US1360257A - Motor-control system - Google Patents

Description

J. H. ALBRECHT.

MOTOR CONTROL SYSTEM.

APPLICATION FILED DEC 20. 19IG.

Patented Nov. 30, 1920.

INVENTOR John H. Albrecht Fiq.5.

UNITED STATES PATENT OFF-ICE.

JOHN H; ALBRECHT, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

MOTOEFCONTROL SYSTEM.

Specification of Letters Patent.

Application filed December 20, 1916. Serial No. 188,016.

To all whom it may concern:

Be it known that I, JOHN H. ALBRECHT,

a citizen of the United States, and a resident of Pittsburgh in the county of Allegheny and State of l 'ennsylvania, have invented a new and useful Improvement in Motor-Control Systems, of which the following is a specification.

My invention relates to motor-control systems and particularl to such systems as are employed in connection with blooming mills of the reversing type and similar machines.

My invention has for its object to provide an arrangement of the character above described whereby the operation of a plurality' of electric motors may be selectively and successively effected.

A reversing blooming mill is usually provided with a front table for receiving ingots from the soaking pits and for delivering the ingots to the main rolls of the mill. a rear table receives the ingots after they have passed through the main rolls and returns the ingot to the rolls for the succeeding pass.

It has been the practice, to some extent, to provide the front and rear tables of blooming mills with a common driving mech- ,anism by means of which thetables may be reversed simultaneously. It will be apparcut that, during the o eration of a mill thus constructed, one or t e other of the tables will always be running idle. It is necessary, also, to reverse the driving motor and the tables as quickly as possible. This arrangement requires that the. entire mechanism must be reversedxeach timethe ingot passes through the rolls.

I provide an arrangement in which separate motors are rovided for driving the front and rear tab es. A single controlling mechanism ,operates either to efit'ect thestarting of one of the motors or.o f both the motors in succession, as desired; The mill -may be operated by driving one table to carry the ingot to the roll while the table for receiving the ingot from therolls may be stationary. In this case, it is only necessary to start the receiving table from rest instead of suddenly changing from full speed in one direction to full speed in the other direction. B means of this arrange ment, a considera le saving in power is efiected and a material amount of wear and of the motors.

strain upon the motors and table mechanism is eleminated.

In the accompanying drawings, Figure 1 is a diagrammatic view of the main circuits of an electric motor for driving the front table of a blooming mill. Fig. 2 is a similar view of the main circuits of an electric motor for driving the rear table of a blooming mill. Fig. 3 is a diagrammatic view of the circuits for controlling the electric motors shown in Figs. 1 and 2. Fig. 4 is a schematic arrangement of the main circuits of one of the motors for driving the tables. Fig. 5 is a table illustrating the sequence of 1 operation of the switches, for controlling one I Referring particularly to Fig. 1, an electric motor, the armature of which is indicated at 1 and which has a series fieldmagnet winding 2, may be employed to drive the front table of a blooming mill. The direction of rotation of the motor is controlled by electromagnetica'lly-operable reversing 1 switches 3, 4, 5 andgti that are respectively provided with'actua ing coils 7, 8, 9' and 10. A sectional starting resistor 12 is controlled by electromagnetically operable switches 13, 14 and 15 that are respectively provided with series actuatin coils 16, 17 and 18. A line switch 19, having an actuating coil 20, controls the main circuit of the 85 motor.

I Reference may now be had to Fig. 2, whichi are identical with those described in connection with the motor 1 of Fig. 1 and they have been designated by the same reference numerals that are applied to the corresponding parts in Fig. 1.

Reference may now be had to Fig. 8 in which the circuits for controlling the switches shown in Figs. 1 and 2 are diagrammatically illustrated. A master switch, or controller 25 comprises an operating handle 26 and a single movable contact segment 27 forcontrolling the various circuits. When the controller handle 26 is in its illustrated or oiP position, the circuits of the several actuating coils of the reversing switches and the line switches are open and the motors are at rest. In its oil position, the contact segment 2'? makes contact with two stationary contact fingers 30 and 30 and the stationary contact finger 39'. A circui is accordingly established from the positive terminal a manually-operable switch 29 through the contact finger 30, the contact segment 2?, contact linger 39, conductor 38 and the actuating coil of the no-voltage relay 3'2 overload re l 31 of the motor 22 to the 've term 1 of a menually-operable sw '1 ie no-voltage relay 3? of the motor 22 is thereupon closed and circuit is established 1 r the no-voltage relay 3'? of the motor 1, which extends from the positive terminal the switch 29 through the contact 30, the contact segment 2' the contact finger 39, the conductor 33, the no-voltege relay 37 and the overload relay 36 of the motor 22, the positive terminal oi the switch 35, the ac tuating coil oi the lie-voltage relay 37 and the overload relay 31 of the motor 1 to the negative terminal of the switch 29. Holding circuits for the two no-voltage relays 37 are established as follows: from the positive terminal or" the switch 35, which is connected to the positive terminal of the switch 29 by the overload relay 36 and the novoltage relay3'i" of the motor. 1, through the overload relay 33 and the no-voltage relay 37 of the motor 22, the actuating coil 0'2 the relay 3? and the overload relay 31 of the motor 22 to the negative terminal of the switch 35; and from the positive terminal of the switch 29 through the overload relay 36, the no-voltage relay 37, the actuating coil of the relay 37 and the overload relay 31 of the motor 1 to the negative terminal of the switch 29. The overload tion of the controller 25 and are maintained closed by the above-described holding circuits subsequently-to the actuation of the controller 25 unless opened by no-voltage or overload conditions.

' When the handle 26 is actuated to the left, as viewed in Fig. 3, the contact segment 27 engages a contact finger 28 to complete a circuit which extends from the positive terminal of the switch 29, through the overload relay 36 and the no-voltage rela 37 of the motor 1, the positive terminal 0 the switch 35, the overload relay 36 and the no-voltage relay 37 of the motor 22, the conductor '38, the contact finger 39, contact segment 27 contact finger 28, actuating coils 8, 10 and 20 and overload relay 31 to the ne tive terminal oi, the switch 29. When t' e contact segment 2? engages the contact finger 28, it disengages the contact fingers 30 and 30. The actuating coils 8, 10 and 20 are energized to close the corresponding switches 4, 6; and 19 and thus complete the circuit .to drive the respective tables to which they of the motor 1 for operation in the forward direction.

Referring particularly to Fig. 1, the mam circuit of the motor 1, which is thus 09mpleted, extends from the positive terminal of a switch 32, through overload relay coil 33, switch 6, armature 1, switch 4-, series field magnet winding 2, actuating coil 16, resistor 12, switch 19, and coil 3 of overload relay to the negative side of switch V 1 m 3 y I The actu go; 4 energ zed by the circuit gust descrioe 01658 S itch 13 and thereoy ses . be stationary when it receives the ingot, in which case the controller handle is permitted to remain in position in which the motor 1 onl is operative.

If it is desire to operate the tables simultaneously, the controller handle 26 is actuated in the same direction to its second operative position. The contact se ment 27 completes a circuit which extends rom the positive terminal of manually operable control switch 35, which is connected, as above described, to the positive terminal of the switch 29, through overload relay 36, novoltage relay 37 which occupies its closed position except upon failure of voltage, conductor 38, contact finger 39, contact se ment27, contact fin or 40, actuating co s 8, 10 and 20 of. switc es for controlling motor 22, and overload relay 31 to, the negative terminal of switch 35. The motor 22 is then started in the same manner as that described in connection withmotor 1. The motors 1 and 22 then operate simultaneously are connected in the same direction.

When it is desired to return the ingot to the rolls, the table which has received the ingot is reversed. In the present case, the

motor 22, which drives the rear table, is

reversed byv first actuating the controller handle 26 to its oil position to open the circuits of the several reversing switches for establishing the circuits of the motors for operation in the forward direction.

The controller handle is then actupted to the right, as viewed in Fig. 3, opening the circuits controlled b the contact segment 27 and the contact ngers 30 and 30 and completing a circuit which extcnds from the positive terminal of the switch 29 through 'pleted by the overload relay. 36 and" the no-voltage relay 37 of the motor 1, the positive terminal of the switch 35, the overload relay 36 and the no-voltage relay 37 of the motor 22, the conductor 38, the contact finger 39, the contact segment 27, contact fin er 42, actuating coils 7, 9 and 20 of switc es which extends from the positive terminal of switch 35, which is connected to the positive terminal of the switch 29, as described above, through overload relay 36, no-voltage relay 37, contact finger 39, contact segment 27, contact finger 43, actuating coils 7, 9 and 20 of switches for controlling mo.- tor 1, and overload relay 31, to the negative side of switch 29. The motor 1 is then started and accelerated in the manner described above, and the front table is operated simultaneously with the rear table and I in the same direction.

In case the currents traversing the series actuating coils 34 and 33 of the overload relays 31 and 36 rise to predetermined values at which the relays are actuated to open their respective circuits, the relays will be retained in their open positionsby reset devices 44 until the controller is again brought to its off position. When the controller occupies its illustrated position, the actuating coils 45 of the several reset devices 44 are ener ized by a circuit comprising the contact nger 30 and the reset devices are actuated to release the relays 31 and 36. This arrangement insures that the motors cannot be started except when the entire resistors 12 are in circuit.

It will be noted that, by means of the above-described arrangement, it is possible to render one of the motors operative while the other remains inoperative. The operator may, if he so desires, operate'both motors simultaneously in the' same direction. In the latter case, the motors are started successively by actuating the controller to its second operative position in. the desired direction. I 7

It is not necessary that the motors be started simultaneously for the reason that the ingot is carried to the rolls by one of the tables only and the time required for the passing of the ingot through the rolls is sufiicient to permit the motor driving the table for receiving the ingot to accelerate to its normal speed. An advanta e of this arrangement consists in the fact that the maximum power necessary for the successive starting of the motors is much less than that required for the simultaneous starting of the motors.

I claim as my invention:

1. The combination with a pair of electric motors and a controller therefor adapt ed to occupy an inoperative position and a pair of operative positions, of a no-voltage relay for each of said motors, means for closing said relays when said controller occupies said inoperative position, means for operating one of said motors when said relays are closed and said controller occupies one of said operative positions, and means for operating said other motor when said relays are closed and said. controller occupies said other operative position.

2. The combination with a pair of electric motors and a controller therefor, of a no-voltage relay for each of said motors, means for closing said relays when said controller occupies one position, means comprising overload relays for maintaining said no-volta'ge relays closed except under predetermined conditions, means comprising said no-volta e relays for establishing circuits for sai motors when said controller occupies other positions, and means for operating one or both of said motors in accordance with the position of said controller.

3. The combination with a pair of electric motors and a-controller therefor, of a no-voltage relay for each of said motors,

means for closing said relays when said con-' troller occupies one osition, means com rising overload relays or maintaining sai novolta e relays closed except under predetermine conditions, means for establishin a startin circuit for each ofsaid motors w en the sai controller occupies other positions,

each of said starting circuits comprising one JOHN H. ALBRECHT.

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