US2650972A - Bushing type circuit interrupter - Google Patents

Description

(i. Haus/v fzs Sepi- 1, 1953 MAsATosHl KUWAYAMA 2,650,972

BUSHING TYPE CIRCUIT` INTERRUPTER Filed March 14, 1951 2 Sl'leecs-Sheefl l INVENTOR. 745A falsi/f gwn/HMH BY l X4/vm,

Patented Sept. 1, 1953 UNITED STATES PATENT OFFICE Masatoshi Kuwayama, Taga, Japan, assignor to Hitachi Limited, Tokyo, Japan Application March 14, 1951, Serial No. 215,504 In Japan April 28, 1950 3 Claims.

This invention relates to an improvement in bushing type circuit breakers, and more particularly to a special construction and arrangement of the arc extinguishing cylinder of the circuit interrupter comprising a plurality of circuit interrupting points arranged in cataract stages, and its object is to provide an electric circuit interrupter having positive and quick arc extinguishing ability in opening the circuit.

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

In the accompanying drawing forming a part of this specication:

Fig. l is a sectional elevation of a bushing type circuit interrupter as an embodiment of this invention showing the parts at the circuit open condition,

Fig. 2 is a sectional elevation of main parts of the bushing type circuit interrupter shown in Fig. l at the closed position, and

Fig. 3 is a sectional elevation similar to Fig. 2 at an intermediate state of circuit opening operation.

Referring to the drawing, I represents an insulator bushing forming an oil tank which is xed on a closed metallic casing 2 supported on post insulators (not shown) to be insulated from the ground. 3 represents a lever xed to an actuating shaft 4 oi the circuit interrupter, which passes through the wall of the metallic casing 2 with oil tight packing and is arranged to be operated from the outside of the casing. 5 represents a link pivoted intermediate of its ends to the end of the lever 3 and at its one end engaging a guide groove yg provided in the casing 2 and at the other end connected to a cross head 6. I represents a movable contact and 8 designates a push rod, these members being fixed to the cross head 6 and projected upward. 9 represents a guide member for the members 'I and 8; and I0 represents the lowest fixed contact serving also as a guide.

I I represents an upper metallic casing xed on top of the bushing I, and I2 represents the oil level. I3 represents a metallic terminal member which is fixed to the upper casing I I and has an arc extinguishing cylinder I4 xed to and suspended from its lower end. The inside of the arc extinguishing cylinder I4 is divided into at least three separate oil chambers A, B and C by means of the partitions I5 and I6. In the lowest oil chamber C, there is formed an arc suppressing chamber I'I which has zig-zag inside surface and .oil outlet holes I8 and oil inlet holes I9. 20 represents an intermediate arc extinguishing xed contact secured to the partition wall Iii. 2l represents an upper stationary Contact fixed to the upper wall of the oil chamber A, and 23 represents an intermediate stationary contact xed to the lower Wall of the chamber A beneath the contact 2| and an arc suppressing chamber Z2 is formed between the contacts ZI and 23 enclosing the arc passage of these contacts. 2:. is an intermediate movable contact which passes through the partition walls I5 and Iii to cooperate with the contact 23 and is held normally in an open lowered position by a spring 26 acting on its collar 25. 21 represents an insulator or insulated rod xed to the lower end of the intermediate movable Contact 24 and extended into the lower oil chamber C, and the rod 2 is covered by an insulator cylinder 23.

Oil chambers A, B, and C are communicated through holes h. In the upper oil chamber A, an arc inducing electrode 29 is projected adjacent to the arc suppressing chamber 22 and a gas blowoi valve 3@ is fitted to the top wall of the oil chamber A. 3| designates a cylinder of an oil jet device provided for the top Wall of the oil chamber A above the pressure generating contact 2 I. 32 is a piston slidably fitted in the cylinder 3l and acted upon by a spring. 33 represents a piston rod xed to the piston 32 and projecting through the pressure generating contact 2 I.

The arc extinguishing cylinder It is entirely surrounded by a protective insulator cylinder 3d which is secured to a part of the upper metal casing I I by means of metal pieces 35 and suspended therefrom into the bushing I. The cylinders I4 and 34 have holes 33 and 3l in their bottom walls for passing therethrough the movable contact 'l and the push rod 8 respectively. G1 represents an insulating liquid between the bottom of the arc extinguishing cylinder I4 and the lower Xed contact I0.

Fig. 1 illustrates a condition when the circuit breaker is open. In order to close the circuit breaker, the operating shaft 4 should be turned clockwise, thereby turning the lever 3, then the link 5 is shifted to raise the cross head 6 vertically. By the vertical upward movement of the cross head 6, the movable contact 'I is moved into the arc suppressing chamber I'I through the holes 35 and is made to contact with the intermediate stationary electrode 2i), while the push rod 8 enters into the insulator cylinder 28 through the holes 3i' and engages the lower end of the insulator rod 2l and moves the latter upwards so that the top end of the intermediate movable contact 24 is forced into the pressure generating contact 2l. Meanwhile the piston rod 33 is pushed up by the top end portion of the movable contact 261 to move the piston 32 upwards and the oil is sucked into the cylinder. Such closed condition of the circuit breaker is shown in Fig. 2, wherein the electric path is established from the upper metal casing and the metallic terminal piece i3 through the upper stationary contact 2 l, the intermediate movable contact 24, the intermediate stationary contact 23, the metallic partition walls l5 and i6, the intermediate stationary contact 2t, the movable contact l, the lower xed'contact lll and the guide metal piece il leading to the lower metal casing 2.

The opening of the circuit breaker is eiected by turning the operating shaft 4 to the counterclockwise direction, thereby quickly forcing down the movable contact 'I and the push rod 8 by the aid of snap spring and the like means (not shown). Upon the downward movement of the members 'l and B, the pressure generating movable contact 24 is moved downwards by the action of the accelerating spring 25 following the downward movement of the push rod 8 and opens the contact with the upper stationary contact 2| and also the movable electrode l opens the contact with the arc extinguishing contact 20, thus eiecting so-called series interruption.

Fig. 3 illustrates an intermediate condition of the circuit opening operation of the present circuit breaker showing the arcs developed'between the cooperating contacts when they are opened. At first, an arc is generated between the pressure generating contacts -2| and r213 producing the pressure by the pressure generating arc, but such are, in case of cutting off a vsmall current, is shifted toward the arc guiding electrode 29 located outside of and adjacent to the arc suppressing chamber 22 by the oil jet caused by the downward movement of the piston 32 and the length of the arc is increased as shown by a2 and the arc decomposes a suincient amount of oil, thereby raising the vapour pressure and forces the fresh oil inthe chamber B into the arc suppressing chamber l'i which encloses the lower contact points andthe arc generated between the contacts 20 and "l is subjected to the oil current and blown laterally out of the passages I8 inducing cooling oil to iiow through the passages I9 and the arc extinguishing action is accelerated. The arc extinguishing oil current, as it consists mainly of a fresh oil in the chamber B,has a high ability of arc extinguishing. Meanwhile the arc generated between the upper Contact points is subjected to the powerful arc extinguishing action so that the arc may be extinguished before the top end of the movable contact l is pulled out of the lower part of the arc suppressing chamber il and the circuit is completely interrupted.

Thus after the arc has been extinguished, the top ends of the movable contact 'i and the push rod 8 respectively are brought to the lowest position through the oil layer G1, the bottom of the protective insulator cylinder I4 and the oil layer G2, and are rested at the circuit open condition as shown in Fig. 1. The gases remaining in the arc extinguishing chamber after the completion of circuit opening operation are exhausted upwards through the blow-off valve 30 -provided in the top wall of the chamber A and the are suppressing chamber is lled with fresh oil.

According to the present invention, the internal members in the arc extinguishing cylinder 4 can be made comparatively simple and the arc extinguishing cylinder can easily be inspected by lifting it up out of the protective insulator cylinder.

Owing to the arrangement of the movable pressure generating and arc extinguishing contacts to move in the same direction relative to the cooperating stationary contacts respectively, the time of opening these contact points can be adjusted by adjusting the movable contacts and the action of oil current caused by the arcs generated at these circuit interrupting points can be selected to be most effective for extinguishing the arc.

The further advantage of this invention is to remarkably improve the circuit interrupting properties of circuit breakers by moving the movable contact and the push rod downwards through the insulating oil layers G1 and G2 resulting in so-called oil interrupting eiect.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a bushing type electric circuit interrupter, in combination an insulator bushing, an are extinguishing cylinder suspended in said insulator bushing, said kare extinguishing cylinder being divided into at least three successive superimposed compartments communicating through small holes, a pressure generating stationary contact fixed on the top wall of the upper compartment thereof, a second stationary contact fixed to the bottom wall of said upper compartment, a pressure generating movable contact member passing through said second contact cooperable with said pressure generating stationary contact, said movable contact being normally biased by a spring into a downward position out of engagement with said pressure generating stationary contact, an arc extinguishing stationary contact xed to the top wall oi the lower'compartment on a vertical line spacedfrom the vertical axis of the contact member, a second movable contact member cooperable with said arc extinguishing stationary contact, an Yinsulated push rod for actuating said pressure generating movable contact member, a cross head to which the lower ends of said second contactmember and said push rod are xed uprightly and with a predetermined distance betweenthem, a guide member xed to the bottom portion of said bushing and having a fixed guide contact and aguide for said second contact member and the push rod respectively, and means for operating the cross head in vertical-up and down directions.

2. A bushing type electric circuit interruptor, comprising an insulator bushing, an arc-extinguishing cylinder suspended in the `insulator bushing, said bushing and said cylinder vcontaining insulating liquid, said arc extinguishing. cylinder being divided into at least-three consecutive chambers by partitions and communicating together through holes in the partitions, a :pressure generating stationarycontact xed to the top wall of the uppermost chamber, a combination stationary lContact and guide xed to the partition of the bottom of the uppermost chamber, a pressure generating-movable contact member for engagement with said stationary contact passed slidably through` said contact and guide and normally biased by a spring to a position out of contact with said stationary contact, an arc extinguishing chamber provided in the uppermost chamber arranged to enclose the pressure generating staticnarycontact, an oil jet/device having a piston acted on by a spring mounted on said cylinder, said piston having a piston rod passing through the pressure generating stationary contact to inject the insulating liquid into the arc extinguishing chamber, an arc extinguishing contact mounted Within the lowermost chamber of said arc extinguishing cylinder, a movable contact member cooperable with said arc extinguishing contact, a guide contact supported below said cylinder in alignment with said arc extinguishing contact, an arc suppressing chamber Within said lowermost chamber surrounding the arc path of the last mentioned cooperating contacts, a push rod arranged to force up said pressure generating movable contact member, a guide frame xed to the bottom end of said bushing and supporting said guide contact and guide for said movable contact member and said push rod respectively the lower ends of which are secured to a cross head, a moving link mechanism for operating said cross head in vertical up and down directions, and a protective insulator cylinder Within said bushing and surrounding said arc extinguishing cylinder.

3. In a bushing type electric circuit interrupter having an upper metallic terminal member, an arc extinguishing cylinder secured to and suspended from the terminal member, spaced partitions within said cylinder dividing it into three superimposed chambers, said partitions having holes providing communication between said chambers, the middle one of said chambers being a reservoir for fresh insulating liquid for extinguishing an arc, a pair of stationary contacts supported within the top and bottom chambers of said cylinder, arc suppressing chambers within the top and bottom chambers for the respective contacts and enclosing their are passages, an intermediate movable contact rod supported by said partitions to be engageable with the contacts of the top chamber when raised and having a downwardly extended rod of insulation material, a spring operating between a iixed part of said contact rod and one of said partitions holding said contact rod out of engagement with the contact of the top chamber, an oil jet cylinder xed to the top of said arc extinguishing cylinder above the contact of the top chamber, a piston slidably positioned within said jet cylinder and having a portion extended into the contact of said top chamber to be raised by said contact rod when lifted into engagement with the contact of the top chamber, a blow-oir valve for residual gases mounted in communication with the top chamber or" said arc extinguishing cylinder, an oil filled bushing enclosing said arc extinguishing cylinder, a protective insulator cylinder extended into said bushing and enclosing said arc extinguishing cylinder and being apertured to receive oil from said bushing, an arc extinguishing movable contact rod for engagement with the contact of the bottom chamber, a push rod for raising said intermediate movable contact rod into engagement with the contact of the top chamber, a stationary contact for guiding the arc extinguishing movable contact rod, a guide member for said push rod, a cross head secured to the lower ends of said arc extinguishing contact rod and said push rod, means for raising said cross head vertically to raise and lower said arc extinguishing contact rod and said push rod so that the top end portions of said arc extinguishing rod and said push rod will be contacted by the fresh liquid in the bushing in the fully lowered position of said cross head, said means comprising a link pivoted at one end on the cross head and held at its other end to move along a xed slot, a lever secured at one end to an operating shaft and pivotally secured at its other end to said link, and a metallic casing having a closed bottom secured to the bottom of said bushing and insulated from the ground and enclosing the cross head, link and lever, said metallic casing being filled with an insulating liquid.

MASATOSHI KUWAYAMA.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,412,858 Baker et al Dec. 1'7, 1946 2,422,569 Leeds June 17, 1947 2,470,611 Friedrich May 17, 1949 2,530,952 Fry Nov. 21, 1950

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