US730376A - Controlling electric motors. - Google Patents

Description

PATBNTED JUNE 9, 1903;

J. w. KELLOGG.- CONTROLLING ELECTRIC MOTORS. APPLICATION FILED NOV. 28, 1902.

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PATENTEDVJUNB 9, 1903 J. W. KELLOGG. CONTROLLING ELECTRIC MOTORS.

' APPLICATION FILED NOV. 28, 1902,

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lNvENToRt James W Kellogg,

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No. 730.376. I PATENTED JUNE 9, 1903. J. WQKHBLQGQ CONTROLLING:- BLEGTRIG MOTORS.

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UNITED STATES Patented June 9, 1903.

PATENT OFFICE.

JAMES W. KELLOGG, OF SCHENECTADY, NEWV YORK, ASSIGN O R TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CONTROLLING ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent N 0. 730,376, dated June 9, 1903.

Application filed November 28. 1902. Serial No- 133.0l1. (No model.)

To alt whom it may concern.-

Be it known that I, JAMES W. KELLOGG, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in ControllingElectric Motors, of which the following is a specification.

My invention relates to electric-motor-con- IO trollin g devices in general, and more specifically to an improved starting device for electric motors.

As illustrated, the apparatus is constructed to operate with a stationary motor as distinguished from one mounted on a wheeled vehicle. In such installations it is customary to have a series of resistance-coils or other starting resistances adapted to be gradually cut into the motor-armature circuit when the current is first sent through the armaturecoils in starting ihe'motor and then cut out gradually as the starting-switch approaches its final position. When this final position is reached, the resistances are all cut out and the full current passes through the armaturecoils, developing the full power of the motor.

It is important that provision should be made to prevent the possibility of the apparatus being left in such position that the cur- 0 rent may be sent through these starting resistances for any considerable period of time,

as they are not designed to do more than to carry the current for a brief interval and would be burned out if long subjected to the heating action of the current. It is also important that the device should be powerless to close the circuit on the motor without inserted resistance-for example, in case of failure of power after once starting the cir- 4o cuit must be incapable of closure again until the resistance is cut in. Starting devices for this purpose as now constructed usually have a spring-switch released by a high-resistance magnet to open the circuit through the re- 5 sistance when the current fails, as well as apparatus operated by a low-resistance magnet in the main circuit to throw a separate circuit-breaker when the current on the circuit rises to a dangerous value. The first of these is called the no-voltage magnet and the Several obsecond the overload-magnet.

construction.

jections apply to a spring-controlled lever.

It is difficult to make sufliciently good contact 5 between the brush and the contact-studs, even with the heaviest springs, and the fact that the circuit is broken at the studs burns them, making them rough, which causes the brush soon to stick in a half-way position and burn out the resistance. My invention overcomes these difficulties by providing an improved 6o means for automatically breaking the circuit outside of therheostat if the starting-switch is left in any other than a running position.

It adds very greatly alsoto the durability of I the control device by removing the biasingspring from the brush-arm and rendering the latter controllable entirely by hand, and yet prevents possibility of danger from such a As the simplest arrangement of circuit is that employed with a motor adapted to run at only one speed, I have not herein shown or described any arrangement for motors employing diiferent resistances for diiferent speeds, but have merely dealt with, the starting resistances which are quickly cut in and cut out as the starting-switch moves up to a running position.

The preferred form of my apparatus is illustrated in the accompanying four sheets ofdrawings, in which- Figure l is a diagrammatic view of the apparatus, showing the parts in the position assumed when the motor has been shut down by opening the controlling-switch. Fig. 2 is a similar view showing the parts in the position assumed when the main-circuit breaker has been set preparatory to throwing the current on again. Fig. is a similar view showing the parts in the position assumed after the circuit has been broken during the operation of the motor by the action of the overload-magnet. Fig. 4 is a sectional view of my improved form of starting-switch lever with cut-out for no-voltage magnet, and Fig. 5 is a perspective view of the main-circuit breaker 5 arm and partly cutaway sleeve or. thimble 011 which it is mounted.

Throughout the drawings like referencefigures indicate like parts.

The terminals of the supply-circuit are rep- 1 oo resented at 1 and 2. Starting with the terminal 1 the current is divided through the branch wire 23, the field-magnets 3 of the motor, and

t 1r ugh the armature 4 of the motor. From thewire 23 the circuit is through the cut-out 24, (When closed,) the wire 25,the no-voltage magnet 26, and wire 27 to contact-piece 12 of the m ain-circuit breaker. From the armature the circuitis through the wire 5 and one or more of the resistance-contacts 6 6, through the brush on arm 30 to the arc-shaped contact-piece 8, and from the field-magnet 3 the circuit is through the wire 7 to said contact-piece 8. From said contact-piece 8 the circuit continues through the wire 9, coils of the overload-magnet 10, and the wire 11 to the contact 12 of the maincircuit breaker. \Vhen the circuit-breaker switch 13 is in position to bridge the space between the contacts 12 and 14, the circuits continue on through the wire 15 to the other terminal 2 of the supply-circuit.

The mechanism for throwing the circuitbreaker through operation of the overloadmagnet consists of the core 16 for the solenoid into which said overload-magnet is formed, the swinging catch 17, operated through pinand-slot connection with said core 16, the toe 18, journaled on the stud-shaft 19 of the rheostat-brush arm, and a partly cut-away sleeve or thimble 20, through the cut-away portion 18 of which the toe 18 projects. The circuit-breaker switch 13 is carried on the illsulation-block 2l,mounted 011 said thimble 20, and the toe 18 is normally under tension from the section 18 of the spiral spring wound around the stud-shaft and fastened to the same by the pin 22, as shown on Fig. 4. Of course a diiferent arrangement of these parts and of the spring might be made to produce the same result and the means of fastening the spring to the stud might be changed.

The apparatus for controlling the circuitbreaker through the action of the no-voltage magnet consists of the armature 28 for said magnet carried by the toe 29, which is similarly journaled on the stud-shaft 19 and projects through the cut-away portion 29 of the thimble 20, said too 29 being undertension from the portion 29 of the spiral spring before described.

The brush-arm 30 is mounted to turn freely on a pivotal stud and is unbiased by anycontrol-spring. It has the handle 31, in which is mounted the spring-plunger 32 and the lower end of which presses on the spring-contact 24 when forced down and bends the same into contact with the cooperating part 24 of the cut-out. The stationary contact-piece 33 is arranged to bridge over the connection from 24 to 24 when the starting-switch is in full running position. (Shown in Fig.

The carbon brush 34, carried in a socket in the under side of the lever 30 and controlled by the spring 35, bridges over the connection from the resistance-contacts 6 6 to the areshaped contact-piece 8.

Such being the construction of the preferred form of apparatus embodying my i11- vention, the operation is as follows: As shown in Fig. 1, the parts are in the normal position assumed when the motor has been shut down and the current is off. The hand of the operator being removed from the handle 31 and his thumb no longer pressing on the springplunger 32, the circuit through the no-voltage magnet has of course been broken and the spring 29 has operated to swing the toe 29, which bears against the thimble 20 at one extremity of the cut-away portion 29, and has rotated said thimble and swung t e bridging-contact 13 of the circuit-breaking switch until it has struck the stop 36, thereby opening the main circuit and preventing the passage of any current through any portion of theapparatus. Then the operator desires to start the motor into operation, he grasps the handle 31 and swings the lever 30 into the position shown in Fig. 2. The forked bearing 37 of the lever brings up against the circuit-breaker switch-arm and swings the same into the position shown to bridge the space between contacts 12 and 14. This motion brings the armature 28 in proximity to the core of the no-voltage magnet 26, so that when the operator presses down with his thumb upon the spring-plunger 32 and closes the circuit through the no-voltage magnet by forcing together the parts 24" and 24 of the cut-out said no-Voltage magnet becomes energized and is strong enough to hold the armature 28 and toe 29 against the pressure of the spring 29 when the reverse motion is given to the brush-arm 30. Such reverse motion swings the arm ultimately into the position shown in Fig. 3. In reaching that position the bridge-piece 34 establishes a circuit through the motor-armature 4 through the resistances 6, which are gradually cut out as the arm reaches its final position in the well-known manner. When the arm is in its final position the bridge-piece 33 permanently closes the circuit around the cut out 24, leaving the connection such that the no-voltage magnet is unaffected when the operator removes his thumb from the springplunger 32. The parts remain in this position. during normal operation of the motor. If the circuit breaks anywhere, of course the no-voltage magnet releases the armature 28, which throws the 1nain-circuit-breaker switch in the manner before described without, however, disturbin the position of the brush-arm of the rheostat, and the latter must be thrown back into position shown in Fig. 2 to reset the circuit-breaker and other parts before the motor can be started up again. In the same way if there is a sudden rush of current in excess of the normal amount the overloadmagnet 10 pulls up the core 16 and trips the catch 1'7, releasing the toe 18, which throws the circuit-breaker switch and puts the parts in the exact position. (Shown in Fig. 3.) It will again be necessary to throw the brush arm back into the position shown in Fig. 2 before the motor can be started up again. If at any time the pressure of the operators tionally holding down the spring-plunger 32. I

This could be done only if the operator malic-iously desired to burn out the apparatus. In all cases of ignorance or oversight or the sudden calling away of the operator before he had pulled the brush-arm around into its final position the automatic cut-out would throw the main-circuit breaker, as before described. It will be evident also that the contacts of the rheostat will not be damaged by acting to open the circuit and that a smooth operating relation between the brush and the studs may.

be maintained. Further, a much better contact can be secured, because the brush-arm is operated each way by hand, and a good hard contact can therefore be allowed for.

The advantages of my invention comprise the automatic breaking of the no-voltage circuit and consequent throwing of the maincircuit breaker whenever the starting-switch is left in any other than full running position, the compact construction and certainty of operation of the circuit-breaking apparatus, and the freedom of the starting-switch from spring control.

It is evident that various changes could be made in the details of construction illustrated without departing from the spirit and scope of my invention. Other forms of cut-out for the no-voltage magnet-circuit might be substituted for that illustrated and the location of such cutout might be changed as well as the arrangement of the connections thereto. It is not necessary that the brush-arm should have an amount of swing that carries it out of contact with its contact-studs, as shown in Figs. 1 and 2 for the sake of clearness.

Other means of closing the no-voltage circuit when the starting-switch is in full running position might be substituted for that shown; but all such variations in detail I 0011- sider mere modifications of the underlying principle of my invention and still within the scope thereof.

Vhat I claim as new, and desire to secure by Letters Patent of the United States, is-

1. In an electric-motor-starting device comprising a no-voltage magnet and a main-circuit breaker cooperating therewith, a nor mally open cut-out located in the no-voltage magnet-circuit.

2. In an electric-n1otor-starting device comprising a starting-switch, a series of resistances, a no-voltage magnet and a main-circuit breaker controlled thereby, the combination of a normally open cut-out in the novoltage magnet-circuit, means for temporarily closing said cut-out by pressure of the operators hand, and means for permanently establishing the no-voltage magnet-circuit after the resistances have all been cut out of. the armature-circuit.

3. A motor-rheostat comprising an automatic cut-out responsive to determinate current conditions, a variable resistance, an unbiased control-lever for adjusting the rheostat, and means for automatically opening the circuit in case of loss of control by the operator.

at. A motor-rheostat comprising an automatic cut-out responsive to determinate current conditions, a variable resistance, an unbiased control-lever, and electric means for opening the circuit in case of loss of I control by the operator.

5. A motor-rheostat comprising an automatic cut-out responsive to underload conditions, at variable resistance, an unbiased control-lever, and electric means for opening the circuit in case of loss of control by the operator.

6. A motor-rheostat comprising a variable resistance, a switch-arm for adjusting the same, overload and underload magnets for opening the circuit, an unbiased controllever, and means by which the magnets break the circuit independently of the switch in case of loss of control.

'7. A motor-rheostat comprising an automatic cut-out responsive to determinate current conditions, a variable resistance, an unbiased control-lever, and means for opening the circuit through the automatic cut-out in case of loss of control by the operator.

8. The combination with a variable resistance, of independent electromagnets responsive to underload and overload conditions and set by the adjusting-lever at or near its off position, and a switch in the motor-circuit common to both said devices.

9. The combination with a variable resistance, of underload and overload devices set by the ad justing-lever while disconnected from the resistance, and a circuit-breaking switch in the motor-circuit released by either of said devices.

10. The combination with a variable resistance, of a spring-impelled circuit-breakin g switch, underload and overload magnets governing its release, and an independent adjusting-lever for the resistance adapted to set the said device at or near its off position.

11. The combination with a variable resistance, of a circuit-breaker, electromagnets for tripping the same and opening the circuit thereat under no-voltage or overload conditions respectively, and means for setting the same by a return of the resistance-lever to its off position.

12. The combination with a variable resistance, of a circuit-breaker, electromagnets for ICC &

tripping the same and opening the circuit thereat under no-voltage or overload conditions respectively, and means for magnetically setting the same by a return of the resistance-lever to its off position.

13. In an electric motor-starting device comprising a starting-switch, a series of resistances adapted to be cut into the armaturecircuit of a motor, a no-voltage magnet and a main-circuit breaker controlled thereby, the combination of a normally open cut-out in the no-voltage circuit, located on the startin g-switch, means whereby the operator when grasping the switch-handle may close the cutout, and means for permanently closing the no-voltage magnet-circuit when the switch is in a running position.

14. In an electric motor-starting device comprising in combination, a main-circuit breaker, mechanism for operating said circuit-breaker, an overload magnet and a novoltage magnet independently connected with said mechanism, a series of resistances and a starting-switch for throwing said resistances into and cutting them out of the motor-armature circuit, the combination of a normally open cut-out in the no-voltage magnet-circuit, means whereby the operator may temporarily close said cut-out while manipulating the starting-switch, and means for retaining said cut-out closed when the startingswitch is in a running position.

15. In an electric motor starting device comprising in combination, a main-circuit breaker, mechanism for operating said circuit-breaker, an overload magnet and a no- Voltage magnet independently connected with said mechanism, a series of resistances and a starting-switch for throwing said resistances into and cutting them out of the motor-armature circuit, the combination of a normally open cut-out in the no-voltage magnetcircuit, means whereby the operator may temporarily close said cut-out while manipulating the starting-switch, and means for closing said cut-out when the starting-switch is in full running position, said temporary means consisting of a spring-plunger in the switclrhandle,

and said permanent means consisting of a bridge-piece located under the switch-handle when in a running position.

16. In an electric motor starting device, the combination of the switch-lever, the stud on which it is pivoted, the circuit-breaker mounted on a partly cut-away sleeve, the two circuit-breaker trippin g-toes journaled on the stud, located within the sleeve and projecting through the cut-away portions thereof, and a spring fastened to the stud and to each of the tripping-toes.

17. In an electric motor starting device, the combination of the switch-lever, the stud on which it is pivoted, the circuit-breaker mounted on a partly cut-away sleeve, the two circuit-breaker tripping-toes j ournaled on the stud, located Within the sleeve and projecting through the cut-away portions thereof, and the double spiral. spring fastened to the stud at its middle and having its projecting ends engaging the tripping-toes, the switch-lever being provided with a forked bearing, the two ends of which inclose the sleeve and trippingtoes.

18. The combination with a variable resistance, of underload and overload devices set by the adjusting-lever at or near its oif position, a switch in the motor-circuit common to both said devices, and means for cutting into circuit the underload device while the resistance is disconnected.

19. In a device for controlling electric motors, a circuit-breaker, an unbiased leverarm, movable contacts operated by said leverarm, studs arranged in the path of the movable contacts, means by which the first movement of the lever-arm closes the breaker and an electromagnet for retaining the breaker in the closed position until the current falls below a predetermined point.

In witness whereof I have hereunto set my hand this 26th day of November, 1902.

JAMES V. KELLOGG.

WVitnesses:

BENJAMIN B. HULL, MARGARET E. WooLEY.

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