US2158846A

US2158846A - Electric circuit breaker

Info

Publication number: US2158846A
Application number: US124131A
Authority: US
Inventors: Balachowsky Georges
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1936-02-27
Filing date: 1937-02-04
Publication date: 1939-05-16
Anticipated expiration: 1956-05-16
Also published as: USRE21848E; FR814518A

Description

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May 16, 1939- G. BALAcHowsKY' 2,158,346

ELEQTRIC CIRCUIT BREAKER Filed Feb. 4, 1937 4 Sheets-Sheet 2 Insulation Ihvewtor:

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May 16, 1939. G. BALAcHowsKY ELECTRIC CIRCUIT BREAKER Filed Feb. 4, 1937 4 Sheets-Sheet 3 Inventor: Georges Bolachowskg,

msnen Patented May 16, 1939 llum. 19M

ELECTRIC CIRCUIT BREAKER Georges Balachowsky, Paris, France, assignor to General Electric Company, a corporation of New York Application February 4, 1937, Serial No. 124,131 In France February 27, 1936 10 Claims.

This invention relates to electric circuit breakers, more particularly to those of the fluid jet type wherein a blast of arc extinguishing iiuld is projected across the arc, and has for its prin- 5 cipal object the provision of an improved circuit breaker of the aforesaid type which shall be emcient and positive in its interrupting effect throughout the entire range of current rating.

In accordance with this invention, the circuit l is preferably opened at two points in succession, and the arc at one point is subjected `to a fluid blast caused by arc generated pressure, and at the other point ls subjected to a fluid blast effected by and in accordance with the circuit l opening operation. In a modified form the arc at a single point is subjected to the combined blast eiect of arc generated and piston created pressures. With this arrangement the heavy current arcs are interrupted by the arc generated blast, and the high voltage low current arcs, if

not interrupted by the aforesaid means, are interrupted by the blast created by the circuit opening movement.

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

Referring to the drawings, Fig. 1 is an elevational view, partly in section, of a high voltage electric circuit breaker embodying the present invention, Figs. 2 and 3 are similar views of a modiiied form of circuit breaker in the closed and partly open circuit positions respectively, Fig. 4 is a view similar to Fig. 1 showing another modied form of the present invention, Figs. 5 to 9 inclusive, are views of another modied form of the present invention, Figs. 10 and 11 illustrate diagrammatically the operation of the antireclosing device shown by Fig. 5 during the opening and closing operations respectively, Figs. 12, 13 and 14 are elevational sectional views of another form of circuit breaker embodying the present invention in the open, partly open and closed circuit positions respectively, and Fig. 15 is a similar view illustrating another modication for low current interruptions.

In certain types of high voltage electric circuit breakers, such as the well-known explosion chamber type wherein an arc generated pressure causes expulsion of oil from the chamber through the arc, the interrupting performance may be very satisfactory at high currents due to the correspondingly high arc pressure, but unsatisfac- (Cl. 20G-150) tory at low or weak currents. On the other hand, the type of circuit breaker which depends solely upon a piston created jet of oil, for example, may have ditiiculty in interrupting high currents due to the counter-pressure created by the arc tencl- 5 ing to oppose the operation of the piston.

The present invention overcomes the above diiiiculties so as to operate satisfactorily throughout the entire range of current rating by applying jets of fluid dielectric, which may comprise 10 any suitable liquid or gaseous arc extinguishing medium, at the point or points of circuit interruption in a definite sequence. With this arrangement, interruption of the circuit is insured by the second applied jet in the event that the l5 first applied jet is not effective.

Referring more particularly to Fig. 1, there is shown a high voltage Vertical break oil circuit breaker comprising relatively movable contact' structure adapted to form two breaks in series. 20 The first break is formed between the fixed contact structure l and a movable intermediate contact 2, which are separable within an oil fllled explosion chamber 3. The intermediate contact 2 is biased by a spring 4 away from the ilxed 25 contact l, its travel being limited by a shoulder 5 forming a stop.

The main movable contact structure, which forms the second break comprises a reciprocally movable operating rod 6 carrying a contact rod 1. Secured to and movable with the contact rod 1 is an insulating piston structure 8 operable within a cylinder 9. The piston structure 8 comprises a cylindrical extension 8', the lower end of which is open and in communication with 35 the cylinder 9, the upper part being closed at 8" except for a central opening for receiving the contact extension l0 of the intermediate contact. The piston structure 8 is also provided with insulating bailes forming an axial iluid 40 passage Il communicating with the cylinder 9 and transverse passages having exhaust nozzles at I2. The movable contact structure is operable through alined openings in the insulating piston 8 so that the passages I2 extend trans- 45 versely thereof.

The breaker housing may comprise any suitable arrangement such as for example a ceramic insulating shell S mounted on a current transformer casing T at its lower end and carrying 50 an oil barile B at its upper end for preventing oil throw.

When the circuit breaker is closed the operating rod 6 is elevated so that the rod contact l engages the intermediate contact 2 at I0, forc- 55 ing the contact 2 upward against the bias of spring 4 until the circuit is completed at the iixed contact I.

In the opening operation' the operating rod 6 is lowered so that the intermediate contact 2, which remains in following engagement with the contact 'i by reason of the spring 4 separates from the fixed contact I thereby forming an arc within the explosion chamber 3. The arc is often extinguished at this stage of the opening operation within the explosion chamber 3 in a manner well known in the art. If, however, the circuit is not interrupted the subsequent separation of the contacts 'I and I0 when the stop member 5 reaches its limiting position forms an arc within the baffle structure at 8 as illustrated in the drawings.

During the circuit opening operation, however. the piston structure 8 has been descending within the cylinder 9 so as to force oil from the cylinder by way of the passages II and I2. Accordingly, when the second arc is drawn transversely of the passages I2, it is immediately subjected to positive transverse oil jets. This second application of the oil jet is not dependent on the size of the current to be interrupted and insures complete opening of the circuit, particularly in the case where the current is too weak to develop sufficient blast pressure within the explosion chamber 3.

The circuit breaker shown by Figs. 2 and 3 comprises a xed contact I3 and an intermediate movable contact I4 which is secured to and carried by the insulating operating rod I5. As illustrated by Fig. 2, the breaker is in the closed circuit position. Movable with the contact I4, which is electrically connected to a conducting block I6,

is an insulating cylinder I1 coacting with a fixed piston member I8. The piston I8 is carried by a conducting tube I9 which is fixed and which also carries an annular xed contact 20. In sliding conducting engagement with the contact 20 is the contact 2| which is carried by the cylinder I'| and which is electrically connected by a conductor 22 to the intermediate contact structure |4|6.

At the upper end of the cylinder there are formed by the insulating structure 24, transverse jet passages communicating at one end through the axial passage 23 with the cylinder I'I and terminating at the exhaust nozzles 25.

In the closed circuit position shown by Fig. 2 the circuit is completed through the xed contact I3, coacting movable Contact structure I4-I6, conductor 22, contacts 20 and 2| and the fixed conducting tube I9 which is suitably connected to the lower breaker terminal.

When the breaker is opened, the rod I5 is lowered so as to cause separation of the contacts I3 and I4. Coincident with the opening movement, the oil within the chamber 26 is subjected to pressure by the relative movement of the cylinder I1 and piston |8 resulting in an oil jet through the

passages

23 and 25 transversely of the arc between contacts I3 and I4 as illustrated by Fig. 3.

As the opening operation progresses, lowering of the cylinder I1 finally causes separation of the contacts 20 and 2| within a chamber defined by the lower part of the cylinder.|'| and the piston I8. In the event that the arc formed by the contacts I3 and I4 and has not been extinguished, which may occur in case a heavy current is to be interrupted, a second arc in series with the first arc is formed between contacts 20 and 2|.

There is then produced below the piston I8 within the chamber 21 a high arc generated pressure which causes immediate acceleration of the downward travel of the cylinder |I so as to augment the force of the oil jet transversely of the arc at 25. This added force applied to the transverse oil jet insures complete opening of the circuit since the arc generated pressure is approximately proportional to the arc current.

The circuit breaker illustrated by Fig. 4 is generally similar in principle to the breaker shown by Fig. 1 and comprises a fixed contact 28 and a coacting intermediate contact 29 which is biased by a spring 30 away from the xed contact. The intermediate contact 29 which also coacts with the movable contact rod 3| carries a piston member 33 which is operable within a fixed insulating cylinder 34. Apertures 35 in the piston are controlled by flap valves 36 for admitting oil to the lower part of the cylinder during the circuit closing operation. The travel of the intermediate contact 29 is limited by abutments at 31 on the cylinder 34.

When the breaker is to be operated from the open circuit position shown by Fig. 4, to the closed circuit position, the operating rod 32 isl elevated so as to cause the rod contact 3| to engage the intermediate contact 29 and move the same against the bias of spring 30 into engagement with the fixed contact 28.

When the breaker is opened, the rod 32 'is lowered and the intermediate contact, which lfollows for a limited distance the contact 3|, separates from the xed contact 28. Separation of the

contacts

28 and 29 takes place within a known form of cross jet explosion chamber including an axial passage 3B in communication with the arc pressure at the Contact 28 and with passages exhausting at 39 transversely of the arc.

fUnder certain conditions interruption of the circuit takes place within the transverse passages 39. The descent of the intermediate contact 29 under bias of the spring 30, however, is somewhat slower than the descent of the contact 3| due to the piston 33 with the result that a second break is formed between the contacts 29 and 3|. If, at this time, the circuit is not interrupted at the first point, the second arc formed between the contacts 29 and 3| is subjected to a transverse jet by way of the passages 40 and 4I due to the descending piston 33. Accordingly, if the arc at the rst break is not interrupted by the arc generated blast through the transverse passages 39, the circuit is very shortly thereafter interrupted by a piston driven jet directed through the second arc at the transverse passages 4 I.

Fig. 5 illustrates another form of circuit breaker generally similar in principle to that shown by Figs. 2 and 3. I'he breaker comprises a main fixed contact 42 and a coacting movable rod contact 43 to which is secured an insulating piston structure 44 operable within a cylinder 45. The piston 44, as in the case of Fig. 1, includes'an extension 44 which is open at its lower end in direct communication with the cylinder 45. The upper end of the piston structure is closed except or a central aperture for receiving the contact 42 and a fluid passage formed by an aperture 46 communicating with the cylinder 45 and a transverse passage 4'| extending transversely of the path of separation of the

contacts

42 and 43.

It will be noted that the diameter of the contact portion of the rod contact ,43 is smaller than that of the main operating extension 48. This difference in diameter enables the lower part of the rod contact, viz. at 48, to make separate engagement with a i'lxed annular contact 49. In the closed circuit position the '

contact portions

48 and 49 are in engagement as well as the

contacts

42 and 43.

In the opening operation the rod 48 is lowered by a suitable linkage indicated at 48 and the piston structure 44 in descending into the cylinder 45 directs a transverse jet through the arc at 41 in the manner previously described. Also, it will banoted that after a predetermined separation of the

contacts

42 and 43 the

contacts

48 and 49 also separate thereby forming two breaks in series. If the arc at

contacts

42 and 43 is not extinguished, a second arc will form between

contacts

48 and 49 thereby increasing the pressure beneath the piston 44. An insulating sleeve 58 is secured to the i'lxed contact structure and guides the contact 43. 'Ihis is best illustrated by the enlarged view in Fig. 6 wherein the arc formed between

contacts

48 and 49 is indicated at 5|.

'Ihe arc generated pressure in the cylinder 45 acts to increase the effectiveness of the oil jet. Accordingly, as in the previous cases a piston created oil jet initiated by and in accordance withthe circuit-opening operation is eiective to interrupt comparatively light or moderate currents, and a force corresponding to the magnitude of the current to be interrupted is further applied to the oil jet in the event that the arc is not interrupted by the rst jet.

It may be advantageous to provide the sliding

contacts

48 and 49 with arc shields so that the normal contact engaging surfaces are not subjected to the arc. Fig. 'I is an enlarged view illustrating such an arrangement, the arc shields 52 and 53 being annular in form and connected to the

contacts

48 and 49 respectively. Fig. 7 illustrates the contacts in the closed circuit positionl andFig. 8 illustrates the operation of the arcing portions in the circuit opening operation.

Where it is advantageous to limit the length of arc 5I in order to prevent excessive arc pressure, as for example, to a distance approximately equal to the radial clearance r between the con.l

tacts

43 and 49, the arc shield 53 is provided with an annular arcing hom 54 as shown by Fig. 9.v

The arcing shield 52 may be provided with a similar arcing portion if desired.

In view of the high pressure which is developed in the cylinder 45 by the arc at 5l, it may be necessary to provide the operating mechanism of the circuit breaker at 48 with an interlocking device which will prevent the mechanism from reversing 'its movement, `thereby tending to reclose the breaker during the opening operation. Any suitable device can be used to this end, Figs. 5, 10 and 11 illustrating a particularly simple and effective interlocking device.

The interlocking device consists of a cam which is rotatably mounted at a ilxed pivot 55, the cam comprising a main portion 58 having a shoulder 51 which. is adapted to engage a roller 58 carried by a rod 59 which is suitably connected to the operating mechanism 48. Since the rod 59 is `actuated during the opening operation in the direction indicated by the arrow at (Fig. 5), the interlocking mechanism assumes successively the positions a to f of Fig. 10. I'hese positions illustrate the elevational views as in Fig. 5.

It will, therefore, be seen that the .follow-up roller 58 iirst lifts the cam 58 about its pivot 55 and then when it reaches position c the-cam drops behind the roller. In this position, which corresponds to separation of

contacts

48 and 48,

the roller is prevented from reversing its movement by the cam surface 51, and reverse or reclosing movement oi' the breaker is thereby precluded. As the opening movement continues the roller lifts the pivoted flap member 8| which is carried by the cam and moves past the iiap finally assuming a position indicated at f.

In the closing operation, which is indicated by the directional arrow 82 of Fig. 11, the roller 58 assumes successively the positions a', h, i and 7'. The iiap 8| which is freely hinged on the cam (position h) enables the roller to liit the cam past the blocking surface 51 so `that the roller can pass without obstruction beneath the cam.

Figs. 12, 13 and 14 illustrate another form of circuit breaker wherein the piston structure for creating the oil blast in `accordance with the circuit opening operation is mounted for limited movement with respect' to the movable contact structure. In this arrangement but one break is necessary for subjecting the arc to both an arc generated blast and a piston created blast.

Referring to Fig. 12 the'single break is formed between the movable contact 84 associated with the insulating piston structure 89 and ,the ilxed contact 85. The nxed contact is also associated with an insulating oil jet chamber having a passage 88 communicating with the arcing space and transverse passages terminating at 81. The chamber is also provided `with a central passage in alinement with the contacts 84 and 88. 'Ihe oil jet chamber above described functions in substantially the same manner as the corresponding structure of Fig. 4 to interrupt the arc between the contacts 84 and 85 by an arc generated cross blast.

The plunger type piston 83 which is mounted for limited sliding movement on the contact 84 operates within a ilxed cylinder 88. As inA the previous instance the piston has formed therein a passage 89 communicating with the cylinder and with transverse passages extending across the path of the movable contact and terminating at 10. 'I'he movable contact 84 is suitably connected to the corresponding breaker terminal through a iixed contact 1|.

Fig. 12 illustrates the breaker in the open-circuit position, the movable contact rod 84 being held in its lower position against vthe bias of a spring 12. 'Ihe spring 12 in this position holds the piston structure 89 against a stop member 13 of the movable contact so that the piston and contact move together during the latter part of the opening stroke and the ilrst part of the closing stroke.

In the closing operation, which is illustrated by Fig. 13, the contact rod 84 is elevated carrying With it under bias of spring 12 the piston structure 83 until the piston engages the upper oil jet chamber. During the latter part of the closing stroke the contact 84 moves independently of the piston structure through the alined contact openings to engage the ilxed contact as illustrated by Fig. 14.

In the opening operation the contact 84 is lowered and during the initial travel thereof the arc between the contacts 84 and 88 is subjected to an arc generated blast through transverse passages 81. When the stop vmember 18 reaches the lower part of the piston from that point on the piston moves as a part of the movable contact structure so as to project an oil blast through the arc at the passages 18.

In the above-described arrangements the oil jets which are intended to insure under all con- 'ditions the interruption of the arc have been assumed to be produced by a piston type compressor. It will be understood, of course, that any other equivalent means may be utilized which is actuated by the operation of the movable contact structure of the breaker. When the interruption of comparatively weak currents only is involved, correspondingly low velocity oil blasts can be used. Such low velocity oil jets can be simply produced by the action of oil, which is comparatively stationary in the circuit breaker tank, on the rod of the movable contact when the crater or root of the arc is switched over to the side of the rod.

A simple arrangement of this character is shown by Fig. 15 wherein the xed contact 14 is surrounded by a iixed oil jet chamber 15 having transverse oil jets similar to those of 6B and 61 of Fig. l2. Here the movable contact rod 16 carries a terminal extension 11 composed of arc-resisting insulating material. In the closed circuit position the extension 11 enters the Contact 14 Which is annular in form so that the circuit is closed at the sides of the contact rod 16. In operation the arc necessarily strikes between the contact 14 and a lateral side of the contact 16, the crater or root of the arc 18 being indicated at 19. The side wash of the oil on the crater of the arc at 19 is sufficient to interrupt the .arc in the case of weak currents.

It shall be understood that the present invention is not limited to any predetermined sequence of operation of the arc generated blast and the piston created blast, That is, the particular operating requirements and interrupting characteristics can be determining as to whether the arc generated blast precedes the piston created blast.

It should be understood that by invention is not limited to specic details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit 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 of the uid blast type comprising relatively movable contact structure, an arc-extinguishing liquid, and means for extinguishing arcing at said contact structure upon opening of the circuit including insulating structure movable in accordance with the circuitopening operation, said insulating structure forming fluid passages adapted to traverse portions of the arc path, said insulating structure also including a piston fordirecting arc-extinguishing fluid through said passages for interrupting the circuit.

2. An electric circuit breaker of the fluid blast type comprising relatively movable contact structure, an arc-extinguishing liquid, and means for extinguishing arcing at said contact structure upon opening of the circuit including insulating structure forming fluid passages adapted to traverse portions of the arc path, said insulating structure also including a piston disposed within a casing containing said arc-extinguishing liquid, means for actuating said insulating structure in accordance with the circuit opening operation for forcing said liquid through said fluid passages, and means for also directing arc generated pressure for effecting the arc-extinguishing operation.

3. An electric circuit breaker of the iluid blast type comprising relatively movable contact structure adapted to form two breaks in series, an arcextinguishing liquid, insulating baiile .structure through which the arc at one of said breaks is drawn and a piston connected to said movable contact structure for confining and subjecting respectively the arc at said one of said breaks to an arc-extinguishing blast of liquid in accordance with the circuit opening operation, and means for utilizing arc pressure generated at the other b reak for also extinguishing arcing.

4. An electric circuit breaker of the fluid blast type comprising relatively movable contact structure adapted to form two breaks in series, an arc extinguishing liquid, means forming an arc-interrupting chamber arranged for conning arc pressure so as to cause a blast of arc-extinguishing liquid from said chamber in response to formation of the arc, one of said breaks being formed Within said chamber, and piston structure operable in accordance with the circuit opening operation for directing arc-extinguishing liquid through the arc at said other break.

5. An electric circuit breaker of the iluid blast type comprising relatively movable contact structure adapted to form two breaks in series, an arc-extinguishing liquid, and an arc chamber within which one of said breaks is initially formed, said chamber arranged to conne arcgenerated pressure for causing a blast of arcextinguishing liquid from said chamber through the arc, and an insulating baffle coacting with a piston movable in accordance with the circuit A opening operation at the subsequently formed break for directing arc-extinguishing liquid through said break for interrupting the circuit in the event that it is not interrupted within said chamber.

6. An electric circuit interruptor of the iiuid blast type comprising relatively movable contact structure, an arc-extinguishing liquid, and means for extinguishing arcing at said contact structure upon opening of the circuit comprising means for directing arc generated pressure so as to cause a blast of arc-extinguishing liquid through one portion of the arc, and insulating structure movable with said contact structure forming a iiuid passage adapted to traverse another portion of the arc path, and a piston also connected to said movable contact structure adapted to force arc-extinguishing liquid through said passage.

'7. An electric circuit interrupter of the uid blast type comprising relatively movable contact structure adapted to form two breaks in series, an arc-extinguishing liquid, means forming an arc chamber within which one of said breaks is formed, said chamber arranged to direct arc generated pressure so as to cause an arc-extinguishing liquid blast, insulating piston structure forming fluid passages adapted to extend transversely of the arc path at the other of said breaks, said last-named break being formed subsequently to said other break, and means relating said piston structure to the movable contact structure so that arc-extinguishing liquid is forced through said passages in accordance with the circuit opening operation for interrupting arcing at said subsequently formed break.

8. An electric circuit breaker of the fluid blast type comprising relatively movable contact structure adapted to form two breaks in series, an arc-extinguishing liquid, insulating structure forming uid passages adapted to traverse the path of the arc at one of said breaks, said insulating structure being operable as a piston in accordance with the circuit opening operation for forcing arc-extinguishing liquid through said pasv sages, and means for directing arc pressuregenoperation ,for driving.arcextinguishing liquid through said passage, means for directing arc pressure generated lat said other break so as to increase the liquid pressure at said piston structure, and means operable upon the formation of said last-named break for blocking'reverse movement of said contact and piston structure whereby said arc generated pressure is eective to augment the liquid blast at said first-named break.

10. An electric circuit breaker of the uid blast type comprising relatively movable contact structure, an arc-extinguishing liquid, means for extinguishing arcing at said contact structure upon opening lof the Icircuit comprising insulating structure forming uid passages adapted to traverse portions of the arc path, said passages being arranged so that arc generated pressure causes an arc-extinguishing blast therefrom, a second insulating structure forming uid passages adapted to traverse other portions of the arc path, said second insulating structure being relatively movable with respect to said first insulating structure, opening of the circuit initially causing arcing in said iirst insulating structure, and means for actuating said second insulating structure as a piston in accordance with the circuit opening operation so as to force arc-extinguishing liquid through the passages therein for interrupting arcing.

GEORGES BALACHowsKY. ,o