US2219171A - Electric circuit breaker - Google Patents

Description

OGL 22. 1940- G. BALAcHowsKY ELECTRIC CIRCUIT BREAKER Filed July 10. i939 Inventor Geer-geg Balachowskg,

Hisl Attorney.

Patented Oct. 22, 1940 UNITED STATES ELECTRIC CIRCUIT Bauma Y Georges Balachowsky, Paris, France, assigner to General Electric Company, a corporation of New York Application July 10, 1939, Serial No. 283,684

' In France July 25, 1938 This invention relates to electric circuit breakers, and more particularly to circuit breakers oi the fluid blast type.

It is an object of this invention to provide a circuit breaker of the above type which provides for rapid separating movement of the switch contacts and which is characterizedin its operation by substantial freedom from re'- striking of the arc after it has once been exm tinguished. 1 l

It is another object oi the invention to provide a simple and compact construction which provides for a more effective use of the .arc-extinguishing iluid as a pressure medium for ac- ;'5 tuating the movable contact of a circuit breaker.

Further objects and advantages of the present invention will become apparent as the following description proceeds, reference being had to the accompanying drawing in which the singie ilgure is an elevational view in section of a Icircuit breaker embodying the invention.

In the particular arrangement illustrated in the drawing the invention is shown embodied in an oil circuit breaker of the cross-blast type.

It will be apparent as the following description proceeds that many features of the invention are not limited to such a circuit breaker and are capable of general application.

Referring to the drawing, the circuit breaker comprises a cylindrical housing ywhich may be made up of a plurality of hollow insulating bushings Iil, secured together in any suitable way and mounted on a base Il which houses a suitable switch-operating mechanism (not shown). The cylindrical vhousing contains a quantity o! suitable insulating uid. such as oil, vthe level of which is indicated by the dotted line I2. The upper end of the switch housing is closed by a cap member I2 which is provided at thetop o with suitable vent openings Il to provide for the escape of gases'liberated during the circuitinterrupting operation of the switch.

An electric circuit through the switch is completed in the closed circuit position thereof through a stationary contact Il', a movable con- Atact il, wiping contact I1, a hollow conducting rod Il and a wiping contact Il. Lead-in conductors 2l are brought into -thehousing at longitudinally spaced points and connected to the fixed contact II and wiping contact I2, respectively. Suitable sealing rings 2| are provided at the ends o! theinsulating bushings to secure them together and'seal the housing to form a4 nuidtight receptacle. The n ed contact il is u supported near the upper end ot the housing and concentrically therewith by any suitable means such as a spider 22 which may be formed as an integral part of the associated lead-in conductor. 'I'he conducting rod I8 and the movable Contact I6 form a two-part movable contact 5 structure which is connect d to an operating mechanism (not shown) -by'n insulating rod 22 coupled to the end 'of the conducting rod and extending into the switch-operating vmechanism housing. 10

The movable contact I 6 is in the form of a rod having a piston 24 on the inner end thereof lying within the hollow rod Il which forms a cylinder in which the piston 24 is adapted to reciprocate. The contact i6 formsa continuation l5 of the rod I8 and is normally biased to extended relationship with respect thereto by a helical compression spring 25 which is housed within the hollow rod between the piston 2l and a shoulder 28; 'I'he electrical circuit between the contact 80 I6 and rod I8 is made through the wiping contact I1 which is mounted in the upper end of the rod. Ports 21 formed in the wall of the hollow rod il permit iiuid to act upon the upper face of the piston 24 to Ir'nove it relative to the rod against the bias of the helical spring 25. Ports 28 in the lower end of the rod permit the escape of iluid from the lower side of-the piston 2l.

In accordance with the present invention a 80 compact and novel arrangement is provided for exerting a pressure on the arc-extinguishing tluid in proximity .to the piston 24 and in the region of separation of the contacts to actuate the movable contact I6 and direct a uid blast across 25 the arc drawn between the contacts. A cylinder 22 o! insulating material is mounted on a supporting spider 30 which extends across the switch housing. The spider also forms a support for the wiping contact Il and may, as il1ustrated,.4n be formed as an integral part oi the lead-in conductor associated therewith. The cylinder extends upwardly into the housing and cooperates 'with a hollow piston 2i also of insulating material which is carried by and is movable in 4:, unison with the hollow rod Il. The piston 2l is secured to the4 rod by a spider 22 which extends across the vlower end of the piston and by a block o! insulating material 22 which partially surrounds the upper end of the rod. The block is preferably formed asan integral part of the piston 2i. The interior of the piston Il and cylinder 2l form a compression chamber 24 which communicates with the interior of the cony ducting rod through the ports 21 and with the 55 surrounding housing through a blast passage 35 which extends across the path of the movable contact and is provided at its outer end with arc-splitting vbaiiles et of insulating material. The movable contact closes the blast passage 3@ in the closed circuit position of the circuit breaker.

In the closed circuit positior` of the circuit breaker described above, the parts are in the relative positions shown in the drawing and a circuit is completed between the lead-in conductors 2@ through the relatively movable contacts i5 and it as previously described. 'Upon the occurrenceof abnormal conditions the operating mechanism of the switch `(not shown) is moved to exert a downward pull on the hollow conducting rod it. At this moment the compression chamber 313 is substantially closed since the movable contact il extends across the blast passage and cuts 01T communication between the interior of the piston Si and the remainder of the switch housing. The' pressure caused by the downward pull on the conducting rod forces fluid into the interior of the rod through the ports 21 and forces the piston 2i and the movable contact it downwardly. As the liquid passes into the interior of the rod the insulating piston 3i also moves downwardly'so that the movable contact itself is subjected to two movements which are additive, that is, the movement of the hollow rod relative to the i'lxed contact and the movement of the movable contact relative to the hollow rod. This feature provides for fast opening movement at the start of the circuit-interrupting operation and insures that the distance between the xed and movable contacts required to prevent restriking is obtained in a very short time. 'I'he movable contact is proportioned relative to. the upper end of the piston 3l of insulating material so that it is withdrawn from the blast passage at substantially the time that the xed and movable contacts have separated suiciently to prevent restriking. At this time the blast of fluid acts upon the arc drawn between the contacts'during separation and forces it into the passage 35 where it is lengthened and nally interrupted. The downward movement of the piston .3l maintains pressure on the piston 2l even after the blast passage is opened by the withdrawal of the movable contact i6. When the downward movement of the hollow rod is completed and with the blast vpassage open the movable contact I6 will immediately start its closing movement under the influence of the compression spring 25. In order to open the circuit permanently before closing movement of the contact I6 is initiated, a disconnecting switch may be provided and operated in timed relation with the opening movement of the circuit breaker contact. The disconnecting switch may be incorporated in the same housing with the circuit breaker contacts, or furnished as a separate unit which is either mechanically or electrically connected to operate in timed relation with the circuit breaker contacts.

From the preceding description it is apparent that the present construction provides an ary rangement for rapidly operating the movable contact of an electric circuit breaker by a mecha- `nism which subjects the movable contact to two the piston 3! to cause movement of the contact l@ and consequently the system is characterized by small inertia forces and correspondingly rapid accelerations.

The present invention is well adapted for use in circuit breakers of the reclosing type because it insures a high operating speed. In such a construction it is necessary to arrange the disconnecting switch in such a manner that it will operate only after the desired number of reclosures have occurred.

While the invention has been shown and described in connection with an oil circuit breaker of the cross-blast type, it is apparent to those skilled in the art that many of the features oi the invention are applicable to breakers employing other arc-extinguishing :uids which are directed in different relation to the arc, and it is intended in the appended claims to cover all modifications falling Within the true spirit and scope of the invention.

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

l. An electric circuit breaker comprising a housing having a body of insulating uid therein, a xed contact and a movable contact mounted in said housing and separable to form an electric arc, said movable contact comprising two relatively movable parts one of which is connected to a switch-operating mechanism and the other of which engages said xed contact in the closed circuit position of said circuit breaker, and means movable by said one part when moved toward open circuit position to force a portion of said uid against a surface of the other part of said movable contact to cause relative movement therebetween in a direction to increase the speed of separation of said ixed and movable contacts.

2. An electric circuit breaker comprising a fixed contact, an operating member having a contact portion movably mounted thereon and normally biased to extended relation therewith in the closed circuit position of said breaker, said contacts being separable to draw an electric arc, and means operable by movement .of said member in a direction away from said xed contact to move said contact portion relative to said member in the direction of movement of'said 'member whereby the speed of separation of said xed and movable contacts is increased.

3. An electric circuit breaker comprising a housing having a body of insulating Vfluid therein, a xed contact and a movable contact mounted in said housing and separable to form an electric arc, said movable contact comprising two relatively movable parts one of which is connected to a switch-operating mechanism and the other of which engages said xed contact in the closed circuit position of said circuit breaker, a piston secured to said one part and a cylinder cooperating therewith to form a compression chamber, said piston being movable with said one part of said movable contact and eiec- `tive to force said liquid against a surface of the other part of said movable contact to move said parts relative to each other in response to opening movement of said one part to increase the speed of separation of the xed and movable contacts.

4. An electric' circuit breaker comprising a housing having a body of fluid contained therein, a fixed contact, a movable contact structure including a hollow conducting rod having a contact portion movably mounted thereon, said conthe operating mechanism of said switch and movable away from said flxed contact during the circuit-interrupting operation of said breaker, the movement of said hollow rod being effective to actuate said second piston to force a portion of said fluid into said hollow rod to move the contact portion thereof relative to said rod in a direction to increase the speed of separation of said contacts.

5. An electric circuit breaker comprising a lhousing having a body of iiuid contained therein, a. fixed contact, a movable contact structure including a hollow conducting rod having a contact portion movably mounted thereon, said contact portion having a piston connected therewith lying Within the walls of said hollow rod and biased to extended relationship therewith, a second piston secured to said movable contact structure and shaped to define a blast passage communicating with the fluid in said housing, said hollow rod being connected to the operating mechanism of said switch and movable away from said fixed contact during the circuit-interrupting operation of said breaker, the movement of said hollow rod being effective to actuate said second piston and force a portion of said fluid into said hollow rod to move the contact portion thereof relative to said rod and to force a blast of uid through the arc formed by separation of said contacts.

6. An electric circuit breaker of the fluid blast type comprising a housing containing a quantity of arc-extinguishing fluid, a iixed contact and a movable contact separable therefrom to ton secured to one part of said movable contact and shaped to define a, fiuidblast passage extending across the path of opening movement of said movable contact, a cylinder in said housing cooperating with said piston to form a compression chamber, said piston being effective upon opening movement of said one part of the movable contact to force said iiuid against a surface on the other part of said contact to move it relative to said one part in a direction to increase the speed of separation of said fixed and movable contacts and to force a blast of arc-extinguishing fluid through said blast passage.

7. An electriccircuit breaker of the-fluid blast type comprising a housing containing a quantity of arc-extinguishing uid, a fixed contact, an elongated operating member having a hollow cylindrical portion, a movable contact extending from said operating member and having a piston portion lying within the hollowv portion thereof and normally biased toward engagement with said fixed contact, a hollow piston secured to said operating member anda cylinder cooperating therewith to form a compression chamber surrounding said operating member, said piston being shaped to define a blast passage leading to the exterior of said compression chamber and crossing the path of opening movement of said movable contact whereby movement of said operating member toward open circuit position of said breaker and the resultant movement of said hollow piston is effective to increase the pressure in said compression chamber to move said movable contact relative to the operating member and to force an arc-extinguishing jet through said blast passage.

GEORGES BALACHOWSKY.

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