DE2633355C3 - Method for filling encapsulated high-voltage systems with an insulating gas - Google Patents

Description

The invention relates to a displacement π according to the preamble of claim I.

The switchgear used here (DF-PS 904063; FR-PSen 1438683: I 514984) only have relat; ν thin system enclosures and can because of their large, flat walls can only withstand slight positive or negative pressures. You are therefore only Can be operated with atmospheric pressure or a slight excess pressure of the insulating gas. As common operating pressures overpressures of 0.2 to 0.3 bar have been found.

Such systems are much cheaper and can be used more universally than known systems (see Calor-Emag-Mitteilungen 1966, booklet J I / HI, pp. 18, 19), their Encapsulation is constructed from heavy cast metal or welded structures, and which is suitable for a subsequent filling with insulating gas can be almost completely evacuated.

It is known (Issue 3 - 1966 of the ETZ supplements, p. 37) _{to fill plant vessels with SF 6} using the so-called displacement method. During the filling process, the insulating gas flows in through an opening in the bottom of the vessel and, due to its five times its weight, displaces the air contained therein, which escapes through openings in the lid. There are drawbacks to this method.

Without further ado, it is only successful with simple symmetrical system parts with favorable flow conditions Internals, such. B. tubular collecting ducts. With box-shaped system housings Their application is difficult with the most varied of built-in components, such as switches, busbars, etc. Ks there is a risk of vortex formation and mixing with the air to be displaced. On the other hand, filling in the insulating gas too slowly causes this a diffusion of the gases. The well-known filling is also quite time-consuming, and that achieved The result is largely dependent on the skill of the filling staff.

In the case of insulating _{gases with lower weight differences to air than SF 6} gas, the tendency to mix with the air without displacing it naturally increases, so that the displacement method then no longer appears to be applicable.

There is also a modified displacement method known (DE-AS 2 Ü48 094). during the suction before or during the introduction of the insulating gas part of the air in the enclosure is carried out by means of a pump arranged at the outlet, until a certain negative pressure (lowest value about Vi of normal pressure) is reached. A complete evacuation the encapsulation is avoided there as too uneconomical. The inflow of the SFe sol! be done so that no excessive flow velocities can arise, the turbulence and thus causing mixtures of the insulating gas with the air still contained in the encapsulation. That Insulating gas can be separated from the gas mixture exiting at the outlet, captured and returned to the Encapsulation filled .verden.

This filling method is also unfavorable for box-shaped system housings for the reasons mentioned above.

The invention is therefore based on the object of specifying a filling method with which a reliable Desired insulating gas density can be achieved depending on the weight of the insulating gas and the shape of the system is independent and with the short filling times

> possible are.

This object is achieved according to the invention by the method with the characterizing features of the claim 1 indicated steps.

The advantages of the filling method according to the invention

> Rens compared to the known displacement methods are in particular that the filling process Can be done in a time-saving manner, automation is possible, a tendency of the gases to diffuse not bothers, it is independent of the weight of the insulating gas

> (no displacement effect), it is largely independent of the shape of the system and its internals, only one opening is necessary for filling.

The application of the new method is particularly indicated for high-voltage switchgear that ~> composed of individual sheet metal boxes filled with insulating gas are. These are designed so that they can be reached without their safety limit - a certain overload due to overpressure or negative pressure, caused by hot and / or climatic conditions Change, endure kc & jten. Appropriately, you will now when filling such a housing go up to the permissible possible load of the plant enclosure to the number of To be able to keep procedural steps low.

> As an example, let us assume the olfactory encapsulation a system holds the maximum permissible load an overpressure of 0.5 bar and a negative pressure of 0.5 bar. To fill the system, the air in the system is first reduced to a negative pressure of

) Extract 0.5 bar and then pure insulating gas up to turbulent filling at an overpressure of 0.5 bar. The turbulent filling process achieves rapid mixing of the gases. Now there is still an air content of around 33.3% in the system. Repeated

"> If the process procedure is carried out with the specified pressures, the proportion of air is already reduced to about 11.1% of the total gas mixture and at one further repetition, air is only ni 3.7%

hold what is required to operate the system with SF "insulating gas will be sufficient in most cases. Finally, the pressure is lowered to the operating pressure. The mixing ratio remains unaffected.

This process can be fully automated. The existing service trolleys for SF ₆ can be used for this after a corresponding conversion. It is known that such SF ₆ service vehicles pump the SF ₆ out of the system when required and store it in liquid form; you can still carry out a drying of the system (see magazine industry and electronics, issue 13, 1975, p. b22). These devices can also be used to recover the SF ₆ gas from the gas mixture of air and SF ₆ taken from the system, as they already contain a compressor and a cooling unit. The gas mixture can be prepared immediately or first filled into a storage bottle under pressure.

To recover the SF ₆ gas, the gas mixture is cooled and, if necessary, compressed, whereby the SK ₀ liquefies.

Almost any mixing ratio can be achieved with the new process.

Claims (2)

Patent claims: 1. A method for filling encapsulated high-voltage systems with an insulating gas, such as SF ₆ , which are constructed in the form of a box, whereby the encapsulation is only suitable for small pressure differences between the inside and outside of the enclosure for reasons of strength, characterized by the following process steps: a) Extraction of part of the gas in the system, b) Filling with pure insulating gas in a turbulent one Flow process up to at least the operating pressure level, c) Repeating the process steps according to a and b until a desired mixing ratio is reached. 2. The method according to claim 1, characterized in that that the gas mixture withdrawn from the system immediately or after intermediate storage is processed to recover the insulating gas contained therein.