High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices – Air-current blowout
Reexamination Certificate
1999-09-10
2001-03-27
Scott, J. R. (Department: 2832)
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
Air-current blowout
C218S060000, C218S065000, C218S066000
Reexamination Certificate
active
06207918
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a compressed gas power switch, in particular for extinguishing an arc of a high short-circuit current, which has a first switching piece and a second switching piece, installed on a common axis with a space between them, and an axially displaceable contact piece, which bridges the space when in the on state and moves away from the first switching piece during switch-off, and is at least partially surrounded by a heating chamber, a second isolating distance being connected in series to a first isolating distance formed between the first switching piece and the contact piece during switch-off.
BACKGROUND INFORMATION
A compressed gas switch is described in principle, for example, in German Patent No. 40 10 007 regarding the contact arrangement and the operation of the axially displaceable contact piece. A heating chamber arranged coaxially with the contact arrangement is described in German Patent No. 41 03 119. Regardless of the particular design of these compressed gas switches, they have the disadvantage that the hot gas makes it difficult to establish the isolating distance during switch-off, so that the time at which the isolating distance is re-established cannot be determined with sufficient accuracy. In addition, controlled switching at zero current is almost impossible, since the inherent delay of the compressed gas power switch is included in the switching sequence (each compressed gas power switch has a different inherent delay determined by the respective manufacturing tolerances, age, environmental conditions, and different masses). European Patent No. 0 334 181 and European Patent No. 0 400 523 describe that a second isolating distance may be connected in series to the first isolating distance of a compressed gas power switch, but this involves a disproportionately large, and therefore high-cost, drive, since the extinguishing gas may only enter the inside containing the secondary contact of the second isolating distance from the outside. This, however, means not only that gas must be made available from the outside, but also that the compressed gas power switch requires a large space.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a compressed gas power switch which allows reliable switching with low drive power and adequate re-establishment of the isolating distance to be achieved regardless of its particular inherent delay or the hot gas in the heating chamber, yet without an increase in the volume occupied by the compressed gas power switch.
This object is achieved according to the present invention by the fact that the second switching piece is axially displaceable and is connected to a piston that may be driven in a switching chamber in respect to the contact piece by the hot gas flowing from the heating chamber into the switching chamber so that the second switching piece moves away from the contact piece.
This provides drive support, since the second switching piece is moved by the extinguishing gas pressure. In addition, the operation of the second switching piece depends on the extinguishing gas and therefore on the current, so that the opening of the second isolating distance is controlled by the characteristics of each individual switching sequence.
According to one advantageous embodiment of the present present invention, the heating chamber is separated from the switching chamber by a bulkhead, which has a valve controllable through the current to be switched and the pressure difference between the heating chamber and the switching chamber. The valve allows the opening time of the second isolating distance to be controlled with an even greater accuracy.
The present invention may also be advantageously configured so that the second switching piece is axially displaceable on the inner periphery of a tubular main current path connected to the compression piston of a compression device forming a sliding contact, the second isolating distance being formed between the second switching piece and the axially displaceable contact piece after a blow hole has been opened by the current-dependent valve via the hot gas driving the piston designed as an annular piston.
Regardless of how the heating chamber is designed, the annular piston in the switching chamber may be connected to the compression piston of the compression device via a compression spring, so that after the completion of a switch-off sequence, it is ensured that the compression spring brings the annular piston and the switching piece connected to it back to their original position.
In order to provide a sufficiently large heating chamber for receiving the hot gases, in particular when switching high short-circuit currents, in another embodiment of the invention the switching chamber downstream from the heating chamber is delimited by a partition running coaxially with the switch axis, which is rigidly connected to both the bulkhead and the compression piston of the compression device, so that an additional heating chamber, connected to the heating chamber upstream from the bulkhead, is formed on the outer periphery of the partition.
According to another feature of the present invention, the valve has one or two ferromagnetic bodies, which in the high-current phase hold the blow hole in the bulkhead closed against the force of compression springs, but open it when the current has reached a certain lower value. The forces of the current of the current path of the compressed gas power switch, i.e., the forces between the two ferromagnetic bodies in a magnetic field (a concentric magnetic field formed around the compressed gas power switch current path due to the short-circuit current to be switched off) may be used.
In order to make use of the forces of the current, a ferromagnetic body in the form of a cover plate over the blow hole may be slidably arranged to form a valve. The cover plate is supported by the compression springs against the current path formed by the switching piece and the axially movable contact piece and its movement is limited by a stop. To guide the ferromagnetic cover plate taking into account a slight friction resistance, it is mounted on tracks or in grooves, preferably made of polytetrafluoroethylene (PTFE).
The current-dependent valve may also be conveniently made of two cover plates made of ferromagnetic material, which oppose one another at the end face of the bulkhead facing the switching chamber at the height of the blow hole and support one another through compression springs.
Both embodiments of the current-dependent valve are also well suited for arrangement on the annular piston at the height of the blow hole; however, in this case it must be ensured that, at least in the area of the current-dependent valve, the annular piston not be made of magnetic material.
Using the forces arising between two ferromagnetic bodies in a magnetic field, in a preferred embodiment of the invention, the current-dependent valve may also be made of a frame made of ferromagnetic material, arranged concentrically with the blow hole within the bulkhead and for which a cover plate made of ferromagnetic material is provided on the side facing the heating chamber upstream from the blow hole. This cover plate is preferably guided by four rods attached to the bulkhead and supported against the bulkhead by compression springs.
REFERENCES:
patent: 3789175 (1974-01-01), Beier et al.
patent: 4293750 (1981-10-01), Marin
patent: 4633049 (1986-12-01), Pinnekamp
patent: 4652709 (1987-03-01), Schade
patent: 4663504 (1987-05-01), Barkan
patent: 5285036 (1994-02-01), Lorenz
patent: 5742016 (1998-04-01), Rolff
patent: 5898149 (1999-04-01), Berger et al.
patent: 23 50 832 (1975-04-01), None
patent: 40 10 007 (1991-10-01), None
patent: 41 03 119 (1992-08-01), None
patent: 0 334 181 (1989-09-01), None
patent: 0 400 523 (1990-12-01), None
patent: 92 14255 (1992-08-01), None
Habedank Bernd-Ulrich
Lorenz Dieter
Kenyon & Kenyon
Scott J. R.
Siemens Aktiengesellschaft
LandOfFree
Compressed gas power switch does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Compressed gas power switch, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Compressed gas power switch will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2445306