FR2701335A1 - Differential protection block with testable functional sub-assembly. - Google Patents

Abstract

Differential protection unit that can be combined with a multi-pole circuit breaker to together constitute a differential circuit breaker. This block comprising: a case consisting of a lower half-case (14A) and an upper half-case (14B) able to enclose together different active elements of the differential protection block, these different active elements constituting at least: a connection assembly ( 22); a coil torus; and a disjunction control mechanism (34). According to the invention, there is provided a frame on which said active elements (22, 34) are fixed, together forming a rigid functional sub-assembly (16); from which it follows that said functional sub-assembly (16) can be connected to the differential circuit breaker in order to be able to perform a functional test of the functional sub-assembly (16) while being able to access at least some of said active elements (22, 34 ).

Description

I 2701335

DIFFERENTIAL PROTECTION BLOCK

  WITH TESTABLE FUNCTIONAL SUB-ASSEMBLY

  The present invention relates generally to a differential protection block which is usually used in association with a multipole circuit breaker. Such a combination of a multipole circuit breaker and a differential protection block constitutes what is commonly called a differential circuit breaker. A conventional differential protection block generally comprises a box in which the various mechanical and electrical elements are enclosed.

  and electronics necessary for its operation.

  In such a case, it is possible, for example, to house a connection assembly constituting electrical conduction paths, a path being provided for each pole of the circuit breaker, a coil toroid intended to be mounted around said electrical conduction paths to detect a differential current. and a circuit breaker control mechanism intended to control a circuit breaker action in the multipole circuit breaker associated with said differential protection block, this control being carried out in response to an electrical signal produced in said coil toroid. In this same box, one can include in addition a number of other elements such as an electronic control card, a power supply card, etc. A major drawback of the differential protection blocks known up to now is that the differential protection block must be fully assembled and connected to the multipole circuit breaker before it can be tested. If the test reveals a malfunction, it is difficult, if not impossible , to determine the source of the malfunction, because all the active elements of the differential protection block are enclosed in the housing of the device. On the other hand, it is more and more common to use cases which are closed by means of non-removable devices, for example rivets, gluing, hot deformation, etc. In this case, the dismantling of the protective block faulty differential is impossible even for the sole purpose of identifying

the source of the malfunction.

  On the other hand, it is a common practice to carry out dielectric tests on electrical panels. These dielectric tests impose to isolate

  the electronic parts before carrying out these tests.

  In known differential circuit breakers, it is necessary either to disassemble the electronic cards contained in each differential protection block or to perform complicated operations intended for

  disconnect the electronic cards.

  An object of the present invention is to propose a differential protection block designed so as to be able to carry out tests before incorporating the active elements of said protection block.

  differential in the device housing.

  Another object of the present invention consists in proposing such a differential protection block making it possible, moreover, to be able to easily isolate the electronic parts contained in the differential protection block before carrying out dielectric tests on an electrical panel containing such

  differential protection blocks.

  The invention therefore relates in particular to a differential protection block associable with a multipole circuit breaker to constitute together a differential circuit breaker, this differential protection block comprising a connection assembly constituting electrical conduction paths for the different poles of the multipole circuit breaker, a toroid with coil intended to be mounted around said electrical conduction paths for detecting a differential current and a tripping control mechanism intended to control a tripping action in the multipole circuit breaker in response to

  an electrical signal produced by said coil torus.

  According to an essential characteristic of the invention, the differential protection block further comprises a chassis on which are fixed

  said active elements together forming a sub-

  rigid functional unit; where it follows that said functional sub-assembly can be connected to the residual current device in order to be able to carry out a functional test of the functional sub-assembly while being able to access at least some of said active elements, said functional sub-assembly then being enclosed in said housing when said functional test

  found it to be functionally satisfactory.

  According to a particular embodiment of the invention, said frame is constituted by a first piece of frame made of molded plastic and by a second piece of frame made of molded plastic.

  can be coupled to the first frame part.

  According to another particular embodiment of the invention, said first and second chassis parts together form, in the coupled position: an envelope substantially completely surrounding a coil toroid; a partitioned passage located in the center of the coil torus and intended to pass through said electrical conduction paths; an insulating support for said electrical conduction paths; and a support for externally disposing said mechanism

disjunction command.

  According to another particular embodiment of the invention, the block further comprises at least one electronic card which 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 cover is provided

  connection which forms a cover and which supports on its face directed downwards connection contacts, whence it follows that, by fixing the connection cover on

  an upper face of the upper half-housing, the cover

  connection hides the window and, simultaneously, the connection contacts of the connection cover automatically establish the electrical connections between the electronic card and the other active parts contained in the housing and, on the other hand, when the cover is removed connection, the electronic card is completely disconnected, thus making it possible to carry out a dielectric test of the differential protection block

  without risk of damaging the electronic card.

  These and other objects, features and advantages of the present invention will be better

  understood during the detailed description of examples of

  embodiment which follows, illustrated by the appended figures and among which: FIG. 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 making up the sub-

  functional 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; 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. FIG. 1 illustrates the operating principle of a differential protection block in the present invention. In this example, the differential protection block is provided for four poles For a differential protection block provided for another number of poles, for example for 2 blades 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, of measuring the sum of the electric currents which flow simultaneously in the four current paths corresponding to the four poles. Consequently, the differential protection block comprises four current paths 1, 2, 3, 4 in which pass the electric currents of the four poles, during normal operation of the device Each current path can be constituted by a metallic structure, for example made of copper, which comprises at each end an input terminal 5 and an output terminal 6 and in its central part an electrical conduction piece 7 A magnetic toroid 8 is arranged so as to simultaneously surround the four electrical conduction pieces 7 When the electrical circuit connected downstream of the differential protection block operates normally, the sum of the electric currents which flow simultaneously through the four pieces of electrical conduction 7 is at all times very substantially equal to zero If the electrical circuit has an anomaly which consists in that part of the electrical current from at least one of the poles is derived so as to pass for example to earth, the sum of the electric currents which flow simultaneously through the four electrical conduction pieces 7 is no longer equal to zero A coil 9 wound around the magnetic core 8 then shows at its connection wires 10, 11 a potential difference or a current electric when the sum of the electric currents which crosses the four electrical conduction pieces 7 is not equal to zero The connection 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 across the terminals of the coil 9 so as to send an electrical signal intended to control er a triggering of a mechanism 13 designed to cause the tripping of the multipole circuit breaker D (Figure 2) connected or coupled

  to the differential protection block.

  Such a differential protection block is well known in the prior art and it is generally in the form of an insulating housing which encloses all the parts constituting the apparatus. We can see in FIG. 3, the shapes general external of the triggering mechanism 13 mentioned above, the triggering mechanism 13 forming part of the parts included in the housing 14 of the differential protection block. FIG. 4 represents, in exploded perspective, the essential elements which constitute the differential protection block. This differential protection block is generally constituted by a functional sub-assembly 16 which includes a certain number of parts which we will describe later but which have the essential characteristic of being able to be assembled so as to form a single functional unit, that is to say a single unit capable of operating. The functional sub-assembly 16 is intended to be enclosed in the housing 14, which is constituted by a lower half-housing 14 A and an upper half-housing 14 B which are made of insulating plastic material and which are intended to come to couple so as to constitute the

  housing 14 inside which the sub-enclosure is enclosed

  functional assembly 16 The housing 14 can, when its two parts are assembled, have a generally external, substantially parallelepipedal shape The block

  differential protection further includes a cover

  connection 18 whose structure and function will

described below.

  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 is constituted so general by an insulating plastic frame 20 on which or in which are mounted and fixed a certain number of parts or active elements of the differential protection block These parts or these active elements are as follows: A first element 22 is called by the continuation "connection assembly" The connection assembly 22 is constituted by a certain 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 FIG. 1.

  Each electrical conduction channel has an input terminal 24, an electrical conduction part 26 and an output terminal 28 For the sake of simplification, a single electrical conduction channel comprises on the

  FIG. 5 the respective references 24, 26 and 28.

  Another element of the functional sub-assembly 16 is constituted by a coil toroid 30 which generally comprises a magnetic torus, a coil wound on the magnetic torus and an external envelope. This torus

  coil 30 will be described in more detail below.

  Another element of functional sub-assembly 16

  consists of an electronic card 32.

  Finally, a last element of the functional sub-assembly 16 is constituted by a mechanism

actuation 34.

  The functional sub-assembly 16 is constituted by a chassis 20 in and around which are respectively fixed the connection assembly 22, the coil toroid 30, the electronic card 32 and the trigger mechanism 34 More precisely, the coil torus 30 is arranged inside the chassis 20 and the other elements 22, 32 and 34 are mounted outside the chassis 20 It is understood that an essential difference compared to the differential protection block of the prior art lies in the fact that, according to the invention, the differential protection block is constituted by a functional sub-assembly which, as its name indicates, comprises all the elements essential for

  operation, and a housing 14 which encloses the sub-

functional unit 16.

  In contrast, in differential protection blocks known to date, the various functional elements are fixed and housed inside a housing, this housing being produced for example in two parts so as to constitute a cavity internal

  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 therein can function properly. Consequently, in the differential protection blocks of the prior art, it is not possible to test the operation of the device taken as a whole before the case is closed, which is annoying because, when the case is closed, it is not possible to detect the cause of a failure observed in the

  differential protection block operation.

  One of the essential parts of the differential protection block 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 is constituted by two independent chassis parts 20 A and 20 B which have a certain mirror symmetry with respect to each other and which are intended to mate with one another The two chassis parts 20 A and 20 B are each made in one piece from molded plastic electrically insulating The chassis part 20 A is very generally in the form of a vertical wall 36 and the chassis part 20 B is 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 20 A and 20 B are coupled on the side of the wall 36 which is directed towards the chassis part 20 B and on the side of the wall 38 which is directed towards the chassis part 20 A, are respectively disposed envelope walls 42, 44 (only the walls of the part 20 B are visible in the figure ) which extend perpendicular to the respective vertical wall 36 or 38 On the frame piece B, we can see in more detail all the walls 42 and 44, although similar walls are provided on the frame piece 20 A The wall 42 constitutes a substantially cylindrical external envelope and the wall 44 constitutes a substantially cylindrical internal envelope Consequently, the space separating the external wall 42 and the internal wall 44 is a substantially annular space which constitutes a housing for the coil toroid 30 A similar annular space is provided in the same way on the chassis part 20 A although it is not visible in FIG. 6 When the parts 20 A and 20 B are coupled together. 'other, the two annular housings form only an annular housing whose overall width is slightly greater than the width of the coil toroid 30 It results

  that to start assembling or mounting the sub

  functional assembly 16, we start by housing the coil toroid 30 in the annular housing limited by the walls 42 and 44, then we couple the two chassis parts 20 A and 20 B so as to completely enclose the

coil toroid 30.

  The frame 20 then takes the form which is shown in FIG. 7 The part which is at the center of the annular wall 44 is hollowed out and forms a transverse passage More precisely, this central hollowed out part comprises four partition walls 46 which are 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 central hollowed-out part In this way, the four pieces of electrical conduction 26 (FIG. 5) can pass right through share respectively the four passages 50 which are separated from each other by the four partition walls 46 Of course, symmetrical similar shapes to the shapes of the elements 42, 44, 46 and 50 are provided on the chassis part 20 A (these shapes 20 A

  not visible in Figure 6).

  After having housed the coil toroid 30 between the cylindrical walls 42 and 44 and after having coupled the two chassis parts 20 A and 20 B, the connection assembly 22 is mounted on the chassis 20. four electrical conduction paths (24, 26, 28) on the chassis 20 The mounting of an electrical conduction path is carried out as follows: An electrical conduction piece 26 is fixed radially at one end 52 ( see Figure 5) of the input terminal 24, then the assembly consisting of the elements 24, 26 and 52 is mounted on the chassis part 20 A so that the electrical conduction part 26 passes right through it one of the housings 50 and that the input terminal 24 is positioned against suitable positioning surfaces provided on the outside of the vertical wall 36 of the chassis part 20 A Next, the output terminal 28 and its extension 54 on the p chassis part 20 B so that the output terminal 28 is positioned against suitable positioning surfaces provided on the outside of the vertical wall 38 of the chassis part 20 B Finally, the end is mechanically and electrically connected 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 by

  so as to constitute an electrical conduction path.

  This electrical conduction path therefore crosses right through the passage 50 which is at the center of the coil toroid 30 housed inside the chassis. We then proceed in a similar manner to mount the other three electrical conduction paths. that each of them passes into one of the three

other passages 50.

  Then, the electronic card 32 is mounted on the chassis 20. This electronic card 32 can be positioned above the chassis 20 by snapping onto snap-fastening means and

  appropriate positioning 56 (see figure 7).

  Next, the disjunction control mechanism 34 (visible in FIG. 5) is mounted on the chassis which includes positioning surfaces and

  appropriate latching 58 (see Figure 7).

  Finally, the necessary electrical connections are made between the coil toroid 30, the electronic card 32 and the circuit breaker control mechanism 34 (these electrical connections not being

shown in the drawings).

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

  functional assembly 16 the lower half-housing 14 A and the upper half-housing 14 B (see FIG. 4) When the two half-housings 14 A and 14 B are thus arranged on the functional sub-assembly 16 and are coupled one to the other, the two half-housings 14 A and 14 B form an external envelope which encloses practically completely

the functional sub-assembly 16.

  This assembly can be completed by adding on the upper half-housing 14 B a connection cover 18 whose structure and construction will be explained later. A differential protection block according to the present invention is then completely assembled, and this block earth leakage protection which test found to be working properly can then be disconnected from the multipole circuit breaker and the electrical test circuit to be stored as a block of

  differential protection good for marketing.

  If the functional test reveals that the functional sub-assembly 16 has a certain malfunction, it can be carried out, depending on the type of malfunction

  revealed, the following two actions.

  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 set 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 by another element

  new We then redo a functional test of the

  functional assembly 16 and, if it then reveals that the repaired functional sub-assembly 16 is functioning correctly, the mounting of the differential protection block can be completed by adapting the housing 14 and the connection cover 18 Then store, as before, this differential protection block as a differential protection block suitable for marketing. The coil toroid 30 as shown in the

  FIG. 5 constitutes a sub-assembly which presents in itself

  even certain characteristics which will now be described The coil toroid 30 has a general external shape of a torus, as can be seen in FIG. 5, to which is added laterally a protruding part 58 which allows the passage of the lead wires of the toroid coil so that these output wires can be connected to the electronic card 32 As can be seen in FIG. 8, this sub-assembly forming the coil toroid 30 has a specific structure which is very particularly advantageous in the part of its use in the functional sub-assembly 16 according to the present invention The coil toroid 30 is constituted, as shown in FIG. 8, by a torus made of magnetic material 60, by two half-shells of insulation 62 A, 62 B which laterally surround the torus 60 on each side, by a coil 64 which is wound around the two half shells 62 A, 62 B, by a carcass 66 (described below ) which is mounted on the winding 64 and by two half shells of external envelope 68 A and 68 B The two insulation half shells 62 A and 62 B serve to create a thin electrically insulating envelope around the torus 60 These two half shells of insulation 62 A and 62 B do not completely meet when they are applied on either side of the torus, in order to leave a space E between them The winding 64 is constituted by at least one insulated winding wire or varnished The winding wire of the winding 64 is wound around the O-ring assembly constituted by the torus 60 and the two half-shells of insulation 62 A and 62 B, 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 keeps the two half-shells of insulation 62 A and 62 B applied against e the torus 60 It follows from this that the assembly constituted by the torus 60, the two half insulation shells 62 A, 62 B and the coil 64 form

a one-piece assembly.

  The carcass 66 may have an annular shape having a section in the general shape of a U, one branch 66 A of which extends along the surface of the winding 64 directed towards the center and of which the other branch 66 B extends along the surface of the winding 64 directed towards the outside In addition, the free ends of the two branches 66 A and 66 B include protuberances directed towards one another 68 A and 68 B, these protuberances having inclined surfaces both towards the bottom of the U-shape and towards the outside It follows from this that when the carcass 66 is in place, as shown in FIG. 8, it encloses, due to its elasticity, the winding 64 The winding 64 is thus substantially applied against the underside of the bottom part 66 C of the U-shaped part 66, against the internal face of the branch 66 A, against the internal face of the branch 66 B, against the inclined directed surface towards the bottom of the U-piece 70 A of the protrusion 68 A and against the inclined surface directed towards the bottom of the U-shaped part 70 B of the protuberance 68 B. The coil toroid 30 further comprises a shield 72 which is constituted by a shield half-shell 72 A and a shielding half-shell 72 B The two shielding half-shells 72 A, 72 B laterally surround each side of the O-ring assembly formed by the parts, 62, 64 and 66 so as to form a quasi-envelope

continues 72 which serves as shielding.

  In FIG. 9, there is an exploded perspective view of the various components which constitute the coil toroid 30 described in relation to FIG. 8 The carcass 66 is in the form of a half-shell which constitutes a recess of substantially toric shape or annular being able to wrap or surround the substantially toroidal external contour of the winding 64 More precisely than what has been described in relation to FIG. 8, it can be seen that the carcass 66 further comprises axially directed lugs 66 A, 66 B which constitute the branches 66 A and 66 B of the part 66 described previously in relation to FIG. 8 The carcass 66 forms with the branches 66 A, 66 B a single

  molded plastic part.

  Figure 10 shows in enlarged perspective view the carcass 66 shown in Figure 9 In Figure 10, we see that this carcass has branches 66 A, 66 B facing each other, these pairs of branches 66 A , 66 B being regularly spaced around the circumference The carcass 66 further comprises a side protrusion 78 which serves to support and guide the connection wires connecting the winding 64 to the outside The carcass 66 can be made of a plastic material insulating with good

  mechanical characteristics of rigidity and elasticity.

  The carcass 66 can serve both to ensure a firm hold of the winding 64 and to ensure a firm connection with the shielding 72 In other words, the carcass 66 serves as a connecting piece between the assembly constituted by the torus 60, the insulation pieces 62 and the

  winding 64 and the assembly consisting of the two half

  shielding shells 72 A and 72 B This carcass 66 therefore makes it possible to fix the assembly of all these parts which together constitute what has previously been called the coil toroid 30 It follows from this that the coil torus constitutes an assembly monobloc in which all the parts which compose it are rigidly connected to each other This monobloc assembly constituting the coil toroid 30 also has the advantage of being removable. In particular, the two shielding half shells 72 A can be easily dismantled, 72 B and the

carcass 74.

  This particular construction of the coil toroid also has the advantage of ensuring good protection of the coil 64 which constitutes the most fragile part of the assembly. Indeed, the carcass 74 encloses the coil 64 in a rigid and elastic manner. thus avoiding any possibility of the appearance of a play at this winding 64, this play being detrimental because it can damage the winding 64 when the assembly is

  subject to certain shocks or vibrations.

  Figures 11 and 12 illustrate the cover

  connection which was mentioned previously The cover

  connection 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 last, that is to say after having already completely assembled the functional sub-assembly 16, after having tested it and deemed good and after having closed the functional sub-assembly 16 in the housing 14 More specifically, the concealment 18 is intended to be fixed on the upper half-housing 14 B when the two half-housings

  14 A and 14 B are already assembled.

  The connection cover 18 ensures the following function When the two half-boxes 14 A, 14 B are assembled, a person responsible for checking an electrical installation including, among other things, a certain number of differential protection blocks according to the present invention can wish to carry out a dielectric test of the installation To carry out such a test, it has hitherto been necessary to disconnect the electronic cards included in the known blocks of differential protection. The particular structure of the connection cover 18 according to the invention makes it possible to automatically carry out such a disconnection of the electronic card. Indeed, the connection cover 18 is in the form of a plate or a cover 80 which has on its face directed downwards 80 A (FIG. 12) terminals or connection contacts 82 When the connection cover 18 is brought to a window 84 (visible in FIG. 4) formed in the half-housing er superior 14 B This window is located above the electronic card 32 contained in the box 14 By thus fixing the connection cover on the face

  upper half of upper case 14 B, cover

  connection 18 hides the window 84 and, simultaneously, the connection contacts 82 of the connection cover 18 automatically establish the electrical connections between the electronic card 32 and the other active parts contained in the housing 14 (in particular the coil toroid, a power supply and the circuit breaker control mechanism) Conversely, when removing the connection cover 18, the card

  electronic 32 is completely disconnected, i.e.

  say that it is completely electrically isolated from the rest of the differential protection block, and it is in this condition possible to carry out the dielectric test mentioned previously, without having to carry out complicated operations of disconnection or disassembly

of the electronic card.

Claims (4)

  1 differential protection block associable with a multipole circuit breaker to constitute together a differential circuit breaker, this differential protection block comprising: a housing constituted by a lower half-housing (14 A) and an upper half-housing (14 B) capable of enclosing together different active elements of the differential protection block, these different active elements constituting at least: an assembly of connections (22) constituting electrical conduction paths (26) for the different poles of the multipole circuit breaker; a coil toroid (30) intended to be mounted around said electrical conduction paths for detecting a differential current; and a trip control mechanism (34) for controlling a trip action in the multipole circuit breaker in response to an electrical signal produced by said coil toroid; Characterized in that it further comprises a chassis (20) on which said active elements are fixed by forming together a rigid functional sub-assembly (16); from which it follows that said functional sub-assembly (16) can be connected to the residual current device in order to be able to carry out a functional test of the functional sub-assembly (16) while being able to access at least some of said active elements (22, 30 , 34), said functional sub-assembly (16) then being enclosed in said housing (14 A, 14 B) when said functional test   found it to be functionally satisfactory.   2 differential protection block according to claim 1, characterized in that said chassis (20) is constituted by a first chassis part (20 A) in molded plastic and by a second chassis part (20 B) in molded plastic connectable to the first frame part.   3 differential protection block according to claim 2, characterized in that said first (20 A) and second (20 B) chassis parts form together, in the coupled position: an envelope (42, 44) substantially completely surrounding a coil toroid ( 30); a partitioned passage (50) located in the center of the coil torus and intended to pass through said electrical conduction paths (26); an insulating support for said electrical conduction paths (26); and a support to dispose externally at least   said disjunction control mechanism (34).   4 differential protection block according to claim 3, characterized in that it further comprises at least one electronic card (32) which can be mounted externally on said chassis in order to control the operation of said disjunction control mechanism (34) in response to an electrical signal   produced by the coil toroid (30).   Differential protection block according to claim 4, characterized in that said half-housing   upper (14 B) includes a window (84) located above   above said electronic card (32) included at   the interior and that there is a cover   connection (18) which forms a cover and which supports on its downward facing face (80 A) connection contacts (82), whence it follows that, by fixing the   terminal cover on an upper side of the half   upper case (14 B), the connection cover (18) hides the window (84) and, simultaneously, the connection contacts (82) of the cover automatically establish the electrical connections between the electronic card (32) and the other parts active contained in the housing and, conversely, when removing the 21 -   cover (18), the electronic card (32) is completely disconnected, thus making it possible to carry out a dielectric test of the differential protection block   without risk of damaging the electronic card.