Electricity: conductors and insulators – Conduits – cables or conductors – Insulated
Patent
1993-12-22
1995-10-03
Nimmo, Morris H.
Electricity: conductors and insulators
Conduits, cables or conductors
Insulated
295921, 174110F, 174110PM, 336205, 336222, H01B 702, H01F 2730
Patent
active
054553920
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an insulated winding according to the precharacterising clause of claim 1, to a process and to a semi-finished product for the production thereof.
Insulated windings of various, usually annular or coil-shaped geometries have the most varied applications in transformers, magnets, converters, loudspeakers etc. For many purposes it is a requirement that the windings also withstand rapid temperature changes, high humidity and chemically aggressive media, as are, for example, contained in the contaminated air found in industrial plants.
In such known windings, the insulation is produced by impregnating the conducting layers with a resin with simultaneous application of a vacuum, optionally filling, providing a surface covering and casting in a mould. This type of production requires several drying operations at elevated temperatures. The resins, filler etc. used are harmful to health and the finished product often requires mechanical finishing to remove beads and flash. Protective measures must be taken to protect terminal lugs and the like.
If there is any departure from this per se well-tried production process, if, for example, less expensive materials are used which are more hygroscopic, or if the operations are performed in locations with higher atmospheric humidity or if the various components are not measured out exactly, the windings obtained do not fulfil high quality requirements. Moreover, there still remains with such known insulated windings exposed to extreme thermal loads the problem of stress fractures in the insulating layer on exposure to large temperature changes since the insulating layer is relatively brittle and has a coefficient of thermal expansion which is very different to that of the embedded electrical wire material.
The present invention is intended to provide an insulated winding according to the precharacterising clause of claim 1 in which the insulating layer forms a monolithic matrix reliably bonded to the conductor layers, even after major changes in temperature.
This object is achieved with a winding according to claim 1.
In the electrical winding according to the invention, the insulating layer retains a certain elasticity and can therefore follow the temperature-determined dimensional changes of the conductor layers without being destroyed, even over a large number of widely varying temperature cycles. The winding may here be produced at low cost using a relatively non-critical operating process, during which no harmful vapours are released.
Windings according to the invention are self-sealing when moderately overheated as the polyolefin just melts, but reforms a monolithic insulating matrix on subsequent cooling.
Windings according to the invention are free of cavities and cannot be penetrated by moisture.
Advantageous further developments of the invention are stated in the subordinate claims.
The further development of the invention according to claim 2 provides that the polyolefin material may also penetrate between the interstices remaining between the individual conductors in the conductor layer. A particularly large contact area between the insulating layer and conductor layers is therefore obtained.
The further development of the invention according to claim 3 is advantageous in respect of the long-term retention of the elastic properties of the insulating layer.
With the further development of the invention according to claim 5, an impermeable covering for the insulating layer is obtained which prevents the penetration of extraneous materials from the surrounding atmosphere and thus again improves the long-term stability of the winding.
In the process stated in claim 6, formation of the monolithic insulating layer around the conductor layers is performed in a manner which is particularly technically simple and is undemanding in terms of process control.
With the further development of the invention according to claim 9, application of the insulating layer material to the conductor layers may be simply achieved as the insulating layer material
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Doroschenko Viktor
Preu Hans
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