US3205331A

US3205331A - Pump means for an electrical switch with a liquid as an arc extinguishing medium

Info

Publication number: US3205331A
Application number: US134941A
Authority: US
Inventors: Thommen Hans; Buhler Karl
Original assignee: Bbc Brown Boveri & Cie
Current assignee: BBC Brown Boveri AG Germany
Priority date: 1960-09-01
Filing date: 1961-08-30
Publication date: 1965-09-07
Anticipated expiration: 1982-09-07
Also published as: NL268023A; GB925341A; CH384055A; NL121859C

Description

2 Sheets-Sheet 1 INVENTORS ATTORNEYS Hans Thommen KarL BU'hLer H. THOMMEN ETAL BY M J YS 1 Sept. 7, 1965 PUMP MEANS FOR AN ELECTRICAL SWITCH WITH A LIQUID AS AN ARC EXTINGUISHING MEDIUM Filed Aug. 30, 1961 p 7, 1965 H. THOMMEN ETAL 3,205,331

PUMP MEANS FOR AN ELECTRICAL SWITCH WITH A LIQUID AS AN ARC EXTINGUISHING MEDIUM Filed Aug. 30, 1961 2 Sheets-Sheet 2 :zauy M j 7W 45 M; azwg TWA INVENTORS Hans T/zommen ATTORNEYS United States Patcnt O 1 Claim. (Cl. 200-150) This invention relates to electrical switching devices and in particular to an improved switching device provided with oil quenching which is especially useful in the changing of transformer taps under load conditions. Because the tap changing is done under load conditions, the operating current must be transferred from one tap to the other through the switch which must, therefore, be designed to carry the. operating current. Moreover, as is known, currents appear during the tap changing operation since the winding part of the transformer between both taps is short-circuited at least through resistors. In order to obtain the necessary breaking capacity, a liquid, which is usually oil, is used as an arc quenching agent when the switch contacts are opened under load, and the switch contacts are thus arranged in a quenching chamber with the oil disposed therein. The switch contacts themselves must be opened at the greatest possible speed which is achieved by jump contacts.

It is known with respect to switches blown with compressed air that the compressed air can be generated by the switch motion itself. A piston with a cylinder is connected with the switching drive and air compressed by the piston is blown against the contacts.

The application of liquid for load switches used in tap changing has the advantage that the dimensions become smaller and the insulation path can be handled better.

In order to obtain a load switch with a high switcholf capacity and the least possible acceleration of masses, the present invention provides an arrangement wherein the movable contact member of the switch is mechanically connected with and surrounded by a movable hollow cylinder to which a valve is applied, this valve communicating with a liquid tank, and wherein the movable contact is rigidly fixed on the cylinder.

A preferred embodiment of the invention is shown on the accompanying drawings in which FIG. 1 is a view in vertical central section of the improved switch showing the switch contacts in closed position;

FIG. 2 is a view in half central section to the left of the center line of the switch showing the contacts in a position intermediate the closed and fully open position; and

FIG. 3 is a view similar to FIG. 2 but showing a half section to the right of the center line and with the contacts depicted in full open position.

With reference now to the drawings, the switch contacts are designated 4 and 5. Switch contact 4 is arranged to be actuated so as to effect opening and closing of the switch contacts, and this contact 4 is seen to be constructed in hollow form and shaped as a nozzle. Switch contact 5 is also movable, this contact being guided for its movement by a stem portion 5a thereof which slides in a sleeve 7a and being loaded int-o a position engageable with the other contact member 4 by means of a helical loading spring 12 surrounding the sleeve 7a, one end of this spring bearing against the contact 5 and the other end being fixed in position by abut- Patented Sept. 7, 1965 ment with the upper end wall of casing 7. The casing 7 also includes a cylindrical chamber wall 3 of insulating material which surrounds the contact members 4, 5. The lower end of the chamber wall 3 is connected to an annular part 1 supported upon a base plate 9 and the annular part 1 surrounds a hollow cylindrical part 2 which is secured to the movable hollow contact member 4. The annular .part 1 includes a semi-circular passageway 1a forming part of the passageway for oil flow to the contacts. An outer cylindrical wall 15 surrounds the cylindrical chamber wall 3 and the cylindrical parts 2 and 15 are secured to a transversely extending shaft 13 which, in turn, is secured to :a driving rod 8 which serves to impart an up and down movement to the concentric double cylinder constituted by the inner and outer cylindrical parts 2 and 15 which is involved in closing and opening the switch contacts 4, 5. The upper end of the outer cylinder 15 is turned inwardly to form a valve ring 10' which together with a movable ring of insulating material 6 forms the valve for the quenching liquid. As shown in the drawing, valve ring 6 surrounds chamber wall 3 and can move between a stop shoulder 11a formed at the lower end of an insulating sleeve 11 which surrounds the casing 7 and an abutment 14 which is secured to the inside of the outer cylinder wall 15. The cylinder space and quenching chamber are connected through the valve (6, 10) with an oil tank which has not been illustrated. This tank can, for example, be disposed directly on the transformer and surround the entire switch so that this lies entirely in oil.

Operation of the switch takes place in the following manner: If the switch contacts 4, 5 are closed and it is desired to open them to the position shown in the left half of the figure to change a transformer tap, the connecting rod 8 is moved downwardly thus carrying with it the outer cylinder 15, the inner cylinder 2 and the movable contact member 4 secured to the latter. Valve ring 10 former at the upper end of cylinder 15 is likewise pulled down and carries with it the movable ring 6. Simultaneously, it closes the cylinder space against the liquid tank. The oil contained in the cylinder space will be forced downwardly in the space between

cylinder walls

15 and 3, through passageway 1a and upward in the space between cylinder walls 2 and 3 to thus reach the position of contacts 4, 5. The fiow path of the oil is indicated by the arrowheaded line as shown in FIG. 2. Because of the oil pressure, contact member 5 will be forced upwardly against the counter action of spring 12 as shown in FIG. 2 and the electric are formed between the now separated contact members 4, 5 will be worked upon and extinguished. The oil can now flow back again into the oil tank through the hollow contact member 4.

To close the contact members 4, 5 the connecting rod 8 moves upwardly from the position indicated in FIG. 3 and contact member 4 engages the other contact member 5. The liquid oil for quenching the are on the next opening operation of the switch contacts is sucked into the hollow cylinder from the outside through the valve (6, 10) simultaneously with rising of the outer cylinder 15. The valve is open inasmuch as valve ring 10 goes upwardly and the mobile part 6 strikes the abutment 14. Spring 12 pushes firmly against the contact member 5 so that a very good and rapid closure of the contacts is obtained.

The advantage of the arrangement is an improved utilization of the quenching liquid and with need for very little space. Moreover, a very simple valve construction is provided using readily available parts. Another advantage of the improved construction is that one obtains a rapid and most efiicient opening of the contacts which can be powerfully accelerated without difficulty and provide a rapid change in the transformer taps.

We claim:

In an electrical switch 'of the type utilizing oil as an extinguishing medium for the are drawn between the switch contacts upon separation thereof, the combination comprising a first hollow contact member and a second contact member in axial alignment, spring means biasing said second contact member into, engagement with said first contact member when said contact members are engaged, a first hollow cylinder concentric with and secured to said first hollow contact member, a second hollow cylinder arranged concentrically with and surrounding said first hollow cylinder in radially spaced relation thereto to establish an annular oil chamber therebetween, a stationary annular member disposed between said first and second hollow cylinders and which establishes a wall for one end of said annular oil chamber, a stationary third hollow cylinder interposed concentrically in said. annular oil chamber intermediate said first and second hollow cylinders for dividing said chamber into inner and outer annular passageways for oil flow, means establishing Communication between said inner and outer annular passageways adjacent said stationary annular member, a valve ring located in said outer annular passageway adjacent the opposite end of said oil chamber, said valve ring being movable between a valve-closed position in contact with an inturned flange on said second hollow cylinder to close said opposite end of said oil chamber and a valve-open position separted from said inturned flange and in contact with an abutment located on the inside of said second hollow cylinder, and a, drive member secured to said first and second hollow cylinders for actuating said cylinders and also said first contact member simultaneously, said valve ring being shiftable from an open position to a closed position automatically upon movement of said first and second hollow cylinders and first contact member in the direction to separate said contact members and thereby force oil to flow from said outer annular passageway into and through said inner annular passageway into the gap between said contact members as they separate and thence through said first hollow contact member.

References Cited by the Examiner UNITED STATES PATENTS 2,442,010 5/48 Leeds et a1. -o 200150 2,781,435 2/57 Heilmann et a1 200--l 2,933,575 4/60 Baker 200 FOREIGN PATENTS 106,3 34 1/39 Australia. 671,326 2/39 Germany.

BERNARD A. GILHEANY, Primary Examiner.