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application Ser. No. 07/889,408 filed Jun. 3, 1991, now ELECTRICAL CIRCUIT BREAKER WITH TWO U.S. Pat. No. 5,239,150 which should be advantaVACUUM CARTRIDGES IN SERIES geously referred to for further details. All these advan
tages of vacuum cartridges arranged in sulphur hexafluBACKGROUND OF THE INVENTION 5 oride, i.e. their small size, their low operating energy
The invention relates to a medium or high voltage and their low heat dissipation, facilitate the housing in a electrical circuit breaker having per pole a support for sinSle enclosure of two or more vacuum cartridges two vacuum cartridges each of which contains a pair of operated by a con, non mechanism. High voltage circuit separable contacts. The pairs of separable contacts are breakers can thus be achieved combining the advanelectrically connected to each other in series by an 10 tages of sulphur hexafluoride insulation and those of electrical connection to increase the voltage withstand vacuum breaking.
of the pole and, each pair comprising a movable contact The vacuum cartridge advantageously comprises a which is connected by a mechanical connection to open coil generating an axial magnetic field in the arc formaand close the two pairs of contacts simultaneously. tion zone, and the arcing contacts are made of a high
A state-of-the-art circuit breaker of the kind men- 15 resistivity material, for example a refractory material or tioned, comprises two vacuum cartridges, arranged one equivalent. The main contacts are advantageously above the other, inside an elongated support, borne by aligned, in the closed position, with two bushings aran insulating console secured to a frame. It is known ranged on opposite sides of the enclosure, so as to rethat the dielectric withstand of vacuum cartridges is duce the trajectory of the rated current flow. The vaclimited and that it is extremely difficult to exceed surge 20 uum cartridges are juxtaposed to this straight current voltages of 100 to 250 KV. By connecting two or more trajectory, in order to facilitate, by reduction of the cartridges in series, it is possible to increase this dielec- i00p effect, switching of the current to the shunt circuit, trie withstand notably and to achieve medium or high formed by the vacuum cartridges. The movable main voltage circuit breakers. The above-mentioned state-of- contact can be a pivoting or rotary knife-blade contact the-art circuit breaker is very voluminous and cumber- 25 providing either single breaking or double breaking, some, and requires a large operating energy, practically ^ arrangement of the vacuum cartridges inside the twice that of a single cartridge. Incorporating such a enclosure is determined by the general architecture of circuit breaker in a cubicle gives rise to serious prob- {he drcmt ... ^ ... d ds Qn ^ ... lems to which should be added the risks of overheating of cartrid t0 be incorporated in the enclosure.
which are also doubled. 30 T C A U J-„ * ♦ j
, . . „ . . . . . In a preferred embodiment, two cartridges are ar
The object of the present mvention is to achieve an , f „ . ... - . ,, . °. , . ,
1..,J • u ■ ranged m parallel with their movable contacts located
electrical vacuum cartridge circuit breaker having a j * J ■ -l.
notably increased dielectric withstand. °An *e samf Slde and connected bV an operating bar.
Another advantageous arrangement is an aligned ar
SUMMARY OF THE INVENTION 35 rangement of the two vacuum cartridges arranged one
The circuit breaker according to the invention is Allowing the other. In the latter case, the two movable characterized in that the two cartridges are rigidly se- contacts of the vacuum cartridges are facing one ancured inside a sealed enclosure which is filled with a other and m connected by a toggle system, ensuring high dielectric strength gas. The enclosure contains an simultaneous operation of the two movable contacts, electrical connection between the pairs of contacts and 40 The operating mechanism performs in the usual mana mechanical connection between the movable ner Pnor opening of the mam contacts and inversely, contacts. Each vacuum cartridge comprises an insulat- closing of the main contacts after that of vacuum caring housing whose creepage distance corresponds to the tridSe contacts acting as arcing contacts. The operating dielectric withstand of the housing in the high dielectric mechanism comprises a rotary shaft passing through the strength gas, and a pair of main contacts is arranged in 45 wal1 of the enclosure and supporting inside this enclothe enclosure to be electrically connected in parallel sure 211 operating crank. This operating crank can be with the pairs of contacts arranged as arcing contacts of double or be achieved by two cranks, each secured to the two serially mounted vacuum cartridges. The cir- tne operating shaft, one of the cranks being connected cuit breaker is operated by the operating mechanism to by a connecting rod to the movable arcing contact, open before the arcing contacts and to close after the 50 whereas the other is connected to the movable main arcing contacts. contact. It is also possible to achieve movement of the
By arranging the vacuum cartridges in the manner movable contacts by mechanically interconnecting the described in U.S. Pat. No. 4,155,315, in an enclosure arcing contacts and the main contact and transmitting filled with sulphur hexafluoride, the external dimen- the operating movement of the rotary shaft directly to sions of the cartridges, and thereby those of the enclo- 55 one of these contacts, notably to the movable main sure, can be appreciably reduced. Connection of the contact. Other operating modes are naturally conceivtwo vacuum cartridges in parallel to the main contacts, able.
also housed inside the enclosure, allows flow of the The circuit breaker according to the invention is permanent current via the main contacts, thereby pre- particularly suited to a medium voltage gas-insulated venting any overheating of the vacuum cartridges 60 installation, the enclosure then comprising an grounded whose contacts can be made of a high resistivity mate- metal envelope. The same enclosure can contain the rial, notably a refractory material which resists the three circuit breaker poles, which enables an additional action of the arc. The vacuum cartridge contacts which reduction of the overall dimensions to be achieved, constitute the arcing contacts of the circuit breaker do Tpttom Of Trf To? A wr\rr;<;
not have current flowing through them under normal 65 BRIEF DESCRIPTION OF THE DRAWINGS operation, and their operating energy can be reduced by Other advantages and features will become more the use of a precompressed contact pressure spring, in clearly apparent from the following description of two the manner described in detail in copendng U.S. patent illustrative embodiments of the mvention, given as non
