is switched off before the N-pole main switch K2 is switched off, the L-pole main switch K1 generates a large number of arcs while being switched off, and these arcs are extinguished gradually under the action of the arc extinguishing device 15, so that the arcs have gradually decreased or are even almost completely extinguished when the N-pole main switch K2 is switched off. Due to the special design of the second contact assembly 26 and the auxiliary contact assembly 50, in order to prevent the arc from burning the auxiliary contact, the N-pole main switch K2 is switched off slightly earlier than the auxiliary switch K3, and at the same time, the residual arcs are then divided into two paths, thereby further facilitating the quick extinction of the arcs, and further effectively reducing the risk of contact damage due to arc ablation. Therefore, it is not necessary to select and use special contact materials and structural designs for the auxiliary contact assembly, for example, it is not necessary to use a special plating layer, tungsten or carbon material, which greatly reduces the production cost. In this case, no current flows through the circuit board assembly, and the current loop of the circuit board assembly is switched off. Since the circuit board assembly is always in a safe voltage range, the possibility of over-voltage breakdown is prevented and the service life of the circuit board assembly is further prolonged. Since the design of the present application can enable the circuit board components to be at a relatively safe voltage level, there is no need to use a circuit board with specific specifications to meet the reliability of the product thereof, and a commonly configured circuit board assembly can be used to meet safety performance requirements and thus greatly reduces the cost of the entire product. It is to be noted that the above-mentioned design of the present application can be applied to a variety of compact circuit breakers and therefore has a wide range of applicability.
As used herein, the term "exemplary" means "serving as an instance, example, or description", and any "exemplary" illustration and embodiment described herein should not be interpreted as a more preferred or a more advantageous technical solution.
It should be understood that although this description is described according to various embodiments, not each of the embodiments only contains one independent technical solution, and such narrative style of the description is merely for the sake of clarity, and those skilled in the art should take the description as a whole and the technical solutions in the various embodiments may also be combined appropriately to form other embodiments which can be understood by those skilled in the art.
The series of detailed descriptions listed above are merely specific descriptions regarding feasible embodiments of the present invention, but not used to limit the scope of protection of the present invention. Any equivalent embodiments or variations made without departing from the technical spirit of the present invention should all be contained within the scope of protection of the present invention.

Claims

A single-stage circuit breaker, comprising
a first accommodation chamber having a first current path formed therein;
a second accommodation chamber having a second current path formed therein;
an electromagnetic trip device (13) arranged in the first accommodation chamber;
a first contact assembly (16) and a first execution assembly (11) used for cooperating with the electromagnetic trip device (13) and located in the first accommodation chamber;
an arc fault and leakage trip device (23) arranged in the second accommodation chamber;
a second contact assembly (26) and a second execution assembly (21) used for cooperating with the arc fault and leakage trip device (23) and located in the second accommodation chamber;
a circuit board assembly (18) for arc fault handling and leakage protection; and
an auxiliary contact assembly (50) arranged inside the second accommodation chamber for effecting safe electrical isolation of the circuit board assembly.
The single-stage circuit breaker of claim 1,
wherein the circuit board assembly (18) comprises a first circuit board (181) and a second circuit board (182),
wherein the first circuit board (181) is accommodated in the first accommodation chamber, and the second circuit board (182) is accommodated in the second accommodation chamber.
The single-stage circuit breaker of claim 2,
wherein one end of the auxiliary contact assembly (50) is electrically connected to the second circuit board (182), and the other end of the auxiliary contact assembly (50) can be disconnected from or connected to the second contact assembly (26).
The single-stage circuit breaker of claim 1,
wherein the auxiliary contact assembly (50) comprises
a first contact member (51), with one end thereof being capable of being bent and deformed under a contact pressure of a movable contact (27) in the second contact assembly (26) and forming a reset force; and
a second contact member (52), with one end thereof being electrically connected to the first contact member (51) and the other end thereof being electrically connected to the second circuit board (182).
The single-stage circuit breaker of claim 4,
wherein the movable contact (27) comprises a first arc-shaped contact end portion (271) and a second long strip-shaped contact end portion (272), wherein the second contact end portion (272) also has a predetermined bending angle.
The single-stage circuit breaker of claim 5,
wherein one end of the first contact member (51) has a bent contact matching portion (511) for engaging with the first contact end portion (271) in a matching manner.
The single-stage circuit breaker of claim 4,
wherein an N-pole main switch (K2) for controlling an N-pole main loop can be formed between a stationary contact (28) and the movable contact (27) in the second contact assembly (26), and an auxiliary switch (K3) for controlling a loop of the circuit board assembly (18) can be formed between the first contact member (51) and the movable contact (27).
The single-stage circuit breaker of claim 7,
wherein when the single-stage circuit breaker is switched from an ON state to an OFF state, the N-pole main switch (K2) is switched off first, and then the auxiliary switch (K3) is switched off; and when the single-stage circuit breaker is switched from the OFF state to the ON state, the auxiliary switch (K3) is switched on first, and then the N-pole main switch (K2) is switched on.
The single-stage circuit breaker of claim 4,
wherein the first contact member (51) is made of an elastic metal wire and the second contact member (52) is made of a conductive wire, and one of end portions of the second contact member (52) is welded or crimped to the first contact member (51).
The single-stage circuit breaker of claim 6,
wherein the contact matching portion (511) is substantially U-shaped.