High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices – Air-current blowout
Patent
1996-11-26
1998-04-14
Scott, J. R.
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
Air-current blowout
218 63, H01H 33985, H01H 33915, H01H 3378
Patent
active
057394954
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a compressed-gas circuit breaker, particularly for high voltages, with two contacts arranged coaxially opposite one another, at least one of which can be driven to move in the axial direction, the two contacts defining in the interrupted state a contact gap, and with a nozzle, made of insulating material, which is connected to the driven contact and which surrounds at least part of the contact gap.
BACKGROUND OF THE INVENTION
Such a compressed-gas circuit breaker is known, for example, from U.S. Pat. No. 4,163,131.
In such an insulating nozzle switch circuit breaker, an intense pressure rise results after the separation of the contacts and the firing of an electric arc due to the heating up of an arc-extinguishing gas in the area of the contact gap, the pressure rise being used by means of the nozzle to achieve during the current zero crossing a blowout of the electric arc and thus a supporting of the extinguishing process.
With the increasing capacity of such high-voltage circuit breakers, the arc-extinguishing gas pressure becomes so intense in the area of the nozzle made of insulating material that the risk of an expansion of the nozzle member arises. This cannot be easily counteracted by producing the nozzle with a more stable material or with a greater wall strength since on the one hand the nozzle material itself is intended to release arc-extinguishing gas under the influence of the electric arc and on the other hand the arc-extinguishing gas nozzle with the drivable contact should be movable as quickly as possible, i.e., should have low mass, at least during the switching off.
OBJECTS AND SUMMARY OF THE INVENTION
The underlying object of the invention is to design a high-voltage circuit breaker of the type described in the introduction such that damage to the nozzle made of insulating material is avoided and nevertheless in this process the fastest possible switching speed is ensured. This objective is solved according to the invention by a high-strength plastic tube abutting coaxially against the outer circumference of the nozzle made of insulating material in its region exposed to the quencher gas pressure.
U.S. Pat. No. 4,786,770 discloses an insulating nozzle switch circuit breaker in which the nozzle made of insulating material is surrounded by a magnetic ring which is provided for the purpose of producing a magnetic field that lengthens the electric arc or allows it to rotate. Such a ring is heavy and accordingly difficult to accelerate. In the previously known switch, this does not entail any disadvantages since the nozzle made of insulating material is not joined to the drivable contact. There, the ring is also not provided for mechanical stabilization of the nozzle made of insulating material, but is provided only for magnetic reasons.
In contrast, the tube according to the invention stabilizes the nozzle made of insulating material against radial expansions due to the compressive loads produced by the expanding arc-extinguishing gas. The high-strength plastic tube does not have to consist of the same material as the nozzle made of insulating material since it does not come into contact with the electric arc and is also not intended to release any arc-extinguishing gas under the influence of the electric arc. Moreover, a less expensive material can be chosen than for the nozzle made of insulating material since the plastic tube has only mechanical stabilization duties and can be built correspondingly small. The plastic tube only needs to be large enough to brace the nozzle made of insulating material in the areas of particularly low wall strength.
The plastic tube can also be integrated into the nozzle member on its outer circumference so that it protrudes as little as possible over the outer contour. This increases the dielectric stability.
An advantageous refinement of the invention provides that the plastic tube consists of a fiber-reinforced plastic.
Such a fiber-reinforced plastic tube has a particularly high mechanical st
REFERENCES:
patent: 3855437 (1974-12-01), Goedecke et al.
patent: 3996439 (1976-12-01), Tokuyama et al.
patent: 4163131 (1979-07-01), Perkins
patent: 4786770 (1988-11-01), Hamano et al.
Lehmann Volker
Marin Heiner
Scott J. R.
Siemens Aktiengesellschaft
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