US2391826A - Fluid blast circuit breaker - Google Patents

Description

Patented Dec. 25, 1945 FLUID BLAST CIRCUIT BREAKER Cedric H. Flurscheim, Bowdon, England, assignor to Metropolitan-Vickers Electrical Company Limited, London W. C. 2, England, a company of Great Britain Application July 22, 1943, Serial No. 495,745 In Great Britain July 30, 1942 8 Claims.

My invention relates to fluid blast electric circuit breakers or switches of the kind in which the circuit is adapted to be opened by the separation of contacts within an arcing chamber to which fluid, such as air or gas under pressure, is supplied during the opening operation. More specifically, my invention is an improvement on the arrangement disclosed and claimed in my copending application, Serial No. 495,746, filed concurrently with this application, now Patent 2,367,934, granted January 23, 1945.

In high voltage circuit breakers or switches a circuit including a resistance has been connected in parallel with the circuit through the main contacts of the circuit breaker during the circuit opening operation so that the current is transferred to the circuit including the resistance, after which the current through said resistance is interrupted thereby finally interrupting the current through the circuit breaker. Such an arrangement is disclosed and claimed in U. S. Reissue Patent No, 22,298, granted April 6, 1943. By using such a parallel resistance path in connection with fluid blast circuit breakers of high interrupting capacity an economical design is obtained since the parallel resistance path operates to reducethe severity of the transient voltage appearing across the circuit breaker main contacts subsequent to the extinction of the arc drawn across said contacts. As is well known, this transient voltage tends to cause restriking of the are after it has once been extinguished.

Various means have been proposed for connecting a shunt resistance across the arc extinguishing contacts. In the copending application referred to above there is disclosed an arc gap connected in series with the resistance with this series arrangement connected in parallel to the main contacts of the circuit breaker. Upon interruption of the are drawn across the main contacts the arc gap in the parallel circuit breaks down and the current which may flow through this parallel circuit is of course limited by the high resistance included in this circuit. The circult across said arc gap may readily be extinguished by a blast of fluid such as air or other suitable gas. It is very essential that the arc strike across said are gap rather than restrike across the main contacts and it is therefore important that no blast of fluid, at said arc gap occurs until after the arc has actually formed thereacross, indicating that the arc has been extinguished across said main contacts. I have found that interruption of the current through the parallel resistance circuit should follow interruption of the arc between the main contacts at an interval of about a quarter of a cycle. Accordingly, it is desirable that there be a time delay in the operation of the means for interrupting the current through the resistance circuit so that are resistance is not introduced into this circuit until after the interruption of the current in the main contacts. In my copending application I have shown an arrangement in which a blast of fluid is supplied to the arc gap connected in the parallel circuit including the resistance after the main contacts have separated a predetermined amount or in other words after a slight delay. Under very high current conditions, however, this slight delay may be objectionable since the current may have transferred to the parallel circuit including said resistance before the main contacts are separated the predetermined amount when the blast of fluid adjacent the arc gap in the parallel circuit is permitted to flow. In such a case it is desirable that a fluid blast be provided very promptly after an arc has formed across the gap in the resistance circuit to extinguish the same as soon as possible.

Accordingly, it is an object of my invention to provide means for controlling the are occurring in the auxiliary circuit including the resistance connected across the main contacts of the fluid blast circuit breaker in response to the current flowing through said arc.

It is another object of my invention to provide a fluid blast circuit breaker having an auxiliary circuit including a resistance connected across the main contacts of the circuit breaker with means controlled by the current flowing through said auxiliary circuit for controlling the interruption of the current flowing in this auxiliary circuit.

Further objects and advantages of my invention will become apparent as the following description proceeds 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.

For a better understanding of my invention reference may be had to the accompanying drawing, in which Fig. 1 is an elevational sectional view of a fluid blast circuit breaker embodying the present invention, and Figs. 2 and 3 are similar views of a portion of Fig. 1 to illustrate modifications of my invention.

Referring now to Fig. 1 of the drawing, I have illustrated an electric circuit interrupting device comprising a main arcing chamber 10 formed of a cylindrical insulating member having integrally "I have shown asim'" formed at the upper end thereof a nozzle II.

' Mounted within the arcing chamber I6 is a stationary contact l2 with the contacting portion thereof extending adjacent thelower end of nozprovided with a line terminal I6 to which the line 11, which together with line I I forms the power circuit to be controlled, is connected. The hood I is provided with lateral openings I8 through which air or gas from thegas blast may escape to atmosphere after passing through nozzle II. The upper portion of hood I5 terminates in a cylinder I 9 in which is reciprocally mounted a piston connected to a movable rod contact 2| adapted to extend through nozzle H and en'- gage with stationary contact I2. A spring 2.2 in cylinder I9 normally biases contact 21 into engagement with contact i2. -Arcing chamber I0 is connected, by'means of a suitable conduit including a portion '23 of "insulating material and portions 24 and '2 5, with cylinder I9 below piston 20 so that when fluid under pressure such as air or any other suitable 'gas enters arcing chamber 56 'from a source not shown, as indicated by the arrow in Fig. 1; this fluid causes piston'ZO to move upwardly to s'eparaterelatively movable contacts I2 and 2| to draw an arc therebetwee'n. At the same timea blast of fluid passesthrough nozzle II and to atmosphere through lateral openings IB to cause rapid 'extin'guishment of the are drawn; Movable contact 21 is electrically connected to "cylinder 22 by means of any suitable "Slidifi g Contact "Such as '25.

In 'iny copendin'g application referred to above, ;I have provided; valve means for controlling the flow'of "gas on the discharge side of the nozzle I I soastosurround'the'contacts by a-good dielectric such 'as a'ir under high pressure thereby decreasing the tendencyof the arc to resume. mere. 1,

valve ineans 27 is' p ov-ided having an upwardly 'e itending piston p0 'n 2-7 "of relatively small {crass "shitload rec "catiilgly inoun'ted in cylinder [9. Valve means- 21 is @150 provided with an upturnedfiange 28 of large diameterjconstructed ss'e's po 'forrn a, piston whims re'cipr'ocalti'n'gly mounted in alar ge c inder '29 forfri'ed in hood I55, v alve mean's =2 1 is'adapted to seat on a cir curn'fere'ntial lip formed on the upper end or "chamber 10 above nozzle 'II. Valve means-21 is biased upwardly in response -to the fluid pressure "existing on the discharge side of nozzle II and is biased downwardly by the fluid pressure arcing charnber I8 which acts on the pistdn po'rtion 21 thereof in cylinder 1'9 byvirtue been bruqii :2wan

In order that valve means f2 may close complet ely" after a predetermined separation of 'relatively movable contacts ZI tomaintain a high pressure air dielectric around'the separated ermta'ct-s, I connect a'predetermined point-bf cy'lin der f9, such asfthe "opening 3! infcylin der {-9 with cylinder 29 in liclfool [I5 "by means of a cenduiit 32. With this arrangement, as soonas contacts I2 and '2I have separated sufiiciently so that piston 20 moves above the pointpif bpening 3I in-cy lin- (bar -I 9, fluidiinder pressure endanger-renter I'll ispermitt'ed to enter cylinder --29 thereby rereiijig ddwn valve means 2''! to engage 'circumferen tial 11p 13B With this arran ement, the pressure ar arran'geme'r'it "in which a maintained on the outlet side of nozzle II bears a predetermined relationship to the pressure below the nozzle II, and when the contacts have separated a predetermined amount the flow of fluid through nozzle I I is stopped completely and the high pressure fluid is permitted to surround the separated contacts so 'as to provide a good insulating dielectric surrounding these contacts. 7 In order to provide the arcing means of the auxiliary circuit connected in parallel with main contacts I2 and 2|, I have provided a second or ai-jiil'iary arcing chamber 33 which is supported on the upper end of cylinder I9. Arcing chamber tsterminates in afnozzle 34 and the upper end of arcing chamber '33 is closed by a hood 35 which includes lateral openings 36 therein through which .fluid from arcing chamber 33 may escape to atmosphere. Depending from the center of hood 35 and extending closely adjacent-to the upper end of nozzle 34 is a stationary electrode 37. Another cooperating electrode =38 comprising "a stationary rod-like member is'disposed vertically :and axially within auxiliary arcing chamber '33 being suitably supported therein as indicated at 3 9. Thiselectrode extends upwardly toward electrode 31 so that the upper end thereof is closely adjacent the nozzle '34. The space between electrodes 3-! and -38 forms the auxiliary arc gap which is serially arranged in a circuit including high resistance 4'0. One terminal-oi high resistance 4i? is electrically connectedwith line terminal 13 while the *other end thereof is connected with hood '35 and consequently with one side of theme gap-between electrodes '31 and '38. The other "side of the arc 'gap is electrically connected through conductor II, the winding "t2 of'a solenoid generally indicated at 43, and conductor 44', with'cylinder I9 and c'onsequen'tly with line terminal I'B so that the auxiliary circuit including resistance 46 isco'nnected in parallel with main contacts -I2 and 21.

The solenoid 3 intludes 'a plunger 55 which is biased to the position'indica-ted in Fig. 1 by means I of a'spririg e5. Plunger' i5is counecte'd toavalve member t? by'means'of a'suitable vaivestem '48. Valve member 4! is adapted to control the new of fluid from arcing chamber I B through conduits 25, '2-3 and 4-9 into auxiliary 'arcingcliariib'er 33, 'SllffiCient hrizatidr1 Of Winding 3 2 bf 5018- noid will cause solenoid plunger 45 'to 'rhove the left With the consequent mfivli'int bf valve memb'er in to semi-t fluid nom ar ing chamber It! 130 enter aufiiliaiy arcing chamber -33. "Arc'in'gchainbe'r 33, as disclosed cope'nding applica tidn referred to above, is also connected to "a ere ere-r mmed point cylinder "I 9 suc h -als dpning 3| by means df a conduitst including 'an i nsulating p'ortion 5 I 'so 1 as to supply fluid iinder'p same 0'' cin'g chamber -33 with a predetermined time delay after the main contacts have been fully separated, such time delay being determined either byfthe length "c'dnduitFfl-and metal-rapped 't the pressurefwave to -t'ravelroin-c md'r IQ to arcing 'chalfilber 33,6? by file ans bf a suit-2,1516 constriction snowmen) which may b e -priivided in 'fcdnduit fiil. I y 4 In "Order that 'v al fe ifiem'br l In be maintained in the lopen position nce -1t has been epened until' the pressure arcing chamber I0 is substantially reduced as by biasing the waive motjshcwm liililiih'"the' 'sft llirce f fluid ifii dr pressure "rcingc'haihbe'r'l prbvide' withih aiiiiiliary arolrig chai'nb er 3 3 a under {52" which isr'nounteda piston 53 having a piston rod 54 adapted to engage valve stem 43 which extends through armature 45 of solenoid 43. Whenever fluid under suficient pressure exists in auxiliary arcing chamber 33 piston 53 is moved to the left so as to hold open valve member 47.

The circuit interrupting operation of the arrangement described above is initiated by opening the main control valve (not shown) to permit fluid, such as air or other gas under pressure, to enter main arcing chamber Ill whereupon fluid under pressure will cause piston to move upwardly separating contacts I 2 and 2|. A blast of fluid through nozzle it will extinguish the are drawn and due to the relatively short gap between electrodes 37 and 38 and the low air pressure still there an arc will be produced across electrodes 3! and 38 by virtue of the high transient voltage, thereby causing current to flow through high resistance ill. If the current to be interrupted by the circuit breaker is relatively small, the current through the winding 42 of solenoid 13 will be insuflicient to open valve 47!. However, after a predetermined time delay fluid under pressure will enter auxiliary arcing chamber 33 through conduit 58 and a blast of fluid will be produced through nozzle 34 to interrupt the current flowing through resistance 40. This can be accomplished without much difficulty since by virtue of resistance 4!] the current flowing through resistance it to be interrupted is much smaller than the current that was interrupted upon separation of contacts I2 and 2!. Under higher current conditions, however, it is desired to have a blast of fluid through nozzle 34 as soon as an arc is produced between electrodes 31 and 38 which indicates that the arc has been extinguished between main contacts l2 and 2!. This is accomplished with my invention by means of solenoid 43 which opens valve 4'! as soon as current flows through resistance 40 under high short circuit conditions and consequently the time delay referred to above is eliminated. This time delay, of course, is provided only to be sure that no fluid under pressure is permitted in auxiliary arcing chamber 33 until current flows in resistance 40.

It should be understood that instead of providing a separate piston such as 53 in Fig. 1, the solenoid plunger 45 might be exposed to the fluid under pressure so as to, in effect, provide a piston for opening valve member 4?, Such an arrangement is disclosed in Fig. 2 in which the corresponding parts thereof are designated by the same reference numerals as in Fig. 1. Cylinder 52 and piston have been eliminated and one end of solenoid armature 45 is exposed to the pressure within arcing chamber 33 so that when valve ll is opened the air pressure acts on solenoid armature 45 to maintain valve 4'! open as long as pressure is maintained within arcing chamber 33 even though the circuit has been interrupted through resistance 40.

Although in Figs. 1 and 2 I have disclosed the electrodes 3'! and 38 as fixedly mounted so as to provide a permanent arc gap, it should be understood that electrodes 3? and 38 might be arranged as relatively movable contacts which are normally in engagement and which are separated to draw an are after the main contacts l2 and 2| have been separated. Such an arrangement is disclosed in Fig. 3 wherein the corresponding parts thereof are designated by the same reference numerals as in Fig. 1. In Fig. 3 the electrode 38 is replaced by a movable contact 56 connected to a piston 51 reciprocally mounted in a cylinder 58 fixedly supported in auxiliary arcing chamber 33 in the same manner as was electrode 38 in Fig. 1. Piston 57 is biased upwardly by spring means 59 so that contact 55 is moved into engagement with electrode 3?. Cylinder 58 is electrically connected with conductor 4%. With this arrangement contact 5'6 is moved downwardly as soon as fluid under pressure enters auxiliary arcing chamber 33 to draw an arc between electrode 3i and contact 53, and thereafter the arrangement operates in exactly the same manner as the circuit disclosed in Fig. 1.

While I have illustrated specific embodiments of my invention it should be understood that my invention is not limited to specific details of constructicn and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing 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. A fluid blast circuit breaker for high voltage power circuits comprising relatively movable contacts separable to form an arc gap therebetween, means for directing an interrupting blast of fluid adjacent said are gap for extinguishment of an are drawn between said contacts, a circuit including a resistance arranged to be connected in shunt with said are gap, means for providing an auxiliary arc gap connected in said circuit ineluding said resistance, and means for supplying and controlling a blast of fluid adjacent said auxiliary arc gap in response to the current flowing in said circuit including said resistance.

2. A fluid blast circuit breaker for high voltage power circuits comprising relatively movable contacts separable to form an arc gap therebetween, means for directing an interrupting blast of fluid adjacent said arc gap for extinguishment of an are drawn between said contacts, a circuit including a resistance arranged to be connected in shunt with said arc gap, means for providing an auxiliary arc gap serially arranged with the resistance in said circuit, means including a valve for producing a blast of fluid adjacent said auxiliary arc gap to interrupt the current flowing through said circuit includin said resistance, and means responsive to the current flowing through said resistance for controlling said valve.

3. A fluid 'blast circuit breaker for high voltage power circuits comprising relatively movable contacts separable to form an arc gap therebetween, means for directing an interrupting blast of fluid adjacent said are gap for extinguishing the are drawn between said contacts, a circuit including a resistance arranged to be connected in shunt with said arc gap, means for providing an auxiliary arc gap serially arranged in said circuit with said resistance, means including a valve for producing a blast of fluid adjacent said auxiliary arc gap to interrupt the current flowing through said circuit including said resistance, and means including a solenoid operatively connected to said valve and responsive to the current flowing through said resistance for controlling the opening of said valve 50 that a blast of fluid is provided adjacent said. auxiliary gap only after the arc is extinguished across said are gap between said relatively movable contacts and an arc is established across said auxiliary gap.

4. A fluid blast circuit breaker for high voltage power circuits comprising relatively movable contacts separable to form an arc gap therebetween, means for directing an interrupting blast of fluid adjacent said arc gap for extinguishing the arc between said centacts, a circuit including v stance arranged to be ceunected in with said are gap, ineans fer providing an auxiliary arc gap serial-1y arranged in said circuit with said resistance and arranged so'that the high transient voltage following extinguisnment of the are drawn between said relatively mbvable contacts will produce arc across said auxiliary gap and cause current to new through said resistance, ineans including a valve for producing a blast or fiuid adjacent said auxiliary are gap to interrupt the current sewn-g through said circult including said resistance, and means including a solenoid operatively connected to said valve and responsive to the current flowing throughsaid resistance for controlling the opening of said valve so that a blast of fluid i's'pro- Yvided adjacent said auxiliary gap only after an arc is established across said auxiliary gap indicating that the arc across said are gap between said relatively 'rnevame contacts is extinguished.

5. A fluid blast circuit breaker "for high voltage power circuits comprising relativelyniovable contacts separable to form an arc gap therebetween, means for directing an interrupting blast '0 f fluid adjacent said arc gap for extinguishing the are drawn between said contacts, a circuit including a resistance arranged to be connected in shunt with said are gap, means for providing an auxiliary arc gap seriall arranged in said circuit with said resistance and arranged so that the high transient voltage following extinguish- Inent of the are drawn between said relatively movable contacts will break down said auxiliary gap and cause current to how through said re- :7:

arc is established across said auxiliary gap in! dicatihg that the across Said arc gap between said relatively in'ovable contacts is extingu-ished, and fluid operated means for holding said Valve in the open position.

'6. A fluid blast circuit breaker for high "Voltage power circuits comprisin relatively movable contacts separable to form "an arc gap therebetween, rneans for "directing an interrupting blast of fluid adjacent said arc gap for extinguishing the are drawn between said contacts, a circuit including a resistance arranged to be connected in shunt with said are gap, means including relatively separable electrodes adapted to provide an auxiliary arc gap -serially connected in said circuit with said resistance and arranged so that the high transient voltage following extinguishment "0f the arc drawn hetween said relativel riiovable contacts will produce an arc across said auxiliary gap and cause current to now through said resistance, means including a valve for producing a blast of fluid adjacent said auxiliary arc gap to interrupt the genesis current "flowing through said circuit including said resistance, "and means including a solenoid operatively connected to said valve and responsive to the current flowing through said resistance for controlling the opening of said valve so that a blast of fluid is provided adjacent said auxiliary gap oniy after an arc is established acress said auxiliary gap indicating that the arc across said are gap between said relatively movable contacts is extinguished.

"-7. A fluid blast circuit breaker for high voltage 'piw'er circuits comprising relatively movable contacts separable to f0r'm an arc gap therebetween, means for directing an interrupting blast of fluid adjacent said are gap for extinguishing the are drawn between said contests, a circuit including a resistance arranged to be connected in shunt with said are gap, means adapted to provide an auxiliary arc gap serial-1y connected in said circuit with said resistance and arranged so that the high transient voltage following extingui'shiri'ent of the are drawn between -said relatively movable contacts will produce arc across said auxiliary gap and cause current to flow through said resistance to interrupt the current flowin'g through said circuit including said resistance, means operative upon a predetermined separation of said contacts for "producing a blast of fluid adjacent said uxiliary arc gap under all operating conditions, and means including a solenoid operated valve responsive 'to the current flowing through said resistance for producing a blast of fluid adjacent said auxiliary gap under high current conditions, said fluid blasts adjacent said auxiliar y arc gap being produced after the arc across said arc gap between saidrelatively movable contacts is extinguished.

'8. A fluid blast circuit breaker for high voltage power circuit comprising a first set of relatively movable contacts separable to form an arc gap therebetween, means for directing an interrupting blast of fluid adjacent said are gap for extinguishing the are drawn between said contacts, a circuit including a resistance arranged to be connected in shunt with said arc gap, a second =set-of relatively movable contacts adapted to provide an auxiliary arc gap serially connected in said circuit with said resistance and arranged so that when the are drawn between said first set of relatively movable contacts is extinguished the current will be transferred to said resistance, means operative upon a predetermined separation of said first set of contacts for producing a blast of fluid adjacent said second set of cont-acts to cause separation thereof to provide said auxiliary arc gap, and means including a solenoid operated valve responsive to the current flowing through said resistance for producing a blast of fluid adjacent said auxiliary arc gap under high -current conditions, said fluid blasts adjacent said auxiliary arc gap being produced after the arc across said are gap between said first-set-of relatively movable contacts is extinguished,

CEDRIC 'FLURsoir'EIM.

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