The invention relates to a transformer or autotransformer having a high-level electrical insulation, of comparatively simplified construction, with incorporated improved terminal blocks and pre-arranged for different types of positioning. In the following description, reference will be made, for simplicity, only to the term "transformer", without limiting nevertheless the improvements of the invention to this apparatus. The characteristics of the transformer according to the invention and the advantages resulting therefrom will become apparent from the following description, made with reference to the Figures of the accompanying two sheets of drawings, wherein:

• Figure 1 is a perspective view of the transformer;
• Figure 2 shows the transformer bobbin with the transformer coils and with the various electrical connections;
• Figure 3 is a bottom plan view of the transformer;
• Figure 4 shows the lower portion of the transformer, as seen from the section line IV-IV of Figure 3;
• Figure 5 is a side elevational and partly sectional view of the transformer, as seen from the line V-V of Figure 1;
• Figure 6 shows one of the two terminal blocks of the transformer, partly in sectional view on the line VI-VI of Figure 5;
• Figure 7 is an elevational view from the inner side of the cover of one of the terminal blocks for the transformer;
• Figure 8 is an elevational view from the outer side of one of the terminal blocks for the transformer.

The transformer according to the invention comprises a bobbin 1 (see Figure 2) made of suitable plastics material, on which the trasformer coils are wound. Integral with the end flanges of the bobbin 1, the seats 2-102 are formed wherein the end portions of metal tongues 3-103 of equal length are pressure-fitted. To the said tongues 3, 103 the terminals of the transformer coils are welded. Thanks to the fact that the seats 2 with tongues 3 and the seats 102 with tongues 103 are disposed on the two opposite flanges of the bobbin 1, they are considerably spaced from each other and, therefore, they are electrically insulated very well from each other. Once the bobbin 1 has been completed by winding on it the transformer coils, it is provided with a metal yoke 4 as shown in Figures 3 and 5, whereafter the transformer is introduced in a chamber formed in a suitable mold and counter-mold, and plastics material having antifire characteristics, good electrical insulation features and good characteristics of resistance to chemical-physical stresses is pressure-injected thereinto, whereby the transformer is provided with an integral casing 5 (Figure 1) which encloses also the yoke 4 and which has the following functions:

- it improves the electrical insulation of the transformer up to levels never found in transformers of conventional type;

- it increases the heat-exchange surface which is licked by the ambient air, by providing said casing with suitable fins of the type indicated, for example, at 105 in Figures 3 to 5;

- it forms at the base of the transformer, preferably at the corner regions of one of the larger sides of the yoke 4, apertured or channelled feet 6 (Figure 1) to be used for securing the transformer in place by means of screws or a mounting guide;

- it defines around the tongues 3, respective sets of housings 7-107 to be used for the formation of terminal blocks.

From Figures 1, 3 and 5 it will be noted that the feet 6 protrude for an equal extent from the bottom of the transformer so as to define therewith a portal-like profile (Figure 5). The feet which are located at one side of the transformer are provided - in the inner side thereof and co-planarly with the bottom of the casing 5 - with respective recesses 8 which permit the transformer to be overhangingly mounted on a DIN guide channel 9 having an "omega" profile (Figure 4), of the type which is used commonly with electrical switchboards for supporting terminal blocks, remote-control switches and other components. The recesses 8 co-operate with the upper edge of the channel 9, whereby the transformer is substantially suspended from said edge. The positioning of the transformer on the channel 9 is, however, stabilized by a latch device arranged intermediately of the bottom of the casing 5 and co-operating with the lower side of said channel. During the formation of the casing 5, in fact, a guide 10 with a substantially inverted "T"-shaped profile, having a longitudinal recess 11, is formed integrally at the bottom of the transformer at an intermediate position and with a transverse orientation. Said guide mounts a latch device 12 of substantially C-shaped profile, provided with an extension 112 which fits into said recess 11 of said guide and which will be acted upon by an opposing spring 13 which may be introduced into said recess 11 through a window 14 provided longitudinally in said latch device, the latter being also provided with:

- a rear stop 212 co-operating with the outer end of the guide 10 at the end of its stroke;

- an external extension 312 with a slot 15 for insertion of a screw-driver or other means to operate the latch in contrast against the action of the respective spring 13;

- one or more front teeth 412, preferably with an inclined front side, adapted to pinch the lower edge of the channel 9 and capable of self-adaptation to the thickness of said edge.

The guide 10 is tapered at the initial part thereof, as indicated at 16 in Figure 3, to permit the extension 112 of the latch to enter perpendicularly the recess 11 in said guide.

The advantages of the two different possibilities of mounting the transformer are apparent and result from the presence of the slotted or apertured feet 6 and from the characteristics described above with reference to Figure 4.

With reference to Figures 1, 5 and 6, it will be noted that the housings 7-107 comprise small substantially parallelepipedal boxes B-B1, opened at one end whereinto a respective, preferably metallic slider 17 is inserted to embrace the tongue 3 or 103, said slider having in the top thereof a threaded hole co-operating with a screw 18 having a head 118 with a slot for a screwdriver, which rotatably engages, without protruding therefrom, a through-hole 19 in the top of each box B-B1, said head being provided with a collar 218 abutting against said top wall of the boxes. The screw 18, moreover, is of such a length as to engage, at its lower end, the tongue 3 or 103. By turning the screw 18 by means of a screwdriver inserted into the hole 19, said screw causes the slider 17 to be lifted or lowered. The wire to be electrically connected to the tongue 3 or 103 is disposed under said tongue and is clamped between said tongue and the bottom wall of the slider 17. From Figure 5 it will be appreciated that the slider 17 is of smaller depth than said boxes B-B1, whereby the latter may be closed by unitary cover structures 20, made of suitable plastics material, provided on the inner side with vertical grooves 120 (Figure 7) into which the partitions between the various boxes B-B1 may fit, and provided with holes 21 (Figure 8) for the passage of the electric wires to be connected to the tongues as mentioned above, and pre-arranged, finally, for application to the housings 7-107 with a firm engagement, by means of adhesives or in any other manner, ensuring a firm and sealed positioning. From Figures 5 and 7 it will be appreciated that the depths of the covers 20 are differentiated and that the slider 17 is provided with an extension 117 slightly protruding from its lower side, directed downwards and which, in the uppermost position of said slider, covers a hole 21 and abuts against the thickest portion of the cover. An excessive pressure is thus avoided of the slider against the tongue 3 or 103, and the inlet is also avoided of foreign matter through the hole 21, after said slider has been raised.

It is to be understood that all minor modifications achieving the same utility and exploiting the same novelty principles may be made to the improved transformer as described and shown. The terminal block housings 7-107 may be arranged, for example, all either on the lower portion or the upper portion, or else on one or both sides of the transformer. The latch device 12 may have a different construction than described and may be guided by different means. The feet 6 may have different configurations.