US2766404A - Pressure responsive antipumping control system for circuit breakers - Google Patents

Description

Oct. 9, 1956 H. B. ASHENDEN 2,766,404 PRESSURE RESPONSIVE. ANTIPUMPING CONTROL SYSTEM FOR CIRCUIT BREAKERS Filed March 16, 1953 United States Patent Ofiice PRESSURE RESPONSIVE ANTIPUMPING CON- TROL SYSTEM FOR CIRCUIT BREAKERS Harry B. Ashenden, Cambridge, Mass., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis.

This invention relates to circuit breakers and more particularly to the closing control circuit of pneumatically operated high speed circuit breakers.

A satisfactory control system for a modern power circuit breaker should perform several functions in addition to opening and closing the breaker. These functions are as follows:

1. Energize the closing circuit long enough to insure complete closing even though the initiating contact is only momentarily closed.

2.Deenergize the closing circuit to cut off the closing power just as the circuit breaker is fully closed.

3. Prevent pumping.

4. Provide electrically trip free operation.

The term pumping is commonly used to refer to unintentional repetitive opening and closing operations of a breaker, while the initiating switch or closing control switch contact is held closed. Unless means are provided to prevent pumping, such operations can occur when a breaker is closed on a faulted line and resulting damage is probable if the fault current is high. The closing control of a circuit breaker should be such that it will close the circuit breaker only once for each operation of the closing control switch.

In the prior art pumping was controlled or eliminated by using a two relay control scheme which utilized a main control relay usually designated X and an auxiliary control relay usually designated Y. Part of the function of the auxiliary or Y relay in the circuit has been to provide trip free operation and to prevent pumping. It is desirable to provide a control system with fewer contacts than the prior art X, Y systems. The new arrangement should provide more positive sequence of action between the closing circuit deenergizing means and the antipumping device by combining these structures in a single device and should eliminate possible functional failure of the antipumping means caused by imperfect operation of the relay due to shock of circuit breaker operation at the time the control relay is attempting to seal in.

In accordance with the invention claimed, a new and improved control arrangement for controlling the closing of a pair of contacts of a circuit breaker structure is provided. This closing arrangement comprises a closing switch, a solenoid valve energized by closure of the closing switch for admitting fluid under pressure from a source of fluid under pressure to the cylinder to close the breaker contacts, and a pressure operated switch responsive to presence of fluid under pressure in the cylinder for closing another pair of contacts for providing a holding circuit for maintaining the solenoid valve energized after reopening of the closing switch. Means are provided for controlling the solenoid valve and comprises a cutoff switch comprising a pair of contacts actuated by fluid being vented through the cylinder of the motor to the cutolf switch to deenergize the solenoid valve upon the piston of the motor reaching a predetermined point in its travel in breaker closing direction.

1 2,766,404 Patented Oct. 9, 1956 An electromagnetic means responsive to the separation of the cutoff switch contacts is provided for locking the cutolf switch contacts open and the solenoid valve deenergized. The electromagnetic means is controlled by the pressure operated switch to cause the electromagnetic means to remain energized until the closing switch opens, the gas pressure in the cylinder decreases to a predetermined value causing the pressure operated switch contacts to separate.

It is therefore one object of the present invention to provide a new and improved control system for circuit breakers of the fluid operated high speed type in which unintentional repetitive opening and closing operations of a circuit breaker are prevented.

Another object of this invention is to provide a new and improved closing control system for a fluid operated circuit breaker in which the circuit breaker contacts close only once for each operation of a control switch.

A further object of this invention is to provide a new and improved circuit breaker operating mechanism in which circuit breaker control is obtained with a minimum of parts.

Other objects and advantages of the invention will become apparent from the following description when read in connection with the accompanying drawing, in which:

Fig. 1 is a diagrammatic view of a circuit breaker, a control circuit, and operating mechanism therefor embodying the present invention;

Fig. 2 is an enlarged view taken on line II-II of the electromagnetic gas blast cutoff switch of Fig. 1 looking in the direction of the arrows; and

Fig. 3 is an enlarged view taken on line IllIIl of the electromagnetic gas blast cutoff switch of Fig. 1 looking in the direction of the arrows.

Referring more particularly to the drawing by characters of reference, a pneumatic motor 1 of the cylinder and piston type is operatively connected by a linkage 2 to a circuit breaker 3.

As diagrammatically shown, the circuit breaker 3 comprises a pair of stationary contact members 4 and a movable contact member 5. The circuit breaker is biased to open circuit position by means of accelerating spring 6. The movable contact member 5 is supported by a breaker rod 7 which, in turn, is supported by lever 8 pivoted at 9. Lever 8 is connected to bell crank 10 by means of rod 11. Bell crank 10 is pivoted at 12 and forms part of linkage 2. The circuit breaker is shown in the closed position and is held there by a latch 13.

Releasing or tripping the latch will open the breaker. This may be done manually or it may be done electrically by the tripping solenoid 14 or automatically on occurrence of fault on the power line 15 by means of fault responsive relay 16., Solenoid 14 actuates latchj 13 counterclockwise to release the linkage 2 to cause separation of contacts 4 and 5 of circuit breaker 3. Linkage 2 may be made of any suitable known type and may be mechanically trip free. The fault responsive relay 16 comprises a movable contact 23 which engages a pair of stationary contacts 24.

Motor 1 may be of any suitable known type operated by a fluid which may be a liquid or a gas. it comprises a main casting 27 defining the lateral wall of the operating cylinder of the motor, a top element 23, a base element 29, and a piston 30. Piston 30 is biased downward by any suitable means such as a helical spring 31 of which one end rests against top element 28 while its other end rests against piston 30. Base element 2? defines a passage 32 which is connected to a duct 33 for admitting gas or other fluid under pressure from a source 34 to the cylinder of motor 1. The flow of gas under pressure from the source to the cylinder of motor 1 is controlled by a solenoid valve 36 comprising a coil 41. Upon admission 'of gas under pressure to motor 1, piston 30 is moved upward against the bias of spring 31. Piston 30 is provided with a ram 37 adapted to engage bell crank 10 to' rotate it counterclockwise. Upon raising of piston 30, the parts by which linkage 2 is constitutedare moved to their position shown in Fig. 1, which causes engagement of contacts dand of circuit breaker 3. Linkage 2 is then latched in 'by latching means 13 and thus linkage 2 restrains circuit breaker 3 in the closed position thereof against the bias of accelerating spring 6. When circuit breaker 3 is closed, piston 36 and ram 37 are free to move to their initial position shown in Fig. 1 under the-combined action of gravity and "spring 31.

The bottom portion of cylinder 27 is connected to'a duct 46. Duct-46 is connected to a pressure operated switch -47 comprising a housing 48, piston 45, piston rod 50 forming a movable contact 5'1 and a pair of stationary contacts 52. Switch 47 is responsive to the presence of gas under pressure in'cylinder -27 of fluid motor 1 for closingcontactsSi and 52 to provide a holding circuit for maintaining solenoid valve 36-energized after reopening of a closing switch 54.

Thecoil 41 of solenoid valve 36 is connectedin series with a-pair of contacts 55, 56 of a cutofi switch 57 across a source of power 58. Switch 57 may be of any suitable known fluidoperated type, and maybe a pneumatically operated switch with extinction of the are by a gas blast.

The arcing contacts of the-cutotf switch 57 comprise two stationary contacts 55 which are bridged by a hollow cylindrical movable contact 56. Contact 56 is secured to a piston-59 which is mounted in acylinder 60. Cylinder 60 forms a part of an insulating housing 61. Housing 61 is connected to an orifice 63 in cylinder 27 of motor 1 by means of 'a duct 64.

Housing 61 is fastened to a frame 65 of suitable electromagnetic means such as an electromagnet 66 by means of bolts 67. Gas under pressure passing 'through'duct 64 from motor 1 enters =the hollow cylindrical contact 56. Contact '56 is provided with apair of slits or openings 6-8 which communicate with the upstream side of piston 59. Gas from 'motor 1 thus passes through slits 63 to the upstream side of piston 59 to actuate piston 59 to separate thec'ontactsi55 andi56. Piston:59.and contact 56 are integrated into one structural unit which is biased into contact closed position by a spring69. Housingafil is provided with vent openings 70 which connect the downstream end of cylinder 60 with theatm'oshere. Normally, the vent openings 76 are closed by piston59 when the contacts 55 and56 are engaged. These vent openings are opened substantially atthe time at which contact 56 separates from contacts 55. Two arc'extinguishing cross blasts are formedsubstantially at the time of arc initiation'between contacts 55 and 56, one at each of the two serially related breaks of the cutoif switch 57.

The electromagnet 66 comprises core structure 71, an armature 72 and a coil 73. Armature 72 forms anintegral part of piston 59 and is arrangedtoiprovide with the core structure 71 a gap 74 therebetween sufliciently large to preclude lifting of the unit 56, 59 and72-by the action of the coil 73 alone. Coil 73, however, locks unit 56, 59 and '72 in the raised position against core structure 71 once the unit has been raised by the action of compressed gas acting on the upstream side :oftpiston 59 to thereby lock the electric'circuit of coil 41 of the solenoid valve 36 open. Electromagnet .66 provides an antipumping feature which prevents repeated attempts of the circuit breaker to close in case of a latch failure and to prevent repeated operations of motor 1 eventhough the circuit breaker stays closed on first closure.

The movement of hell crank either in circuit breakor opening or closing direction causes action of circuit breaker auxiliary contacts or switch 75. Switch 75 comprising a movable contact 76 and two pairs of stationaiy contacts 77 and 78 is actuated by'aro'd 79, a-bell crank 80 pivoted at 81 and a link 82 connected to hell crank 10. With the circuit breaker 3 in contact closed position contacts 76 and 77 are in engagement and with the circuit breaker 3 in contact open position contacts 76 and 7 8 are in engagement.

With the circuit breaker 3 in contact closed position, tripping switch 85 may be closed to complete a circuit from source 58 through a conductor .86, solenoid 14., a conductor 87, contacts 76, .77 of the auxiliary switch 75, a conductor 68 and back to the source of supply 53. The .ener-gization of solenoid 14 causes the latch 13 to rotate counterclockwise and to release linkage 2, which causes spring 6 to separate contacts 4.and 5 of circuit breaker 3.

With the circuit breaker 3 in contact open position, closing switch 54 may be .closed to complete an electric circuit from the source of power 58, through a conductor 89, contacts 91 and 91 of a pressure responsive switch 92 similar to switch 47, a conductor 96, auxiliary switch contacts 76, -78 (closed'when the circuit breaker 3 is open), a conductor 10%, contacts "55 and 56 of cutotl switch 57, a conductor 101, coil 41 of solenoid valve 36 and conductor 88 to thesource of supply 58.

Upon energization of coil 410i solenoid valve 36, the valve admits gas under pressure from reservoir 34 to pass through duct 33, valve 36 and duct 32 to the opening in cylinder '27 of fluid motor '1 under piston 35. The gas under pressure in cylinder 27 actuates piston 36 upward and rod 37 actuates bell crank ltlcounterelockwise to close the circuit breaker 3. Gas under pressure in cylinder 27 under piston 30 also actuates piston 49 or" the pressure operated switch 47 to close contacts Stand 52 and complcte'a circuit from the source of power 58 through a conductor 98, cont-acts '51 and 52 of the pressure operated switch 47, a conductor 99, a conductor-160, contacts'55 and 56 of the cutoif switch 57, a conductor 10.1, coil 41 of solenoid valve 36, conductor '88 to the power supply 58. This 'holding circuit maintains coil 4-1 .of :solenoid valve 36 energized and solenoid valve 36 open until thecircuit breaker 3 is closed even though closing :switch 54 is closedonly for a limited time.

.As piston 30 of fluid motor-1 reaehesthe breaker closed position, it uncovers orifice 63 in'eylinder 27 and provides asmeans for gas under pressure belowpiston 30 to flow through 'duct 64, housing 61,0pening -68 of contact 56 to the upstream side of'piston 59. Movement'of piston 59 upwardi'causes interruptionof the current flow in the circuit -energizing:coil-41 of solenoid valve 36. Thus, the arcing contacts 55 and 56-are actuated by gas being vented throughcylinder27-to thecutofl switch 57. Deenergization of:coil '41 causeselosing-of solenoid valve 36 and the cutoffzofgas to motor'].. Upon the cut off of gas to motor 1 by=valve:36, the valve provides a passage for gasunder'pressure under piston 30 of motor 1 to escape to 1 atmosphere, itherehy permitting piston 30 to return to its lower-position, as shown.

IClosingof switchr5'4 a'lso establishes a circuit from the power supplyrSS throughclosing switch 54, conductor 89, a conductor 103, coil 73 of cutoff switch 57, conductor:88 to powerzsupply 58. Thus, if closing switch 54 is still closed when the-circuit breaker contacts 4 and 5 engage andpiston 59 of cutoif switch '57 separates contacts 55 an'd 56, coil"73 will remain energized and will hold armature 72-against core '71 and-maintain contacts 55 and 56 separated untilclosing switch 54 is opened. Such action ofthe-electromagnetic means 66 takes place in response toseparation of contacts 55, 56 as coil 73 is incapable oflifting'armature 72 as long as the contacts are in the closed posi'tion shown.

Further, there is a holding circuit from the power supply 58 through conductor 98, contacts 51 and 520i the pressure operate'd'switeh- 47, a resistor 105, conductor 89, 'conduetor 103, coil73of cutofI' switch 57, conductor 88=to-the=powersupply 58. As long ascontacts 55'and 56'of'cuto'tfswitch 57 remain separated, coil 41 of solenoid valve 36 cannot be energizedto provide a flow of gas under pressure to motor 1 for repeat closing circuit breaker action. The electromagnetic means 66 is controlled by the pressure operated switch 47 which causes the electromagnetic means 66 to remain energized until switch 54 opens or the pressure in cylinder 27 below piston 30 decreases to a predetermined value causing the pressure operated switch contacts to separate. Therefore, circuit breaker 3 can close only once for each operation of closing switch 54.

This operating arrangement or system is nonpumping. It is also electrically trip free as simultaneous closure of switches 54 and 85 results in the breaker remaining open 'or tripping open. It is particularly advantageous because of its smplicity and reliability.

Although but one embodiment of the present invention has 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.

It is claimed and desired to secure by Letters Patent:

1. In combination: a circuit breaker comprising a pair of contacts, a source of fluid under pressure, means for closing said contacts comprising a cylinder and a piston movably arranged therein, a closing switch, a solenoid valve energized by closure of said closing switch for admitting fluid under pressure from said source to said cylinder to close said breaker, a pressure operated switch responsive to presence of fluid under pressure in said cylinder for closing a pair of contacts in a holding circuit for maintaining said solenoid valve energized after reopening of said closing switch, means for controlling said solenoid valve comprising a cutoff switch comprising a pair of contacts actuated by fluid being vented through said cylinder to said cutoff switch to deenergize said solenoid valve upon said piston reaching a predetermined point in breaker closing direction, and electromagnetic means responsive to separation of said cutoff switch contacts for locking said cutofl switch contacts open and said solenoid valve deenergized, said electromagnetic means being controlled by said pressure operated switch to cause said electromagnetic means to remain energized until said pressure in said cylinder decreases to a predetermined value and said pressure operated switch contacts separate.

2. In combination: a circuit breaker comprising a pair of contacts, a source of fluid under pressure, means for closing said contacts comprising a cylinder and a piston movably arranged therein, a closing switch, a solenoid valve energized by closing said closing switch for ad mitting fluid under pressure from said source to said cylinder to close said breaker, a pressure operated switch responsive to the presence of fluid under pressure in said cylinder for closing a pair of contacts in a holding circuit for maintaining said solenoid valve energized after reopening of said closing switch, means for controlling said solenoid operated valve comprising a cutofl switch comprising a pair of contacts actuated by fluid being vented through said cylinder to said cutoff switch to deenergize said valve upon said piston reaching a predetermined point in breaker closing direction, and electromagnetic means responsive to separation of said cutofl' switch contacts for locking said cutofl switch contacts open and said solenoid valve deenergized, said electromagnetic means being controlled by said pressure operated switch to cause said electromagnetic means to remain energized until said closing switch opens.

3. In combination: a circuit breaker comprising a pair of contacts, a source of fluid under pressure, means for closing said contacts comprising a cylinder and a piston movably arranged therein, a closing switch, a solenoid valve energized by closing said closing switch for admitting fluid under pressure from said source to said cylinder to close said breaker, a pressure operated switch responsive to the presence of fluid under pressure in said cylinder for closing a pair of contacts in a holding circuit for maintaining said solenoid valve energized after reopening of said closing switch, means for controlling said solenoid operated valve comprising a cutofli switch comprising a pair of contacts actuated by fluid being vented through said cylinder to said eutofi switch to deenergize said valve upon said piston reaching a predetermined point in breaker closing direction, and electromagnetic means responsive to separation of said cutoff switch contacts for locking said cutoff switch contacts open and said solenoid valve deenergized, said electromagnetic means being controlled by said pressure operated switch to cause said electromagnetic means to remain energized until said closing switch opens and said pressure in said cylinder decreases to a predetermined value causing said pressure operated switch contacts to separate.

4. In combination: a circuit breaker comprising a pair of contacts, a source of fluid under pressure, means for closing said contacts comprising a motor operable by fluid under pressure and comprising a cylinder and a piston movably arranged therein, means for returning said piston to the initial position thereof upon closing of said breaker, a linkage for operatively relating said breaker to said motor, tripping means for causing said linkage to open the breaker, a ram on said piston separate from said linkage and cooperating therewith for reclosing the breaker, a closing switch, solenoid valve means energized by said closing switch for admitting fluid under pressure from said source to said cylinder to close said breaker upon closure of said switch, a pressure operated switch responsive to the presence of gas under pressure in said cylinder for closing a pair of contacts in a holding circuit for maintaining said solenoid valve energized after reopening of said closing switch, means for deenergizing said valve upon a predetermined travel of said piston in breaker closing direction and for locking said valve closed, said deenergizing means comprising a cutoff switch comprising a pair of contacts actuated by fluid being vented from said cylinder through said cutofl? switch to interrupt the electric circuit which energizes said solenoid valve, and electromagnetic means responsive to separation of said cutoff switch contacts for locking said cutoff switch contacts open and said solenoid valve deenergized, said electromagnetic means being controlled by said pressure operated switch to cause said electromagnetic means to remain energized until said pressure in said cylinder decreases to a predetermined value causing said pressure operated switch contacts to separate.

5. In combination: a circuit breaker comprising a pair of contacts, a source of fluid under pressure, means for closing said contacts comprising a motor operable by fluid under pressure and comprising a cylinder and a piston movably arranged therein, means for returning said piston to the initial position thereof upon closing of said breaker, a linkage for operatively relating said breaker to said motor, tripping means for causing said linkage to open the breaker, a ram on said piston separate from said linkage and cooperating therewith for reclosing the breaker, a closing switch, solenoid valve means energized by said closing switch for admitting fluid under pressure from said source to said cylinder to close said breaker upon closure of said switch, a pressure operated switch responsive to the presence of fluid under pressure in said cylinder for closing a pair of contacts to provide a holding circuit for maintaining said solenoid valve energized after reopening of said closing switch, means for deenergizing said valve upon a predetermined travel of said piston in breaker clos" ing direction and for locking said valve closed, said deenergizing means comprising a cutofl switch comprising a pair of contacts actuated by fluid being vented from said cylinder through said cutofl switch to interrupt the electric circuit which energizes said solenoid valve, and electromagnetic means responsive to separation of said cutoff switch contacts for locking said cutofif switch open and said solenoid valve deenergized, said electromagnetic means being controlled by said pressure operated switch 6. In combination: a circuit breaker comprising a pair :of contacts, a source of .fiuid under pressure, means for .closing'saidrcontacts comprising a motor operable by fluid :under pressure and comprising a cylinder:and a :piston movablyrarranged therein, means for :returning'said pis- ;ton;to:the1initial position thereof upon-closing of said breaker, :a linkage foroperatively relating said breaker to said motor, tripping means for causing-said linkage 10 0138111116 breaker,.a ram on said'pistonseparate from said linkage ..and cooperating therewith for reclosing the breaker, aclosing :switch, solenoid valve rrieans-energized by said closing switch fQnadm'itting :fluid under pressure from said source to said cylinder to close said breaker uponclosure of said switch, a pressure operated switch responsive to-the presence of "fluid under pressurein said cylinder for closing a-pairofcontacts to provide'a holding circuit for maintaining said valveenergize'd a'fterreopening of said closing switch, means for deenergizing said valve upon a predetermined travel of'said piston iii-breaker closingdirection and :for locking said valve closed, said deenergizing meanscompr'isingaswitch comprising a pair of contacts actuated-by fluid beingvented fromsaid cylinder throughsaid cutoif switch=tointerrupt the electric-circuit which energizes said solenoid 'valve, and electromagnetic means responsiveto-separation of said-cutofi switch contacts for locking said cutofi switch open and said solenoid valve deenergized, said electromagnetic means being controlled by-said-pressure-operated switch to cause said electromagnetic means to remain energized until said closing switch opens, and said pressure in said cylinder decreases to apredetermined value causingsaid pressureoperated switch contacts to separate.

7. In combination: a circuit breaker comprising a pair -of. power interrupting: contactsand a pair ofauxiliary-con- ;tacts, a-source-offluid underpressure common means for closing said interrupting contacts and opening said auxiliary contact comprising :a cylinder and apistonmovably arranged therein, a-closing switch, a valve,:a solenoid for actuating said valve, a source of electrical power, means for causing a current to flow from said source through 'said Clos'ingswitch upon closure thereof through'said auxiliary contact and said solenoid, said solenoid valve upon energization thereof admitting fluid under pressure from said-sourceto saidcylinder to close said interrupting contacts and'opensaid auxiliary'contacts, a pressure operated switch responsive to the presence of fluid under pressure in said cylinder for closing a pairof contacts in a holding circuit beforeopening of said auxiliary contacts for maintaining said solenoid valve energized after reopening of said closing switch, means for controlling said solenoid valve comprising a cutofi switch comprising a pair of contacts actuated'by fluidbeing vented through said cylinder through said cutofi switchto atmosphere to deenergize said solenoid valve upon said piston reaching a predetermined point in breaker closing direction, and electromagnetic means responsive .to separation of said cutofi switch contacts for locking said cutoii switch contacts open and said solenoid valve deenergized, said electromagnetic means being controlled by said pressure operated switch torcausesaid electromagnetic means to remain energizedtuntil said pressureinsaid cylinder decreases to a predetermined value causing said pressure operated switch contacts to separate.

.Referenc es Cited in the file of this patent UNITED STATES PATENTS 2,346,147 Boisseau Apr. 11, 1944

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