Title of Invention

A DIFFERENTIAL UNIT COMPRISING A DEVICE FOR ELECTRICAL CONNECTION

Abstract

The present invention relates to a differential unit comprising a device for electrical connection of a differential unit onto a circuit breaker or similar and a differential unit equipped with such a device. This connection device comprises a certain number of conductors (6 to 9,19) each electrically connected via one of their ends to the output terminals of the differential unit after passing through the toroid (5) of the differential unit, said conductors being designed to be electrically connected each by their opposite end to one of the output terminals of the circuit breaker. This device is characterized in that at least one of the above-mentioned conductors (6 to 9, 11) is a rigid conductor with a solid core, said conductor presenting a first end (19a) designed to be electrically connected in the corresponding terminal of the circuit breaker and a second end (19b) welded at the end onto a contact strip (26 to 29) mechanically or electrically connected t 0 the corresponding output terminal of the differential unit (B) FIG 1

Full Text

The present invention relates to a device for electrical connection of a differential unit to a circuit breaker or similar, comprising a certain number of conductors designed to electrically connect the output terminals of the circuit breaker to the output terminals of the differential unit, said conductors passing through the toroid. Several solutions have been envisaged to make this connection. One of the solutions consists in using sheathed flexible braids each connecting one of the output terminals of the differential unit to one of the terminals of the circuit breaker by means of a semi-rigid conductor in the form of a crank made of enameled wires passing through the toroid, the braids and conductors being connected to the upper part of the toroid. The semi-rigid conductors, however, due to their crank shape, are particularly cumbersome and require a certain volume to be set aside for them to enable them to be handled. In addition, the diameter of the enameled wires constituting said conductor is in general limited to 4.5 mm, since increasing this diameter would lead to considerably increasing the size of the toroid. Another solution consists, to achieve this connection of a differential unit of high rating to a circuit breaker, in providing sheathed braids of large cross section directly connecting the output terminals of the circuit breaker to those of the differential unit, after passing through the toroid. However, in this solution, a toroid window of enlarged dimension has to be provided. Another solution consists in providing foil sheets extending underneath the circuit breaker and connecting the circuit breaker to the differential unit by means of sheathed braids passing through the toroid and joined to the foil sheets above the toroid. The drawback of this solution, however, lies in the fact that a large space is required underneath the circuit breaker. In addition, in all these solutions, the connection device considerably encumbers the upper part of the unit situated above the toroid. And finally a last solution is known in which each of the terminals of the differential unit and of the circuit breaker are directly connected by a semi-rigid cable passing through the toroid and one of whose ends is curved then flattened so as to be welded flat onto a strip associated to one of the terminals of the differential unit. This solution results in a large space being required at the level of the connection zone to the terminals of the differential unit. This solution, reserved for small ratings, cannot be extended to high ratings, since this would lead to an even larger space requirement at the level of this zone. SUMMARY OF THE INVENTION The present invention overcomes these problems and proposes a connection device for connecting a differential unit to a circuit breaker, and a differential unit comprising this device, enabling a differential unit of high rating to be achieved in a small space, and also a process for implementation of this device. For this purpose, the object of the present invention is to achieve a device of the kind previously mentioned, this device being characterized in that at least one of the above-mentioned conductors is a rigid conductor with a solid core, said conductor presenting a first end designed to be electrically connected to the corresponding terminal of the circuit breaker and a second end welded at the end onto a contact strip mechanically and electrically connected to the corresponding output terminal of the differential unit. According to a particular embodiment, the above-mentioned conductor(s) is (are) welded at the end onto one, called first, of the ends of an (respectively several) intermediate conductor(s) passing through the toroid whose second end is electrically and mechanically connected to the corresponding strip. According to a particular feature, the intermediate conductor(s) is (are) welded at the end onto the strip(s). According to an alternative embodiment, the second end of the intermediate conductor(s) is in a single part with the strip(s). Advantageously, the above-mentioned conductor(s) and/or intermediate conductors is (are) single-strand. Advantageously, the above-mentioned conductor(s) and/or intermediate conductors is (are) made of copper. According to a particular feature, the above-mentioned conductor(s) and/or intermediate conductors present(s) a circular cross section. According to another particular feature, the conductors and/or intermediate conductors are shaped in such a way that the cross section of all the conductors together is appreciably circular, in order to minimize the space occupied thereby inside the toroid. According to a particular embodiment, the apparatuses being of the two-pole type, the conductors and intermediate conductors if applicable are two in number and both present a semi-circular cross section. According to another embodiment, the apparatuses being of the four-pole type, the conductors and intermediate conductors if applicable are four in number, each of the conductors presenting a cross section in the shape of a quarter-circle. Advantageously, from the moment they enter the toroid, the conductors or intermediate conductors extend in straight manner up to the strips. Advantageously, the second end of the conductor(s) and/or intermediate conductors is brazed-welded to the corresponding strip(s). Advantageously between their two ends, the conductor(s) or intermediate conductor(s) is (are) folded four times at right angles. Advantageously, the above-mentioned conductors) and/or intermediate conductors) is (are) covered with an insulating coating of epoxy type. The object of the invention is also a process for implementing a device as previously described, consisting in threading the toroid around the second end(s) of the conductor(s), and then in sliding said toroid along said conductors in a direction opposite to said ends, and then in performing welding at the end of said ends onto the strips. The object of the invention is also to achieve a differential unit equipped with a device comprising the above-mentioned features taken alone or in combination. According to a particular feature, the differential unit comprising a tripping finger extending protruding out from the face of said unit designed to be adjoined to the circuit breaker, it comprises in addition a protection finger extending appreciably parallel to said tripping finger over a slightly greater length than that of said finger and designed to absorb the shocks instead of the tripping finger. BRIEF DESCRIPTION OF THE DRAWINGS But other advantages and features of the invention will become more clearly apparent from the following detailed description which refers to the accompanying drawings given for example purposes only and in which : - Figure 1 is an exploded perspective view illustrating a differential unit equipped with a connection device according to the invention, - Figure 2 is a perspective view of said unit on which auxiliaries are ready to be fitted, - Figures 3 and 3a are two perspective views illustrating the differential unit and more particularly its upper face designed to receive the auxiliaries, respectively before and after fixing of the auxiliaries, - Figure 4 is a cross sectional view, illustrating the welding process of the cables onto the strips, and - Figure 5 illustrates in perspective view another embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In figure 1, a differential unit B can be seen designed to be associated to a circuit breaker (not represented) by means of a connection device E according to the invention, for protection of an electrical installation supplied by the electrical power system, said unit having the function of performing detection of earth fault currents. The mechanism M of the differential unit B is designed to be housed in a case comprising a base 1 and a front panel 2 and able to receive one or more auxiliaries 3, 4 as will be explained further on. It mainly comprises a differential current transformer T constituted by a toroid 5, primary conductors 6 to 9, formed by the active conductors of the installation and secondary windings (not represented) at whose terminals a differential fault signal is established when a fault occurs in the primary conductors. This secondary winding is connected to a tripping means such as a high sensitivity relay (not represented), said relay performing tripping by activating a tripping finger 10 (fig.2) situated on a side face of the unit, when the secondary signal exceeds a preset threshold. This tripping finger 10 is mechanically connected to the circuit breaker tripping mechanism in the associated position of the two apparatuses, so as to bring about tripping of the lock of a switchgear apparatus protecting the circuit when this secondary signal exceeds a preset threshold. This differential unit B is of the four-pole type and comprises at its bottom part four terminals 11 to 14 electrically connected to the active conductors 6 to 9 of the installation, which are connected to the four terminals belonging to the circuit breaker and situated at the bottom part of its case, by means of a connection device E according to the invention. This device E comprises, for each of the terminals 11 to 14 of the unit, a rigid copper conductor 19 presenting a diameter of 6 mm, said conductor 19 being folded four times appreciably at right angles. This conductor 19 comprises at one 19a of its ends a flat 20 able to be fixed into one of the terminals of the circuit breaker, and is designed to be electrically connected via its other end 19b to one of the terminals 11 to 14 of the differential unit. It can be seen in particular in figure 1 that each conductor 19 comprises a first connection part a extending parallel to the side faces 21 of the cases, a second part b perpendicular to the first extending parallel to the bottom face 22 of the cases and to the rail, a third part c extending appreciably perpendicularly to the second b along the toroid 5 appreciably parallel to the side faces 21 of the unit, a fourth part d appreciably perpendicular to the third c and extending parallel to the upper part 24, 25 of the differential unit and of the toroid 5, and a fifth part e appreciably perpendicular to the fourth d, and passing through the toroid 5 to be fixed by brazewelding at its free end to a connection strip 26 to 29 of the corresponding terminal of the unit. Due to the fact that these conductors 6 to 9 are welded at the end to the corresponding strips 26 to 29, the space taken up at the level of connection to the output terminals 11 to 14 of the differential unit B is reduced, which makes it possible to use rigid conductors of large diameter and therefore to achieve a differential unit of high rating, enabling a range of system-powered differential units to be obtained of all sensitivities including 30 mA. It can be noted that the strips are advantageously made of tinned copper. This reduced size of the mechanism, on the one hand at the level of the connection zone, and on the other hand around and in particular above the toroid, as the conductors 19 follow the outline of the toroid 5 exactly, enables the differential unit case to receive auxiliaries 3, 4 plugged into housings 34, 35 provided on each side of the toroid 5 in the upper face 24 of the differential unit, opposite the one 22 comprising the terminals 11 to 14 as is represented in figures 2, 3 and 3a. These auxiliaries 3, 4 are fixed to the case B by clipping and can perform several functions i.e. for example differential fault signal, remote opening, leakage current indication. These auxiliaries 3, 4 are fitted simply by a translation movement (fig. 3a) after the blanking covers 30, 31 have been removed by a rotational movement with a screwdriver. At the end of the movement, a click and passage of a hangup point tell the user that the accessory is correctly assembled (fig. 3a). For disassembly without tools, the auxiliaries simply have to be pulled out of their housing and the clip-on blanking covers 30, 31 put back in place if required. It can be seen in figure 2 that the tripping finger 10 protrudes out perpendicularly from the adjoining face 21 of the differential unit, which makes it exposed to impacts which may be caused for example by a fall. These impacts in the direction of the tripping finger 10 may result in malfunctioning of said finger 10 and therefore prevent normal operation of the mechanism. In the embodiments of differential units B according to the invention, due to the use of rigid cables 19, the apparatuses are relatively heavy and association of two apparatuses is achieved in most cases automatically. This has the result that when the association is performed or in the case of a fall or a shock, the tripping ftnger is even more exposed to receive shocks of large intensity. In order to overcome this shortcoming, the differential unit B comprises on its adjoining face 21 adjoined to the circuit breaker, a protection finger 32 extending parallel to the tripping finger 10 near to the latter, and designed to absorb the shocks exerted in the direction of the tripping finger 10. The welding process of the conductors 6, 8 onto the strips 26 to 29, as illustrated in figure 4, is the following : The toroid 5 is first of all moved in translation according to the arrow A. Then, with the gripping contacts 33 keeping the connections secure, an electrode 34 is moved in the direction of the strips 26, 29 and applied on the face f of the strips opposite the toroid 5, so as to perform brazewelding of the end of the conductor onto the copper strip in the Y axis of the toroid 5. The use of a phosphorous brazing burner improves the welding efficiency (better resistance to tear). According to the embodiment illustrated in figure 5, the above-mentioned conductor(s) is (are) welded at the end onto one 36a, called first, of the ends of an (respectively several) intermediate conductors) passing through the toroid (T) whose second end 36b is electrically and mechanically connected to the corresponding strip 26 to 29. This embodiment, in addition to the advantages already described in the previously described embodiment, enables the space required above the toroid to be even further reduced. The implementation process of the corresponding device is the following. The toroid is fitted around the intermediate conductor(s) 36 securedly affixed to the strips, making the toroid slide along the intermediate conductors 36 in the direction of the strips 26 to 29, then welding is performed at the end of the conductors onto the intermediate conductors 36. Advantageously, the intermediate conductor(s) 36 is (are) welded at the end onto the strip(s). According to an alternative embodiment, the second end 36b of the intermediate conductor(s) 36 is in a single part with the strip(s). It can be noted that the primary conductors 6 to 9 made of rigid copper wire, with a diameter of 6 mm, are advantageously coated with an insulator of epoxy type for example. A differential unit B has therefore been achieved by means of the invention presenting a high rating and small dimensions. It is thus possible to achieve a range of auxiliarized differential units with ratings up to 125A without increasing the dimensions as compared to the units currently used. This rigidity of connections enables a quick and simple association with the circuit breaker making the circuit breaker-differential unit assembly more compact, optimizing connection of the bottom rail switchgears. It can also be noted that the epoxy coating of the conductors, by powder paint deposit, will provide insulation of the conductors from one another and contributes to optimization of the internal window of the toroid. The invention enables the size of the differential channel to be optimized to the maximum according to the axis of the rail and a range of self-powered 125A of all sensitivities including 30mA to be achieved, in small overall dimensions, for example in a size 99 mm wide. This type of link reduces the dimensions according to the Y axis to the minimum by eliminating the curving operations of the primaries after passing through the toroid. This link also reduces the volume according to the X and Z axes due to the density of copper passed through the toroid window. These small dimensions enable additional functions to be housed within the dimensions of the basic apparatus (in series or on option). CLAIMS 1. A device for electrical connection of a differential unit to a circuit breaker or similar, comprising a certain number of conductors designed to electrically connect the output terminals of the circuit breaker to the output terminals of the differential unit, said conductors passing through the toroid, characterized in that at least one of the above-mentioned conductors (6 to 9, 19) is a rigid conductor with a solid core, said conductor presenting a first end (19a) electrically connected to the corresponding terminal of the circuit breaker and a second end (19b) welded at the end onto a contact strip (26 to 29) mechanically and electrically connected to the corresponding output terminal of the differential unit. 2. The device according to claim 1, characterized in that the above-mentioned conductor(s) is (are) welded at the end onto one (36a), called first, of the ends of an (respectively several) intermediate conductor(s) (36) passing through the toroid (T) whose second end (36b) is electrically and mechanically connected to the corresponding strip (26 to 29). 3. The device according to claim 2, characterized in that the intermediate conductors) (36) is (are) welded at the end onto the strip(s). 4. The device according to one of the claims 2 or 3, characterized in that the second end (36b) of the intermediate conductor(s) (36) is in a single part with the strip(s). 5. The device according to any one of the previous claims, characterized in that the above-mentioned conductor(s) (6 to 9) and/or intermediate conductors (36) is (are) single-strand. 6. The device according to any one of the previous claims, characterized in that the above-mentioned conductor(s) (6 to 9) and/or intermediate conductors is (are) made of copper. 7. The device according to any one of the previous claims, characterized in that the above-mentioned conductor(s) (6 to 9, 19) and/or intermediate conductors (36) present(s) a circular cross section. 8. The device according to any one of the previous claims, characterized in that the conductors (6 to 9) and/or intermediate conductors (36) are shaped in such a way that the cross section of all the conductors together is appreciably circular, in order to minimize the space occupied thereby inside the toroid. 9. The device according to claim 8, characterized in that the apparatuses being of the two-pole type, the conductors (6 to 9) and intermediate conductors (36) if applicable are two in number and both present a semi-circular cross section. 10. The device according to claim 8, characterized in that the apparatuses being of the four-pole type, the conductors (6 to 9) and intermediate conductors (36) if applicable are four in number, each of the conductors presenting a cross section in the shape of a quarter-circle. 11. The device according to any one of the previous claims, characterized in that from the moment they enter the toroid (5), the conductors (6 to 9, 19) or intermediate conductors (36) extend in straight manner up to the strips (26 to 29). 12. The device according to any one of the previous claims, characterized in that the second end (19b) of the conductor(s) (6 to 9) and/or intermediate conductors (36) is brazed-welded to the corresponding strip(s) (26 to 29). 13. The device according to any one of the previous claims, characterized in that between their two ends, the conductors) (6 to 9) or intermediate conductor(s) is (are) folded four times at right angles. 14. The device according to any one of the previous claims, characterized in that the above-mentioned conductor(s) (6 to 9) and/or intermediate conductors) is (are) covered with an insulating coating of epoxy type. 15. A process for implementing a device according to claim 1, characterized in that it consists in threading the toroid (T) around the second end(s) (19b) of the conductors), and then in sliding said toroid along said conductors in a direction opposite to said ends, and then in performing welding at the end of said ends onto the strips. 16. A process for implementing a device according to claim 2, characterized in that it consists in threading the toroid (T) around the intermediate conductors) (36) securedly affixed to the strips, making the toroid slide along the intermediate conductors (36) in the direction of the strips (26 to 29), and then performing welding at the end of the conductors onto the intermediate conductors (36). 17. The differential unit comprising a connection device according to any one of the claims 1 to 14. 18. The differential unit according to claim 17, characterized in that it comprises at least one auxiliary module (3, 4) able to be plugged into the input face (24) of the differential unit case on each side of the toroid (5). 19. The differential unit according to claim 18, characterized in that the auxiliary modules (3, 4) comprise a fault indication auxiliary and/or a remote opening module, and/or a leakage current indication module. 20. The differential unit according to any one of the claims 17 to 19, comprising a tripping finger (10) extending protruding out from the face (21) of said unit (B) designed to be adjoined to the circuit breaker, characterized in that it comprises a protection finger (32) extending appreciably parallel to said tripping finger (10) over a slightly greater length than that of said finger (10) and designed to absorb the shocks instead of the tripping finger (10). 21. The differential unit according to any one of the claims 17 to 20, characterized in that the range of the differential unit B is a self-powered 125A range of all sensitivities including 30mA. 22. A process and device for electrical connection of a differential unit to a circuit breaker or sinilar and a differential unit with a connection device substantially as described herein and illustrated with reference to the accompanying drawings.

Documents:

2762-mas-1998-abstract.pdf

2762-mas-1998-claims duplicate.pdf

2762-mas-1998-claims original.pdf

2762-mas-1998-correspondence others.pdf

2762-mas-1998-correspondence po.pdf

2762-mas-1998-description complete duplicate.pdf

2762-mas-1998-description complete original.pdf

2762-mas-1998-drawings.pdf

2762-mas-1998-form 1.pdf

2762-mas-1998-form 26.pdf

2762-mas-1998-form 3.pdf

2762-mas-1998-form 4.pdf

abs-2762-mas-1998.jpg