High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices – Air-current blowout
Reexamination Certificate
1999-09-08
2001-05-29
Donovan, Lincoln (Department: 2832)
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
Air-current blowout
C218S043000, C218S048000
Reexamination Certificate
active
06239399
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a compressed gas interrupter, in particular a high-tension circuit-breaker, comprising, in an enclosure which extends along a longitudinal axis, a first contact assembly including a first permanent current contact and a first arc contact, a second contact assembly mobile along the longitudinal axis relative to the first contact assembly and including a second permanent contact and a second arc contact respectively adapted to be connected to the first permanent contact and to the first arc contact, and a system for inserting a resistor when the interrupter closes, the resistor being electrically connected in series between the first arc contact and the first permanent current contact.
2. Description of the Prior Art
A resistor of the above kind limits the effects of transient currents in the grid when the interrupter is closed. In practice, the resistor is inserted during closing of the interrupter when an electrical connection is made between the arc contacts and is short-circuited before the connection between the permanent current contacts is made. The resistor must not be inserted when the interrupter is opened.
The resistor insertion time can vary from one installation to another. It is generally dependent on the speed at which the mobile contact assembly moves. Some interrupters have an insertion time in the order of 6 ms for a mobile contact assembly speed in the order of 4 m/s. Some installations require the use of interrupters which can produce a much longer resistor insertion time, in the order of 14 ms.
An aim of the invention is to propose a resistor insertion system with which a long resistor insertion time is obtained.
Another aim of the invention is to propose a closure resistor insertion system which is compact and has few component parts.
SUMMARY OF THE INVENTION
To this end, the invention consists in a compressed gas interrupter comprising, in an enclosure which extends along a longitudinal axis, a first contact assembly including a first permanent current contact and a first arc contact, a second contact assembly mobile along the longitudinal axis relative to the first contact assembly and including a second permanent contact and a second arc contact respectively adapted to be connected to the first permanent contact and to the first arc contact, and a system for inserting a resistor when the interrupter closes, the resistor being electrically connected in series between the first arc contact and the first permanent current contact, wherein the resistor insertion system comprises two auxiliary contacts a first of which is electrically connected to the first permanent current contact and the second of which is connected to the first arc contact, the two auxiliary contacts are mounted to be mobile relative to each other along the longitudinal axis so as to be able to move toward each other when the interrupter closes to make a connection that short-circuits the resistor and so as to be constrained to move together along the longitudinal axis when the interrupter closes before making the connection which short-circuits the resistor.
With the above arrangements, a resistor insertion time is obtained corresponding to the time needed for the two auxiliary contacts to move toward each other plus the travel time of the two auxiliary contacts when they are constrained to move together.
In one particular embodiment of the interrupter of the invention, the first arc contact is in the form of a rod on which slides a metal block carrying the second auxiliary contact and the block is pushed along the longitudinal axis when the interrupter closes by a nozzle fastened to the second arc contact. The resistor insertion time can therefore be adjusted to suit the speed of the mobile contact assembly.
In another embodiment of the interrupter of the invention, the block has a substantially conical end which nests inside the nozzle. This eliminates the effect of impact on the block when the interrupter closes, which contributes to moving the block at the same speed as the mobile contact.
In a further embodiment of the interrupter of the invention, the block has a tubular extension which extends along the longitudinal axis and on which slides an insulative member fastened to the first auxiliary contact, the tubular extension having one end forming a piston which cooperates with a recess in the insulative member so that the piston is fastened to the insulative member when the interrupter closes by virtue of a pressure drop created in the recess in the insulative part between the piston and the insulative part. The auxiliary contacts are therefore constrained to move together, when the interrupter closes, by a simple pneumatic system employing a suction effect that does not require any linkage.
In a further embodiment of the interrupter of the invention, the block comprises an internal chamber which is divided by a radial shoulder of the rod of the first arc contact and a ring is placed in the chamber against the radial shoulder of the rod so that displacement of the block along the rod of the first arc contact when the interrupter closes compresses the spring at the same time as the chamber fills with gas and, when the interrupter opens, the spring on expanding applies a return force which tends to move the block automatically in the opposite direction at the same time as the gases are expelled from the chamber via an orifice therein, the orifice being sized to oppose the return force of the spring. These arrangements procure disconnection of the auxiliary contacts when the interrupter opens which is effective only after disconnection of the arc contacts and the permanent current contacts, in a simple manner, with few component parts and by pneumatic means. Accordingly, the resistor cannot be inserted when the interrupter opens.
In a further embodiment of the interrupter of the invention, the first auxiliary contact and the first permanent current contact are mounted on and fastened to a tube mobile along the longitudinal axis and a spring is placed against the mobile tube to oppose movement of the tube along the longitudinal axis when the interrupter closes, the spring exerting a return force when the interrupter opens which tends to move the tube automatically in the opposite direction along the longitudinal axis.
One embodiment of an interrupter in accordance with the invention is described in more detail below and shown in the drawings.
REFERENCES:
patent: 4338500 (1982-07-01), Pham Van et al.
patent: 4393291 (1983-07-01), Stewart et al.
patent: 4996399 (1991-02-01), Thuries et al.
patent: 5276285 (1994-01-01), Pham et al.
patent: 5742017 (1998-04-01), Perret
patent: 5841614 (1998-11-01), Perret
patent: 2 737 937 (1997-02-01), None
patent: 2 751 781 (1998-01-01), None
Alstom France S.A.
Donovan Lincoln
Sughrue Mion Zinn Macpeak & Seas, PLLC
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