WO1998019195A1

WO1998019195A1 - High voltage insulator

Info

Publication number: WO1998019195A1
Application number: PCT/DE1997/002339
Authority: WO
Inventors: Stefan Hain; Walter Gross; Norbert Koch
Original assignee: Siemens Aktiengesellschaft
Priority date: 1996-10-25
Filing date: 1997-10-13
Publication date: 1998-05-07
Also published as: DE19644483C1

Abstract

In order to prevent fissures from occurring also at particularly low temperatures on an optical fibre (7a,7b) placed inside (5) an insulator (1), the inner area (5) of said insulator is filled with foam (13) at an overpressure. The foam froths up with insulating gas, especially SF6. The insulator is especially suitable for measuring arrangements in high voltage technology.

Description

description

High voltage insulator

The invention relates to an insulator for high voltage, in particular high voltage, with a housing, through the interior of which at least one optical waveguide is guided in the longitudinal direction and led out at the end, the interior being filled with a foam.

Such an insulator is known from US Pat. No. 3,485,940. The insulator used there is used to hold a current measuring arrangement on a high-voltage line. The foam there is a polyurethane foam and is only used as a filler.

When using optical waveguides and such a foam, there is the problem that there is no connection between the foam and the surface of the optical waveguide. This can result in gaps on the surface of the optical waveguide, which then form a creepage path for a rollover.

The invention is based on the object of specifying an isolator which, with a simple structure, offers the greatest possible dielectric strength for optical fibers laid therein.

Starting from the preamble of claim 1, this object is achieved according to the invention in that the foam is foamed with SF6 in such a way that there is an overpressure in the interior of the insulator with respect to the housing environment.

This combination of features results in a particularly simple construction of the insulator, the dielectric strength inside the device even under the most difficult operating conditions Isolators remains. This applies in particular to temperature fluctuations. Insulators of this type must maintain their functionality under outdoor conditions at temperatures down to approximately -50 ° C. The formation of longitudinal gaps must therefore also be prevented in the case of material expansion and shrinkage.

When the insulator is manufactured, the pressure tightness, e.g. for assembly work, even be abandoned for some time. This results in only slight diffusion losses of the gas in the foam. The optical waveguide is preferably only installed at the end of the production of the insulator, so that the risk of damage is kept low.

The overpressure should not exceed 2 bar. It is preferably in a range between 0.2 to 1 bar, a value of 0.5 bar having proven to be advantageous in practice. In this way, the insulator housing is not subjected to excessive pressure, but the longitudinal gap formation is sufficiently prevented.

The housing of the insulator is advantageously at least partially made of a composite material. As a result, the insulator is stable and reliable, even when it is elevated

Internal pressure, given. A PU foam (polyurethane foam) is preferably used as the foam.

A preferred application of the isolator is in measuring arrangements in high-voltage technology, in which on one

High-voltage potential arranged measuring means are provided. From these, the corresponding measurement data or information is then conducted to earth potential via at least one optical waveguide. The measuring means can be arranged mechanically at the head end of the insulator. An embodiment of the invention, further advantages and details are explained below with reference to the drawing.

The figure shows an insulator 1 with a housing 3. The housing 3 is provided with shields 4 in its outer area in a known manner. The screens 4 can be made of porcelain or silicone, for example. The housing 4 can also be made of porcelain and / or a composite material, e.g. an epoxy resin composition or a glass fiber material.

By way of example, two optical waveguides 7a, 7b are shown in the figure, which are guided through the interior 5 of the insulator. They are carried out through the closed head and foot ends 9 and 11, respectively.

The interior 5 is filled with a foam, in particular a polyurethane foam 13. The foam 13 is introduced into the interior 5 with an overpressure. The overpressure compared to the ambient atmosphere is a maximum of 2 bar. A favorable range is 0.2 to 1 bar. An overpressure of approx. 0.5 bar has proven itself in practice. This is because a longitudinal gap between the foam 13 and the optical fibers 7a and 7b is prevented.

In principle, the connection between such a foam and the surface of optical fibers is problematic. Due to the excess pressure, the foam 13 lies tightly against the optical waveguides 7a and 7b, as a result of which a longitudinal gap is prevented. An additional advantage is achieved by using SF6 (sulfur hexafloride) as a foaming agent, which achieves an insulating effect. Prin- Other insulating gases, for example nitrogen, can also be used.

In this way, the optical waveguides 7a, 7b can be guided straight through the insulator 1 without causing any damage

Voltage or field strength stress occurs. The foam 13 is introduced into the interior 5 via a filling opening, not shown, in a known manner. If necessary, a further additional opening, e.g. be provided at the opposite end of the insulator 1 for the escape of air.

A preferred application of the isolator 1 is for measuring arrangements. For this purpose, means 14 for measuring value acquisition can be provided at the head end 9, which may include a sensor 15, e.g. an optical or magnetic current sensor, which is arranged on a high-voltage line 17.

The present construction principle can in principle be used for any bushings or other insulator arrangements in medium or high voltage technology.

Claims

claims

1. Insulator (1) for high voltage, in particular high voltage, with a housing (3), through the interior (5) of which at least one optical waveguide (7a, 7b) is guided in the longitudinal direction and led out at the end, the interior (5) is filled with a foam, characterized in that the foam (13) is foamed with SF6 in such a way that there is an overpressure in the interior (5) relative to the housing environment.

2. Insulator according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the overpressure is a maximum of 2 bar.

3. Insulator according to claim 2, d a d u r c h g e k e n n z e i c h n e t that the

Overpressure is in the range between 0.2 to 1 bar.

4. Insulator according to claim 3, d a d u r c h g e k e n n z e i c h n e t that the

Overpressure is approx. 0.5 bar.

5. Insulator according to one of claims 1 to 4, wherein the foam is a polyurethane foam.

6. Insulator according to one of claims 1 to 5, characterized in that the housing (3) is at least partially made of a composite material.

7. Isolator according to one of claims 1 to 6, d a d u r c h g e k e n n z e i c h n e t that means (14) for measuring value acquisition on a high-voltage line (17) are arranged at the head end of the housing.

8. Insulator according to claim 7, d a d u r c h g e k e n n z e i c h n e t that the

Means (14) serve to detect a current.