US2443260A - Circuit breaker - Google Patents

Description

June l5, 1948. G. A. MATTHEWS 2,443,260

CIRCUIT BHEAKER Original Filed May 7, 1940 Patented June l5, 1948 CIRCUIT BREAKER George A. Matthews,

The Detroit Edison Detroit, Mich., assignor to Company, Detroit, Mich.,

a corporation oi New York Original application May 333,875, now Patent No.

'1, 1940, serial No. 2,352,556. ama June Divided and this application April 18, 1942, Serial No. 439,576

Claims. (Cl. 175-234) This invention relates to clrcuitfbreakers and particularly to single-pole recloslng circuit breakers capable of a fast initial opening. .l

This application is a division of my copending application Serial No. 333,875, tiled May 7, 1940, Apparatus for Protecting Power Lines, that matured into Patent No. 2,352,556 on `June 27, i944; which patent was re-issued under No. 22,872 on April 29, 1947. As stated'therein, serious damage or complete burn oi! occurs in the case of even transient faults as commercially available switchgear cannot open the line in less than -about V, second. The best performance claimed forany prior experimental circuit ybreaker has been an opening oi' a 60 cyclecircuit'in 5 cycles after fault initiation, and it is `apparent that faster operation is essential if burn oil is to be prevented. The present invention contemplates a reclosing circuit breaker having an initial opening time substantially lower than that attained, or contemplated by, the prior workers in this iield. Claims to certain detalls of switch construction are presented in my divisional application Serial No. 22,620, tiled April 22, 1948.

An object of this invention is to provide a circuit breaker of stable operating characteris tics that has an initial opening time substantially less than that of prior circuit breakers. An object is to provide a single-pole circuit breaker of light weight that is entirely self -contained and includes timing mechanism for eil'ecting a plurality of `timed reclosures before a ilnal lockout in the case of a permanent fault. Another object is to provide a quick-acting circuit breaker that may be subjected to overloads approximating its tripping values for. long periods without damage from overheating or change in operating characteristics. More specifically, an object is to provide a circuit breaker including an operating coil or winding in series with the line for opening the circuit breaker, shunted across the operating winding, and a controlrcoil'traversed by the line current, or a preselected fraction of the line current, whereby the line current is normally shunted around the operating winding and ilows through the operating winding only upon the opening of the control switch. l

These and other objects and'advantages of the invention will be apparent from the following speciilcation when taken with the accompanying drawings in which:

Pig. 1 is a central section through a single-pole, oil insulated circuit breaker embodying the innation:

a normally closed control switch that connects lever 88 to the Fig. 2 is a schematic diagram of the same; and

Fig. 3 is an enlarged fragmentary view of the circuit breaker contacts.

The circuit breakers contemplated by this invention, as employed for the protection of the conventional three-phase electrical distribution systems, are light weight, fully automatic, singlepole circuit breakers that each includes its own mechanical timing equipment and requires no auxiliary circuits or devices for full automatic operation. As shown in Figs. 1 and 2, the circuit breaker includes a control coil and operating coil 8| in series between terminals 82, 83, the operating coil 8| being normally shunted by the switch 84 that is opened by the control coil 88 against a spring 84'. This switch and the main breaker switch are of the reciprocating rod type, as described and claimed in my prior Patent No. 2,167,665, granted August 1, 1939, Circuit Breaker, in which an arc-extinguishing chamber of annular cross-section is formed by horn fiber or other organic material.

The core or plunger 85 of coil 8l is secured to a metal rod 86 which carries the movable contact 8l of the circuit breaker and terminates in a rod 88A of horn fiber or the like. The stationary breaker contacts include a main contact 88 that is normally engaged by the rod 86 or its movable contact 81, and an arcing contact 90 above and spaced from the main contacts. The arcing contact 80 is connected to the main contact 88 through a spiral coil 9i coaxial with the rod 86 ing contact 81 and the arcing contact 80 when the breaker opens, and the coil is wound in the sense opposite that of the operating coil 8|. 'I'he shunt or control switch 84 is of simpler design as the arc drawn across its contacts can be extinguished without the aid of an arc-spinning coil.

'Iiming mechanism 82 is provided to delay the second and subsequent openings of the breaker, but the first opening takes place with no delay. The timing mechanism is indicated generally by the block diagram overlying the junction of the operating lever 98 of switch 84 and the link 84 armature of the type of mechanism the opening of the control coil 88. Any desired may be employed to delay yshunt switch 84 for intervals of 60 cycles or upward when the fault is still on the line at the rst or subsequent closures of the breaker. The detailed construction is not illustrated since it forms no part of the present invention.

, plate extends across the upper end ofthe` jin sulator 96 and constitutes the support lfor the con trol switch and the breaker assembly, andthe control mechanism is located inthe domed clo- 'i'he breaker is housed within a chamber.turni-fy prising a hollow insulator 00 and=f .e osurle. 91, 08 of metal that carry the. termina sleeves 99 to which the closures are boite andi recessed to receive a mounting.'bra3.clret-|0|i,;L

sure 91 above the-plate |0|. The insulatorjSB is preferably lled with oil to approximatelygV the f lower face of the plate I0| which supports. alll of the switch and control mechanism. Y

The framework of the breakervv` assembly ,in-

cludes a series of rods |02. a metal plate" |03 on which the coil 8| rests,'and a plurality of horn ber plates'or disks |04. Insulating rods |05 are threaded upon rods |02 to secure the plate |03 against spacing sleeves |05' on rods |02,V,and. rods |02' are threaded upon therods mitocarry; the ldisks |04. A dashpot for arresting the open-1 ing movement of the breaker is formed-by'i-zthe enlarged lower end 85' of the core 85 andacyl` inder |06 that is mounted betweentheplate403.,l The top portionof the cylinder flares inwardly above vent `operi- 'r ings that permit a free escape of oil from within and the upper disk |04.

the cylinder during'the maior part of the opening movement of the rod 86. 'i

The two intermediate plates |04 are separated slightly and are recessed to receive small horniiber disks |04 that form the outer wall of the f arc-suppressing chamber. The small plates may I be replaced when the diameter of the chamber has been appreciably increased by the erosion of The arc-spinning coil 9| Ais n the horn liber.V mounted between the two lower disks I 04, and connected between arcing contact 90 that is recessed into the lower lface of the upper disk of this pair and a iianged brass tube |00 that is bolted to' the bottom disk |04 to support the main contact assembly. The main contact 09 includes a plural-fl ity of arcuate segments secured to the upper as the circuit opens but the downwardmotion.

of the switch rod 86 is delayedby the escape? ment mechanism. The escapement mayfbe of known types, including means for locking the' breaker in open position aftena" predetermined n number of reclosures if thefaultf'is still on the..

line and'means for resetting '.froxnny point in the schedule of reclosures whenV the breaker closes on a sound line. The time-delay may be ofthe customary order of from to 60 cycles, but the specific design of the escapement' mechanism is not vanessential feature oi this invention. v

The method of operation of the circuit breaker will be apparent from the foregoing description? In the case of a single phase line, a circuit breaker is connected in series with one side of the line at the terminals 82, .83. An ungrounded three-phase circuit can be protected by locating circuit breakers in two of the line conductors.

The tripping value of the circuit bieaiel .may

respectively. The insulator` is providedwy frrielt'fsil 8i-w en't l vatinggwiriding*8[i ni"ay 'thereforeV be designed tol develop] 'a-heavyjforce iordisplacing the mov-l L ablecontact 81 'lat'.,hi

springY ||4,. arid.Y agement*with*v 4 .1. f us `cl asdesiredbutwillusually be set up he rated l'current capacity ,i-,lin'ef current' does not ow atingfwinding under normal oph'roughgthef-operating winding huntlngswitch V84 opens. The oper- The inventonis distinguishczd from. prior cir- .lcuitbreakers o' theseriespperating winding type .l in that vthe'v oadfcurrentis normally by-passed ingvwinding. Theprior circuit open* to ythe objections of seriy A an Vjcci l" dafmagev due to the continuous o ug'hdthei operating .winding of load current approximating? but somewhat less than theftrippingvyaluey Thisfoverheating unnated by thepresfent invention as the control coil need devglo nlyNa--.elatively small force to Y witchfu..K` Itis therefore pospra'cti'caLto design the coil sumcient force for an exceedingly open'the shu ti sible, andent 8l to develop? .high speed-'opening lof the' breaker as the wlnding 8| is subjected only to .a momentary current surge of high 'magnitude` Y The'reciprocating rod and arc-extinguishingchainber construction also contribute tohighfspeed' operations as a 1 to 2 inch movement of theirodigwhich movement is suicient to separate thefbreaker contacts and suppresstherarc,y isobtained in1 about 2 to 3 cycles with operating coils l8| of ypractical design.

The initial opening of Vthe breaker takes piace within an intervalfthat depends =upon the magnitude ofthe fault current, as'shown graphically by1 curve. Bofjliig.4 lof .my-prior application, but

the subsequent ,openings-are, delayed by the timing mechanism .gglt'o'l supply current to a persistl Aent .fault for periodsofabout 30 cycles and upaiward, thereby'tovbiow sectionalizing fuses or to burn the conductorsdowndf 4there are no sectionalizing fuses, in the case o ffa, persistent fault,

or to lock-outthebreake` in the open position if the persistent fault cannot be votherwise cleared from/ the system;` :Time :val-ues are lstated in cycles on a o'cyclesperlsecond basis since it is the usual practice infthisV art to measure the operv ating timesfofiprotective switchgearwith oscillof 1 graphs that'generate aftiming wave" of the fre- ",quency v, 'for 'f the electritv'iiiv 4.distribution system. '-Theinover apparatus -hasbeen tested and used on lines supplied. with alternating current of a -frequency `of"60. cycles persecond but the protective methods. and apparatus may be used on direct current lines or on alternating current line's energized at`25 cycles .per second or at other frequencies The quick actinglcircuitbreakers are particu'- larly useful'infprotective systems, as described in my prior application, which include line shorting ,contactors Vfora substantially instantaneous suppression'of fault currents, but may be used to advantage in `any protective system where high "operating speed is desirable. -The high opening speeds of the new circuit breakers, are attained by making the operating coilrl a series element in thev line to be protected, whereby a suddenand heavy current surge traverses the coil 8| upon the opening of the control switch 84 .which normally, by-passes the line current around the n tripping current is deterclosingfspring' ,o1 the shuntting? riditi'ons., ndaheavymand sudden cur-v the preselected breaker-opening value, since the line current is by-passed around the operating coil 8| until the line current reaches that value at which the control coil I opens the by-pass switch Il.

It is to be understood that the invention is not restricted to the particular embodiment herein illustrated and described, and that various V changes that may occur to those familiar with the design and construction of circuit breakers fall within the spirit of my invention as set forth in the following claims.

I claim:

1. A circuit breaker comprising a pair of terminals for connecting the circuit breaker in series in the line to be protected, a pair of separable contacts, spring means normally retaining said contacts in engagement, electromagnetic means including lan operating coil for opening said contacts, said operating coil kand contacts being conductively connected in series between said terminals, a shorting circuit connected across said operating coil, and means responsive to overload current on said line for opening said shorting circuit, thereby to pass the overload line current through said operating coil to develop a power surge for opening said contacts.

2. A circuit breaker comprising a pair oi' terminals for connecting the .circuit breaker in series in the line to be protected, a pair of separable contacts, spring means normally retaining said contacts in engagement, electromagnetic means including an operating coil for opening said contacts, said operating coil and contacts being conductively connected in series between said terminals, a normally closed control switch shunted across said operating coil, and means responsive to a predetermined overload condition for opening said control switch, thereby to pass the line current through said operating coil to develop a torce to open said contacts.

3. A circuit breaker comprising a pair of terminals for connecting the circuit-.breaker in series in the line to be protected, a pair of separable contacts, spring means normally retaining said contacts in engagement, electromagnetic means including an operating coil for opening said contacts, said operating coil and contacts being conductively connected in series between said terminals, a normally closed control switch shunted across said operating coil. and a control coil responsive to a predetermined overload condition for opening said control switch to pass the line current through said operating coil, thereby to develop a power surge to open said contacts.

4. A circuit breaker comprising a pair of terminals for connecting the circuit breaker in series in the line to be protected, a pair of normally closed contacts, spring means yieldingly holding said contacts in engagement, electromagnetic means including an operating coll for opening said contacts, said operating coil and contacts being connected in series between said terminals, a normally closed control switch shunted across said operating coil, and a control coil ior opening said control switch, said control coil being connected between said terminals in series with said operating coil and normally closed contacts.

5. A v circuit breaker comprising a rod carrying a contact cooperating with a stationary contact, a core of magnetic material fixed to said rod, spring means yieldingly retaining said rod in contact-closed position, an operating coil for displacing said core and rod axially to open said contacts, a normally closed control switch shunted across the operating coil, and a control coil conductively connected in series with said operating coil for opening said control switch.

6. In a circuit breaker, insulating material deilning a cylindrical arc-extinguishing chamber, cooperating contact means comprising a stationary contact and contact means including a cylindrical contact member axially movable in said chamber, a rod of insulating material secured to said cylindrical contact member and movable thereby into the arc-extinguishing chamber upon an opening movement of the cylindrical contact member, a core of magnetic material secured to said contact member, an operating coil for moving said core and member axially to open said contact means, a pair of terminals for connection to a line, circuit elements connecting said coil and contact means in seriesy between said terminals, a normally closed shorting circuit across said operating coil, and means responsive to a predetermined overload condition for opening said shorting circuit, thereby to pass the line currentthrough said operating coil to open said contact means.

7. In a circuit breaker, lthe invention as set forth in claim 6, wherein said shorting circuit includes a normally closed control switch, and said means for opening said shorting circuit comprises a control coil for opening said control switch.

8. In a circuit breaker, the invention as set forth in claim 6, wherein said shorting circuit includes a normally closed control switch, and said means for opening comprises a control coil in series with said operating coil for opening said control switch.

9. In a circuit interrupter, the combination with a nuid container having an open end, a line terminal at the opposite closed end of the fluid container including a contact at the interior of the container and line connecting means at the exterior of the fluid container, a metal mounting member extending across the open end of said fluid container, and a second line terminal on said mounting member, of an interrupting assembly supported on and removable as a unit from said iluid container with said mounting member; said assembly comprising separable contacts, a core of magnetic material carrying one of said contacts, an operating coil surrounding said core, a normally closed control switch across said operating coil, a control coil conductively in series with said contacts for opening said control switch under predetermined overload conditions, thereby to pass the line current through said operating coil to energize the same to separate said contacts, means for reclosing said contacts, means connecting said operating coil electrically in series between said mounting member and one of said separable said shorting circuit responsive means including an operating coil conductively connected in series with said sepam'ounting member is in operative position with respect to said iiuidcontainer.

A'10. In a circuit interrupter, a unitary assembly for mounting upon the open top of a hollow insulator having aline terminal at the lower end thereof, said assembly comprising a mounting member to extend across and be'secured over the open end ofthe hollow insulator, a line terminal on said mounting member, a pair of separable contacts, electro-responsive means for separating said separable contacts, means for reclosing said contacts, and resilient means for automatically connecting one of said separable contacts with the line terminal at the'lowcr end of the hollowv insulator when said mounting member is in operative position with respect to said hollow insulator; said electro-responsive means including an operating coil conductively connected between said line terminals, a control switch normally *closed across said operating coil, and-means responsive to a predetermined overload condition to open said control switch.

ll. In a circuit interrupter, the invention as recited in claim l `wherein said means responsive t0 a predetermined overload condition comprises a controlcoil conductively connected in series with said separable contacts.

12..In a circuit interrupter, a uid container having an open end, a terminal cap for said end, a line terminal at the opposite end of said'. container having a portion extending through the Y assembly terminal and resiliently stressed against said line terminal in 'said operative position of the parts relative to the container; said electro- Number rable contacts, a control switch normally shunted' across said operating coil, and means responsive to a predetermined overload condition to open said control switch.

13, In a reclosing circuit breaker, a pair o! line vterminals for connecting the circuit breaker in series in the line to be protected, a pair of normally closed contacts, spring means yieldingly holding said contacts in engagement, electromagnetic means including an operating coil for opening said contacts, said operating coil and contacts being conductively connected in series between said terminals, a control switch shunted across said operating coil, spring means normally retaining said control switch in closed condition, thereby short-circuiting said operating coil, means 'responsive to a predetermined overload condition for opening said control switch, and time-delay means to prevent immediate reclosure of `said control switch by said spring means.

141.1111' a reclosing circuit breaker. the invention as recited in claim 13,:wherein said means for 'opening saidcontrol switch comprises a control coil in series with said contacts.

15. In a reclosing -circuitbreaken the invention as recited in claiml; in combination with timeldelay meansv to retard the reclosure of said contacts by said spring means upon opening thereof through energi'zation of said operating coil.

GEORGE A., imi'i'rnnws.V

REFERENCES CITED UNITED STATES PATENTS Name y Date Hilliard Sept. 19, 1905 Basch 1 Sept. 21, 1915 Schon Dec. 12, 1922 Biles May 21, 1929 Wallace 1 Nov. 2, 1943

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