US1448381A - Control system - Google Patents

Description

Mar. 13, 1923. 1,448,381

- E. M. BOUTON CONTROL SYSTEM Filed Maw 12, 1919 WITNESSES: INVENTOR Jig gar Bot/fan Patented Mar. 13, 1923.

UNITED STATES PATENT OFFICE.

EDGAR M. BOUTON, OE WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

CONTROL SYSTEM.

Application filed May 12, 1919.

To all whom it may concern.

Be it known that I, EDGAR M. Bouroia, a citizen of the United States, and a resident of lVilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Control Systems, of which the following is a specification.

My invention relates to reversing systems for electric motors and it has for its object the provision of a reversing system that shall be particularly adapted for push-button control.

According to the present invention, the motor may be started in either direction upon the actuation of one of two push-buttonswhich effect the closing of one or the other of two reversing contactors. The pushbuttons may then be released, the contactor coils being maintained energized by holding circuits comprising switches mechanically connected to the open reversing contactor-s and protective resistors. The commonly employed additional mechanically connected switches are thereby done away with and the use of the resistors avoids difficulties in operation due to the counter-electromotive force of the II10tOI,',&S will hereinafter be explained.

The accompanying drawing is a diagrammatic view of circuits and apparatus embodying my invention.

An electric motor, having an armature 1 and a shunt field-magnet winding 2, is connected between line conductors 3 and 4, the armature 1 being connected in series with an accelerating resistor 5. The resistor 5 is adapted to be short-circuited by a contactor 6 having a coil 7 that is adapted to be energized by the counter-electromotive force of the motor. The direction of operation of the motor is determined by a pair of reversing contactors 8 and 9 having energizing coils 10 and 11, respectively, the circuits of which are adapted to be initially closed by start push-button switches 12 and 13 and which may be opened, at any time, by a stop push-button switch 14. The reversing contactors 8 and 9 are supplied with contact members 15 and 16 which are open when the corresponding reversing contactors are closed and closed when the corresponding reversing contactors are open. The contact members 15'and 16 are adapted Serial No. 296,615.

to close a dynamic-braking circuit comprising the armature 1 and a dynamic-braking resistor 17 A pair of resistors 18 and 19 are connected, in parallel, between the line conductor 4 (through the start push-button switches 12 and 13, respectively,) and a terminal 20 of the dynamic-braking resistor 17.

Assuming that it is desired to start the motor in the forward direction, the start push-button switch 12 may be actuated, whereupon a circuit will be completed from the line conductor 3, through the stop push-button switch 14, the coil 10 and the start push-button switch 12, to the line conductor 4. The coil 10 becoming thus energized, will effect the closing of the contactor 8, whereupon the circuits of the motor will be established for operation, in the forward, direction, from the line conductor 3 through the accelerating resistor 5, the lower member of the reversing contactor 8, the armature 1 and the upper member of the reversing contactor 8, to the lineconductor 4. When the counter-electromotive force of the motor attains a predetermined value, the coil 7 will become sufliciently energized by the circuit extending from one terminal of thearmature 1, through the lower member of the reversing contactor 8, the coil 7, the dynamic-braking resistor 17 and the contact members 16, to the other terminal of the armature 1, to elfect the closing of the contactor 6 and the consequent short-circuiting of the accelerating resistor 5.

The above. operation has been described upon the supposition that the start pushbutton switch 12 has been maintained in its actuated position. The operation will be substantially the same, however, if, after the initial operation of the start pushbutton switch 12, it be immediately released for, upon the closing of the reversing contactor 8, a holding circuit for the coil 10 becomes established from the line conductor 3, through the stop push-button switch 14, the coil 10, the resistor 18, the contact members 16 and the upper member of the reversing contactor 8 to the line conductor 4..

without the aid of any mechanically connected switches additional to those requirec for effecting dynamic-braking.

To stop the motor, the stop push-button switch 1 1 may be actuated to break the circuit of the coil 10, whereupon the reversing contactor 8 willfall open by gravity, incidentally effecting the closing of the contact members 15. The dynamic-bral-zing circuit becomes thereupon established for the motor from one terminal of the armature 1, through the contact members 15, the resistor 17 and the contact members 16, to the other terminal. of the armature 1.

To start the motor in the reverse direction, the start push-button switch 13 may be actuated. The operation is substantially the same as that above described except that the holding circuit of the coil 11 comprises the dynamic-braling resistor 17. The ohmic value of this resistor is so low as not materially to affect the operation. On the other hand, the circuit of the coil 7, which formerly comprised the resistor 17, now excludes that resistor.

The resistors 18 and 19 are so designed as to maintain the coils 10 and 11 energized to such degree that the contactors 8 and 9 may remain closed when they have become closed, but not to effect the closing of the contactors in the first instance. Otherwise,

the coils 10 and 11 would become simultaneously sufficiently energized to effect the actuation of both contactors 8 and 9 upon the actuation of either push-button switch By means of the above-described arrangement of circuits, I am enabled to effect-the push-button control of a motor without the employment of more switches than are required without such control, and without fear of the coils 10 and 11 being maintained energized by the counter-electromotive force of the motor upon the actuation of the stop push-button switch 14;

Modifications within the spirit and scope of my invention will obviously occur to those skilled in the art and are intended to be covered by the appended claims.

I claim as my invention:

1. The combination with an electric motor and a pair of reversing switches therefor, each having an actuating coil, of means for initially energizing said coils, a pair of resistors and a pair of switches respectively associated with said reversing switches, said pair of switches being open when the associated reversing switches are closed and being closed through the one or the other resistor when the associated reversing switches are open for maintaining energized the coils of the reversing switches with which they are not associated after said initial energization ceases.

2. The combination with an electric motor,

a pair of reversing switches therefor, each having an actuating coil, and a pair of switches for dynamically braking said motor, of a pair of switches for initially energizing said coils, and a pair of resistors, each of said dynamically-bralring switches being adapted to connect the coil of one of said reversing switches in circuit with one of said resistors to maintain said coil energized.

3. The combination with an electric motor having an armature, a pair of reversing switches for said motor, each having an actuating coil, a dynamic-braking resistor, and a pair of switches mechanically connected to said reversing switches for connecting said. dynamic-braking resistor into circuit with said armature, of a pair of switches for respectively energizing said coils initially, a pair of resistors, and means for connecting one of said reversing switches, its actuating coil, the switch mechanically connected to the other reversing switch and one of said pair of resistors in series to maintain said actuating coil energized.

4:. The combination with a dynamo-electric machine, and a plurality of switches for governing different operations thereof, each switch having an actuating coil, of means for manually energizing the one or the other of said coils temporarily, a plurality of auxiliary switches actuated oppositely to the movements of said governing switches, a plurality of resistors and means comprising said auxiliary switches for maintaining energized through one or another resistor the coils of the governing switches with which they are not associated subsequent to the cessation of such manual energization.

5. The combination with an electric motor and a pair of reversing switches therefor, each having an actuating coil, of aplurality of push-buttons biased to the open position and adapted when closed to energize the one or the other of said coils, a plurality of resistors and a plurality of switches respectively associated with said re versing switches to close through one or another of said resistors when the associated reversing switches are open for maintaining energized the coils of the reversing switches with which they are not associated after the active push-button is released.

6. The combination with an electric motor, a plurality of reversing switches therefor, each having an actuating coil, and means for dynamically braking said motor, of means for initially energizing the one or the other of said coils, and a plurality of translating devices respectively adapted to be connected through a portion of said dynamicbraking means and the coil of one of said reversing switches to maintain that coil energized. V

7. The combination with an electric motor, and a plurality of reversing switches therefor, each having an actuating coil, of means for initiall energizing the one or the other of said coi s, and a plurality of translating devices respectively adapted to be connected through a contact-making portion of one reversing switch and the actuating coil of another immediately upon said means becoming inoperative to maintain that coil energized.

8. The combination with an electric motor, and a plurality of reversing switches there- EDGAR M. BOUTON.

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