What is irrelevant for an electrical fuse

For the application of the safety conductor according to the invention, various manufacturing methods can be considered:

a conductive coating is e.g. B. applied in the screen printing process over the circumference of the roll. From this z. B. by "milling" - as known from the production of carbon film resistors - or by etching in the manner of printed circuit board technology, a conductor strip is obtained, the beginning and end of the conductor strip being on the opposite end of the winding. One end of the conductor strip is connected, for example by soldering, to the connection line of the coil, and the connection line leading to the outside is attached to the other end of the conductor strip.

b In another version, a safety wire is placed around the circumference as a safety conductor, which is interrupted in the event of the winding being destroyed. The connections are attached in the same way as the procedure described above. This version is particularly suitable for coverings made using the immersion process, as the safety wire is fixed by an additional immersion process and integrated into the cover.

c In a further embodiment, the path of the safety conductor is produced in that it is applied directly using the screen printing process.

d In another version, the fuse conductor is produced using the additive technology known from circuit board technology.

e Furthermore, the path of the fuse conductor is produced in such a way that the conductor path is formed by metallizing z. B. is applied in the process of metal vapor deposition or metal spraying. It is also possible to proceed as described under a, that first of all a flat metallization of the casing takes place and then the conductor is produced by "milling".

Finally, the path of the safety conductor is produced by applying a narrow, preferably self-adhesive, thin metal foil tape.

The fuse conductor preferably runs in a spiral shape directly around the capacitor winding and is then attached to the cover applied thereafter. Instead of being placed under the cover, the safety conductor can also be placed on top of the cover and arrested with it. Finally, in the latter case, an additional coating can be placed over the fuse conductor.

In a particularly advantageous embodiment of the fuse according to the invention, the fuse conductor, in order to increase its functionality, is provided at intervals with cross-sectional reductions as predetermined breaking points. The different cross-sections result in very good interlocking with the casing, so that the safety conductor is securely fixed over the relatively small distances. A possible elastic deformation of the metal electrical conductor material and a possible "migration" of the fuse conductor without breakage with possibly only slight surface deformations of the capacitor winding are thus excluded. The cross-sectional reductions can be designed as a perforated notch and / or as wedge-shaped incisions on one or both sides on the edge of the safety conductor.

The invention is suitable for all metallized film capacitors in dry construction, for. B. for MKP capacitors as motor and fluorescent lamp capacitors.

The invention will be explained below with reference to the embodiments shown in the drawing. Show it

1 shows a fuse according to the invention with a fuse conductor applied to the envelope of the capacitor winding and

2 shows a fuse according to the invention with a fuse conductor running under the envelope of the capacitor winding.

In Fig. 1, a capacitor winding 10 made of (not shown) metallized plastic film is shown, in which sprayed contact layers 11 and 12 are provided on the end faces, which serve as upper and lower contact bridges. The capacitor winding 10 is provided on all sides, that is to say also on the end faces, with a hard, brittle and tightly fitting covering 13. With 14, 15 two outwardly led connections arranged on one end face of the capacitor winding are designated. The connection 14 is welded or soldered to the contact layer 11 directly at the point 17. The connection 15 is connected to the beginning of an electrical fuse conductor 16 which surrounds the coil 10 in a spiral shape and at the other end is electrically conductively connected to the other contact layer 12 at the point 18, e.g. B. is soldered or welded. In the event of internal damage to the capacitor winding 10 and an associated geometric deformation, the sheath 13 tears or shatters, so that the conductor section of the fuse conductor 16 lying in the area of ​​destruction of the sheath 13 is immediately interrupted: The electrical circuit through the capacitor winding 10 is thus safely disconnected .

In Fig. 2, the same parts are provided with the same reference numerals as in FIG. The only, but essential, difference to the fuse according to FIG. 1 is that the fuse conductor 16 runs directly on the surface of the capacitor winding 10 and thus spirally within the sheath 13. This embodiment can be produced in an optimal way, the safety conductor 16 nevertheless being particularly well adhered to the sheathing 13 when it is applied.