EP3140847B1

EP3140847B1 - Circuit breaker with arc extinguishing barrier

Info

Publication number: EP3140847B1
Application number: EP15736655.0A
Authority: EP
Inventors: Fabrizio Fabrizi; Roberto Boffelli
Original assignee: BTicino SpA
Current assignee: BTicino SpA
Priority date: 2014-05-07
Filing date: 2015-04-22
Publication date: 2019-03-06
Anticipated expiration: 2035-04-22
Also published as: RU2016142721A3; WO2015177817A1; RU2016142721A; RU2672852C2; CN105097376A; EP3140847A1; CN105097376B; CL2016002814A1

Description

The present disclosure refers to the technical field of electrical installations and, more particularly, regards a circuit breaker with arc extinguishing barrier.
As is known, a circuit breaker includes an electrical circuit comprising at least two contact elements at least one of which is a movable contact that can be moved from an open position to a closed position and vice versa. In the open position, the two contact elements are spaced apart and the electric circuit of the circuit breaker is open. Conversely, in the closed position, the two contact elements abut each other and the electric circuit of the circuit breaker is closed. In certain types of circuit breakers, such as moulded case circuit breakers, in order to facilitate the extinction of electric arcs that are triggered during the opening/closing of the electric circuit of the circuit breaker, there is typically provided a so-called deionizing cell housed in an internal chamber of the circuit breaker called arc extinguishing chamber.
A parameter that characterizes the performance of a circuit breaker is the so-called breaking capacity, which is defined as the maximum short-circuit current that a circuit breaker can interrupt at the operating voltage for a maximum of three operations without it being damaged and its protection characteristics altered. The intensity of current at breaking capacity is significantly higher (by several orders of magnitude) than the maximum rated current of the circuit breaker. The latter is another characteristic parameter and is defined as the maximum current that can be supported by the circuit breaker for an unlimited time.
The breaking capacity is a parameter dependent on the constructional characteristics of the circuit breaker, such as, for example, the size of the circuit breaker, the size of the deionizing cell and the extinguishing chamber and whether or not elements are present suitable to deflect the arc, such as, for example, the ferromagnetic elements described in European patent EP1998349 A1 . The document " JP 2005 235670 A " discloses a circuit breaker according to the preamble of claim 1.
The object of the present disclosure is to provide a further solution that allows improving the performance of a circuit breaker in terms of breaking capacity.
This object is achieved through a circuit breaker as generally defined in claim 1. Preferred and advantageous embodiments of said circuit breaker are defined in the attached dependent claims.
The invention will be better understood from the following detailed description of a particular embodiment, provided by way of example and, therefore, in no way limiting, in relation to the accompanying drawings, wherein:

Figure 1 is a three-dimensional view of an embodiment of a circuit breaker;
Figure 2 is a side plan view of the circuit breaker of Figure 1 showing a first and second case coupled together;
Figure 3 is a three-dimensional view of the circuit breaker of Figure 1, wherein is predominantly visible the upper face of the circuit breaker;
Figure 4 is a side sectional view of a first possible embodiment of the circuit breaker of Figure 1;
Figure 5 is a side sectional view of the circuit breaker of Figure 4, wherein the two cases are shown uncoupled from each other;
Figure 6 is a three-dimensional view of the first case of the circuit breaker of Figure 1;
Figure 7 is a three-dimensional view of the second case of the embodiment of the circuit breaker of Figure 4, wherein are visible a plurality of mobile arc extinguishing barriers;
Figure 8 is a plan view showing, respectively, a first contact branch, a second contact branch and a mobile arc extinguishing barrier of the circuit breaker of Figure 1 wherein the above-mentioned elements are in a first operating configuration;
Figure 9 is a plan view showing the first contact branch, second contact branch and mobile arc extinguishing barrier of Figure 8 wherein the above-mentioned elements are in a second operating configuration;
Figure 10 is a plan view showing the first contact branch, second contact branch and mobile arc extinguishing barrier of Figure 8 wherein the above-mentioned elements are in a third operating configuration;
Figure 11 is a three-dimensional view in partial section of the second contact branch and of the mobile arc extinguishing barrier of Figures 8-10, wherein the second contact branch and the mobile barrier are in the configurations of Figures 8 and 9;
Figure 12 is a three-dimensional view of a first variant embodiment of the second case of Figure 7, comprising a plurality of mobile arc extinguishing barriers wherein said barriers are shown in a first operating position;
Figure 13 is a three-dimensional view of the case of Figure 7, wherein the mobile arc extinguishing barriers are shown in a second operating position; and
Figure 14 is a plan view of a second variant embodiment of the second case of Figure 7, comprising a plurality of mobile arc extinguishing barriers wherein said barriers are shown in a first operating position;
Figure 15 is a plan view of the case of Figure 14, wherein the mobile arc extinguishing barriers are shown in a second operating position.

In the figures, equal or similar elements will be indicated by the same reference numbers.
With reference to the attached figures, a non-limiting embodiment of a circuit breaker is shown, globally indicated with 1. In the particular embodiment of Figure 1, the circuit breaker 1 is, for example, a moulded case circuit breaker. A moulded case circuit breaker, as opposed to an "open" circuit breaker has a housing made of insulating material that, in addition to providing protection against external agents, supports the internal circuits and mechanisms of the circuit breaker and terminals for connection to the external line and load circuits.
Currently, moulded case circuit breakers are generally used as protective devices in the fields of electrical distribution, industrial automation and advanced service fields to interrupt currents having, for example, a value up to 3200 A. Some manufacturers in the industry provide the market different types of moulded case circuit breakers with different functions, since, for example, the market requires various types of moulded case circuit breakers, each of which can be equipped or not with an internal residual current protection device. One possible type of moulded case circuit breaker is represented, for example, by automatic circuit breakers with magnetothermic type trip system, which, in practice, comprises only electromechanical devices. Another possible type of moulded case circuit breaker is, for example, an automatic circuit breaker with electronic type trip system, wherein the trip system is interlocked with an electronic control.
In the particular example shown in the figures and which will be described below, the circuit breaker 1 is a multipolar circuit breaker and, in particular, a tripolar circuit breaker. According to a variant embodiment, the circuit breaker 1 is a four-pole circuit breaker. However, the teachings of this description also extend to circuit breakers having a different number of poles, for example unipolar or bipolar.
From now on we will refer, without thereby introducing any limitation, to the case where in the circuit breaker 1 is, as in the example shown in the figures, a multipolar moulded case circuit breaker.
With reference to Figures 1 and 2, according to an advantageous and non-limiting embodiment, the circuit breaker 1 comprises a first case 10, made of an electrically insulating material such as, for example, a resin, and a second case 20 coupled to the first case 10, also made of an electrically insulating material such as a resin. The cases 10 and 20 are formed, for example, by injection moulding, in two pieces separate from each other. In the above-mentioned advantageous embodiment, with reference to Figure 5, the circuit breaker 1 comprises at least one fastening element 31,32 adapted to couple and maintain the first case 10 and the second case 20 integral to each other. It is preferable to provide a plurality of fastening elements 31,32. According to an embodiment, the at least one fastening element 31,32 is adapted to removably couple the two cases 10,20, and, for example, is embodied by one or more screws 31,32 or in one or more pairs of screws 31,32. In an alternative embodiment, the at least one fixing element 31,32 is an irreversible fixing element and, for example, is embodied by at least one rivet. In the particular example shown in the figures, a plurality of fastening elements are provided in the form of screws or pairs of screws 31 that, passing through the first case 10, are inserted in suitable seats 42 of the second case 20 and in the form of screws or pairs screws 32 that, passing through first the second housing 20, are inserted in suitable seats 41 provided in the first housing 10.
According to a possible embodiment, the first case 10 comprises a first case portion 11 and a second case portion 12 made in two separate pieces, for example by injection moulding, and coupled together. The second case portion 12 is operatively interposed between the first case portion 11 and the second case 20. Preferably, the first case 10 comprises a lid 13 removably coupled to the first case portion 11. The lid 13 is, for example, coupled to the first case portion 11 by means of screws that, passing through the lid 13, are inserted in respective screwing seats provided in the first case portion 11.
With reference to Figure 6, according to an advantageous embodiment, the first case 10 comprises a front face 4 and a rear face 5 opposite to the front face and the second case 20 is coupled to the first case 10 from the side the rear face 5. For the purposes of this description, "front face" means the face of the first case 10 that, during normal use of the circuit breaker 1, is facing the operator and is opposite to an installation wall, for example the wall of an electrical panel. Preferably and not limited to, the rear face 5 of the first case 10 has a protruding portion 6 and a recessed portion 7 that define a step, and the second case 20 is arranged above the protruding portion 6 at the recessed portion 7 for levelling said step and imparting a general outer shape of rectangular parallelepiped to the assembly formed by the first case 10 and the second case 20. Furthermore, the second case 20 is preferably shaped like a half-shell with a quadrangular plan or generally quadrangular.
The circuit breaker 1 also comprises a manual control device 3, such as a rotary control lever 3. The manual control device 3 can be alternately moved between two positions corresponding, respectively, to an operational state of opening and an operational state of closing of the moulded case circuit breaker 1. The manual control device 3, for example, passes through an opening provided in the first case 10. Preferably, the manual control device 3 projects from the front face 4 of the first case 10. The manual control device 3 can also be actuated by a motorized device coupled to the moulded case circuit breaker, for example as shown in Figure 5 of European patent EP 2001036 B1 .
The manual control device 3 is operatively connected to an actuating mechanism housed and supported by the first case 10 and adapted to determine the switching of the circuit breaker 1 between the two operating states of opening and closing. Different types of actuating mechanisms are known to an expert in the field that can be used in a circuit breaker 1 and, for this reason, it is considered superfluous to dwell on this mechanism in more detail in this description. Generally, an actuating mechanism may include levers, elastic elements, connecting rods, a rotary actuating mechanism 15 (visible in Figures 8-10) as, for example, described in European patent EP 2259278 B1 , etc. From now on, the actuating mechanism will be indicated with the reference 15 to indicate the whole through one of its parts.
With reference to Figures 8-10, the circuit breaker 1 comprises at least a first contact branch C1 comprising at least a first contact element P1 and at least a first support element S1 of the first contact element P1, at least a first connection terminal T1 electrically connected to, or integrated into, the first support element S1. The actuating mechanism 15 of the first support element S1 is adapted to move the latter so that the first contact element P1 can be moved from a rest position (shown in Figure 8) to a working position (shown in Figure 9) and vice versa.
According to a preferred embodiment, the first contact element P1 and the second contact element P2 are pads made of a highly conductive material, such as sintered silver alloy.
Preferably and non-limitingly, the first case 10 houses and supports the first contact branch C1 and the actuating mechanism 15. In other words, the first case 10 performs a supporting function for the first contact branch C1 and the actuating mechanism 15.
Furthermore, the circuit breaker 1 comprises a second contact branch C2 comprising at least a second contact element P2, adapted to be contacted by the first contact element P1 when this is in the working position, at least a second support element S2 of the second contact element P2 and at least a second connection terminal T2 electrically connected to, or integrated into, the second support element S2. As can be clearly seen in Figure 7, preferably and non-limitingly, the second case 20 houses and supports the second contact branch C2. In other words, the second case 20 performs a supporting function for the second contact branch C2.
It should be noted that, although the embodiment that provides for a division of the case of the circuit breaker 1 into the first case 10 and the second case 20, and the provision of the first contact branch C1 in the first housing 10 and the second contact branch C2 in the second housing 20, is advantageous, the teachings of the this description are not limited to the particular type of case of the circuit breaker, since such teachings also apply to moulded case circuit breakers with a single case or even circuit breakers of the open type.
The circuit breaker 1 further comprises a mobile barrier 60 or mobile arc extinguishing barrier (hereinafter also indicated by "mobile barrier"), electrically insulating and adapted to be moved between:

a first operating position, for example as represented in Figures 8, 9 and 11, wherein the mobile barrier 60 allows the second contact element P2 to be contacted by the first contact element P1, as shown in Figure 9; and
a second operating position, for example as represented in Figure 10, wherein the mobile barrier 60 is at least partially operatively interposed between the first contact element P1 and the second contact element P2 to interfere, in the passage of the first contact element P1 from the working position to the rest position, with an electric arc that extends between said contact elements P1,P2. For this reason, the mobile barrier 60 can be called a mobile arc extinguishing barrier. For the purposes of this description, the expression "interfere with the electric arc" is equivalent to saying "divert, lengthen, split and/or interrupt the electric arc" for the purpose of a more rapid extinction of the electric arc.

Preferably, the mobile barrier 60 is made of an electrically insulating material, for example polyamide, preferably reinforced with fibreglass. More preferably, the mobile barrier 60 is made of an electrically insulating and self-extinguishing material.
According to an advantageous embodiment, the above-mentioned electrically insulating material is supplemented with gasifying material, such as, for example, phosphorus, i.e., a material that, when subjected to elevated temperatures such as the temperatures that are reached inside a circuit breaker and in the vicinity of the contact elements when an electric arc is triggered, releases gases that allow facilitating the extinction of the electric arc.
Preferably, the mobile barrier 60 is rotatable about an axis of rotation in order to be rotated from the above-mentioned first operating position to the above-mentioned second operating position and vice versa.
In the case where, as in the example shown, the circuit breaker 1 is multipolar, the at least one first contact branch C1 and the at least one second contact branch C2 each comprise a plurality of contact branches, each associated with a respective electrical phase of the circuit breaker 1. In the case of a multipolar circuit breaker 1, it is convenient that the actuating mechanism 15 be common to the various contact branches and that it be controlled by a common actuating element 3. In the case where the circuit breaker 1 is multipolar, the circuit breaker 1 preferably comprises a plurality of mobile barriers 60, each associated to a respective electrical phase of the circuit breaker 1. Preferably, said mobile barriers 60 can be moved independently of each other.
Preferably, as shown in Figures 8 and 9, the first support element S1 is an electrically conductive arm rotatably hinged, directly or indirectly, to the first case 10 in order to be rotated about an axis of rotation between two angularly spaced positions corresponding, respectively, to the rest position (Figure 8) and the working position (Figure 9) of the first contact element P1. Clearly, these positions correspond, respectively, to the operating state of opening and to the operating state of closing of the circuit breaker 1. According to a preferred embodiment, for example as shown in Figures 8 to 13, the axis of rotation of the mobile barrier 60 and the axis of rotation of the first support element S1 are parallel to each other.
For example, the first support element S1 is a conductive arm, for example made of copper, bound to the actuating mechanism 15 and the latter is rotatably hinged to the first case 10, is supported by it and is made of electrically insulating material. It is possible to provide that this bond between the conductive arm and the actuating mechanism 15 provides, in any case, and in a manner known per se, a possibility of residual movement of the rotary arm and, therefore, of the first support element S1 with respect to the actuating mechanism 15, for example to recover the wear of the contact elements P1,P2 or to compensate for any misalignment.
In the case wherein a plurality of first contact branches C1 is provided, each of these is equipped with a first support element S1 and all the first support elements S1 are preferably bound to the same actuating mechanism 15.
With reference to Figures 8-10, according to an embodiment, the first contact branch C1 comprises a bar conductor 18, for example made of copper, having an end portion, for example, provided with a through hole, which is the first connection terminal T1. For example, the connection terminal T1 is a part of, or is electrically connected to, a connecting terminal not shown in the figures. Preferably the bar conductor 18 is electrically connected to the first support element S1 via a flexible conductive braid 16, directly or by interposition of a conductive fastening plate 17 to which one end of said flexible braid 16 is welded. In this latter case, the conductive fastening plate 17 is, for example, riveted to the bar conductor 18.
For the purposes of this description, "bar conductor" means a conductor with a cross-section, preferably quadrangular and more preferably rectangular, such as to ensure a certain rigidity to the conductor as opposed to relatively flexible conductors such as wires, cables, or wire braids.
With reference to Figures 8-11, according to the embodiment, the second support element S2 comprises a movable arm 27, for example made of copper, adapted to allow a rotation of the second contact element P2, so that it can rotate relative to the first contact element P1 due to a repulsive effect when a current of very high intensity flows through the circuit branches C1,C2, for example due to a short circuit and, in any case, greater than the rated current of the circuit breaker 1. For the purposes of this description, repulsive effect means a physical phenomenon based on which, in a condition wherein the contact elements P1, P2 are in contact with each other and are crossed by a current of very high intensity, the two conductors 27 and S1 are subject to an electrodynamic force that tends to move them away from each other because crossed by high-intensity currents flowing in the opposite direction.
According to the above-mentioned embodiment, the second support element S2 further comprises at least one elastic element 26 acting, by compression or traction, on the movable arm 27 and configured to maintain, in a condition of regular operation of the circuit breaker 1, the second contact element P2 as close as possible to the first contact element P1 when the latter is in the working position, shown in Figure 9. Preferably, in the above-mentioned embodiment, the mobile barrier 60 is adapted to be moved by the movable arm 27 against the action of the at least one elastic element 26 that, acting on the movable arm 27, tends to maintain the second contact element P2 as close possible to the first contact element P1. In turn, the movable arm 27 is adapted to interfere in abutment with the mobile barrier 60 to maintain said mobile barrier 60 in the first operating position (Figures 8, 9 and 11). Note that, in the above-mentioned embodiment, the mobile barrier 60 is adapted to be moved by the movable arm 27 to pass from the first to the second operating position and vice versa.
According to a preferred embodiment, the axis of rotation of the mobile barrier 60 and the axis of rotation of the movable arm 27 are parallel to each other.
In the embodiments shown in Figures 4-5 and 7-13, the second support element S2 comprises two elastic elements 26, in particular two helical metal springs, acting by traction on the movable arm 27. Also in these embodiments, the second support element S2 comprises a fixed bar conductor 28, for example made of copper, in the example integral with the second case 20, and the movable arm 27 is rotatably hinged to the fixed bar conductor 28. In the example shown in the figures, an end portion of the fixed bar conductor 28 represents the second connection terminal T2. For example, the second connection terminal T2 is a part of, or is electrically connected to, a connecting terminal of the circuit breaker 1 not shown in the figures.
For example, the movable arm 27 is rotatably hinged to a pin 39, for example being provided with a forked end portion, visible in Figures 4 and 5, fit astride said pin 39. Preferably the pin 39 is made of copper. According to an embodiment, the fixed bar conductor 28 is bent so as to define a first recess adapted to accommodate the pin 39, which may be resting or fixed to the fixed bar conductor 28 and which, in the example, is held in place by movable arm 27 and by the at least one elastic element 26. If the fixed bar conductor 28 is bent so as to define a second recess opposite to the first recess, it is possible to provide that the second support element S2 comprises a further pin 49, for example made of steel, to which can be bound a first end portion of the at least one elastic element 26. It is possible to provide a further pin 40, for example made of steel, that protrudes from the movable arm 27 in order to be able to bind to this the second end portion of the at least one elastic element 26. For example, the pin 40 is engaged and embedded in the movable arm 27 and passes through it so as to project out of it from two opposite sides. In this way it is possible to bind to the movable arm 27, a pair of elastic elements 26. Note that, to realise the fixed bar conductor 28 in such a way that it has two opposing recesses that serve as seats for the two pins 39 and 49, it is sufficient to shape the fixed bar conductor 28 so that an end portion of this has an S or Z-shape.
According to an advantageous embodiment, the second support element S2 comprises a screen 69 made of ferromagnetic material, for example made of iron, between the movable arm 27 and the fixed bar conductor 28 adapted to reduce the repulsive effect between the movable arm 27 and the fixed bar conductor 28.
According to a preferred embodiment, with reference to Figure 11, the mobile barrier 60 comprises two lateral walls 62 parallel to each other, or substantially parallel, only one of which is visible in Figure 11, and a central, bridge-connection wall 61 between the lateral walls 62. The central bridge-connection wall 61 is transverse to the lateral walls 62 and is adapted to act as a screen element suitable to interfere with an electric arc to deflect, lengthen and/or break it. Again with reference to Figure 11, according to an embodiment, the mobile barrier 60 comprises a cross member 64 that connects the lateral walls 62 and is perpendicular to them. This cross member 64 is spaced from the central, bridge-connection wall 61 so that between the cross member 64 and said central wall 61 is defined an opening passed through by the movable arm 27 when the mobile barrier 60 is in the first operating position (Figures 8, 9 and 11). In the example shown in Figure 11, the movable arm 27 interferes in abutment with the mobile barrier 60, and, in the particular example shown without thereby introducing any limitation, interferes in abutment with the cross element 64, to bring the mobile barrier 60 from the first operating position, shown in Figure 9, to the second operating position, shown in Figure 10. Furthermore, the movable arm 27 interferes in abutment with the mobile barrier 60, to bring the mobile barrier 60 from the second operating position, shown in Figure 10, to the first operating position shown in Figure 9, due to the elastic return effect exercised by the at least one elastic element 26 on the movable arm 27. In the particular example shown, without thereby introducing any limitation, the movable arm 27 interferes in abutment with the mobile barrier 60 because the plug 67 interferes with the side walls 62 of the movable barrier 60 to return the movable barrier 60 from the second operating position to the first operating position.
In other words, one can see how, in the example described, the mobile barrier 60 is adapted to be moved by the movable arm 27, which interferes in abutment with it, to be moved from the first to the second operating position and vice versa. Keep in mind that, in addition to the particular mechanical solution described above, there are other possible particular and equivalent embodiments based on the feature of providing an interference in abutment between the movable arm 27 and the barrier 60 for the movement of the mobile barrier 27 from the first to the second operating position and vice versa. One of the generally possible ways to achieve this result is that of providing that, as in the example shown, the mobile barrier 60 in the first operating position is arranged astride the movable arm 27. Another possible way to achieve this result is that of providing that the mobile barrier 60 has a body provided with a through opening crossed by the movable arm 27 or generally of a recess crossed by the movable arm 27.
Note that, in the general embodiments described above, the mobile barrier 60 moves from the first operating position only when the movable arm 27 moves due to the repulsive effect in contrast to the elastic element 26. Therefore, the mobile barrier 60 moves from the first operating position only in overcurrent conditions and not at each opening of the circuit breaker 1 by means of the manual control device 3. The general embodiment described above also has the advantage of not requiring complex, dedicated movement systems of the mobile barrier 60 and the related advantage of making the circuit breaker 1 highly reliable.
Preferably, the lateral walls 62 of the mobile barrier 60 are rotatably hinged to rotate about an axis of rotation. In figure 11, this axis of rotation is defined by the pin 63 that protrudes from the lateral wall 62. An identical pin may be provided on the other lateral wall 62, not visible in Figure 11. The above-mentioned pins 63 may be used, for example, to bind the mobile barrier 60 to the second case 20. In the example shown in Figures 8-11, the second contact branch C2 comprises a support frame 70 of the mobile barrier 60 to which the mobile barrier 60 is rotatably hinged.
Preferably, the support frame 70 is made of electrically insulating material.
According to an advantageous embodiment, the support frame 70 of the mobile barrier 60 comprises a first portion 8a of deionizing cell 8a,8b of the circuit breaker 1 comprising a plurality of sheet conductive elements. The circuit breaker 1 also comprises a second portion 8b of deionizing cell adapted to be juxtaposed to the first portion 8a of deionizing cell when the second case 20 is coupled to the first case 10.
According to a particularly advantageous embodiment, the first case 10 includes an arc extinguishing chamber 19, housing the first portion 8b of deionizing cell 8a,8b and having an opening 9 facing towards the second case 20.
Keep in mind that, although the embodiment of the example described has an extinguishing cell 8a,8b formed from two distinct portions, the teachings of this description are also applicable to circuit breakers with a single extinguishing cell not physically divisible into two distinct pieces.
In the embodiment described above, with reference to Figures 4,5 and 7-11, the mobile barrier is moved automatically by the movable arm 27 when, starting from a state of closure of the circuit, a short circuit or an overcurrent occurs such as to move, due to the repulsive effect, the movable arm 27 in order to move away the two contact elements P1, P2 until reaching the configuration of Figure 10 (in which even the first support S1 has returned to the rest position due to the effect of an automatic release of the circuit breaker 1). Clearly, the configuration of Figure 10 represents a limit configuration since it is not said that, when the mobile barrier has reached the end-of-stroke position shown in this figure, the support S1 has simultaneously reached the rest position. What should be kept in mind is that, in the above-mentioned embodiment, the mobile barrier 60 is moved to, at least partially, interpose itself between the two contact elements P1,P2, between which there is an electric arc that is thereby deflected, lengthened and/or split by the same mobile barrier 60 in order to bring the arc close to the extinguishing cell. This results in a more rapid extinction of the arc and thus increases the performance of the circuit breaker 1 in terms of breaking capacity.
Figures 12 and 13 show a variant embodiment of the second case 20 that differs from the second case 20 of Figure 7 in that the mobile barrier 60 is such as to interrupt the arc, since the mobile barrier 60, cooperating in the second operating position represented in Figure 13 with an electrically insulating cell 65 provided in the circuit breaker 1, forms a screen that, for example, by covering the second contact element P2, is such as to interrupt the arc. For example, in the second operating position, the mobile barrier 60 is suitable to flank the above electrically insulating cell 65 to form a screen that isolates the first P1 and the second P2 contact elements from each other. The electrically insulating cell 65 preferably has a front opening adapted to receive, at least partially, the mobile barrier 60 when the latter is in the second operating position.
For example, the electrically insulating cell 65 is integrated into a support frame of the mobile barrier 60 similar to the support frame 70 of Figure 11 wherein, the sheets that form the portion of deionizing cell 8a would not, preferably, be provided, while there could, in any case, the portion of deionizing cell 8b could be provided in the first case 10.
Figures 14 and 15 show a further variant embodiment wherein the mobile barriers 60 are rotatable about respective axes of rotation perpendicular to the axis of rotation of the first supporting elements S1 and, in the example, also perpendicular to the axes of rotation of the conductive arms 27. The mobile barriers 60 are, for example, rotatably hinged to the walls of the second case 20 or to a support frame similar to the support frame 70 of Figure 11.
Furthermore, the embodiment shown in Figures 14 and 15 differs from the embodiment of Figure 7 in that only one elastic element 26 is provided for each of the second support elements S2 of the second contact elements P2 and in that, for each electric phase, two mobile barriers 60 are provided that, in the second operating position (Figure 15), are set alongside one another to form a screen that isolates the second contact elements P2 from the first contact elements P1.
Still with reference to Figures 14 and 15, it is possible to provide that the mobile barriers have walls or arms not visible in the figures adapted to cooperate with the movable arms 27 to move the barriers 60 from the first operating position (Figure 14) to the second operating position (Figure 15) and vice versa.
Thus far, possible embodiments have been described wherein the mobile barrier 60 is adapted to be moved by the second support element S2 and in particular by the movable arm 27. However, it is possible to provide alternative embodiments wherein the mobile barrier 60 is adapted to be moved by the first support element S1.
According to an embodiment, the circuit breaker 1 comprises an automatic protection system with a trip system adapted to bring the first contact element P1 to the rest position upon the detection of a short-circuit or overcurrent condition. The body of knowledge of an expert in the field includes the various types of trip systems, both of the fully electromechanical type (automatic magnetothermic circuit breakers) and interlocked with an electronic control (automatic electronic circuit breakers). The above-mentioned automatic protection system can also be indifferently provided, or not, with a residual current protection system.
Obviously, a person skilled in the art, in order to satisfy contingent and specific needs, may make numerous modifications and variations to the circuit breaker 1 described above, all however contained within the scope of the invention as defined by the following claims.

Claims

Circuit breaker (1) comprising:
- at least a first contact branch (C1) comprising at least a first contact element (P1) and at least a first support element (S1) of the first contact element (P1), at least a first connection terminal (T1) electrically connected to, or integrated into, the first support element (S1);

- an actuating mechanism (15) of the first support element (S1) adapted to move the latter so that the first contact element (P1) can be moved from a rest position to a working position and vice versa;

- a second contact branch (C2) comprising at least a second contact element (P2), adapted to be contacted by the first contact element (P1) when this is in the working position, at least a second support element (S2) of the second contact element (P2) and at least a second connection terminal (T2) electrically connected to, or integrated into, the second support element (S2);
wherein the circuit breaker (1) further comprises an electrically insulating mobile barrier (60) adapted to be moved between:
- a first operating position wherein the mobile barrier (60) allows the second contact element (P2) to be contacted by the first contact element (PI); and

- a second operating position wherein the mobile barrier (60) is at least partially operatively interposed between the first contact element (P1) and the second contact element (P2) to interfere, in the passage of the first contact element (P1) from the working position to the rest position, with an electric arc that extends between said contact elements;
characterized in that:
the second support element (S2) comprises a movable arm (27) adapted to rotate about an axis of rotation and wherein the circuit breaker (1) further comprises at least one elastic element (26) acting on the movable arm (27) and configured to maintain, in a condition of regular operation of the circuit breaker (1), the second contact element (P2) as close as possible to the first contact element (P1) when the latter is in the working position.
Circuit breaker (1) according to claim 1, wherein the mobile barrier (60) is rotatable about an axis of rotation in order to be rotated from the first operating position to the second operating position and vice versa.
Circuit breaker (1) according to claims 1 or 2, wherein the at least one first support element (S1) is rotatable about an axis of rotation to rotate between two angularly spaced positions corresponding, respectively, to the working position and the rest position of the first contact element (P1).
Circuit breaker (1) according to claims 2 and 3, wherein the axis of rotation of the mobile barrier (60) and the axis of rotation of the first support element (S1) are parallel.
Circuit breaker (1) according to claim 1, wherein the mobile barrier (60) is adapted to be moved by the movable arm (27) to pass from the first to the second operating position and vice versa.
Circuit breaker (1) according to claims 2and 5, wherein the axis of rotation of the mobile barrier (60) and the axis of rotation of the movable arm (27) are parallel.
Circuit breaker (1) according to claim 5, wherein the movable arm (27) is adapted to interfere in abutment with the mobile barrier (60) to move the mobile barrier (60) from the first to the second operating position and vice versa.
Circuit breaker (1) according to claim 5, wherein, in the first operating position, the mobile barrier (60) is arranged astride the movable arm (27).
Circuit breaker (1) according to any of claims 1 to 4, wherein the mobile barrier (60) is adapted to be moved by the first support element (S1).
Circuit breaker (1) according to any of the preceding claims, wherein the mobile barrier (60) is made of an electrically insulating material with the addition of material adapted to release gas when said barrier (60) is subjected to a temperature increase caused by said electric arc.
Circuit breaker (1) according to any of the preceding claims, comprising an arc extinguishing chamber (19) housing a deionizing cell (8a, 8b) and wherein in the second operating position, the mobile barrier (60) is adapted to interfere with said electric arc by interposing itself between the contact elements (P1, P2) to bring the electric arc towards the deionizing cell (8a, 8b).
Circuit breaker (1) according to any of claims 1 to 10, wherein the circuit breaker (1) comprises a cell (65) made of electrically insulating material, and wherein, in the second operating position, the mobile barrier (60) is adapted to flank said cell (65) made of electrically insulating material to form a screen that isolates the first (P1) and the second (P2) contact element from each other.
Circuit breaker (1) according to any of the preceding claims, wherein the circuit breaker (1) is a moulded case circuit breaker and comprises:
- a first case (10) housing and supporting the first contact branch (C1) and the actuating mechanism (15);

- a second case (20) coupled to the first case (10) housing and supporting the second contact branch (C2);

- at least one fastening element (31, 32) adapted to couple and maintain the first (10) and the second (20) case integral to each other.
Circuit breaker according to claim 13, wherein the second case (20) houses and supports the mobile barrier (60) .
Circuit breaker (1) according to any of the preceding claims, wherein the circuit breaker is multipolar and wherein:
- said at least one first contact branch (C1) and the at least one second contact branch (C2) each comprise a plurality of contact branches, each associated to a respective electrical phase of the circuit breaker; and

- the actuating mechanism (15) is common to the various branches and the circuit breaker (1) comprises a plurality of mobile barriers (60), each associated to a respective electrical phase of the circuit breaker.