High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices
Patent
1993-10-13
1995-04-04
Scott, J. R.
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
218 81, H01H 3310
Patent
active
054039835
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an arc quenching apparatus for circuit breakers, based on a plate chamber construction. The apparatus comprises a quenching space in which each phase has a stationary contact and a knife contact pivotable in relation thereto, and which has a quenching chamber in whose body member, made of an insulating material, quenching plates are disposed in a spaced-apart relation so as to be located successively in relation to the path of the opening movement of the knife contact. The arc quenching installation according to the invention is particularly suitable for use in SF.sub.6 -insulated medium-voltage circuit breakers.
A basic construction of the kind described above is known, for instance, from the Applicant's earlier load circuit breaker of the type OETL 250 . . . 3150 (the FIGURES refer to ampere values), wherein the quenching plates are disposed in the form of a circular arc substantially perpendicularly to the tangent of the path of the knife contact.
Another extinguishing apparatus based on a plate chamber construction is known from European Patent 0 157 242. In this apparatus, a stationary contact and a quenching chamber are disposed on a busbar. The quenching plates of the quenching chamber are disposed in the chamber in parallel with the tangent of the starting point of the path of the knife contact and in a spaced-apart relation, and further superposed with an overlap so that the distance between the movable knife contact and the quenching plates increases as the opening movement of the knife contact proceeds.
The advantage with the quenching installations of the type described above, based on a plate chamber construction, is that the actual circuit breaking operation is successful with a small amount of energy. However, the problem with this apparatus has been found to be that the arc will produce a layer of soot on the quenching plate support structure made of an insulating material, and this soot layer will make the support structure conductive between the quenching plates. As a result, the breaking capacity of the circuit breaking apparatus is strongly impaired.
SUMMARY OF THE INVENTION
The purpose of the present invention is to remove this problem and to achieve an arc quenching apparatus by means of which the breaking capacity of a circuit breaker based on the plate chamber principle can be made considerably better than heretofore. This is achieved with the apparatus of the invention, which is characterized in that stop means are disposed between the ends of the quenching plates on the knife contact side and the body member, the stop means preventing direct contact with the body member at least in the spaces between the quenching plates.
The basic idea of the invention is to introduce between the ends of the quenching plates on the knife contact side and the support structure of the quenching plates (the body member of the quenching chamber), which is made of an insulating material, means preventing direct contact with the body member at least between the quenching plates, thus preventing the passage of the arc to the support structure or to the vicinity thereof. Such means can also be located over the topmost quenching plate and under the lowermost quenching plate.
The improved breaking capacity achieved on account of the invention means that the breaking will be successful with currents markedly higher than heretofore, or, correspondingly, that with the same current values a considerably higher number of breaking times than heretofore is achieved.
In accordance with two advantageous embodiments of the invention, the stop means are constituted by ridges or steps made in the quenching plates. Thus one avoids using separate barrier members, and the stop means are easy to manufacture for instance in connection with the die cutting of the quenching plates.
The invention will be explained in more detail in the following, with reference to examples according to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1a is a side vie
REFERENCES:
patent: 4511772 (1985-04-01), Link et al.
patent: 4521653 (1985-06-01), Yoshiyasu et al.
patent: 4629840 (1986-12-01), Dirks et al.
patent: 4650938 (1987-03-01), Genba
patent: 4654490 (1987-03-01), Leone et al.
ABB Stromberg Sahkonjakelu Oy
Scott J. R.
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