EP0611224B1 - Differential protection unit with functionally testable sub-assembly - Google Patents

Description

The present invention relates generally a differential protection block which is used usually in combination with a circuit breaker multipolar. Such a combination of a circuit breaker multipolar and a differential protection block constitutes what is commonly called a circuit breaker differential.

A classic differential protection block generally includes a housing in which are enclosed the various mechanical, electrical elements and electronics necessary for its operation. In such a case, one can for example house a connection assembly constituting electrical conduction, one channel being provided for each pole of the circuit breaker, a coil toroid intended to be mounted around said electrical conduction paths for detect a differential current and a mechanism disjunction command intended to command an action of circuit breaker in the associated multipole circuit breaker said differential protection block, this command taking place in response to an electrical signal produced in said coil torus. In this same case, we can further include a number of other elements such an electronic control card, a card power, etc.

A major drawback of protective blocks differential known so far lies in the fact that the differential protection block must be fully mounted and connected to the multipole circuit breaker before it can be tested. If the test reveals a dysfunction, it is difficult, if not impossible, to determine the source of the malfunction, because all the active elements of the protection block differential are enclosed in the housing of the device.

On the other hand, it is more and more common to use housings which are closed by means of non-removable devices, for example rivets, a bonding, hot deformation, etc. In this case, the dismantling of the defective differential protection unit is impossible even for the sole purpose of identifying the source of the malfunction.

On the other hand, it is common practice to perform dielectric tests on panels electric. These dielectric tests impose to isolate the electronic parts before carrying out these tests. In known differential circuit breakers, proceed either to disassembly of the electronic cards contained in each differential protection block either perform complicated operations intended for disconnect the electronic cards.

An object of the present invention is to offer a differential protection block designed from so that we can test before incorporation active elements of said protection block differential in the camera body.

Another object of the present invention consists in offer such a differential protection block also making it possible to easily isolate the electronic parts contained in the block of earth leakage protection before testing dielectric on an electrical panel containing such differential protection blocks.

The invention therefore relates in particular to a block differential protection can be associated with a circuit breaker multipolar to constitute together a circuit breaker differential, this differential protection block comprising a connection assembly constituting electrical conduction paths for the different poles of the multipole circuit breaker, a coil toroid intended for be mounted around said electrical conduction paths to detect a differential current and a disjunction command intended to command an action of circuit breaker in the multipole circuit breaker in response to an electrical signal produced by said coil torus.

The differential protection block according to the invention is characterized in that it further comprises a frame on which said said are fixed active elements together forming a subset rigid functional, said chassis being constituted by a first molded plastic chassis part and by a second piece of plastic frame molded can be coupled to the first part of the chassis, from where results that said functional subset can be connected to the residual current device in order to be able perform a functional test of the functional subset while being able to access at least some of said active elements, said functional subset being then locked in said housing when said test functional deemed it functionally satisfactory.

According to a preferred characteristic of the invention, said first and second chassis parts together form, in coupled position: an envelope substantially surrounding completely a coil torus; a partitioned passage located in the center of the coil torus and intended to pass to the through said electrical conduction paths; a insulating support for said conduction paths electric; and a support to dispose externally said disjunction control mechanism.

According to another particular embodiment of the invention, the block further comprises at least one card electronic can be mounted externally on said chassis in order to control the operation of said disjunction control mechanism in response to a electrical signal produced by the coil toroid.

According to another particular embodiment of the invention, said upper half-housing comprises a window located above said electronic card included inside and a connection cover is provided which forms a hood and which supports on its face downwards of the connection contacts, hence it follows that, by fixing the connection cover on an upper face of the upper half-housing, the connection cover hides the window and simultaneously connection cover connection contacts come automatically establish electrical connections between the electronic card and other active parts contained in the case and, conversely, when remove the connection cover, the electronic card is completely disconnected, allowing you to dielectric test of the differential protection block without risk of damaging the electronic card.

la figure 1 est une vue schématique d'un principe de fonctionnement d'un bloc de protection différentielle selon l'invention ;

la figure 2 est une vue en perspective montrant les formes générales externes d'un bloc disjoncteur ;

la figure 3 est une vue en perspective d'un mécanisme d'actionnement incorporé dans un bloc de protection différentielle accolé au disjoncteur de la figure 2 ;

la figure 4 est une vue en perspective éclatée d'un bloc de protection différentielle, dans laquelle on distingue entre autre un sous-ensemble fonctionnel du bloc de protection différentielle, ce sous-ensemble étant dans une configuration assemblé ;

la figure 5 est une vue en perspective éclatée montrant les principaux éléments constituant le sous-ensemble fonctionnel représenté sur la figure 4 ;

la figure 6 est une vue en perspective montrant deux parties séparées formant un châssis qui constitue une des pièces du sous-ensemble fonctionnel de la figure 5 ;

la figure 7 est une vue en perspective du châssis de la figure 6, le châssis étant représenté dans une position assemblée ;

la figure 8 est une vue en coupe simplifiée montrant la structure d'un tore à bobine qui constitue l'une des pièces du bloc de protection différentielle représenté sur les figures précédentes ;

la figure 9 est une vue en perspective éclatée du tore à bobine représenté sur la figure 8 ;

la figure 10 est une vue en perspective montrant de façon plus détaillée un élément formant enveloppe du tore à bobine représenté sur la figure 9 ;

la figure 11 est une vue en perspective d'un cache de raccordement qui constitue l'une des pièces pouvant optionnellement faire partie d'un bloc de protection différentielle selon la présente invention, ce cache de raccordement étant vu par dessus d'une façon associée à une carte électronique incluse dans le même bloc de protection différentielle ; et

la figure 12 est une vue en perspective du cache de raccordement de la figure 11, la vue étant prise par dessous.

These objects, characteristics and advantages, as well as others of the present invention will be better understood during the detailed description of embodiments which follows, illustrated by the appended figures and among which:

Figure 1 is a schematic view of an operating principle of a differential protection block according to the invention;

Figure 2 is a perspective view showing the general external shapes of a circuit breaker block;

Figure 3 is a perspective view of an actuating mechanism incorporated in a differential protection block attached to the circuit breaker of Figure 2;

Figure 4 is an exploded perspective view of a differential protection block, in which there is among others a functional sub-assembly of the differential protection block, this sub-assembly being in an assembled configuration;

Figure 5 is an exploded perspective view showing the main elements constituting the functional sub-assembly shown in Figure 4;

Figure 6 is a perspective view showing two separate parts forming a frame which constitutes one of the parts of the functional sub-assembly of Figure 5;

Figure 7 is a perspective view of the chassis of Figure 6, the chassis being shown in an assembled position;

Figure 8 is a simplified sectional view showing the structure of a coil toroid which constitutes one of the parts of the differential protection block shown in the previous figures;

Figure 9 is an exploded perspective view of the coil torus shown in Figure 8;

Figure 10 is a perspective view showing in more detail an envelope member of the coil toroid shown in Figure 9;

FIG. 11 is a perspective view of a connection cover which constitutes one of the parts which can optionally be part of a differential protection block according to the present invention, this connection cover being seen from above in an associated manner an electronic card included in the same differential protection block; and

Figure 12 is a perspective view of the connection cover of Figure 11, the view being taken from below.

Figure 1 illustrates the operating principle of a differential protection block in this invention.

In this example, the protection block differential is provided for four poles. For a block differential protection provided for another number of poles, for example for 2 poles or 3 poles, the parts included in the block are in number corresponding to this number of poles.

The principle consists, in a very well-known manner, in measure the sum of the electric currents flowing simultaneously in the four current channels corresponding to the four poles. Therefore, the block differential protection has four ways of current 1, 2, 3, 4 in which the currents pass electrics of the four poles, during operation normal of the device. Each current path can be constituted by a metallic structure, for example in copper, which has a terminal at each end input 5 and an output terminal 6 and in its part central a piece of electrical conduction 7. A torus magnetic 8 is arranged so as to surround simultaneously the four pieces of electrical conduction 7. When the electrical circuit connected downstream of the block differential protection operates normally, the sum of the electric currents flowing simultaneously through the four conduction pieces electric 7 is very substantially equal at all times to zero. If the electrical circuit has an anomaly which is that part of the electric current at least one of the poles is derived so as to pass through example to earth, the sum of the electric currents which circulate simultaneously through the four pieces of electrical conduction 7 is no longer equal to zero. A coil 9 wound around the magnetic core 8 then makes appear at its connection wires 10, 11 a potential difference or an electric current when the sum of electrical currents flowing through the four pieces of electrical conduction 7 is not equal to zero. The connecting wires 10 and 11 of the coil 9 are connected to an electronic card 12 which is intended to detect the appearance of a certain electrical voltage or a certain electrical current to coil 9 terminals so as to send a signal electric designed to control a trip of a mechanism 13 designed to cause the disjunction of the multipole circuit breaker D (figure 2) connected or coupled to the differential protection block.

Such a differential protection block is good known from the prior art and it presents itself in a way general in the form of an insulating housing which contains all the parts making up the device. We can see in Figure 3, the general external forms of the trigger mechanism 13 mentioned above, the trigger mechanism 13 forming part of the parts included in the housing 14 of the protection block differential.

FIG. 4 represents, in exploded perspective, the essential elements that constitute the block of differential protection. This protective block differential is generally made up of a functional subset 16 which includes a certain number of parts which we will describe later but which have the essential characteristic of power be assembled to form a single whole functional, i.e. a single set that can function.

The functional sub-assembly 16 is intended to be enclosed in the housing 14, which is constituted by a 14A lower half-case and one upper half-case 14B which are made of insulating plastic and which are intended to mate so as to constitute the box 14 inside which the sub-assembly is enclosed functional 16. The housing 14 can, when its two parts are assembled, present a shape general external substantially parallelepiped. The block differential protection also includes a connection cover 18 whose structure and function will be described below.

• Un premier élément 22 est appelé par la suite "assemblage de connexion". L'assemblage de connexion 22 est constitué par un certain nombre de voies de conduction électrique indépendantes (le nombre de ces voies de conduction électriques étant égal au nombre de pôles du bloc de protection différentielle considéré), comme cela a été évoqué en relation avec la figure 1. Chaque voie de conduction électrique comporte une borne d'entrée 24, une pièce de conduction électrique 26 et une borne de sortie 28. Par souci de simplification, une seule voie de conduction électrique comporte sur la figure 5 les repères respectifs 24, 26 et 28.
• Un autre élément du sous-ensemble fonctionnel 16 est constitué par un tore à bobine 30 qui comprend de façon générale un tore magnétique, une bobine enroulée sur le tore magnétique et une enveloppe externe. Ce tore à bobine 30 sera décrit plus en détails par la suite.
• Un autre élément du sous-ensemble fonctionnel 16 est constitué par une carte électronique 32.
• Enfin, un dernier élément du sous-ensemble fonctionnel 16 est constitué par un mécanisme d'actionnement 34.

In FIG. 5, there are, in exploded perspective, the different essential elements which constitute the functional sub-assembly 16 represented in an assembled manner in FIG. 4. In FIG. 5, it can be seen that this functional sub-assembly 16 consists of generally by an insulating plastic frame 20 on which or in which are mounted and fixed a number of parts or active elements of the differential protection block. These parts or active elements are as follows:

• A first element 22 is hereinafter called "connection assembly". The connection assembly 22 consists of a number of independent electrical conduction paths (the number of these electrical conduction paths being equal to the number of poles of the differential protection block considered), as has been mentioned in connection with the FIG. 1. Each electrical conduction channel has an input terminal 24, an electrical conduction piece 26 and an output terminal 28. For simplicity, a single electrical conduction channel has the respective references 24 in FIG. 5, 26 and 28.
• Another element of the functional sub-assembly 16 is constituted by a coil toroid 30 which generally comprises a magnetic toroid, a coil wound on the magnetic torus and an external envelope. This coil toroid 30 will be described in more detail below.
• Another element of the functional sub-assembly 16 is constituted by an electronic card 32.
• Finally, a last element of the functional sub-assembly 16 is constituted by an actuation mechanism 34.

The functional sub-assembly 16 is constituted by a frame 20 in and around which are fixed respectively the connection assembly 22, the toroid at coil 30, the electronic card 32 and the mechanism trigger 34. More precisely, the coil toroid 30 is arranged inside the chassis 20 and the others elements 22, 32 and 34 are mounted outside the chassis 20. We understand that an essential difference compared to art differential protection block prior resides in the fact that, according to the invention, the differential protection block consists of a functional subset which, as its name suggests, contains all the elements essential to operation, and a housing 14 which encloses the sub-assembly functional 16.

In contrast, in protective blocks differential known to date, the different functional elements are fixed and housed inside of a housing, this housing being produced for example in two parts so as to constitute an internal cavity intended to enclose all the functional elements. It follows from this that it is necessary to close the housing so that the functional elements contained in the interior can function properly. By therefore in differential protection blocks of the prior art, we cannot test the operation of the device as a whole before the case is closed, which is annoying because that, when the case is closed, you cannot detect the origin of a failure observed in the differential protection block operation.

One of the essential parts of the protective block differential according to the present invention is constituted by the chassis 20. This chassis 20 is shown in detail in FIGS. 6 and 7. The chassis 20 consists of two independent chassis parts 20A and 20B which have some mirror symmetry with respect to to each other and which are intended to mate one to the other. The two chassis parts 20A and 20B are each made in one plastic part molded electrically insulating. Frame part 20A generally takes the form of a vertical wall 36 and the chassis part 20B presents itself similarly very generally in the form of a vertical wall 38. The two vertical walls 36 and 38 are substantially parallel to each other when the two chassis parts 20A and 20B are mated. On the side of the wall 36 which is directed to frame part 20B and to the side of the wall 38 which is directed towards the chassis part 20A, are respectively disposed of the envelope walls 42, 44 (only the walls of room 20B are visible on the figure) which extend perpendicular to the wall respective vertical 36 or 38. On the chassis part 20B, we discern in more detail all of the walls 42 and 44, although similar walls are provided on the chassis part 20A. The wall 42 constitutes a substantially cylindrical outer shell and the wall 44 constitutes an envelope substantially internal cylindrical. Therefore, the space separating the outer wall 42 and the inner wall 44 is a space substantially annular which constitutes a housing for the coil toroid 30. A similar annular space is arranged in the same way on the chassis part 20A well that it is not visible in Figure 6. When the parts 20A and 20B are coupled to each other, the two annular housings form only one housing annular whose overall width is slightly greater than the width of the coil toroid 30. It results from that only to start assembling or mounting the subassembly functional 16, we start by housing the torus at coil 30 in the annular housing limited by the walls 42 and 44, then we couple the two pieces of chassis 20A and 20B so as to completely enclose the coil toroid 30.

The chassis 20 then takes the form which is shown in Figure 7. The part at the center of annular wall 44 is hollowed out and forms a cross passage. More precisely, this hollowed out part central includes four partition walls 46 which extend along an axis 48 which is perpendicular to the vertical wall 38. The partition walls 46 share in four passages the cross section of the part hollowed out central. In this way, the four pieces of electrical conduction 26 (Figure 5) can pass through part by part respectively the four passages 50 which are separated from each other by the four walls of partition 46. Of course, similar symmetrical shapes the shapes of elements 42, 44, 46 and 50 are provided on chassis part 20A (these forms of part 20A not visible in Figure 6).

After having housed the coil toroid 30 between the cylindrical walls 42 and 44 and after coupling the two chassis parts 20A and 20B, the assembly is mounted of connections 22 on the chassis 20. To do this mounting, we mount each of the four conduction channels electrical (24, 26, 28) on the chassis 20. The mounting of an electrical conduction path is carried out from the next way. We fix a conduction piece electric 26 radially at one end 52 (see figure 5) of the input terminal 24, then we go up the assembly formed by elements 24, 26 and 52 on the part of frame 20A so that the part of electrical conduction 26 runs right through one of the housings 50 and that the input terminal 24 comes position against positioning surfaces adapted on the outside of the vertical wall 36 of chassis part 20A. Then we mount the terminal outlet 28 and its extension 54 on the workpiece chassis 20B so that the output terminal 28 come and stand against surfaces of adapted positioning on the outside of the vertical wall 38 of the chassis part 20B. Finally, we mechanically and electrically connects the end free from the electrical conduction piece 26 to extension 54 of the output terminal 28.

It follows from this that the elements 24, 52, 26, 54 and 28 are electrically connected to each other from so as to constitute an electrical conduction path. This electrical conduction path crosses by therefore right through passage 50 which is at center of the coil toroid 30 housed inside the chassis 20. We then proceed in a similar manner to mount the other three electrical conduction paths of so that each of them goes into one of the three other passages 50.

Then, we mount on the chassis 20 the card electronic 32. This electronic card 32 can come position itself above the frame 20 coming from snap onto snap-in means and appropriate positioning 56 (see figure 7).

Then we mount the control mechanism of circuit breaker 34 (visible in figure 5) on the chassis 20 which includes positioning surfaces and appropriate latching 58 (see Figure 7).

Finally, we make the electrical connections required between the coil torus 30, the card electronic 32 and the control mechanism disjunction 34 (these electrical connections not being shown in the drawings).

When we have completed this assembly, we obtain a monobloc assembly which constitutes the subset functional 16 as shown in FIG. 4. The functional sub-assembly 16 includes all the elements mechanical, electrical and electronic that allow its operation. It follows from this that it is then possible to connect input terminals 24 and output terminals 28 respectively to terminals of the multipole circuit breaker D and a electrical circuit (not shown) simulating a charge electric. We can then, in a classic way, act on the electrical charge so as to perform a test functional of the functional subset 16 as well connected to a multipole circuit breaker.

If this functional test does not reveal any malfunction, we can then complete the assembly of the differential protection block when mounting on the sub-assembly functional 16 the lower half-housing 14A and the upper half-housing 14B (see FIG. 4). When the two half-housings 14A and 14B are thus arranged on the functional sub-assembly 16 and are coupled one to the other, the two half-housings 14A and 14B form a outer shell which contains almost completely the functional sub-assembly 16.

We can complete this assembly by adding on the upper half-casing 14B a connection cover 18 of which structure and construction will be explained by the after. We then completely assembled a block of differential protection according to the present invention, and this differential protection block whose test has revealed that it was working properly can then be disconnected from multipole circuit breaker and circuit electrical test to be stored as a block of differential protection good for marketing.

• Si le dysfonctionnement révélé est d'un type qui a provoqué une certaine destruction de certaines parties du sous-ensemble fonctionnel 16 de telle sorte qu'il est jugé que le sous-ensemble fonctionnel 16 ne peut pas être réparé, la totalité de ce sous-ensemble fonctionnel 16 est mise au rebut.
• Si le dysfonctionnement révélé est d'un type qui correspond à une panne d'un seul des éléments fonctionnels constituant le sous-ensemble fonctionnel 16, c'est-à-dire une panne soit de l'assemblage de connexion 22, soit du tore à bobine 30, soit de la carte électronique 32, soit du mécanisme de commande de disjonction 34, soit d'un autre élément accessible et démontable individuellement, on peut procéder soit à une intervention directe sur l'élément défectueux, par exemple un réglage, soit à un démontage de l'élément défectueux et à un remplacement par un autre élément neuf. On refait alors un test fonctionnel du sous-ensemble fonctionnel 16 et, s'il révèle alors que le sous-ensemble fonctionnel 16 réparé fonctionne correctement, on peut parachever le montage du bloc de protection différentielle en adaptant le boítier 14 et le cache-raccordement 18. On stocke alors, comme précédemment, ce bloc de protection différentielle en tant que bloc de protection différentielle bon pour une commercialisation.

If the functional test reveals that the functional sub-assembly 16 has a certain malfunction, the following two actions can be carried out, depending on the type of malfunction revealed.

• If the malfunction revealed is of a type which has caused a certain destruction of certain parts of the functional sub-assembly 16 so that it is judged that the functional sub-assembly 16 cannot be repaired, the whole of this sub functional assembly 16 is scrapped.
• If the malfunction revealed is of a type which corresponds to a failure of only one of the functional elements constituting the functional sub-assembly 16, that is to say a failure either of the connection assembly 22, or of the torus coil 30, either of the electronic card 32, or of the disjunction control mechanism 34, or of another element accessible and removable individually, it is possible to carry out either a direct intervention on the defective element, for example an adjustment, either disassembly of the defective element and replacement with another new element. We then redo a functional test of the functional sub-assembly 16 and, if it then reveals that the repaired functional sub-assembly 16 is functioning correctly, we can complete the assembly of the differential protection block by adapting the housing 14 and the connection cover 18. We then store, as before, this differential protection block as a differential protection block good for marketing.

The coil toroid 30 as shown in the figure 5 constitutes a sub-assembly which presents in itself certain characteristics which will be described now. The coil torus 30 has a shape general external of a torus, as we can see on the Figure 5, which is laterally attached a part in protuberance 58 which allows the passage of the output wires of the toroid coil so that these leads can be connected to the electronic card 32. As we can see it in figure 8, this sub-assembly forming the torus coil 30 has a specific structure which is particularly advantageous in the context of its use in functional sub-assembly 16 according to the present invention. The coil toroid 30 is made up, as shown in Figure 8, by a torus in magnetic material 60, by two half shells of insulation 62A, 62B which surround laterally of each side of the torus 60, by a winding 64 which is wound around the two half shells 62A, 62B, by a carcass 66 (described below) which is mounted on the winding 64 and by two half shells of external envelope 68A and 68B. The two half insulation shells 62A and 62B used to create a thin envelope electrically insulating around the torus 60. These two half shells insulation 62A and 62B do not fully meet when applied on either side of the torus 60, in order to leave a space E between them. The winding 64 consists of at least one insulated winding wire or varnished. The winding wire of the winding 64 is wound around the toroidal assembly constituted by the torus 60 and the two insulation half-shells 62A and 62B, and the winding action is carried out so that the winding wire is constantly kept under a certain tension, so that when the winding is completed, the permanent tension of the winding wire generally constitutes a certain permanent force which holds the two half insulation shells 62A and 62B applied against the torus 60. It follows from this that the assembly constituted by the torus 60, the two half insulation shells 62A, 62B and the winding 64 form a one-piece assembly.

Carcass 66 may have an annular shape having a section in the general shape of a U including one branch 66A extends along the surface of the winding 64 directed towards the center and of which the other branch 66B extends along the surface of the coil 64 directed towards outside. In addition, the free ends of the two branches 66A and 66B include protuberances directed towards each other 68A and 68B, these protuberances having surfaces inclined both towards the bottom of the U-shape and outward. It follows from this only when the carcass 66 is in place, as is shown in Figure 8, it encloses, due to its elasticity, the winding 64. The winding 64 is thus applied substantially against the underside of the bottom part 66C of the U-shaped part 66, against the face internal part of branch 66A, against the internal face of the branch 66B, against the inclined surface directed towards the bottom of the U-shaped part 70A of the protrusion 68A and against the inclined surface directed towards the bottom of the U-piece 70B of protrusion 68B.

The coil toroid 30 further comprises a shield 72 which is constituted by a shielding half-shell 72A and a shielding half-shell 72B. The two half shielding shells 72A, 72B surround laterally each side of the toroidal assembly formed by the parts 60, 62, 64 and 66 so as to form a quasi-envelope continues 72 which serves as shielding.

In FIG. 9, there is a perspective view exploded the different components that make up the torus coil 30 described in connection with Figure 8. The carcass 66 is in the form of a half shell which constitutes a substantially shaped recess toric or annular which can envelop or surround the substantially toroidal external contour of the winding 64. more precisely than what has been described in relation with FIG. 8, it can be seen that the carcass 66 comprises at in addition to the axially directed legs 66A, 66B which constitute branches 66A and 66B of room 66 previously described in relation to Figure 8. The carcass 66 forms with the branches 66A, 66B a single molded plastic part.

Figure 10 shows in perspective view enlarged the carcass 66 shown in FIG. 9. On Figure 10, we see that this carcass has branches 66A, 66B facing each other, these couples branches 66A, 66B being regularly spaced on the circumference. The carcass 66 further comprises a lateral protrusion 78 which is used to support and guide the connection wires connecting the winding 64 outside. Carcass 66 can be made in one insulating plastic material having good mechanical characteristics of rigidity and elasticity. Carcass 66 can be used to both provide holding the winding 64 firmly and ensuring a connection closes with shield 72. In other words, the carcass 66 serves as a connecting piece between the assembly constituted by the torus 60, the insulation parts 62 and the winding 64 and the assembly constituted by the two half-shells 72A and 72B shielding. This carcass 66 therefore allows to fix all of these parts which together constitute what was previously called the coil toroid 30. It follows from this that the coil toroid 30 constitutes a one-piece assembly in which all of the its component parts are rigidly connected to each other to others. This monobloc assembly constituting the torus coil 30 also has the advantage of being removable. In particular we can easily disassemble the two shielding half shells 72A, 72B and the carcass 74.

This particular construction of the coil torus 30 also has the advantage of ensuring good protection of the winding 64 which constitutes the most fragile of the whole. Indeed, the carcass 74 encloses in a rigid and elastic manner the winding 64 avoiding thus any possibility of appearance of a game at the level of this winding 64, this play being detrimental because can damage the winding 64 when the assembly is subject to certain shocks or vibrations.

Figures 11 and 12 show the terminal cover connection cover which was mentioned previously. The 18 is a part which can optionally be provided on the differential protection block according to the present invention as described above. The connection cover 18 is designed to be mounted in last, that is after having already completely assembled the functional sub-assembly 16, after having tested and found to be good and after enclosing the sub-assembly functional 16 in the housing 14. More precisely, the cover 18 is intended to be fixed on the upper half-casing 14B when the two half-casings 14A and 14B are already assembled.

The connection cover 18 ensures the next function. When the two half-housings 14A, 14B are assembled, a person responsible for checking a electrical installation including among others a certain number of differential protection blocks depending on the present invention may wish to perform a test installation dielectric. To perform such test, it was necessary until now to disconnect electronic cards included in known blocks differential protection. The particular structure cover 18 according to the invention allows automatically perform such disconnection from the electronic card. Indeed, the connection cover 18 is present in the form of a plate or cover 80 which has on its face directed downwards 80A (FIG. 12) terminals or connection contacts 82. When brings the connection cover 18 to a window 84 (visible in Figure 4) formed in the half-housing higher 14B. This window is located above the electronic card 32 contained in the housing 14. In thus fixing the connection cover on the face upper half of upper case 14B, the connection cover 18 hides window 84 and simultaneously the connection contacts 82 of the connection cover 18 automatically establish connections between the electronic card 32 and the others active parts contained in the housing 14 (in especially the coil toroid, a power supply and the trip control mechanism). At the opposite, when removing the cover 18, the card electronics 32 is completely disconnected, i.e. that it is completely electrically isolated from rest of the differential protection block, and it's in this condition possible to perform the test dielectric mentioned above, without having to perform complicated disconnection or dismantling operations of the electronic card.

Claims (4)

1. A differential protection unit able to be associated to a multipole circuit breaker to constitute together a differential circuit breaker, this differential protection unit comprising :

   a case formed by a bottom half-case (14A) and a top half-case (14B) able to enclose together different active elements of the differential protection unit, these different active elements constituting at least :

   a set of connections (22) constituting electrical conduction channels (26) for the different poles of the multipole circuit breaker ;

   a toroid with a coil (30) designed to be fitted around said electrical conduction channels to detect a differential current ; and

   a tripping control mechanism (34) designed to command a tripping action in the multipole circuit breaker in response to an electrical signal produced by said toroid with coil ;

   characterized in that it comprises in addition a frame (20) on which said active elements are fixed forming together a rigid functional sub-assembly (16), said frame (20) being constituted by a first frame part (20A) made of moulded plastic material and by a second frame part (208) made of moulded plastic material able to be coupled to the first frame part,

   which results in said functional sub-assembly (16) being able to be connected to the differential circuit breaker in order to enable a functional test of the functional sub-assembly (16) to be carried out while at the same time being able to access at least some of said active elements (22, 30, 34), said functional sub-assembly (16) then being enclosed in said case (14A, 14B) when said functional test has deemed it to be functionally satisfactory.
2. The differential protection unit according to claim 1, characterized in that said first (20A) and second (20B) frame parts form together, in the coupled position :

   an enclosure (42, 44) appreciably completely surrounding a toroid with a coil (30) ;

   a partitioned passage (50) situated in the centre of the toroid with coil and designed to enable said electrical conduction channels (26) to pass through ;

   an insulating support for said electrical conduction channels (26) ; and

   a support to dispose at least said tripping control mechanism (34) externally.
3. The differential protection unit according to claim 2, characterized in that it comprises in addition at least one printed circuit board (32) able to be fitted externally on said frame in order to command operation of said tripping control mechanism (34) in response to an electrical signal produced by the toroid with coil (30).
4. The differential protection unit according to claim 3, characterized in that said top half-case (14B) comprises a window (84) situated above said printed circuit board (32) included inside and that a connection cover (18) is provided which forms a cover and which supports connection contacts (82) on its downwardly directed face (80A), which results, when the connection cover is fixed onto the upper face of the top half-case (14B), in the connection cover (18) masking the window (84) and, at the same time, the connection contacts (82) of the connection cover automatically establishing the electrical connections between the printed circuit board (32) and the other active parts contained in the case and, in the opposite case, when the connection cover (18) is removed, the printed circuit board (32) being fully disconnected thus enabling dielectric testing of the differential protection unit to be performed without any risk of damage to the printed circuit board.

Images