US 4,843,199 AGranted

Gas-blast circuit breaker

AssigneeBBC Brown, Boveri & Company, Limited

InventorLutz Niemeyer

Life of this patent

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Abstract

A gas-blast circuit breaker has two switching elements disposed in a casing filled with arc-extinguishing gas and capable of being brought into or out of engagement with each other along one axis. One of these two switching elements defines an arc-extinguishing jet nozzle and can be guided during switching-off through a heating chamber. The heating chamber stores which is formed by heating up arc-extinguishing gas pressurized gas by means of a switching arc. When low currents are switched, a comparatively high pressure is built up in the heating chamber. On the other hand, a relatively low pressure develops during switching of large currents. This results from the inclusion in the second switching element of an insulation capping which extends around the outer surface and reaches to the front end face thereof, an arcing contact on its outer surface which receives the switching arc during the heating up phase of the switching process and also an arc-extinguishing contact which is separated from the arcing contact by the capping. The root point of the switching arc is commuted, shortly before the current to be switched off passes through zero, to the arc-extinguishing contact.

Claims13

Dependent claims

A gas-blast circuit breaker, comprising:

a casing filled with an arc-extinguishing gas;
a first, cylindrically shaped, switching element secured to said casing and having a first arcing contact;
a second, cylindrically shaped, switching element, mounted to move into and out of engagement with said first switching element along a common axis of said switching elements and having a nozzle shaped forward end and a second arcing contact disposed on an exterior surface of said switching element;
an arc-extinguishing-contact adjacent a forward free end of said second switching element and a capping of insulating material extending from said second arcing contact of said second switching element to said arc-extinguishing-contact thereof;
enable an arc, drawn during a switching-off operation of said circuit breaker, to freely develop between said respective first and second arcing contacts of said first and second switching element;
and
an expansion chamber defined by said casing and effective for collecting arc-extinguishing gas generated by an arc developing in said heating chamber, said heating chamber and expansion chamber being so disposed relative to one another as to cause said arc to initially develop between said respective first and second arcing contacts and to be, thereafter and shortly before a current to be switched off passes through zero, commuted through the action of said of arc-extinguishing gas to said arc-extinguishing contact of said second switching element.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/129,728Filed 7 Dec 1987
Priority: CH 4883/868 Dec 1986
Granted: 27 Jun 1989
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H01H 33/7038
Characterised by flow directing elements associated with contacts: characterised by a conducting tubular gas flow enhancing nozzle
H01H 33/98
Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid: the flow of arc-extinguishing fluid being…
H01H 33/7007
Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid: wherein the flow is a function of the…
H01H 33/7076
Characterised by flow directing elements associated with contacts: characterised by the use of special materials