US2240803A - Circuit breaker control system - Google Patents

Description

' M y 6, 1941- M. SCHIESSER 7 2,240,803

CIRCUIT BREAKER CONTROL SYSTEM I Filed June 27, 1938 3:2: HIIIIEIIIII v K i 6 a 46 2.4

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Patented May 6, 1941 2,240,803 ICE 2,240,803 cmcurr BREAKER common SYSTEM Manschiesser, Baden, Switzerland, assignor to Aktiengesellschaft Brown Boveri & Cie., Baden, Switzerland, a Joint-stock company of Switzerland Application June 27, 1938, Serial No. 215,968

In G

Claims.

This invention relates in general'to improvements'in circuit breaker control systems and more particularly to a system utilizing a circuit breaker comprising serially connected arcing contacts and disconnecting contacts in which the arcing contacts are immediately reclosed after current interrupting operation thereof and in which the ermany July 31, 1937 I cross section and partially in elevation of an arcdisconnecting contactsopen only upon repeated operation of the arcing contacts.

It is well known to provide a control system for causing a circuit breaker to reclose immediately upon interrupting operation thereof and to thereafter reopen and remain open if the operating condition having caused the first opening of the circuit breaker is still present. The repeated operation of the entire circuit breaker mechanism requires a period of time which is material and this operation results in noticeable effects in the operation of the circuits controlled by the circuit breaker and of apparatus connectedtherewith. It is therefore desirable to reduce, as much as possible, the weight and the travel of the particular circuit breaker element serving to open and reclose the circuit. This result is most conveniently obtained by utilizing circuit breakers having fluid operated arcing contacts which are light in weight and whichtravel only a short distance while being swept by a. fluid blast to momentarily interrupt the flow of current therethrough and having disconnecting contacts operable only after reclosing and reopening of the arcing contacts to thereafter maintain the circuit open. The arcing and disconnecting contacts are suitably interlocked by electric or mechanical means to open the disconnecting contacts after any predetermined number of openings and reclosures of the arcing contacts.

' It is therefore one of the objects of the present invention to provide a circuit breaker control system for causing only part of the circuit breaker mechanism to operate to momentarily open the circuit controlled thereby, the entire circuit breaker mechanism being actuated only to maintain the circuit open.

Another object of the present invention. is to provide a circuit breaker control system for causing the disconnecting contacts of the circuit breaker to open only upon repeated opening of the circuit breaker arcing contacts.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawing, in which:

Fig. l diagrammatically illustrates one embodiment of the present invention applied to the control of a circuit breaker having contacts opening under the action of gravity;

Fig. 2 diagrammatically illustrates a modified embodiment of the present invention applied to the control of a circuit breaker of the fluid operated type in which the arc is extinguished by a fluid blast; and

Fig. 3 is an enlarged view partially in axial ing chamber and of the associated disconnecting contacts of the embodiment illustrated in Fig 2. Elements performing the same function in the ,different embodiments shown are designated therein by the same reference character.

- Referring more particularly to the drawing by characters of reference, numeral 6 designates an electric line or circuit of any type such as a three phase alternating current line energized from a suitable generator or a plurality of generators (not shown). Circuit 6 is controlled by a circuit breaker generally designated by I comprising cooperating contacts 8 designated as arcing contacts and cooperating contacts 9 designated as disconnecting contacts serially connected with contacts 8 in circuit 9. Contacts 9 are assumed to be of any suitable known type of light weight contacts having a short stroke permitting rapid opening and reclosure of circuit 6 but incapable of safely maintaining the circuit open under all operating conditions. Contacts 9 may be of any known slow acting type incapable of safely interrupting the flow of current therethrpugh but designed to safely maintain circuit 8 open after interruption of the flow of current therethrough at contacts 8.

Contacts 9 may be closedby any suitable means such as a closing coil ll adapted to be energized from a battery I! through auxiliary contacts l3 of the circuit breaker when contacts 8 are open. Coil ll thus recloses contacts 8 whenever these contacts are caused to open and the contacts are thereafter maintained in closed position by means of a latch ll. The latch may be withdrawn by means of a solenoid or trip coil IE to permit the contacts to open under the action of gravity, which action may be aided by accelerating means such as a spring l1. Contacts 9 are maintained closed by a latch 18 against the action of gravity and of a spring l9 but may only be closed manually after opening thereof. Latch I8 may beincluding battery I! and solenoid l8 responsive to an. operating condition of circuit 9 for causing opening of contacts 8 without affecting contacts 9. In the present embodiment the control means are assumed to be selectively responsive to the magnitude of the flow of current through circuit 9 for causing interruption of excessive currents flowing through the circuit by reason of overloading thereof or of the presence of a fault condition therein. It is evident however that the system may also be made responsive to any operating condition of circuit I other than abnormal conditions thereof, for example the system may respond to the direction of the flow of current through the circuit or to other quantities to regulate the iiow of energy between the generators connected with the different portions of the circuit.

The control-system includes a current transformer 22 comprising a. primary winding serially connected with one of the conductors of circuit 8 and a secondary winding supplying the coil of a relay 23 having contacts 24. Contacts 24 control the connection of solenoid II with battery l2 through contacts 28 and coil 21. of a time delay relay 2I and also control the momentary connection of solenoid 20 with battery 12 through contacts 29 and coil 21 of relay 28. Relay 2I is conventionally represented on the drawing as being of the dashpot retarded type but it will be understood that any other suitable known type of time delay relay may be utilized instead. -Battery- I2 may also be connected with solenoid 20 through a hand operated switch 30.

The drawing shows the system in the normal the fully open position thereof.

opening of contacts I and I is thus obtained to operating condition thereohcontact's I' and I being closed to complete circuit I. Upon the occurrence of the operating condition to which the system is responsive, i. e. flow of current above a predetermined value through circuit 8, current transformer 22 energizes the coil of relay 23 with current of such value as to cause operation of the relay to close contacts 24. Current thereupon flows from battery 12 through solenoid II, contacts 28 and coil 21 of relay II and through contacts II back to the battery. Solenoid II withdraws latch II without however aifecting latch II because of the lost motion of coupling 2i. Contacts I open to interrupt the flow of current through circuit, I, thus also causing the coil of relay II to be deenergized. Relay II accordingly returns to the position shown to open contacts 24.

When contacts I are substantially fully open, contacts II connect closing coil II with battery l2. Contacts I are thereby immediately reclosed by the closing coil in response to the opening of the contacts to reestablish the connection'between the two portions of circuit I. During the opening and reclosing operation of contacts I,

rent through circuit I again reaches the value at which relay 23 operates, relay 2I again closes contacts 24. Contacts 28 then being open, solenoid i8 is not energized. A circuit is then however momentarily completed from battery 12 through solenoid 20, contacts 29, coil 21 and contacts 24 back to the battery. Solenoid II is thereby momentarily energized and operates independently of solenoid II .to withdraw both latches l4 and i8 -to cause opening of contacts 8 and I. Coupling 2| forms an interlock between latches II and i8 whereby contacts I are caused to open whenever contacts 9 are caused to open. The coupling is however so adjusted that contacts I are released first and that contacts I are released only when contacts I reach substantially A sequential cause the flow 01' current in circuit I to be interrupted at contacts I and to cause the circuit to be thereafter maintained open at contacts I. Upon contacts 8 reaching the fully open position thereof, contacts 13 again connect closing coil H with battery i2 to cause a second reclosure of contacts 8. Circuit I may ultimately be restored by manually reclosing contacts 9.

Relay 28 may also be so adjusted as to open contacts 26 and to close contacts 2I'only after any predetermined number of openings and reclosures of contacts I. Regardless of the number of openings of contacts I, contacts 28 should however always close while contacts I are being reclosed to obtain final opening of contacts I and operation of contacts I in the proper sequence. It will be understood that the system may also be otherwise arranged to provide, as in the system illustrated, means momentarily responsive to an operating condition of circuit I relay 28 operates in response to the flow of the current through coil 21 during the initial portion of the opening period of contacts I. Relay 2I constitutes an interlock between solenoids II and 20 which may be given diflerent adjustments to vary the manner in which contacts I'and I are controlled. For example relay II may be so adjusted as to open contacts II after latch II has been withdrawn and to momentarily close contacts 29 after contacts I have fully opened but before contacts I have reclosed. Latches II and II are then momentarily rendered jointly responsive to the operation of relay 2I after reclosure of contacts I to cause contacts I to open and also to cause contacts I to open with contact! I.

If, upon reclosure of contacts I, the flow of current through circuit I fails to rise to the value at which relay 21 operates, contacts I and I remain closed. After a time delay depending on the adjustment of relay II the latter returns to the position shown and the entire system is then again in the original condition thereof illustrated on the drawing.

after a predetermined time delay following an occurrence of the operating condition for causing opening of contacts I and I, and more particularly to provide time delay means responsive to the operating condition for momentarily rendering solenoid II- inoperative and for momentarily rendering solenoid 20 responsive to the operating condition.

The embodiment illustrated in Fig. 2 is directed to the control of a circuit breaker utilizing fluid under pressure such as compressed air, the source of fluid preferably being a reservoir II wherein air is maintained at a substantially constant pressure by a suitable compressor (not shown). The circuit breaker preferably comprises a pin-- rality of pole portions of similar construction illustrated in greater detail in Fig. 3. Briefly stated each pole portion comprises an arcing chamber 32 enclosing arcing contacts I, of which one is of annular shape and is arranged about the discharge orifice of the arcing chamber. The other aming contact is of plug shape mounted on a suitable contact separating means such as a piston 32 arrangedifor reciprocatory movement within a cylinder II communicating with chamber 22. A resilient means such as a spring II provides for reclosing of contacts I following opening thereof by admission or compressed air into chamber I2.

Piston II is provided with an extension carrying one of contacts I which is in the form of a pair of laminated brushes cooperating with the other one of contacts 9 which consists of a double knife blade pivoted on a bracket 31. Chamber 32 and bracket 31 carry the terminals of the circuit breaker to which .the conductors of circuit 6' are attached and are mounted on reservoir II through hollow insulators 33 and 33 respectively. The disconnecting contacts may be opened and closed by means of an operating shaft 40 connected therewith through insulating connecting rods M.

To close contacts 9 shaft 40 is actuated through a suitable crank mechanism by a piston 52 arranged for reciprocatory movement in a cylinder 43. Cylinder 43 may be placed in communication with reservoir 3| through a valve 4 controlled by a solenoid 46. The solenoid may be connected with battery l2 through a switch 41 to cause closure or contacts 3. To open contests 9 shaft 40 is actuated through a second crank mechanism by a second piston 48 arranged for reciprocatory movement in a second cylinder 49. Cylinder 49 may be placed in communication with reservoir 3! through a valve 50 controlled by a solenoid iii. A needle valve 52 may be inserted between valve 50 and cylinder 49 for in troducing an adjustable time delay in the opening 9. main valve 59 for admitting air from reservoir ii i through insulators 38 into chambers 32. Solenoid Si is connected with battery it through contacts 26 and through switch M. Solenoids ti and ti may also be manually connected with battery it through a hand switch St.

The system being in the condition illustrated in Fig. 2, p010. OCCIIIIGHCB Of flOW current above a predetermined magnitude through cir cult 8, current transformer 22 supplies the coil of relay 23 with sumcient current to cause operation of the relay to close contacts 24. Solenoid Si is thereby connected with battery i2 and aotuates valve 58 to cause air to be admitted from reservoir 3| into arcing chambers 32, The piston 33 of each pole is thereby momentarily actuated downward to separate contacts 8. The

arcs drawn between the contacts are blown out by the air blasts escaping from the arcing chambers through the annular arcing contacts. Upon interruption of the flow of current through circuit 6, solenoid 51 returns to the position shown to cause valve 58 to reclose. Thesupplyof compressed air to arcing chambers 32 is thereby discontinued and springs 35 return the arcing contacts to the closed position thereof to restore the continuity of circuit 5.

Contacts 8 may thus open and reclose only once or may open and reclose a predetermined number of times in a period during which relay 2! is actuated in response to the flow of current through circuit 6 to ultimately close contacts 29. Upon closure of contacts 29 a closure of, contacts 24 will cause both solenoids 5| and 51 to be enwill be apparent, that valves 58, 58 and 59 and pistons 38 have very little inertia and that the arcs drawn at contacts '8, which are violently blown by the air blasts, may be extinguished in a very short time. The entire opening and reclosing operation of contacts 8 is thus of such short duration as to generally render the interruption of the dew of current through circuit 6 unnoticeable.

11 upon reclosure of contacts 9 the flow of current through circuit 6 then causes operation of relay 23, contacts 24 again close while contacts 29 are likewise. closed. Solenoids 5| and 51 are thus jointly energized to cause valves and 55 to open. Opening oi valve 56 again causes contacts 8 to open to interrupt the flow of current through circuit 6. Opening of valve 50 causes admission of air from reservoir 3i into cylinder 49 whereby contacts 9 are caused to be opened in 1 a. period of time depending on the setting of valve 52. Upon interruption of the flow of current at contacts 8 relay 23 returns to the position shown to cause valve 56 to reclose. Contacts 8 are thereby caused to reclose a second time. Valve 50 is then however 'mechanically interlocked with piston it to maintain the valve open until contacts 9 have reached the fully open position thereof. The circuit breaker is then'permanently opened and the circuit may be reclosed by manual actuation of switch 4?.

Although but two embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of .the

. invention or from the scope of the appended claims. i

It is claimed and desired to secure by Letters Patent:

i. In combination, an electric circuit, a'circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in said cir-. cuit, means comprising a solenoid operable responsive to an operating condition of said circuit for causing opening of said arcing contacts without affecting said disconnecting contacts, means providing for reclosing of said arcing contacts following opening of said arcing contacts. means,

comprising a second solenoid'momentarily operable responsive to the said operating condition after reclosure of said arcing contacts for caus ing opening of all said contacts andmeans com prising a lost motion connection between said solenoids whereby actuation of said second solenoid actuates said first solenoid.

2. In combination, an electric circuit, a circuit breaker comprising cooperating arcing contacts [and cooperating disconnecting contacts serially ergized' and valves 50 and 55 are thus made jointly responsive to the flow of current through circuit 5 at the time of reclosure of contacts 8 after a predetermined number 01! momentary openings of contacts 3. If however the flow of current through. circuit 8 is then restored at a value insufficient to cause operation of relay 23, the system will return to the position shown. It

connected with said arcing contacts in said circuit, means comprising'a solenoid operable responsive to an operating condition of said circuit for causing opening of said arcing contacts without affecting said disconnecting contacts, means providing for reclosure of said arcing contacts following opening of said arcing contacts, means comprising a second solenoid -momentarily responsive to the said operating condition after reclosure of said arcing contacts operable independently of the first said solenoid to cause opening of all said contacts and means comprising a lost motion connection between said solenoids whereby actuation of said second solenoid actuates said first solenoid.

3.-In combination, an electric circuit, a circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in said circuit, a latch for holding said arcing contacts in closed position, means for causing opening of said arcing contacts comprising a solenoid operable in response to an operating condition of said circuit for withdrawing said latch, means responsive to opening oi said arcing contacts for causing reclosure of said arcing contacts, a second latch for holding said disconnecting contacts in closed position, means for causing opening of all said contacts comprising a second solenoid for withdrawing both said latches, and time delay means responsive to said operating condition for momentarily rendering the second said solenoid responsive to said operating condition.

4. In combination, an electric circuit, a circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in said circuit, a latch for holding said arcing contacts in closed position, means for causing opening of said arcing contacts comprising a solenoid operable in response to an operating condition of said circuit for withdrawing said latch, means responsive to opening of said arcing contacts for causing reclosure of said arcing contacts, a second latch for holding said disconnecting contacts in closed position, means for causing opening of all said contacts comprising a second solenoid for withdrawing both said latches, and time delay means responsive to said operating condition for momentarily rendering the first said solenoid inoperative and for momentarily rendering the second said solenoid responsive to said operating condition.

5. In combination, an electric circuit, a circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in said circuit, means for causing opening of said arcing contacts comprising a source of fluid under pressure, contact separating means, and a valve for connecting said source with said contact separating means, means responsive to an operating condition 01 said circuit for momentarily opening said valve to cause momentary opening 01' said arcing contacts, means for causing opening of said disconnecting contacts comprising a second contact separating means and a second valve for connecting said second contact separating means with said source, and time delay means responsive to said operating condition to open the second said valve after a predetermined number of momentary openings of said arcing contacts.

6. In combination, an electric circuit, a circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in said circuit, means for causing opening 01 said arcing contactscomprising a source of fluid under'pressure, contact separating means, and a valve for connecting said source with said contact separating means, means selectively responsive to the flow of current through said circuit for causing opening of said valve to cause opening of said arcing contacts by said contact separating means and interruption of said flow or current at said arcing contacts, means for causing reclosure of said valve upon interruption of said flow of current, resilient means for reclosing said arcing contacts upon reclosure of said valve, means for causing opening or said disconnecting contacts causing opening of the said second valve, and

means selectively responsive to the flow oi current through said circuit for rendering the said valve opening causing mean jointly responsive to the flow of current through said circuit at the time of reclosure of the first said arcing contacts.

'7. In combination, a polyphase electric circuit, a circuit breaker comprising an arcing contact and a disconnecting contact serially connected in each phase oi. said circuit, means responsive to an operating condition of said circuit for causing opening thereof by said arcing contact, means for reclosing said circuit by said arcing contact,

and means momentarily responsive to said operating condition after a predetermined time delay following an occurrence of said operating condition for causing opening of all said contacts, said last said means comprising means providing actuation of all or said disconnecting contacts upon all actuations of one of said disconnecting contacts.

8. In combination, an electric circuit, a circuit breaker comprising an arcing contact and a disconnecting contact serially connected with said arcing contact in said circuit, means comprising a solenoid operable responsive to an operating condition of said circuit for causing opening thereof by said arcing contact, means providing for reclosing of said circuit by said arcing contact, means comprising a second solenoid momentarily operable responsive to the said operating condition after reclosure of said circuit at said arcing contact for causing opening or all said contacts, and a lost motion connection between said solenoids.

9. In combination, an electric circuit, a circuit breaker comprising an arcing contact and a disconnecting contact serially connected with said arcing contact in said circuit, means for causing opening of said circuit by said arcing contact comprising a source of fluid-under pressure, contact operating means, and a valve for connecting said source with said contact operating means, means responsive to an operating condition of said circuit for momentarily opening said valve to cause momentary opening or said circuit by said arcing contact, means for causing opening of said circuit by said disconnecting contact comprising a second contact operating means and a second valve for connecting said second contact operating means with said source, and time delay means responsive to said operating condition to open the second said valve after a predetermined number of momentary openings of said circuit by said arcing contact.

10. In combination, a polyphase electric circuit, a circuit breaker comprising an arcing contact and a disconnecting contact serially connected in each phase 01 said circuit, means responsive to an operating condition of said circuit for causing opening thereof by said arcing contact, means for reclosing said circuit by said arcing contact, and means momentarily responsive to said operating condition after a predetermined time delay following an occurrence of said operating condition for causing opening of all said contacts, said last said means comprising common means for actuating all said disconnecting contacts.

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