EP0456583B1 - Homopolar transformer for differential switches or circuit breakers, and mounting method - Google Patents

Abstract

A homopolar transformer (10) includes a cylindrical magnetic circuit (11) housed in an insulating envelope (18) formed by assembling two half-castings (20, 22). The external wall (32) of each half-casting (20, 22) includes first and second breakable flaps (40, 42) able to be in a non-broken state allowing automatic snap-fitting of the abutting half-castings (20, 22), and in a broken state revealing two diametrically opposed windows (70, 72) in the envelope (18), the distance d between the windows (70, 72) corresponding substantially to the outer diameter of the magnetic circuit (11). Applications: differential circuit breakers and switches. <IMAGE>

Description

The invention relates to a differential transformer, comprising a magnetic circuit of cylindrical or toric shape, housed in an envelope of molded insulating material constituted by the end-to-end assembly of two conjugate half-shells, and primary phase windings and of neutral wound on the envelope, each half-shell of which encloses an annular space delimited by a tubular internal sheath traversed by said windings. Such a transformer is known from document FR-A-2 147 816.

The two half-shells of the insulating protective covering of the magnetic circuit are generally assembled by means of adhesive tape or glue. Such an assembly requires a specific bonding operation which complicates manufacturing. The primary phase and neutral windings, as well as the secondary measurement winding are then wound on the envelope so as to surround the magnetic circuit. The zero sequence transformer or totalizer is then ready for housing in the housing of the differential device. The axis of the zero sequence transformer can be positioned longitudinally in a direction parallel to the large lateral faces (EP-A 275750 and 264314), or transversely in a perpendicular direction (FR-A 2.627.324). In the first case, the longitudinal positioning of the transformer requires a fairly large space across the width of the housing. In the second flush, the transformer is generally housed in a corner of the housing, which prevents the presence of cells for housing the neutral terminals at this location.

A first object of the invention consists in perfecting the production of a zero sequence transformer for a differential device.

The zero sequence transformer according to the invention is characterized in that the outer wall of each half-shell has first and second breakable flaps, which may be in an unbroken state allowing automatic snap-in of the abutment half-shells, and in a broken state showing two diametrically opposite windows in the envelope, the distance d between the windows corresponding substantially to the outside diameter of the magnetic circuit.

It is then possible to arrange the transformer longitudinally in the central zone of the housing while respecting the standard width of 18 mm. The neutral connection side can be made either downstream or upstream.

The external wall of each half-shell is equipped with first and second diametrically opposite circular sectors joined together by said breakable flaps, each flap being connected to the wall by a breakable mechanical connection coming from molding with the half - corresponding shell.

The presence of the flaps protects the magnetic circuit during transport and handling, and on the other hand prevents post-molding deformations of the half-shells.

The half-shells are assembled by snap-fastening, avoiding the disadvantages of applying adhesive tape or bonding. Coding pins are provided to impose a correct assembly of the half-shells.

The protection of the magnetic circuit is completed by the insertion of a pair of damping buffers between the bottom of each half-shell, and the corresponding front face of the magnetic circuit.

A second object of the invention relates to the method of mounting the transformer in a housing of a differential device. The shutters are removed after the coils have been wound. primary windings on the envelope, and just before mounting the transformer in the housing, the appearance of windows allowing the longitudinal positioning of the magnetic circuit in the space between two large parallel walls of the housing.

• la figure 1 est une vue éclatée en perspective du transformateur homopolaire sans les enroulements primaires et secondaires.
• la figure 2 montre une vue en perspective du transformateur en position assemblée après bobinage des enroulements;
• les figures 3 et 4 sont des vues de profil de la figure 2;
• la figure 5 est une vue similaire de la figure 2, montrant la phase d'enlèvement des volets brisables;
• la figure 6 est une vue similaire de la figure 2 après enlèvement des volets;
• la figure 7 représente une vue en coupe transversale du bloc déclencheur différentiel après mise en place du transformateur;
• les figures 8 et 9 sont deux coupes longitudinales de la figure 7 avec bornes de neutre à gauche ou à droite.

Other advantages and characteristics will emerge more clearly from the description which follows of an embodiment of the invention given by way of nonlimiting example, and represented in the appended drawings, in which:

• Figure 1 is an exploded perspective view of the zero sequence transformer without the primary and secondary windings.
• Figure 2 shows a perspective view of the transformer in the assembled position after winding of the windings;
• Figures 3 and 4 are side views of Figure 2;
• Figure 5 is a similar view to Figure 2, showing the phase of removal of breakable flaps;
• Figure 6 is a similar view of Figure 2 after removal of the flaps;
• Figure 7 shows a cross-sectional view of the differential trip unit after installation of the transformer;
• Figures 8 and 9 are two longitudinal sections of Figure 7 with neutral terminals on the left or right.

In the figures is shown a zero sequence transformer 10 having a magnetic circuit 11, on which are wound primary windings 12, 14 of phase and neutral, and a secondary measurement winding (not shown) electrically connected to a control relay 13 of a mechanism 15 of trigger. Such a zero sequence transformer 10 can be used in a differential switch, or in a differential trip unit 16, (fig. 7) adaptable to a circuit breaker unit. The mechanism 15 is of the type described in document FR-A 2,628,262.

The magnetic circuit 11 of the zero sequence transformer 10 has a cylindrical shape, obtained either by winding a ferromagnetic sheet, or by sintering a pulverulent material based on ferrite. The magnetic circuit 11 is surrounded by an insulating envelope 18 constituted by the assembly of two half-shells 20, 22 of conjugate shapes. A pair of damping pads 24,26 shaped as washers of spongy material, in particular foam-based, is interposed between the opposite front faces of the magnetic circuit 11 and the respective bottoms of half-shells 20,22 (fig. 1) .

Each half-shell 20, 22 has an annular space 28, delimited by a tubular internal sheath 30 traversed by the primary windings 12, 14, and by an external wall 32 furnished by a plurality of grooves 34 for receiving the turns constituting said windings 12 , 14. The outer wall 32 is formed by two diametrically opposed circular sectors 36, 38, joined together by a pair of breakable flaps 40, 42 capable of closing off two semi-rectangular openings 48, 50 delimited by two opposite flat bases, 52, 54 extending parallel to each other.

Each flap 40,42 comes from molding with the half-shells 20,22 and is connected to the wall 32 by a breakable mechanical connection 56, comprising a tab with a narrowed section at the fixing points. The central part of the link 56 is equipped with a retaining spout 58 and an adjacent hooking flange 60.

The end face of the abutment of the first half-shell 20 includes coding pins 62 at the level of the sector 36, and orifices 64 for positioning at sector 38. Conversely, the end face of abutment of the second half-shell 22 is provided with coding pins 62 on sector 38, and orifices 64 on sector 36.

The mounting and implementation of the zero sequence transformer 10 is carried out as follows:

In FIG. 1, the bringing together of the two half-shells 20, 22 along the axial direction xx ′ causes the insertion of the magnetic circuit 11 into the coaxial annular spaces 28 of the envelope 18.

The abutment of the two half-shells 20,22 is authorized after introduction of the coding pins 62 in the orifices 64 conjugate. The final assembly of the casing 18 is carried out by snap-fastening of the four spouts 58 on the corresponding hooking flanges 60. The presence of the flaps 40, 42 completely closes the insulating envelope 18 and provides effective protection of the magnetic circuit 11 during transport, handling, and the winding phase of the primary windings 12, 14. The flaps 40, 42 also play the role of conformers of the envelope 18, thereby avoiding post-molding deformations.

After winding of the primary windings 12,14 on the envelope 18 (fig. 2 to 4), it suffices to break the connections 56 of the four flaps 40,42 (fig. 5), so as to reveal two windows 70,72 rectangular from the abutment of the 48.50 conjugate openings (fig. 6). The distance d (fig. 3) between the bases 52, 54 of the two opposite windows 70, 72 corresponds substantially to the outside diameter of the magnetic circuit 11. The snap disappears, but the primary windings 12, 14 ensure the maintenance of the two shells 20 , 22 in the close position.

The zero sequence transformer 10 according to FIG. 6 can then be housed in the housing 73 of the differential trip unit 16 (fig. 7 to 9). The windows 70, 72 make it possible to adapt the diameter of the magnetic circuit 11 to the space between the two walls 74, 76, despite the fact that the diameter of the external wall 32 of the casing 18 is greater than the width of the trigger block 16 The presence of the two windows 70, 72 allows the transformer 10 to be housed in a standard 18 mm box 73.

The magnetic circuit 11 can also have a toroidal shape.

Note the longitudinal arrangement of the zero sequence transformer 10 extending in the central area of the housing 73 in a direction parallel to the large side walls 74,76. The housing 73 has cells 80, 82 allowing the presence of neutral terminals 84 on the left (fig. 8) or on the right (fig. 9) depending on the type of electrical installation.

Claims (8)

1. A homopolar transformer for a differential switch or circuit breaker, comprising a magnetic circuit (11) of cylindrical or toroidal shape, housed in an enclosure (18) made of moulded insulating material formed by end-to-end assembly of two conjugate half-shells (20, 22), and phase and neutral primary windings (12, 14) wound onto the enclosure (18), each half-shell (20, 22) of which encloses an annular space (28) bounded by a tubular internal sheath (30) through which said windings pass, characterized in that the external wall (32) of each half-shell (20, 22) comprises first and second breakable flaps (40, 42), designed to be in an unbroken state enabling the abutted half-shells (20, 22) to be automatically clipped together, and in a broken state making two diametrically opposite windows (70, 72) appear in the enclosure (18), the distance d between the windows (70, 72) corresponding appreciably to the external diameter of the magnetic circuit (11).
2. The homopolar transformer according to claim 1, characterized in that the wall of each half-shell (20, 22) is equipped with a first and a second diametrically opposite circular sector (36, 38) joined together by said breakable flaps (40, 42), each flap being joined to the wall (32) by a breakable mechanical link (56) cast with the corresponding half-shell (20, 22).
3. The homopolar transformer according to claim 2, characterized in that the mechanical link (56) of each flap (40, 42) is equipped with a retaining nose (58) and an adjacent latching edge (60), enabling automatic clipping together of the two half-shells (20, 22).
4. The homopolar transformer according to claim 2 or 3, characterized in that the front abutment face of one of the half-shells (20) is provided with error prevention pins on the first sector (36), and positioning orifices (64) on the second sector (38), and that the conjugate front face of the other half-shell (22) comprises error prevention pins on the second sector (38), and positioning orifices (64) on the second sector (36).
5. The homopolar transformer according to one of the claims 1 to 4, characterized in that a damping pad (24, 26) is inserted between the magnetic circuit (11) and the base of each half-shell (20, 22).
6. The homopolar transformer according to one of the claims 2 to 5, characterized in that the cylindrical lateral surface of the insulating enclosure (18) comprises a plurality of grooves (34) receiving the primary windings (12, 14).
7. The assembly process of a case of a homopolar transformer according to one of the claims 1 to 6, characterized in that removal of the flaps (40, 42) is performed after the primary windings (12, 14) have been wound onto the enclosure (18), and just before the transformer (10) is fitted in the case (73), the appearance of the windows (70, 72) enabling the magnetic circuit (11) to be positioned longitudinally in the space between two large parallel walls (74, 76) of the case (73).
8. The assembly process according to claim 7, characterized in that the bases (52, 54) bounding the two windows (70, 72) of the enclosure (18) come into engagement against the two walls (74, 76) to perform wedging of the transformer (10) in the centre zone of the case (73).

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