DE8534806U1 - Tubular busbar - Google Patents

Description

Tubular busbars with cooling through their own stimulated gas flow.

Tubular busbars made of copper or aluminum offer opposite Flat bars are known to have two advantages: the increase in resistance due to current displacement is lower, and the dielectric The strength of the surrounding gas is higher due to the more homogeneous field. Therefore, pipe rail systems can be used with comparatively little Conductor cross-section and small dimensions of the surrounding encapsulation can be built. Such Sfomschieneanlagen are for example described in more detail in the following publication: Petry, H .: SF, -insulated single-phase metal encapsulated Rohrgasksbel for Medium voltage. Elektrizitätswirtschaft 83 (1984) pp. 776 - 779.

Because of the relatively small and rounded outer surface it is the heat dissipation with pipe rails is worse than with several parallel flat rails of the same cross-section. In particular, wears normally the inner surface of the pipe rails does not contribute to the cooling, since the gas inside is dormant and practically the same temperature as the conductor assumes. The innovation is the pipe rails in a suitable arrangement to be provided with flow openings (holes) so that a self-excited gas flow, i.e. not forced by a fan, is created, which leads to the constant exchange of the heated inner gas with the outer cooler gas leads. Figure 1 shows an example of a vertical and Figure 2 shows a horizontal arrangement according to this innovation.

The self-excited gas flow comes about due to the lower specific weight of the heated gas compared to the p.b.cooled gas. The heated gas thus undergoes thermal buoyancy force, which is known to lead to a gas flow and iv a heat flow (convection).

t ItIlIt ti I *

This thermosiphon effect is from numerous other uses known, but has not yet been used for the internal cooling of pipe rail systems.

In the case of a vertical pipe arrangement (FIG. 1), the

ii gas flow strongest, and the longer the pipe the better. f

It is also important to keep the flow resistance small. f

For this purpose, the holes 1 in the conductor 2 should be as large as possible. To the I

To allow flow outside the pipe is required. J

if necessary, the disc support isolators necessary for centering |

gates 3 also holes 4. The self-excited gas flow is in |

Figure 1 indicated by arrows. I.

The coaxial aluminum pipe encapsulation 5 can also be omitted without |

to significantly impair the thermosyphon effect. Instead of the f

shown pole-wise encapsulation is also a three-pole box conveying]

moderate sheet steel encapsulation possible. As insulating gas between conductor and
Encapsulation is common, for example, with air or sulfur hexafluoride.

In the case of a horizontal pipe arrangement (FIG. 2), the thermosiphon effect is significantly less; With a suitable arrangement of the flow openings, however, there is also an improvement in cooling and
thus to achieve an increase in the current-carrying capacity. It is useful to have a distance at the top and bottom of the pipe 6
of for example 500 mm holes 7 and 8 to be provided. The top row 7
is offset from the lower row 8 so that one hole each
^zw: rule two adjacent holes on the opposite edge of f

comes to rest. This creates a gas flow, as shown in FIG. 2 p

drawn. j

A unipolar or '' ·

three-pole encapsulation possible, or the encapsulation can be omitted entirely. i

In Figure 2, the pipe conductor 6 is without encapsulation via post insulators 9j |

attached to the building ceiling 10. G

- 3 - j *

I I t

The screw fastening of the pipe 6 to the post insulators 9 is expediently carried out with the aid of an opposite hole 8, through which a socket wrench can be inserted.

Even if the thermosyphon effect remains small with a horizontal arrangement, the arrangement is particularly good with unencapsulated pipe rails holes in the conductor are advantageous, as they are the more or less strong air currents that always prevail in a building leads to the fact that the inside of the pipe flows through and is thereby cooled.

In all arrangements, the number and diameter of the holes must not be too large, as this reduces the electrical resistance and thus the heat losses in the conductor become too great. A hole diameter that is approximately half as large is useful like the pipe inside diameter.

The cooling shown by self-excited gas flow is applicable not only to tubular busbars, but also to other tubular conductors, e.g. in switchgear, transformers and switchgear.

The self-excited coolant flow according to the innovation described is not only effective with gases, but also with liquids, E.g. with insulating oil in transformers, if tubular conductors are used there.

The cooling effect in the arrangements described can be significantly increased if through suitable fan constructions and cooling air ducts a forced coolant flow is generated outside and inside the pipe. However, such an expense is considerable and also has disadvantages due to the noise, the dust swirling up and the limited service life of fans. That's why Fans generally only for occasional use for short periods of time current overload of busbars appropriate.

Claims (4)

EXPECTATIONS 1. Tubular busbar, characterized in that a self-excited gas flow through the arrangement of flow openings arises, which causes additional cooling. 2. Tubular busbar according to claim 1, characterized in that that in the pipelines flow openings in each case at one as possible are high and as low as possible. 3. Tubular busbar according to claim 1 and 2, characterized in that that with a vertical arrangement of the pipe ladder at the upper end and at the lower end of the tube each have one or more holes Holes are attached. 4. Tubular busbar according to claim 1 and 2, characterized in that that with a horizontal arrangement of the Rohrleitar al .; upper Edge of the pipe, distributed along the length, holes are made and that at the lower edge of the pipe, also distributed along the length, Holes are attached, which are assigned to the upper holes so that they are each between two adjacent holes.