TECHNICAL FIELD The present invention relates to a disconnecting element and to an electric disconnector comprising said disconnecting element.

Electric disconnectors are switching devices installed on electric lines, generally inside electric modules, and are suitable to selectively interrupt or restore the electrical continuity of the line. In particular, electric disconnectors are mainly used to interrupt the electrical continuity of the line so that the portion of the electric line downstream of the disconnector is electrically isolated from the portion of the electric line upstream of the disconnector.

Said arrangement is necessary during maintenance work on the electric line to ensure that maintenance operations are performed on isolated portions of the line so as to guarantee the safety of workers . BACKGROUND ART

Prior art electric disconnectors normally comprise from one to four disconnecting elements. Each disconnecting element is arranged between a first and a second terminal of a respective conductor of the electric line and comprises an arm, extending along a longitudinal axis and having a free end, provided with an electric contact, and a connecting end, opposite to the free end and pivotally connected to a frame of the electric module. The electric contact is permanently connected to one of the terminals of the conductor, for example the first terminal, by means of a connection inside the arm and an electric coupling at the connecting end. Moreover, the arm is movable between two positions: a closed position in which the electric contact is connected to a terminal (in this case the second terminal) of the respective electric line conductor; and an open position in which the contact is disconnected from the second terminal .

However, such disconnectors cannot be adapted to suit the different types of electric modules available on the market, which differ mainly in terms of their size and the layout of the electric line conductor terminals . Disconnector manufacturers must therefore produce a specific disconnector for each type of electric module available on the market, which clearly has economic disadvantages. DISCLOSURE OF INVENTION

A purpose of the present invention is to provide a disconnecting element, a disconnector and an electric module that overcome the aforesaid drawbacks of the prior art; in particular, a purpose of the present invention is to provide a disconnecting element and a disconnector that can be adapted to suit different types of electric modules and at the same time are simple and cheap to produce .

In accordance with the aforesaid purposes, the present invention relates to a disconnecting element for an electric disconnector, an electric disconnector and an electric module as claimed respectively in claims 1, 11 and 12.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will become clear from the following description of two non- limiting embodiments thereof, with reference to the figures in the accompanying drawings, in which:

- figure 1 is a schematic view of an electric disconnector according to the present invention installed on an electric line; - figure 2 is a schematic view from above of the electric disconnector of figure 1;

- figure 3 is a schematic front view of a detail of the electric disconnector of figure 1;

- figure 4 is a side view, with some parts shown in cross-section and some removed for the sake of clarity, of a disconnecting element according to the present invention in a first operating position,-

- figure 5 is a front view of the disconnecting element of figure 4 ; - figure 6 is a front view of the disconnecting element according to the present invention in a second operating position;

- figure 7 is a front view of the disconnecting element according to the present invention in a third operating position; and

- figure 8 is a front view of a second embodiment of the disconnecting element according to the present invention in an operating position.

BEST MODE FOR CARRYING OUT THE INVENTION In figure 1, reference number 1 indicates an electric module, which is schematically illustrated, arranged on an electric line 2, which includes a plurality of conductors 3. In the electric module 1 there is housed an electric disconnector 4 for selectively interrupting or restoring the electrical continuity of the line 2. More in detail, each conductor 3, inside the module 1, is provided with a respective first terminal 5 and with a respective second terminal 6, which are selectively connectable and disconnectable by means of the disconnector 4. The electric module 1 is also provided with ground terminals 7. As shown in figure 2, the disconnector 4 comprises at least one disconnecting element 8. In the non- limiting example described and illustrated herein, the disconnector 4 is a three-pole disconnector and comprises three disconnecting elements 8, which are aligned with one another along a given axis C. In particular, the disconnecting elements 8 are connected to one another by means of a sleeve 100, which is fixed to a frame 101 of the module 1 by means of support brackets 102 (shown more clearly in figure 3) .

With reference to figure 3, each disconnecting element 8 is arranged between the first terminal 5 and the second terminal 6 of a respective conductor 3 of the electric line 2. Each disconnecting element 8 comprises an arm 9, extending along a longitudinal axis A, an arm 10, extending along a longitudinal axis B, and electric connecting means 11 (visible in figure 4) for electrically connecting the arm 9 and the arm 10. The arm 9 and the arm 10 are connected to one another so as to be rotatable independently from one another about a same axis of rotation, which in this case coincides with the axis C, orthogonal to the axes A and B. As described in more detail below, the arm 9 and the arm 10 can assume a plurality of angular positions about the axis of rotation C independently from one another. In particular, the arm 9 and the arm 10 are respectively connected to movement means 103, which comprise a system of levers 104 and at least two control shafts 105.

With reference to figure 4, the arm 9 comprises an insulating body 13 and two conductive bars 14.

The insulating body 13, made of an electrically insulating, self-extinguishing material, preferably epoxy resin, extends along the axis A and has a free end 15 and a connecting end 16, opposite to the free end 15. The insulating body 13 comprises an externally finned portion 18, which extends substantially starting from the free end 15 for approximately half of the overall length of the insulating body 13 and is provided with a plurality of annular fins 19 which extend substantially around the insulating body 13. The insulating body 13 comprises an internal coupling portion 20, which is arranged substantially in proximity to the connecting end 16. The internal coupling portion 20 has a blind cavity 22, which is substantially cylindrical in shape, to house the electric connecting means 11 and comprises a plurality of first annular guiding elements 23. The cavity 22 extends about the axis C. The first annular guiding elements 23, two of which are illustrated in the example here described, are coaxial to and arranged around the cavity 22. The insulating body 13 also comprises two longitudinal seats 24 for housing the conductive bars 14. The longitudinal seats 24 extend substantially parallel to the axis A starting from the free end 15 leading into the cavity 22.

The conductive bars 14, for example made of copper, are housed in the longitudinal seats 24 and are connected to the electric connecting means 11. In particular, the conductive bars 14 extend substantially parallel for a section 26 outside the insulating body 13 and define a forked electric contact 27. The electric contact 27 of the arm 9 is suitable to be connected to a terminal (in the example in figures 3, 4 and 5 the first terminal 5) of the respective conductor 3 of the electric line 2 or to the ground terminal 7 (as in the configurations of figure 6 and figure 7) , depending on the angular position of the arm 9.

The arm 10 comprises an insulating body 29 and two conductive bars 30. The insulating body 29, made of the same material used to make the insulating body 13, extends along the axis B and has a free end 31 and a connecting end 32, opposite to the free end 31. The insulating body 29 comprises an externally finned portion 34, which extends substantially starting from the free end 31 for approximately half of the overall length of the insulating body 29 and is provided with a plurality of annular fins 35 that extend substantially around the insulating body 29.

The insulating body 29 comprises an internal coupling portion 36, which is arranged substantially in proximity to the connecting end 32. The internal coupling portion 36 has a blind cavity 38 for housing the electric connecting means 11 and comprises a plurality of second annular guiding elements 39, complementary in shape to the first annular guiding elements 23. The cavity 38 extends about the axis C. The second annular guiding elements 29, of which there are two in the example described here, are coaxial to and arranged around the cavity 38. The insulating body 29 also comprises two longitudinal seats 40 for housing the conductive bars 30. The longitudinal seats 40 extend substantially parallel to the axis B starting from the free end 31 leading into the cavity 38. The conductive bars 30, which are also made of copper like the conductive bars 14, extend along the longitudinal seats 40 and are connected to the electric connecting means 11. In particular, the conductive bars 30 extend substantially parallel for a section 42 outside the insulating body 29 and define a forked electric contact 43. The electric contact 43 of the arm 10 is suitable to be connected to a terminal (in the example in figures 3, 4, 5 and 7 the second terminal 6) of the electric line or to the ground terminal 7, depending on the angular position of the arm 10. The arm 9 and the arm 10 are rotatingly inserted on a supporting pin 45 of the electric connecting means 11, which defines the axis C of rotation. The first annular guiding elements 23 and the second annular guiding elements 39, which are complementary in shape, are coupled so as to define a pivotable joint between the arm 9 and the arm 10. Moreover, the cavity 22 of the insulating body 13 and the cavity 38 of the insulating body 29 are adjacent so as to define a cylindrical seat 106 that houses the electric connecting means 11. In an alternative embodiment of the present invention that is not illustrated, the first and the second arm are respectively provided with three conductive bars.

The electric connecting means 11 comprise an electric contact 48, a bush 49 and a ring 50.

The electric contact 48 is of the so-called tulip type and comprises two disks 51, pairs of plates 53, retaining springs 54 and two conductive rings 55 arranged in contact with the conductive bars 14 and 30. The disks 51 are attached to a central portion of the supporting pin 45 and are arranged substantially parallel and at a distance D from one another. The disks 51 support the pairs of plates 53. In particular, each -disk 51 is -provided with a plurality of notches 56, which are uniformly distributed along the perimeter of the disk 51. In the non-limiting example described and illustrated herein each disk 51 has eight notches 56.

Each pair of plates 53 is provided with two notches 57, arranged at a distance D from one another.

The pairs of plates 53 are arranged around the disks 51 so that the notches 56 of the two disks 51 are engaged by the respective notches 57 of the pairs of plates 53. In this way the pairs of plates 53 are uniformly distributed around the disks 51. In the non- limiting example described and illustrated herein there are eight pairs of plates 53. The connection between the pairs of plates 53 and the disks 51 is made more stable thanks to the presence of the retaining springs 54 , which are wrapped around the pairs of plates 53 and hold them against the disks 51. The pairs of plates 53 are provided with two pointed portions 58, which are placed in contact with the conductive rings 55.

The conductive rings 55 are inserted on the supporting pin 45 and are arranged at the sides of respective disks 51 and in contact with the conductive bars 14 and 30 respectively of the arm 9 and of the arm 10 .

According to an alternative embodiment of the present invention that is not illustrated a sliding electric contact is used instead of the tulip contact 48.

The ring 50, preferably made of metal, is arranged around the electric contact 48 so as to electrically shield the electric contact 48.

The bush 49, preferably made of PTFE, is arranged around the ring 50 and acts as a bearing.

As mentioned previously, during use, the disconnecting elements 8 of the disconnector 4 can assume different operating positions. In particular, the arm 9 and the arm 10 of each disconnecting element 8 can independently assume a plurality of angular positions about the axis C of rotation. In the non-limiting example described and illustrated herein, the arms 9 and 10 can rotate by a maximum of 180° about the axis of rotation C. According to an alternative embodiment of the present invention that is not illustrated the arms can rotate by 360° about the axis of rotation C.

Figure 5 shows a first operating position of one of the disconnecting elements 8 of the disconnector 4 in which the arm 9 and the arm 10 are arranged at 180° with respect to one another. In the non- limiting example shown in figure 5, the contact 27 of the arm 9 and the contact 43 of the arm 10 are connected respectively to the first terminal 5 (figure 3) and to the second terminal 6 (figure 3) of the respective conductor 3 of the electric line 2 to restore the continuity thereof.

Figure 6 shows a second operating position in which the arm 9 and the arm 10 are arranged substantially adjacent to one another. In this example they are arranged at approximately 10° with respect to one another. In the non-limiting example shown in figure 6, the contact 27 of the arm 9 is connected to the ground terminal 7 (figure 3) and the contact 43 of the arm 10 is disconnected from the terminals 5 and 6 (figure 3) of the respective conductor 3 of the electric line 2. Figure 7 shows a third operating position of the disconnecting element 8 in which the arm 9 and the arm 10 are arranged at approximately 90° with respect to one another. In the non-limiting example shown in figure 7, the contact 27 of the arm 9 is connected to the ground terminal 7 (figure 3) and the contact 43 of the arm 10 is connected to the second terminal 6 (figure 3) of the respective conductor 3 of the electric line 2.

According to an alternative embodiment of the present invention illustrated in figure 8, at least one of the arms 9 and 10 of each disconnecting element 8 of the disconnector 4 is provided with an extension 60 to enable the use of the disconnector 4 even in electric modules in which the terminals of the conductors of the electric line are arranged at a greater distance from each other. The present invention has the following advantages. Firstly, the fact that the two arms 9 and 10 can assume a plurality of angular positions about the axis of rotation C makes the disconnector 4 according to the present invention extremely flexible and adaptable for use in different types of electric modules.

Moreover, the overall dimensions of the disconnector 4 according to the present invention are smaller than those of the prior art disconnectors.

Lastly, the disconnector 4 according to the present invention is air insulated thus avoiding the use of pollutant substances such as SF ₆ gas.

Finally, it is clear that modifications and variations may be made to the disconnector and to the disconnecting element 8 described herein without departing from the scope of the appended claims.