Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electrical power distribution systems and devices
Reexamination Certificate
1999-12-23
2001-05-22
Scott, J. R. (Department: 2832)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electrical power distribution systems and devices
C174S016200, C218S043000, C218S044000, C218S083000
Reexamination Certificate
active
06236562
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a section of an electrical high-voltage system. This system is suitable for transmitting high electrical power in the megawatt to gigawatt range. The currents and voltages occurring here lie in the kA and kV range, respectively. A typical system includes multi-phase generator output lines, in which in the individual phases, operating currents between 5 and 30 kA and operating voltages of, for example, 15 or 21 kV occur. Such a high-voltage system has sections in which considerable heating occurs as a result of relatively high power losses. Sections in which the current is led through a contact transition, for example a switching point, are subject to considerable heating. Such switching points are generally generator switches.
BACKGROUND OF THE INVENTION
Generator switches are usually cooled via natural convection and radiation. If such switches are of unencapsulated design, then the power loss of the conductor is transmitted in the form of heat to an extinction-chamber insulator which contains the contact arrangement of the switch and has cooling ribs led vertically. The heat absorbed by the extinction-chamber insulator is dissipated to the surroundings by convection and radiation. Such generator switches are marketed by ABB High Voltage Technologies Ltd, Zurich/Switzerland under the type designation HEI 1 . . . HEI 5. Furthermore, the abovementioned company also markets generator switches, with the type designation HEC3/HEC4, in which the conductor and the extinction-chamber insulator are arranged in a housing filled with an insulating gas, in particular with air. The heat formed in the conductor and predominantly led to the extinction-chamber insulator is then given up to the housing via natural convection and radiation. In this case, the heat is given up as a result of the temperature differences which become established between the conductor or extinction-chamber insulator the and housing. The heat absorbed by the housing is led off to the surroundings via natural convection and radiation because of the temperature difference between the housing and the surroundings. The heat flow in such a system is automatically established, depends primarily on geometrical dimensions and the materials and surface configurations used and is limited by the mechanisms of heat dissipation. If the generator switch is of threephase design, the three phases being arranged beside one another, the housing of the phase arranged in the center always has the highest temperatures, since the side walls cannot give up any radiation energy, and then has to be cooled particularly intensively.
SUMMARY OF THE INVENTION
The object is therefore set on providing a section for a high-voltage system having cooling means which is of the simplest possible construction and nevertheless permits a considerable increase in the system current without changing the geometric dimensions of the system.
According to the invention, the section of the high-voltage system, preferably designed as a generator switch, has as its cooling means at least one flow source arranged in the interior of the housing and designed in such a way that, during the operation of the system, two mirror-symmetrical circulation part flows are formed which are bounded by the plane of symmetry and which are in each case guided without recirculation along a first housing wall from a second housing wall, which is intersected by the plane of symmetry, to a third housing wall, which is intersected by the plane of symmetry. As a result of these measures, the transfer of heat from the conductor to the housing is increased, and therefore a limiting temperature on the conductor is not exceeded, the said temperature being determined by the insulation classes of the insulators holding the conductor.
Particularly efficacious heat transfer to the housing is achieved if flow sources are provided, each of which is assigned to one of the two circulation part flows. In this case, the plane of symmetry is preferably aligned predominantly vertically. The first housing wall is then a side wall, the second housing wall is a top and the third housing wall is a bottom of the housing. If the two flow sources are then fixed to opposite ends of the bottom of the housing and if the side wall coming from the respective end then has flow guide surfaces, the circulation part flows then extend in the same way as natural convection, and particularly sparingly dimensioned flow sources are then adequate. In this case, the flow guide surfaces reaching into the side walls prevent or reduce any recirculation of the circulation part flows, and thus improve the dissipation of heat from the conductor to the housing quite significantly.
The flow sources can also be fixed to the opposite ends of the top of the housing or the bottom of the housing, without the use of flow guide surfaces. In order to ensure that the two circulation part flows extend without recirculation, the two flow sources should then be arranged either on the bottom of the housing and then produce a flow which rises at the side walls and is directed counter to natural convection, or should be arranged on the top of the housing and then produce a flow which falls at the side walls and which supports the natural convection in a manner which is particularly advantageous in terms of energy.
If the section of the system has at least three housings which each accommodate a conductor and which are arranged with their housing side walls beside one another and at a distance from one another, forming vertically aligned channels, then the flow sources should be provided in the central housing of the three. The heat led to the housing side walls by the circulation part flows can then be led away by the chimney effect of the two channels. This chimney effect can be assisted by one or more flow sources fitted outside the housing.
It is preferable if, in at least one of the channels, there is arranged an intermediate wall, parallel to the bounding side walls of this channel. This intermediate wall picks up radiation energy from the side walls surrounding the channel, and this energy can then be removed from the channel as a result of the chimney effect. At the same time, the intermediate wall reduces the volume flow and hence the capacity of the flow sources located on the outside. The channel should have a width such that the volume flow led through the channel is not interfered with, with or without the intermediate wall, and the air forming the said volume flow is not heated up too severely.
Particularly good dissipation of heat from the intermediate wall to the air stream, which rises as a result of convection and/or the additional flow sources, is achieved by means which are moulded into the intermediate wall in order to enlarge its surface area. Such means can comprise corrugations which are led vertically and/or longitudinal ribs, but can also comprise a further intermediate wall led parallel to the intermediate wall, which in a particularly advantageous way can be connected to the intermediate wall by longitudinal ribs led vertically.
REFERENCES:
patent: 3230293 (1966-01-01), Turgeon
patent: 3364838 (1968-01-01), Bradley
patent: 4378461 (1983-03-01), Haginomori
patent: 664 852 (1988-03-01), None
Kübler Günter
Malfa Enrico
Parneix Sacha
Wilfert Gunter
Asea Brown Boveri AG
Burns Doane Swecker & Mathis L.L.P.
Scott J. R.
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