Hollow insulator and method for its manufacture

Description

[0001] The invention relates to a hollow insulator for high electrical voltages and a method for manufacturing such a hollow insulator.

[0002] The invention relates in particular to hollow insulators for air-insulated high-voltage devices or high-voltage components, such as outdoor circuit breakers or outdoor bushings. Hollow insulators for high electrical voltages are frequently manufactured from ceramic materials or composite materials such as fiber-reinforced plastics. Ceramic hollow insulators exhibit high mechanical strength, especially against bending. However, there is a risk of bursting when a ceramic hollow insulator is subjected to high gas pressure. Hollow insulators made of composite materials are mechanically less stable, but more burst-resistant than ceramic hollow insulators. Hollow insulators are known, for example, from EP1812940B1, CN102129896A, WO2009109216A1, and CN102280231A.

[0003] The invention is based on the objective of providing an improved hollow insulator for high electrical voltages and a method for manufacturing such a hollow insulator.

[0004] The problem is solved according to the invention with regard to the hollow insulator by the features of claim 6 and with regard to the method by the features of claim 1.

[0005] Advantageous embodiments of the invention are the subject of the dependent claims.

[0006] A hollow insulator according to the invention for high electrical voltages comprises an insulating tube and a sheathing of the insulating tube made of a fiber-reinforced plastic, which rests against an outer surface of the insulating tube. The insulating tube is made of a ceramic material, glass, or plastic.

[0007] A hollow insulator according to the invention thus advantageously combines the mechanical stability of an insulating tube made of a ceramic material, glass, or plastic with the burst resistance of fiber-reinforced plastics. A hollow insulator according to the invention is therefore mechanically more stable than a hollow insulator made of a fiber-reinforced plastic and more burst-resistant than a hollow insulator made, for example, of a ceramic material, glass, or plastic.

[0008] One embodiment of the invention provides for an electrically insulating shield arranged around the insulating tube and the sheathing. This embodiment of the invention is particularly advantageous when the hollow insulator is used outdoors, where it is exposed to changing weather conditions, especially precipitation.

[0009] A further embodiment of the invention provides for at least one flange arranged at one end of the hollow insulator, with a flange collar extending annularly around a longitudinal axis of the hollow insulator. For example, at least one flange is connected to the insulating tube or to the sheathing. Flanges arranged at the ends of the hollow insulator advantageously enable a reliable and simple connection of the hollow insulator to other components.

[0010] In the inventive method for manufacturing a hollow insulator for high electrical voltages, an insulating tube is made of a ceramic material, glass, or plastic, and the insulating tube is sheathed with a fiber-reinforced plastic. The method enables the production of a hollow insulator with the advantages mentioned above.

[0011] The method according to the invention provides that the insulating tube is sheathed with the fiber-reinforced plastic by arranging at least one prefabricated fiber mat around the insulating tube and subsequently impregnating the plastic into the at least one fiber mat by vacuum impregnation. The method enables the sheathing of an insulating tube made of a ceramic material with a fiber-reinforced plastic.

[0012] Another embodiment of the method provides that a flange is arranged at at least one end of the insulating tube before it is sheathed. This flange is then connected to the insulating tube, for example, by cementation. Alternatively, a flange can be arranged at at least one end of the sheathing after the insulating tube has been sheathed. This flange is then connected to the sheathing, for example, by adhesive bonding.

[0013] The properties, features and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more easily understood in connection with the following description of exemplary embodiments, which will be explained in more detail in conjunction with a drawing.

[0014] The single figure shows a sectional view of a hollow insulator 1 for high electrical voltages. The hollow insulator 1 comprises an insulating tube 3, a sheath 5 of the insulating tube 3, a shield 7 and two flanges 9, 11.

[0015] The insulating tube 3 is made of a ceramic material, glass, or a plastic such as polymethyl methacrylate. The sheathing 5 is made of a fiber-reinforced plastic, for example, a fiber-reinforced epoxy resin, and rests against an outer surface of the insulating tube 3. According to the invention, to produce the hollow insulator 1, the insulating tube 3 is sheathed with the fiber-reinforced plastic by arranging at least one prefabricated fiber mat around the insulating tube 3 and then impregnating the plastic into the at least one fiber mat by vacuum impregnation.

[0016] The flanges 9, 11 are arranged at opposite ends of the hollow insulator 1 and each has a flange collar 15 extending annularly around a longitudinal axis 13 of the hollow insulator 1. In the embodiment shown in the figure, each flange 9, 11 is connected to an outer surface of the casing 5. For this purpose, the flanges 9, 11 are, for example, glued to the casing 5. An alternative embodiment (not shown) provides that the casing 5 only surrounds a section of the insulating tube 3 extending between the flanges 9, 11, and each flange 9, 11 is directly connected to the insulating tube 3. For this purpose, the flanges 9, 11 are, for example, cemented to the insulating tube 3.

[0017] The shielding 7 is made of an electrically insulating material, for example, silicone. The shielding 7 is arranged on an outer surface of the casing 5 between the flanges 9, 11 and has several ring-shaped, shield-like lamellae 17 extending around the longitudinal axis 13 of the insulator.

[0018] Although the invention has been further illustrated and described in detail by means of preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived from them by the person skilled in the art without leaving the scope of protection of the invention.

Claims

1. A method for production of a hollow insulator (1) for high electrical voltages, wherein - an insulating tube (3) is fabricated - and the insulating tube (3) is jacketed with a fibre-reinforced plastic, and wherein - the mechanically stable insulating tube (3) is fabricated from a ceramic material or a glass or a plastic, characterised in that the insulating tube (3) is jacketed with the fibre-reinforced plastic by arranging at least one prefabricated fibre mat around the insulating tube (3) and subsequently introducing the plastic into the at least one fibre mat by vacuum impregnation.

2. The method according to claim 1, characterised in that, before jacketing (5) the insulating tube (3), a flange (9, 11) is arranged on at least one end of the insulating tube (3).

3. The method according to claim 2, characterised in that the at least one flange (9, 11) is connected to the insulating tube (3) by cementing.

4. The method according to claim 1, characterised in that, after jacketing (5) the insulating tube (3), a flange (9, 11) is arranged on at least one end of the jacket (5).

5. The method according to claim 4, characterised in that the at least one flange (9, 11) is connected to the jacket (5) by an adhesive connection.

6. A hollow insulator (1) for high electrical voltages, comprising - an insulating tube (3) - and a jacket (5) of the insulating tube (3) fabricated from a fibre-reinforced plastic and abutting an outer surface of the insulating tube (3), produced according to a method in accordance with any one of claims 1 to 5.

7. The hollow insulator (1) according to claim 6, characterised by an electrically insulating shield (7) arranged around the insulating tube (3) and the jacket (5).