US2102768A - Liquid break circuit breaker - Google Patents

Description

21, 1937. H. TRENCHAM ET AL LIQUID BREAK CIRCUIT BREAKER Filed Jan. 7, 1956 Inventors: Henrg Tr encham,

Harold E. "ox,

T eh Attorneg.

Patented Dec. 21, 1937 UNITED STATES PATENT OFFICE Cox, Dollia IIiILIandemEngIanQaIignoI-I to General Electric Company, a corporation of New York Application January 1, 1m, Serial No. sun In Great Britain January 7, 1935 4 Claims. (Cl. 200-15.)

The present invention relates to liquid break circuit breakers of the impulse type, i. e., in which during separation of the contacts a positive flow of insulating liquid is produced between the con- 5 tacts by means of a piston moved simultaneously with the contact separation whereby the are formed when the breaker is interrupting a current is extinguished. In such a device the amount of energy used must be large when it is required to interrupt heavy currents. The pressure applied to the piston must be suflicient to accelerate the necessary volume of liquid to the requisite velocity and to do this against any back pressure which may result from gas formation at the contacts.

The present invention has for its object the improvement of circuit breakers oi this kind by either reducing or compensating for the pressure set up by the formation of gas when interrupting a heavy short circuit.

The invention is particularly concerned with circuit breakers of the kind wherein the :arc, between cooperating contacts when interrupting circult, is drawn in a closely restricted,space.surrounding the contacts, and a jet of oil is forced transversely across the path of the arc.

Our invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize our invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In the accompanying drawing are shown constructions embodying the invention, Fig. 1 being a transverse section through one form of the invention and Figs. 2, 3 and 4 representing sections of alternative constructions.

Referring to Fig. 1, there is illustrated an outer casing l supporting through an insulator I a housing I containing the fixed contact 4, the hous ing being in part supported from a second insulator I through which the lead to the fixed contact is brought through the wall of the casing l. A second contact I is supported on an insulator I similarly mounted to insulator I on the upper wall of the casing I, and forms the other terminal of the circuit breaker. Contact is made and broken between contacts 4 and I by means of a moving rod I which slidably engages the contact I and is moved into and out of engagement with the contact 4 by a horizontal motion brought about by a linkage enclosed in the spherical extension I of the casing I, the extension I being attached to the casing through an intermediate cylindrical member II.

The housing 8 enclosing the fixed contact 4 provides a cylindrical portion II which is open at the right-hand end to the inside of the housing I and within which reciprocates a piston II attached through an insulating rod II to the linkage in the spherical extension I. The left-hand end of the housing I is closed by a pair of spaced insulating plates I4, II, which provide an aperture II through which the contact rod I is moved to engage the contact 4. The passageway ll between the plates l4, II communicates through an aperture II in the plate l4 with the left-hand side of the piston II.

Between the outer face of a removable arcing tip it of the contact 4 and the adjacent face of the insulating plate I4 is a venting passageway 20 which, it will be noticed, is in communication with the face of the piston it within the housing 3.

Thus the cooperating pair of contacts may consist of a rod contact moving axially in a closely fitting cylindrical space and engaging with a socket contact situated at one end of the cylindrical space, the are being subjected to the action of a transverse jet of oil introduced by openings in the walls of the cylindrical space, conveniently situated forthe purpose and communicating with the cylinder and piston, and with a venting space respectively.

In such a circuit breaker it will be seen that gas formed by the action of the arc will have the eliect of tending to plug up the venting hole for the oil jet and to build up a back pressure against which the piston must act to force oil across the arcing space.

An electric circuit breaker of the impulse type according to the invention has the moving contact withdrawn from engagement with the fixed contact through an aperture formed in a pair of spaced transverse members, the space between which forms a passageway into which the insulating liquid is forced by the piston during the circuit opening movement, a venting passage being provided for permitting the escape of gas from the space immediately adjacent the fixed contact. The venting passage may be in communication with the side of the piston remote from that which provides the pressure in the insulating liquid for forcing it through the passageway. Alternatively, the venting passage maybe in communication with an expansion chamber or may be provided in the fixed contact itself.

When the contact rod I is moved in circuit opening direction to the left from the position shown in chain lines in which it is in engagement with contact 4, the piston II is moved simultaneously in the same direction, thus providing a flow of insulating liquid such as oil with which the casing I is filled and a jet of oil is expelled through the pamageway I'l across the path of the are formed between the contact 4 and the rod 8, thereby extinguishing the arc. The purpose of the passageway 20 is to ensure that the bubble of gas which is formed by the vaporization of the insulating liquid due, to the heat of the arc does not provide a back pressure tending to stop the jet of liquid since the gas can escape through this vending passage and provide a pressure on the side of the right hand piston which assists the piston in providing the flow of oil. A bleeder aperture may be provided in the top of the housing 8 to enable it to refill with oil after a circuit opening movement has been made.

The circuit breaker has been illustrated with the contact movement in a horizontal plane, but it is to be understood that it may equally well. and preferably is, arranged to operate with a vertical axis of contact separation. The description herein given will apply mutatis mutandis to either arrangement.

The linkage which causes movement of the contact rod 8 and the piston l2 will now be described. A transverse shaft 2| journalled in the wall of the extension 9 carries an arm 22 and is provided externally with an operating handle which may be actuated manually or otherwise. The crank arm 22 is pivotally connected to an adjustable link 28 which is, in turn, pivoted to a lever 24. At the lower end, lever 24 is pivotally connected intermediate the ends of a link 25 which is'pivotally mounted at its upper end at a fixed fulcrum 28 and is linked at its lower end near the middle of a link 21 which is pivotally connected at 28 to the contact rod 8. At its upper end the lever 24 is pivotally connected to a floatinglever 29 which is in turn loosely connected to the insulating rod l3 which actuates the piston i2. A pin 30 at the lower end of link 21 works in a slot in floating lever 28 which has the movement of its upper end controlled in one direction by an abutment II.

The linkage is shown in the position in which the operating shaft 2| has been rotated counterclockwise so as to extend spring 32 which biases the piston l2 to the left and it will be noted that further rotation counterclockwise of shaft 2| will cause lever 24 to rotate link 25in a counterclockwise direction, thereby rotating the link 21 clockwise and moving rod 8 to the right to cause contact engagement. This movement will extend biasing spring 33, which biases the contact rod 8 in a circuit-opening direction. The breaker is now closed and the contact rod 8 is biassed in the circuit opening direction and the piston I2 is similarly biassed in a direction to cause the desired flow of oil across the arc formed when the contacts separate. Rotation of shaft 2| will be afiected to such an extent that crank arm 22 and link 23 will become slightly overset so as to hold the breaker in the circuit closed position. On rotating shaft 2| in a clockwise direction, the linkage will be released and the springs 32 and 33 will cause the movement of the piston l2 and contact rod 8 in a direction to the left, thereby opening the breaker contacts and extinguishing the arc.

Fig. 2 shows a modification in which the jet of oil is produced by the piston l2 being located below the fixed contact 4 and the jet of oil being produced vertically upwards through the passageway II. The head of oil which resists the fiow of oil through the passage i1 is thus reduced, the normal oil level being somewhat above the contact 4. In this modification, also, the venting passage 20 communicates with an expansion chamber 84 which is mounted at the upper side of the housing 8 and is mainly above the oil level. The expansion chamber 84 is provided with a bleeder aperture 84, which allows air to enter the expansion chamber and permits any oil which may have been forced therein by the pressure of the gas to drain out of the expansion chamber.

In Fig. 3 is shown a further modification in which contact separation takes place in a vertical direction and in which the venting passage 20 communicates with a passage 88 formed in the wall of the housing 8, the other details of the arrangement remaining mainly as described inconnection with Fig. l.

In Fig. 4, which is a further modification, the venting passage is provided by making the fixed contact 4 hollow so that gas can escape directly through the passage in the centre of the contact.

'Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed we declare that what we claim is:

1. An electric circuit breaker of the impulse type comprising means forming a chamber containing an arc-extinguishing liquid, relativelymovable contacts separable within said liquid, one of said contacts movable through a wall of said chamber, means forming a passage transverse to the path of said movable contact, a piston, one side of which is in communication with said chamber and the opposite side with said passage and actuating means for biasing said piston in a direction to cause a blast of arc-extinguishing liquid through said transverse passage and across the are formed therein, the arc pressure generated in said chamber also acting on said one side of said piston so as to aid said transverse last.

2. An electric circuit breaker of the impulse type comprising means forming a chamber containing an arc-extinguishing liquid, relatively movable contact structure separable within said liquid, said contact structure also adapted to draw an arc exteriorly of said chamber, means forming a passage transverse to said arc, a piston, one side of which is in communication with said chamber, and the opposite side with said passage, and an actuating spring for biasing said piston in a direction to cause a blast of arc-extinguishing liquid through said transverse passage and across said are, the arc pressure generated in said chamber also acting on said one side of said piston so as to aid said transverse blast.

3. An electric circuit breaker of the impulse type comprising a casing forming an arc chamber containing an arc-extinguishing liquid, relatively movable contact structure separable within said liquid, said contact structure also adapted to draw an arc exteriorly of said chamber, insulating structure forming a passage transverse to said arc, a piston mounted for reciprocal movement within said casing and arranged so that one side of said piston is subjected to the arc pressure generated in said chamber, and the opposite side is in communication with said passage and actuating means common to said contact structure and piston for causing circuit opening, movement of said contact structure and operation of said piston in a direction to cause a blast of arcextinguishing liquid through said transverse passage and acrossthe arc, the arc pressure generated in said chamber and acting on said one side of said piston also aiding said transverse blast.

4. An electric circuit breaker of the impulse type comprising an arc chamber containing an arc-extinguishing liquid, relatively movable contact structure adapted to draw an are upon opening of the circuit within and exteriorly of said chamber, means forming a passage transverse to the exterior portion of said arc, a piston for driv- 10 ing a blast of arc-extinguishing liquid through said passage for interrupting said are, and actuating means for said piston, said piston being subject at one side to pressure generated in said are chamber and being in communication at the opposite side with said passage whereby the arc pressure generated in said chamber tends to sustain said arc-extinguishing blast.

HENRY TRENCHAM. HAROLD ERNEST COX.

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