US2586115A - Bushing type electric circuit breaker - Google Patents

Description

Feb. 19, 1952 o. TANGE ETAL BusHINC TYPE ELECTRIC CIRCUIT BREAKER Filed May 25, 1949 I f Am Patented Feb. 19, 1952 BUSHING TYPE ELECTRIC CIRCUIT BREAKER toyuki Tange and Seiiti Morita, Taga-Mat, Tag'a-Gun, Japan, assignors to Hitachi Limited, Tokyo, Japan, a corporation of Japan Application May 25, 1949, Serial No. 95,294

3 Claims. (Cl. Z110- 150) rlhis invention relates to electric circuit breakers, and more particularly to an electric circuit breaker immersed in an oil filled bushing, and has for its object to provide an electric circuit breaker having higher insulating strength between two electrodes in case of opening circuit.

A further object is to stabilize the circuit interrupting effect after the electric arc had been extinguished.

Another object of the invention is to pre- 'vent the creeping discharge or flash over bethe contact.

With the above objects in view the invention consists of novel details of construction and combination of parts hereinafter fully described and claimed.

Referring now to the drawing;

A single gure is a sectional elevation of a bushing type oil circuit breaker embodying this invention.

Referring now to the drawing, I designates an insulator cylinder, such as a porcelain bushing, which is oil-tightlyv sealed at its bottom by a metal cover II and secured to a metal cap I2 put on supporting insulator I3. III designates an upper metal casing which is secured tightly to the top of the bushing I0 and encloses therein a suitable switch operating mechanism I5. I6 designates an operating insulator for the mechanism I` According to the present invention, a rprotective insulator cylinder I'I is suspended from the upper casing I4 by means of metal pieces I8 and a cylinder I9 of insulating material such as Bakelite cylinder is put in the cylinder II and secured to its bottom 2D. A number of arc suppressing chambers 2I are formed in the cylinder I9 and a lower stationary electrode 22 is xed in the cylinder I9. 23 is a conductor rod tting into the lower contact piece 2.4 fixed to the bottom plate II and engaging in a hole 25. 26 is a terminal lead, 21 an upper stationary electrode fixed to the pillar 28. 29 designates a moving electrode passing through the' member 2'I and guided thereby, 30 is an upper terminallead. It is an essential feature of the invention that the insulating oil gap G is provided between the top of the arcsuppressing cylinder I9 and the lower end of the cylinder 3| enclosing the upper fixed electrode 21 and forming the circuit interrupting chamber 32 therein. 33 represents insulating oil. v

The above construction is most effective in positively 'increasing the insulating strength beteen the fixed electrode 22 and the lower end of the moving electrode 29 in its circuit open pcsition and in absolutely preventing the rearcing phenomena since gases generated and following the moving electrode 29 when the electrode is moved upwards aparting from the lower electrode 22 can freely expand and iind the way through the oil gap G into the annular oil space between the cylinders I'I and I9, and finally the lower end of the electrode 29 passes through the oil gap G and retires into the chamber 32 so that the electrode 29 can easily get rid of gaseous zone. Moreover according to the present invention, the arrangement of the circuit breaker allows no possibility of moistures entering into the protective cylinder I'I through the bottom plate 20 and of depositing carbo- `naceous substances on the inner surfaces of arc suppressing cylinder so that the danger of causing creeping discharge along the inner surface of the insulating cylinder. Thus the present invention is effective in promoting circuit interrupting ability of such circuit breakers and maintaining higher dielectric strength of insulating Aa fixed contact adjacent the bottom of said protective insulator cylinder, a movable contact reciprocably mounted adjacent the top of said protective insulator cylinder, means for reciprocating the movable contact into and out of engagement with the fixed contact, an arc suppressing cylinder of lesser diameter than the protective insulator cylinder mounted within the latter, forming with same part of an oil chamber and enclosing the fixed contact, a plurality of partitions having aligned apertures therein of slightly greater diameter than the movable contact through which the movable contact is adapted to pass with close clearance, and forming a series of oil filled arc suppressing chambers,

' an insulator cylinder of lesser diameter than the protective insulator cylinder positioned within the latter in alignment with the arc suppressing cylinder forming with the protective insulator cylinder part of the oil chamber and having a bottom with an aperture therein and said bottom being spaced from the top of the arc suppressing cylinder to form an oil filled gap as part of the oil chamber, and means for reciprocating said movable contact through the aperture in the bottom of the insulator cylinder and the apertures in the partitions in theV arc suppressing cylinder to and from engagement with the fixed contact.

'2. An electric circuit breaker comprising an insulator bushing having a closed bottom forming an oil tank, an insulated support for the insulator bushing, a casing secured in the top of the insulator bushing, a protective insulator cylinder suspended from the casing and positioned within the insulator bushing and extending downwardly from the top of the latter into the oil tank, an arc suppressingcylinder of lesser diameter than the protective insulator cylinder positioned Within the protective insulator cylinder and secured to the bottom of the latter and forming with same part of a main oil chamber, a fixed contact within the arc suppressing cylinder, means within the arc suppressing cylinder forming a series of separate oil lled arc suppressing chambers, an insulator cylinder of lesser diameter than the protective insulator cylinder suspended from said casing and positioned within the protective insulator cylinder in alignment with the arc suppressing cylinder forming with the protective insulator cylinder part of the main oil chamber I having a bottom with an aperture therein and with said bottom forming with the arc suppressing cylinder an oil gap as part of the main oil chamber, a movable contact reciprocably mounted adjacent the top of said insulator cylinder, guide means at the top of the insulator cylinder for said movable contact and forming with the bottom of the insulator cylinder an arc extinguishing chamber, and means within said casing for reciprocating said movable contact through the arc suppressing chamber, the gap between the insulator cylinder and the arc suppressing cylinder, and the oil lled arc suppressing chambers within the arc suppressing cylinder into and out of engagement with the xed contact whereby the insulating strength between the movable and fixed contacts is quickly restored upon the return stroke of the former by the arc being extinguished in the oil lled arc suppressing chambers within the arc suppressing cylinder, the gases emitted from the top of the arc suppressing cylinder being prevented from entering the arc suppressing chamber in the insulator cylinder as the movable contact is withdrawn through the aperture in the bottom of the latter by being dispersed in the oil gap between the insulator cylinder and the arc suppressing cylinder.

protective insulator cylinder positioned within4 the latter and secured to the bottom of the latter and forming with same part of a main oil chamber, means within the arc suppressing cylinder forming a series of separate oil nlled arc suppressing chambers, an insulator cylinder of lesser diameter than the protective insulator cylinder suspended from said casing and positioned Within the protective insulator cylinder in alignment with the arc suppressing cylinder forming with the protective insulator cylinder part of the main oil chamber and having a bottom with an aperture therein and with said bottom forming with the arc suppressing cylinder an oil gap as part of the main oil chamber, a movable contact reciprocably mounted adjacent the top of said insulator cylinder, guide means at the top of the insulator cylinder for said movable contact and forming with the bottom of the insulator cylinder an arc extinguishing chamber, and means within said casing for reciprocating said movable contact through the arc suppressing chamber, the

aperture in the bottom of the insulator cylinder,

the gap between the insulator cylinder and the arc suppressing cylinder, and the oil filled arc suppressing chamber within the arc suppressing cylinder into and out of engagement with the iixed contact whereby the insulating strength between the movable and fixed contacts is quickly restored upon the return stroke of the former by the arc being extinguished in the oil lled arc suppressing chambers within the arc suppressing cylinder, the gases emitted from the top of the arc suppressing cylinder being prevented from entering the arc suppressing chamber in the insulator cylinder as the movable contact is withdrawn through the aperture in the bottom of the latter by being dispersed in the oil gap between the insulator cylinder and the arc suppressing cylinder.

OTOYUKI TANGE.

SEIITI MORITA.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,155,814 Hewlett Oct. 5, 1915 2,227,134 Hara Dec. 31, 1940 2,475,765 Wallace et al. July 12, 1949`

Images