US2283693A - Electric circuit breaker - Google Patents

Description

y 1 ,1 2 'w. E. PAUL' 2,283,693 ELECTRIC CIRCUIT BREAKER I Filed Feb. 29, 1940 His Attovneg.

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Patented May 19, 1942 ELECTRIC CIRCUIT BREAKER William E. Paul, Schenectady, N. Y., assignor to General Electric New York Company, a corporation of Application February 29, 1940, Serial No. 321,470 4 Claims. (01. 200-150) My invention relates to electric circuit breakers and more particularly to circuit breakers of the impulse type wherein a jetof oil or other suitable arc extinguishing liquid is projected across the are formed by opening the circuit.

An object of my invention is to provide an improved circuit breaker of the above mentioned type which will operate with a minimum of fire hazard. 7

Another object of my invention is to provide an improved circuit breaker of the above mentioned type which employs a minimum of liquid during the arceextinguishing operation.

A further object of my invention is to provide an improved circuit breaker which will open the circuit at a plurality of points during a half cycle of current.

' My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed outin the claims annexed to and forming a part of this specification.

In the drawing, Fig. l is a sectional side elevation of a porcelain bushing provided with. an embodiment of my invention; Fig. 2 is a'sectional side elevation of the central portion of the bushing illustrated in Fig. 1 which contains my improved circuit breaker arrangement; Fig. 3 is a side elevation in partial section of the bushing illustrated in Fig. l in a plane 90 degrees removed from that of Fig. 2, and Fig. 4 is an end elevation in partial section along the lines 4 4 of Fig. 2.

In the arrangement illustrated in the drawing I provide a circuit breaker unit with an interrupting chamber for the contacts filled with oil and an exhaust chamber which connects with the interrupting chamber adjacent the contacts, the exhaust chamber being only partially filled with oil, the remainder containing a compressible gas. Thus asthe contactsseparate,ahighvelocityjet of oil will be displaced from the interrupting chamber across the are into the exhaust chamber which is adapted to receive the displaced liquid, e

since it is partially filled with a compressible gas. When a plurality of units are employed according tomy invention, the circuit may be broken at a plurality of points in a half cycle of current.

Referring to the drawing, in Fig. 1 I have illustrated an electric circuit breaker of the impulse type having similar interrupting units In, H, l2, and [3. These units are connected in series in a circuit I 4, l5 and are mounted in a bushing l6 which defines a switch casing and is filled with any suitable arc-extinguishing fluid, such as oil. The current is conducted to the breaker units through-two similar metallic perforated tubular members I! and I8, which in addition act as a supporting arrangement therefor. As will be seen more clearly in Fig. 2, the tubular members I! and I8 are each provided at their inner ends with a flange member l9. suitable nonconducting material in turn clamp the circuit breaker units between the fianged tubular members. The flanged members are electrically connected to the adjacent units by means of straps 2| and 22. Each unit is in turn electrically connected in series with the adjacent unit by similar straps 23, 24, 25, as will be seen more clearly in Fig. 3.

Since each of my improved circuit breaker units H to [3 are equivalent it is deemed necessary to describe only one such unit.

In order to provide an arrangement for allowing the are produced by the separation of the contacts to be extinguished with the minimum of movement of arc-extinguishing liquid, I provide an interrupting or contactchamber 26 and an exhaust chamber 21. These chambers may be formed with walls of any suitable insulating material, The interrupting and exhaust chambers are adjacent each other and an interconnecting opening 28 is provided between these two chambers. This blowout opening may be divided into several sections by insulating barriers, if desired. In the interrupting chamber I provide relatively movable contacts 29, 30 adjacent the interconnecting passage 28, see Fig. 4. The relatively movable contacts, 29 and 30 are in turn carried by pivotally mounted contact bars 3|, 3'. respectively. These contact bars are biased toward each other by spring members 33 and 34 so that the contacts are normally in their closed position.

The contact bar 3| is electrically connected to the adjacent strap member by a bolt 35 and a pigtail 36. The contact bar 32 is similarly electrically connected to the contact strap adjacent to it. Since the interrupting units are placed in a bushing or container which is filled with oil, the interrupting chamber will be filled with oil or submerged therein while the exhaust chamber will be only partially filled, the remaining portion containing any suitable resilient cushion, such as an entrapped gas, such as air. Thus the bushing acts as a reservoir for the arc-extinguishing liquid. V

In order to provide an arrangement for actuating the contacts and for substantially simultaneously producing the jet or blast of oil across Bolt members 20 of r the contacts and into the opening between the interrupting and exhaust chambers, I provide pressure generating means, such as an insulating piston or displacer block 31. This actuating block is within the interrupting chamber and is adapted to move longitudinally thereof. This displacer block has a protruding portion 38, the corners of which are normally adjacent camming surfaces 39 and 40 on the contact arms 3| and 32 respectively. In order that the displacer block may displace the oil before it in the interrupting chamber, it is provided with extending portions 4| and 42 which are adapted to slide on the side walls of the interrupting chamber. The displacer block 31 is latched in the position shown in the drawing and is provided with a spring member 43 which is in compression when the block is so held by a stop 44. Thus, when the stop is moved the force of the spring member will actuate the displacer block quickly toward the contacts. This will cause the protruding portion 38 to abut against the camming sections 39 and 40, thus separating the contacts and sub stantially simultaneously causing a jet of oil to pass at a relatively high velocity over the point of separation and up through the opening 28. In order to provide an operating arrangement for the stop member 44 I provide a rod member 45 to which the stop 44 is attached. This rod member projects up through the center of the bushing and is accommodated by suitable openings in the interrupting chamber and displacer block. Since the exhaust chamber is annular in shape the rod may project through its center. Thus when it is desired to actuate the circuit breaker the rod member 45 is depressed. This action lowers the stop member 44 sufficiently to allow the displacer block 31 to move under the action of the spring member and thus ride on the inclined surface of the stop 44 toward the camming surfaces of the contact arms.

Any suitable number of circuit breaker units may be employed and in the illustrated embodiment of my invention I have used four such units of the type described above. connected in series in the line in which they are placed and are operated successively so that the current will be broken at a number of points on the alternating current wave. The time between successive breaks may be controlled by suitably placing the stops 44 on the operating rod, and in the arrangement shown the time necessary to actuate the circuit breaker units I0 to I3 is substantially a half cycle of 60 cycle current.

Thus, it will be seen if the circuit breaker unit II] is actuated after the current has passed through its zero value, the circuit breaker unit l2 will be actuated at the time the current is approaching its zero value, the opening of the final breaker I3 being effected with no current being broken.

In order to provide an arrangement for moving the operating arm 45 I provide a latch member 46 which normally holds the rod and the stop member 44 in operative position, that is with the contacts closed. Any suitable arrangement may be employed for tripping the latch member 46 and in Fig. 1, I have illustrated a relay 41 for actuating the latch 46. This relay is electrically connected to a bushing transformer as so that when excessive current passes through the bushing, sufficient current will be induced in the bushing transformer to actuate the relay ,5, which in turn unlatches the rod 45. This will allow the operating rod member 45 to move down- These units are wardly under the force of a spring member 49 which is held in compression during normal operation, that is when the contacts of the circuit breaker units are closed. The spring member 49 abuts against a stationary abutment 50 and a bracket member 5|. which is attached to the rod member 45.

The operation of my improved electric circuit breaker is as follows: Upon a condition of excessive current taking place the relay 4'! will unlatch the operating rod member 4'5, thus allowing it to move under the action of the spring member 49. As the operating rod member moves downwardly the stop 44 will move away from engagement with the displacer block 3?, allowing it to ride on the inclined surface of the stop. This will allow the displacer block to move longitudinally in the interrupting chamber, toward the contacts. As the displacer block 3'! rides on the inclined surface of the stop member 44 the protruding portion 38 of the spacer block will abut against the inclined surfaces 39 and 40, thus causing the contacts to separate. Substantially simultaneously with the separation of the contacts, oil will be forced at a relatively high velocity across the point of separation of the contacts and then up through the opening 28 into the annular exhaust chamber 32'. Since the exhaust chamber is only partially filled with oil, the gas which is above the oil will be easily compressed, thus allowing for the displacement of the oil jet through the opening 28 at a relatively high velocity. Furthermore, when a number of circuit breaker units are employed according to my improved arrangement, the oil will be displaced at a relatively high velocity, since each displacer block does not have to displace all the head of oil to the top of the bushing, because each interrupting chamber exhausts into an exhaust chamber in which there is a compressible gas. Thus, the hydrostatic pressure at the point of application of the blast to the arc is minimized. This result also obtains even though one unit is employed where the exhaust chamber is below the level of the arc-extinguishing liquid. The products of combustion caused by extinguishing the arc will pass through the opening 28. The formation of these gases will increase the gas pressure in the exhaust chamber, causing the level of the oil therein to lower a sufficient amount so that a portion of these gases may escape through a vent opening 52 which is below the normal level of the oil in the exhaust chamber and bushing. The top of the bushing may also have a vent. A very short time after the contacts in the breaker unit If! will have been actuated the contacts in the breaker H will be actuated. The time interval between the actuation of the contacts in unit IE] and unit H is merely dependent upon the time it takes their stop members to pass down below their respective displacement blocks. In like manner the remaining units will be actuated.

In view of the foregoing, it will be seen that I provide an electric circuit breaker which is adapted to operate at high voltages under severe operating conditions with a minimum of fire hazard. Furthermore, because I provide an interrupting chamber and a resilient cushion for the blast, such as a communicating exhaust chamber only partially filledwith oil, I am able to extinguish the arc with the movement of a relatively small amount of arc extinguishing fluid at a relatively high Velocity, since the gas above the oil within the exhaust chamber may be easily compressed. In order to provide an electric circuit breaker which will open the circuit as close to the zero value of current as possible, I employ a plurality of my improved circuit breaker units in an eflicient and simple manner. These units are superposed one on the other and placed in a bushing which is in turn filled with oil, the units being efiiciently operated by a rod which may be reciprocated. Of course, the units may be operated by any other suitable mechanism, the chambers taking the form of any suitable shapes. Thus, it will be seen that when a plurality of interrupting units are used according to my improved arrangement, the jet of oil may still be obtained at a relatively high velocity, since the displacer blocks do not have to move the entire head of oil in the bushing.

Although I have shown and described particular embodiments of my invention, I do not desire to be limited to the particular embodiments described and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An electric circuit breaker including relatively movable contacts, means forming an interrupting chamber and an annular exhaust chamber, said chambers being interconnected by an opening, said contacts being separable in said interrupting chamber substantially adjacent said opening, an arc-extinguishing liquid filling said interrupting chamber and said opening and partially filling said exhaust chamber, the remaining unfilled portion of said exhaust chamber containing a compressible gas, means including a piston for actuating said contacts and for simultaneously effecting a displacement of a portion of said liquid from said contact chamber over the point of separation of said contacts and through said opening into said exhaust chamber, said gas being compressed to allow said displacement of said liquid to occur at a relatively high velocity, and operating means for effecting movement of said actuating means including a rod member passing substantially through the center of said annular chamber and having a cam normally abutting against said piston, said cam being movable relative to said pistonupon movement of said rod so as to allow movement of said piston to cause actuation of said contacts and displacement of said liquid.

2. An electric circuit breaker including rela tively movable contacts, means forming an interrupting chamber and an inverted annular exhaust chamber above said interrupting chamber, an arc extinguishing liquid in which said chambers are immersed, said chambers being interconnected by an opening, said contacts being separable in said interrupting chamber substantially adjacent to said opening, arc-extinguishing liquid substantially filling said interrupting chamber, said exhaust chamber being below the level of said arc-extinguishing liquid and having a gas cushion, a displacer member having resilient means for separating said contacts, cooperable surfaces on said member and said contacts, said member while separating said contacts also causing a blast of liquid through the,

gap formed upon separation of said contacts and through said opening into said exhaust chamber, said gas cushion being compressible so that back pressure due to the head of liquid above the point of separation of said contacts is minimized, and means for biasing said displacer means to the initial position for permitting closing of said contacts.

3. An electric circuit breaker of the liquid blast type comprising an insulating casing containing an arc-extinguishing liquid, an arc-interrupting chamber immersed in said liquid within said casing, relatively movable contacts separable to form an arc gap in said chamber a material distance below the level of said liquid, pressure means in said casing for causing a blast of said liquid from said interrupting chamber transversely across said are gap and through an exhaust opening to interrupt arcing upon separation of said contacts, and a resilient cushion immersed in said liquid and disposed immediately above said exhaust opening exteriorly of said are interrupting chamber thereby] to provide less resistance within said liquid to said blast so that said liquid blast can fill the space between said contacts at high speed.

4. An electric circuit breaker of the liquid blast type comprising an elongated vertically positioned insulating casing containing an arcextinguishing liquid, a plurality of interrupting units in substantially vertical alignment in said casing, each of said units including relatively movable contacts separable to form an arc gap in said liquid, pressure means in said casing for causing a blast of said liquid transversely across each of said arc gaps, and a plurality of resilient cushions immersed in said liquid, each cushion being disposed immediately above the exhaust end of a corresponding liquid blast so that said cushion is compressed by the liquid blast thereby to provide less resistance within said liquid to the rapid movement of said blast through the respective arc gap.

WILLIAM E. PAUL.

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