US2021499A - Circuit breaker - Google Patents

Description

9, 1935- L. B. CHUBBUCK ET AL 2,021,499

C IRCUIT BREAKER Filed April 24, 1934 5 Sheets-Sheet 1 INVENTORS. Lafiard B C/ZL/buc/t, George/ Wis/m7? (i Weak;

WITNESSES ATTOR EY Nov. 19, 1935. B, CHUBBUCK Er AL 2,021,499

CIRCUIT BREAKER Fil ed April 24, 1954 5 Sheets-Sheet 2 Leo/70 x2 3. C/n/bfiuck, George 1?. Wis/mm 4i lf 'en L. L Jeppesew.) KW MQ TTOR Y Nov. 19, 1935. L. B. cHuBBucK-ET AL 2,021,499

CIRCUIT BREAKER Filed April 24, 1934 5 Sheets-Sheet 3 ATTORN Patented Nov. 19, 1935 UNITED STATES PATENT orrics 11 Claims.

Our invention relates generally to electrical apparatus and it has particular relation to circuit breakers which are used for opening and closing electrical power circuits.

The object of our invention, generally stated, is to provide a circuit breaker having a motoroperated closing mechanism which shall be simpie and eflicient in operation and which may be readily and economically manufactured and installed.

The principal object of our invention is to provide for connecting a motor to the movable contact members of a circuit breaker.

Another object of our invention is to provide atrip' free connection between a motor-operated closing mechanism and the movable contact members of a circuit breaker.

A further object of ourinvention is to provide for preventing the au'tgnnaticreclosure of a" cir'- cuit' breaker after it has operated once, while the closing switch is held the operated 1308ition.

A Still further object or our invention is' to provide for operating a circuit breaker by" means of a motor and mechanically'and electrically" oper'ated clutches connected in series between the motor and the movable contact members or the circuit breaker.

Other objects of our invention will in be obvious and in part a'p'pear hereinafter.

Our invention accordingly is disclosed in the embodiment hereof shown in the accompanying drawings" and comprises the features of construction', combination or" elements, and arrangementof parts which will be exemplified in the construction hereinafter setforth, and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding the nature and scope of our invention, reference may had to the-following detafled' descripfidn, taken connection with the accompanying drawings; in which-z Figure 1 is a view, partlyin' side elevation and partly in section, illustrating a concrete embodiment' of our invention; t

Fig. 2 is an enlarged view, partly in; section, showing a part of the motor-operated mechamam;

Fig. 3' is a view; partly n side elevation and partly in section, taken along the line III -III* of Fig. 4; showing detailsof constructioiroi the" motor-operated mechanism; v o

Fig. 4 is a sectional view taken along the line IV IV' of Fig. 3; and showing additional de- (Cl. its- 254) tails of construction of the motor-operated mechanism; and

Fig. 5 is a diagrammatic view orthe motoro'perated mechanism and control circuits which may be used for controlling its operation. 5

Referring now particularly to Figs. 1 and 2 of the drawings, the rererenee character l0 des'' ignates generally a circuit breaker having fixed contact members H and I2 and a movable contact member I 3 mounted within a suitable tank It. Since the circuit breaker l0 constitutes no part of the invention,- it will be understood that the particular embodiment thereof illustrated in the drawings is provided solely for the purpose of describing the invention more fully.

In order to operate the movable contact member' l3 into engagement with the fixed contact membrs' I i and II, a motor I5 is provided which may oi the polyphase squirrel-cage type. As illustrated; the motor i5 is mounted underneath a connecting mechanism; shown generally at ii,- the' housing I? of which may be moimted di-' rec'tly on the tank It by welding or otherwise. The motor i5 provided with a' drive shaft f8 extending into the connecting mechanism It where it is connected to a," smart H which is rotatably mounted therein, as will be more fully described hereinafter;-

Ilft' 10; carrying the movable contact member I3; is" connected to thehe'iiagonal shaft l9, by means of a link 2i, operating l ver 22 comprising oppositely extending arms 23 and 24 link 25, and arm 2 6, which is secure to the Shaft i9 illustrated; the o erating level I! is" mounted for" rotation on a shaft 2T. It will also be observed that a depending' arm Ill is attached and an accelerating spring 29 is connected between the arm 28 and a fl'xed pin" 30* in eraer to more rapidly meet the opening of the-contact membe s or the circuitbreaker l0.

As will be set forth hereinafter, the anti 2 is caused" to slightly overtravel after the arm members of the" circuit breaker i0 are closed inf order to provide for deiener'gizirig the motor l5 after itis certain that the'contact members have 0 been closed and latched in" this position; With' a view to reducing the incident to the stopping of the connecting mechanism, a bore spring 35 is provided and mounted on a suitable 50 bolt 3G which is slidably mounted, as illustrated, in a block-31.

In the event" that it is desired to close the circuit breaker 10' manually, ahandle (not shown) may be inserted in a socket 3| which may be integrally formed with the upper arm 24 of the operating lever 22.

A tripping mechanism, shown generally at 38, is provided having a dashpot 39 of the customary type, for controlling the time of operation of the tripping device. The details of connection and operation of the tripping device 38 will be set forth hereinafter. It will be noted, however, that the tripping device 38 includes a tripping winding 40 surrounding an armature 4|, Fig. 2.

In order to more clearly describe the invention, the connecting mechanism 16 in Fig. 1 has been illustrated with its parts in the position which they assume when the contact members of the circuit breaker H] are in the open position. In Fig. 2, the connecting mechanism I6 is illustrated in a position corresponding to the closed condition of the contact members of the circuit breaker l5.

With particular reference to Fig. 2 of the draw ings, it will be observed that the upper operating arm 24 is provided with a short integrally formed lever arm 43 to which a connecting link 44 is attached for operating an auxiliary switch 45. The connecting link 44 is connected to a suitable operating arm 46 mounted on a shaft 41 of the auxiliary switch 45.

In order to open the circuits which are closed for energizing the motor 15 after the contact members of the circuit breaker I!) have been moved to a predetermined position, a limit switch, shown generally at 50, is provided having a fixed contact member 51 and a movable contact member 52, the latter being pivoted in a suitable U-shaped frame 53 on a pin 54. It will be observed that the lower end of the movable contact member 52 is provided with a roller 55 which is disposed in the path of a cam 56 that is mounted on the shaft 19 and rotates therewith. A compression spring 5'! is provided, as shown, for biasing the movable contact member 52 into engagement with the fixed contact member 5|.

In the event that the circuit breaker Ill should be tripped immediately after the closing operation has been initiated, and after the limit switch 56 has been operated to the open position, it is desirable to maintain the limit switch 50 in the open position so that the circuit breaker II] cannot automatically reclose to perform what is commonly known as a pumping action. Therefore, a holding winding 58 is provided which is arranged to be energized, as will be set forth hereinafter, upon energization of the motor 15. When the movable contact member 52 is operated to the open position by means of the cam 56, an armature 59 mounted on the upper end of the contact member 52 is moved into the magnetic field generated by the winding 58 so that the contact member 52 is held in the open position so long as the winding 56 is energized.

Referring now particularly to Figs. 3 and 4 of the drawings, a detailed description will be given of the connecting mechanism l6, which is proyided for causing driving engagement between the shaft 18 driven by the motor l5 and the shaft l9 which is directly connected to the movable contact member 13 of the circuit breaker l 0. For this connection, it is desirable to provide means whereby this connection may be accomplished with a minimum expenditure of energy and at the same time insuring that direct and positive connection will be maintained during the closing operation. It is also desirable to pro- ..vide for breaking the connection between the driving shaft [8 and the driven shaft 19 at any time while they are in driving engagement in order to prevent the contact members of the circuit breaker In from closing, for instance on a short circuit, or for any other reason, making it desirable to break the driving connection. It is also desirable to provide for connecting the motor l5 to operate the contact members of the circuit breaker Hi to the closed position from any last position of the motor l5. That is, the rotor of the motor I5 and the mechanism connected directly thereto need not be in any particular position relative to the other parts of the device in order that the circuit breaker I!) may be opera-ted.

With the foregoing conditions in mind, a clutch, shown generally at 65, is provided of the band friction type. The clutch 65 comprises a drum 66 which is mounted for rotation with the shaft l8. Surrounding the drum 66 is positioned 20 a helical clutch band 61, the upper end or high torque end, Fig. 4, of which is secured to a worm wheel 68 which is mounted for rotation around the drum 66. A worm 69 is mounted on the motor shaft l8 and in engagement with the worm wheel 68 for driving it.

The clutch band 61 is provided in the form of a helix around the drum 66 with a slight clearance therebetween for gripping the drum 66 when the lower end or low-torque end, Fig. 4, is held with respect to the drum 66. When a relatively slight force is applied to the low-torque end of the clutch band 61, it immediately grips the drum 66, thereby successively causing the succeeding turns of the clutch band 61 to engage the drum 66. Due to the frictional engagement between the succeeding turns of the clutch band 61 with the drum 66, only a relatively slight force is required to hold the band6l in driving engagement with the drum 66, while a relatively large torque may be transmitted from the Worm wheel 68 to the drum 66.

Since only a relatively slight torque need be applied at the low-torque end of the clutch band 61, the cross-sectional area of the turns may be gradually diminished, as illustrated, from the high-torque end to the low-torque end, as will be readily understood.

In order to provide the slight torque which is required for operating the clutch 65, an electromagnetic clutch, shown generally at 13, of the face plate type is provided. The face plate 14 is secured to the low-torque end of the clutch band 61 and mounted for rotation around the shaft l9 through the provision of a suitable bush- 5. ing 15. The electro-magnetic clutch 13 also comprises a winding-housing clutch plate 16 which is mounted for rotation with the shaft I9, and carries a winding H in a suitably recessed opening in the face.

It will be observed that, as long as the winding IT remains de-energized, the face plate 14 will be free to rotate around the shaft 19, together with the clutch band 61 and the worm wheel 68, as driven by the worm 69. However, as soon as 65 the winding H is energized, further relative movement of the face plate 14 with respect to the shaft I9 is arrested, thereby causing the lowtorque end of the clutch band 61 to engage the drum 66 with the result that the remaining turns 70 of the clutch band 61 are brought into frictional engagement with the drum 66 and causing the shaft [9 to be rotated to operate the circuit breaker ID to the closed position.

In order to hold the contact members of the circuit breaker I0 in the closed position, a latch pivotally mounted on a suitable shaft 8| is provided having a recessed portion 82 disposed to engage a roller 83, which is carried by the plate 16, of the electro-magnetic clutch 13. A-

coil spring 84 is provided for biasing the latch 80 into engagement with the roller 83. Since the roller 83, which is caused to engage the latch 80, is mounted on the clutch plate 15, which in turn is fixed on the shaft I 9 for rotation therewith,

it will be understood that the movable contact member I3 of the circuit breaker I0 will be held in engagement with the fixed contact members II and I2, since the shaft I9 is directly connected to the lift rod 20 through the lever arrangement, which has been previously described.

With a view to tripping the circuit breaker I0 to the open position, a latch arm 85 is secured to the shaft 8I so that movement thereof causes a corresponding movement of the latch 80. As illustrated, the latch arm 85 extends inwardly underneath the band friction clutch 65 and into the path of movement of a cross piece 86 carried by a cradle member 81, which is pivotally mounted about a shaft 88. The cradle member 81 is provided with an additional cross-piece 89, which is positioned in the path of movement of the armature 4I. It will be understood, therefore, that the cradle member 81 will be moved in a clockwise direction on energization of the tripping winding 40, thereby causing the latch arm 85 and latch 80 to be moved in a counter-clockwise direct-ion, and removing the recessed portion 82 of the latch 80 from engagement with the roller 83 and permitting the contact member I3 of the circuit breaker I0 to be moved to the open position under the combined influence of the forces of gravity and the accelerating spring 29.

It will be understood that additional tripping mechanisms 38 may be provided having additional armatures 4| for engaging the cross-piece 89 of the cradle member 81 in the event that it is desirable to control the tripping of the circuit breaker I0 in response to other conditions not set forth in this specification, as will be readily understood.

Referring now particularly to the diagram illustrated in Fig. 5 of the drawings, it will be observed that the circuit breaker I0 is provided for connecting sections of power conductors 9I, 92 and 93 together. It will be also observed that a switch, as shown generally at 94, is provided for connecting the windings of the motor I5 to the conductors 9|, 92 and 93. While the main power circuit may be used to supply current for operating the motor I5, it will be readily understood that any other suitable source of power may also be used.

A protective relay, shown generally at 95, .is provided having an energizing winding 95 arranged to be energized from the secondary winding 91 of a current transformer. While the protective relay 95 is illustrated as being responsive to current flow in the power conductors, it will be readily apparent that its operation may be controlled in response to any other variable factor in the transmission system, as may be desired.

A rectifier 98 of the copper-oxide type may be provided for supplying direct-current for energizing the winding I1 of the electro-magnetic clutch 13.

In operation, assuming that it is desired to close the circuit breaker I0, the close switch I9I is depressed, thereby energizing the winding 11 of the electromagnetic clutch 13 and winding I09 of the switch 94 through the rectifier 98.

The circuit for energizing the winding 11 of the electro-magnetic clutch 13 may be traced from the energized conductor 9! through conductor I02, contact members I03 of the closed switch IOI, conductor I04, contact members I05 of the protective relay 95, which are normally closed,

conductor I06, contact members 5I and 52 of the limit switch 50, conductor I01, rectifier 98 and conductor I08 to energized conductor 92. The circuit connections between the winding 11 and the rectifier 98 are obvious.

It will be observed that the winding I09 of the switch 94 is connected in parallel circuit relation with the rectifier 98, and, therefore, it is unnecessary to trace the circuit whereby it is energized.

As soon as the switch 94 is operated to the closed position, the windings of the motor I5 are energized, thereby causing it to rotate the shaft I8. The winding 11 of the electro-magnetic clutch 13 being energized, the band friction clutch is operated to directly connect the shaft I8 to the shaft I 9, and as a result the circuit breaker I0 is operated to the closed position.

When the circuit breaker I0 is in the fully closed position, the slight overtravel permitted by the linkage between the shaft I9 and the lift rod 20 is sufficient to permit the cam 56 to engage the roller 55, thereby causing the contact members 5| and 52 of the limit switch 50 to be opened against the force of the biasing spring 51. These contact members are held in the open position by means of the winding 58, which is energized on the operation of the closed switch IOI over an obvious circuit.

As soon as the circuit breaker I0 has been closed, the switch IOI may be released. This action, however, only de-energizes the winding 58, the motor I5 and the winding 11 of the electro-magnetic clutch having been de-energized through the opening of contact members 5| and 52, as will be readily understood.

In the event that a short circuit should exist on any of the conductors 9i, 92 or 93, causing a flow of current in the winding 96 of the protective relay 95 beyond a predetermined amount, the contact members I05 thereof will be opened and contact members IIO will be closed. The opening of contact members I05 immediately causes the de-energization of both the motor I5 and the winding 11 of the electro-magnetic clutch 13 provided they are energized, thereby permitting the contact members of the circuit breaker I0 to be immediately operated to the open position. This then provides what is known as trip free operation.

If the circuit breaker I0 has been completely closed and latched before the occurrence of the fault, the closure of the contact members III) completes a. circuit for energizing winding 40 of the tripping device 38, thereby releasing the latch from engagement with the plate 16 of the electro-magnetic clutch 13 and permitting the circuit breaker I0 to be opened, as willbe readily understood.

The circuit for energizing tripping winding 40 may be traced from energized conductor 9|, through conductors I02 and III, contact members IIO of the protective relay 95, conductors H2 and H3, winding 40, conductor II4, contact members II5 of the auxiliary switch 45, and conductors H6 and I08 to energized conductor 92.

In the event that it is desired to manually trip the circuit breaker ID, the trip switch H1 may be operated. Since the contact members I 18 of the trip switch I I! are connected in parallel circuit relation with the contact members H0 of the protective relay 95, it is unnecessary to trace again the circuit for energizing the tripping winding 40 on operation of the trip switch I ll.

Since certain further changes may be made in the above construction, and different embodiments of the invention may be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. A circuit interrupter comprising, in combination, relatively movable contact members disposed to open and close an electrical circuit, a motor for operating said contact members to the closed position, a band friction clutch interposed between said contact members and said motor, and an electro-magnetic clutch disposed to effect the operation of said band friction clutch to provide driving connection between said motor and said contact members.

2. A circuit interrupter comprising, in combination, relatively movable contact members disposed to open and close an electrical circuit, a motor for operating said contact members to the closed position, a band friction clutch interposed between said contact members and said motor, a latch disposed to automatically hold said contact members in the closed position, and an electromagnetic clutch disposed to effect the operation of said band friction clutch to provide driving connection between said motor and said contact members.

3. A circuit interrupter comprising, in combination, relatively movable contact members disposed to open and close an electrical circuit, a motor for operating said contact members to the closed position, contact means for controlling the operation of said motor, a closing mechanism connected directly to said contact members and disposed to provide a slight overtravel for operating said contact means to deenergize said motor on closure of said contact members, a band friction clutch interposed between said closing mechanism and said motor, a latch disposed to automatically engage with said closing mechanism during said overtravel period, and an electromagnetic clutch disposed to effect the operation of said band friction clutch to provide driving connection between said motor and said closing mechanism.

4. A circuit interrupter comprising, in combination, relatively movable contact members disposed to open and close an electrical circuit, a motor for operating said contact members to the closed position, and a band friction clutch and an electro-magnetic clutch disposed in series relation between said contact members and said motor to effect driving connection therebetween.

5. A circuit interrupter comprising, in combination, relatively movable contact members disposed to open and close an electrical circuit, a motor, and a band friction clutch and an electromagnetic clutch disposed in series relation between said contact members and said motor for effecting driving connection therebetween to operate said contact members to the closed position, said electro-magnetic clutch being disposed at the low-torque end of said band friction clutch whereby only a relatively small force is required to effect said driving connection.

6. A circuit interrupter comprising, in combination, relatively movable contact members disposed to open and close an electrical circuit, a 5

motor, a band friction clutch comprising a drum directly connected to said contact members and a helical band disposed around said drum and having the high-torque end directly connected to said motor, and an electro-magnetic clutch disposed between the low-torque end of said band and said drum for effecting driving connection therebetween, thereby permitting said motor to operate said contact members to the closed position. 15

7. A circuit interrupter comprising, in combination, relatively movable contact members disposed to open and close an electrical circuit, a motor, a band friction clutch interposed between said contact members and said motor, an electro- 20 magnetic clutch of the face plate type disposed to effect the operation of said band friction clutch to provide driving connection between said motor and said contact members for operating them to the closed position regardless of the last posi- 25 tion of the motor, and circuit means for connecting said motor and said electro-magnetic clutch to a source of electric power.

8. A circuit interrupter comprising, in combination, relatively movable contact members dis- 30 posed to open and close an electrical power cir. cuit, a motor for operating said contact members to the closed position, a band friction clutch interposed between said contact members and said motor, an electro-magnetic clutch disposed to effect the operation of said band friction clutch to provide driving connection between said motor and said contact members, circuit means for connecting said motor and said electro-magnetic clutch to a current source, and relay means con- 4 nected to be responsive to the occurrence of a fault in said power circuit for deenergizing said electro-magnetic clutch, thereby substantially instantaneously disconnecting said contact members from said motor. 43

9. A circuit interrupter comprising, in combination, relatively movable contact members disposed to open and close an electrical power circuit, a motor for operating said contact memhere to the closed position, a band friction clutch 5o interposed between said contact members and said motor, an electro-magnetic clutch disposed to effect the operation of said band friction clutch to provide driving connection between said motor and said contact members, circuit means for connecting said motor and said electro-magnetic clutch to a current source, a latch disposed to automatically hold said contact members in the closed position, electrical means for tripping said latch to release said contact members for move- 60 ment to the open position, and relay means con nected to be responsive to the occurrence of a fault in said power circuit for simultaneously deenergizing said electro-magnetic clutch, thereby substantially instantaneously disconnecting said 65 contact members from said motor in the event said electro-magnetic clutch is not already deenergized, and energizing said electrical means for tripping said latch in the event said latch has operated to hold said contact members in 70 the closed position.

10. A circuit interrupter comprising, in combination, relatively movable main contact members disposed to open and close an electrical circuit, a motor for operating said contact members to the closed position, a band friction clutch interposed between said main contact members and said motor, an electro-magnetic clutch disposed to effect the operation of said band friction clutch to provide driving connection between said motor and said main contact members, circuit means for connecting said motor and said electro-magnetic clutch to a source of electrical energy, a switch for controlling the operation of said circuit means to energize said motor and clutch on closure thereof and anti-pumping means operable when said contact members have been operated to a predetermined position for preventing a second closure thereof until said switch is released and again closed.

11. A circuit interrupter comprising, in combination, relatively movable main contact members disposed to open and close an electrical circuit, a motor for operating said contact members to the closed position, a band friction clutch interposed between said main contact members andtsaid motor, an electro-magnetic clutch disposed to effect the operation of said band friction clutch to provide driving connection between said motor and said main contact members, circuit means for connecting said motor and said electro-magneticclutch to a source of electrical energy, a switch for controlling the operation of said circuit means to energize said motor and clutch on closure thereof, and anti-pumping means comprising normally closed auxiliary contact members connected in series circuit relation with said circuit means and disposed to be opened when the main contact members of the circuit interrupter are moved to a predetermined position, thereby opening the energizing circuit for said motor and said clutch, and a holding winding disposed to be energized on closure of said switch for maintaining said auxiliary contact members in the open position as long as said switch remains in the closed position.

LEONARD B. CHUBBUCK.

GEORGE R. WISHART.

K. L. LIGAARD JEPPESEN.

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