US1758709A - Control system - Google Patents

Description

May 13, 1930. P. M SHANE 1,758,709

CONTROL SYSTEM Filed Jan. 16, 1926 2 Sheets-Sheet 1 INVENTOR WITNESSES: 2 @WW Fhe/an M 577mm.

'. ATTRNEY Patented May 13, 1930 TES PATENT OFFICE- PHELAN MCSHANE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA CONTROL SYSTEM Application filed January 16, 1926. Serial No. 81,769.

My invention relates to control systems and more particularly to the control of a plurality of motive devices individually from an associated control station and selectively from a common control station.

One object of my invention is to provide means for selectively controlling electroresponsive devices from a common control sta-. tion, such as from a traveling crane, and for automatically returning said devices to a predetermined position upon releasing said control.

Another object of my invention is to provide a master switch for each of the several motors, each of the switches having means for preventing the operation of a selector switch under predetermined conditions.

Another object of my-invention is to provide a single Wire control system that effects the operation of an electroresponsive device in the one or the other direction while ener gizing the wire in one direction only.

My invention is especially applicable to the control of soaking pit covers, or to the control of the doors on reheating and open hearth furnaces, or the like, in steel mills. In the steel industry, ingots are brought from the ingot stripper in a heated condition but require further heating before they are in proper condition to be conveyed to the bloom-' ing or rolling mill. The ingot is, therefore, conveyed to a soaking pit, where it is heated to the desired temperature. The soaking pits are provided with covers which may be opened and closed by means of an electric motor.

out requiring the assistance of workmen on the floor of the soaking-pit room. It is, therefore, possible to materially reduce the number of floor operators that are required in the soaking-pit room.

My invention will be best understood by reference to the accompanying drawing in which,

Fig. 1 is a diagrammatic plan view of the soaking pits;

Fig. 2 is a diagrammatic view of the motor circuits for one of the soaking-pit-cover motors, and

Fig. 3 is a diagrammatic View of the control circuits of one of the cover motors.

Referring to Fig. 1 of the drawing, a plurality of soaking pits are shown arranged in groups A, B, C, D, E, F, G, each group comprising four pits, 1, 2, 3 and 4, extending across the fioor of the building. Tracks 5 and 6 are provided on each side of the building for conveying the ingot buggies 7 and 8v .The ingots, after having been heated in the soaking pits, are conveyed to a transfer roll table 9 and from there to the approach table 11 to be conveyed to the blooming mill. Traveling cranes 14 and 14? are provided for lifting the ingots into and out of the various soaking pits.

Each soaking pit is provided with a cover that is normally closed during the heating operation and is operated to its open or closed position by a motor 15 that is illustrated in Fig. 2. Each motor 15 comprises an armature winding 16 and a field winding 17 that are respectively energize-d from supply conductors 18 and 19. The energization of the motor armature 16 is controlled by reversing switches 21, 22, 23 and 24, of a familiar character. A dynamic braking circuit may be provided through relays 25 and 26 and a resistor 27, in a well-known manner when the reversing switches are in their open positions. 1 i

A starting resistor 28 is connected between the armature 16 and supply conductor 19 in circuit with the operating coils of accelerating relays 29 and 31, which are connected to operate the magnetic accelerating switch 33 in a well-known manner, to short-circuit a portion of resistor 28, when the current through the motor armature has decreased to a predetermined value. The magnetic accelerating switch 34 is similarly operated by accelerating relay 35 when the current in the 55 A. The connection of one relayic47 to motor armature has decreased to a second predetermined value, to short-circuit the remainder of resistor 28. Inasmuch as the operation of the several relays illustrated in Fig. 2 is well known, further detailed description thereof is deemed unnecessary.

A line contactor 32 is provided for com pleting the circuit through its contactmemer 32a from the motor armature to the sup-I ply conductor 19. Aninterlock 32?) connects a conductor. 36 with supply conductor 18 by means of conductor 39, as shown in Fig. 3, when the contactor 32 is closed. The operating coil of the line contactor 32 may be ener= gized initially through a reset push-button 38 and the interlock 326, the latter thereby providing low-voltage protection for the control system. The conductor 36 is connected to contact members -11. -13 and 45 of a master switch 40, one of which is associatedwith' These contact members are,

each motor. adapted to respectively engage contact members 42, H and 16. p

As indicated in the drawingof the master switch, the contact members 43 and 4.4 are in engagement when the master switch is in its zero or ofl position. The contact members 41 and 42 are in engagement when the master switch is in its second forward position, and thecontact members 45 and 16 are in engagement when the master switch is in its second reverse position. In the first position, either forward or reverse, none of the cooperating parts of contact members are in engagement.

A relay 47 is provided having its operating coil connected between the supply conductor 19 and a collector rail 51 by means of conductors 48 and 49. The collector rail 51 is adapted to be engaged by-a collector shoe 52, which is connected with contact member 53 ofa selector switch 56. This switch may be located in the cab of a traveling crane. The contact member 53 is adapted to engagecontact member 5-1 and complete a circuit through conductor 55, contact member 57a of the low voltage relay 57. collector shoe 58, and the conductor 59 to the supply conductor 18. t A selector switch reset 61 is provided for completing a circuitin parallel relationto that through the contact member 57 a of the l owvoltage relay 5?. Vhen the selector switch 56 is in the off position the reset 61 is closed, and when the selector switch is in an operative position the reset 61 is open.

The selector switch 56 is also provided with cooperating pairs of contact members 62,63; 64, 65; and 66, 67 that are respectively connected to collector-shoes 68,. 69 and 71. Collector rails 51, 72, 73 and 74 are respectively connected to operating relays 47 for eachmotor in one group of 'soaklng pits,"

such as for the pits 1, 2, 3 and 4 of group ized negative collector rails 75,76 and77 are also provided, each section corresponding to i one group ofsoaking pits. The negative collector rails 75,176and 77 are adapted to be connected through a collector shoe 7 9; to the operating coil of the low-voltage relay 57 'lien thecrane is in a positionsuchthat thecollector shoes 52, 68. 69, .71 andTS) engage collector rails 51,"a'2 ."3, 74 and 75, re

spectively,which is theposition necessary for the crane to handle material into or out of the associated group of soaking pits, the

selector switch 56 may operate the cover motor of any pit of that group of four. 'lie'n the corresponding'master switch 40 is in its ofl position, the contact members 13 and M are in engagement and normally complete a circult through conductors 92, 93, contact member 17. limit switch 89, and the operating coil of reversing switches 22 and :21, thus actuating these reversing switches to operate the motor'15 in a direction to close a the soaking pit cover. When the cover has been operated to its closed position, the limit switch 89 is opened, thus deenergizing the reversing switches 22 and 24.

Should the crane'operator the cover of the soaking pit that is operated bythe motor 15, the selector switch 56 would be set to effect engagement of contact members 53 and 54, thusact-uating the relay 4;?

and causing the contact member 47a to close a circuitthrough conductor 92, limit switch 91 and operating coils of reversing switches .21 and 23. thus causing the ,motor15 to be operated in a direction ,to open the soaking pit cover. When it is desired to again close the soaking pit cover, the selector switch 56 is operated to disengage the contact members 53 and54, thus releasing the relay 47 and desire to open breaking the circuit through the contact member 17a,. thereby deenergizing the reversing switches 21 and 23 and, at the same time, completing a circuit through the contact member 176 and actuating the reversing switches 22 and 24, thus again causing the causeengagement of contact members, 41 and motor to be operated in a direction to close the soakmg pitcover. t J While relay 47 is in its illustrated orde 42, a circuit iscomplet'edtlirough limit switch 91 and themoperating, coils of reversing switches21and23, causing the motor 15 to operate in a direction to open the corresponding cover. By throwing the master switch 40 to the first forward position, the motor may be stopped at any point. The return of the master switch to the OE position, causing engagement of the contact members 43 and 44, completes a circuit through the reversing switches 22 and 24 thereby causingthe motor 15 to operate in a direction to close the cover.

The operation of the motor may be stopped at any point by throwing the) master switch to the first position, forward or reverse. By throwing the master switch 40 to its second reverse position, causing engagement of contact members 45 and 46, a circuit is completed through contact member 47 6, limit switch 89, and the operating coil of reversing switch 22 and 24, thus causing operation of the motor 15 in a direction to close the soaking pit cover.

It will be noted that since the crane collector rails are sectionalized, the control collector shoes of the crane make contact with particular sections only when the crane is in position to work the pits that they control. The low-voltage relay 57 furnishes low-voltage protection to the soaking pit cover motors, when operated from the crane, and automatically prevents the opening of the pits should the crane run down the soaking pit building with one of the selector switches closed; Should the crane move so that the collector shoes disengage one section of collector rails while one pair of contact members of the selector switch 56 is closed, the relay 57 will be deenergized and will drop open. It is then necessary for the selector switch 56 to again be returned to its off position, closing the reset 61 and the relay 57, before any of the motors may be operated from the crane.

Each soaking pit cover may be operated either from the crane by means of the selector switch 56 or from the floor by means of its associated master switch 40. Only one control wire is required from the selector switch to the control relay 47 for each cover motor. The soaking pit cover may at any time, be rendered inoperative from the crane by placing its associated floor master switch 40 on the first point in either direction, thus providing safe means for inspecting a pit without danger of the cover being opened while an attendant is examining the pit.

If the soaking pit cover is opened from the crane, the relay 47 will remain in its upper position until released by the selector switch 56, thereby interrupting the circuit through the contact member 475 and preventing the operation of the reversing switches 22 and 24 by the master switch 40, thus preventmg closing of the cover until the selector switc 56 has been moved to its ofl position or until the crane has moved so that the collector shoe 52 disengages -the collector rail 51. It will also be noted that a circuit is closed through the reversing switches 22 and 24 when the master switch 40 and the selector switch 56 are returned to their ofl position, thus automatically causing the soaking pit cover to close.

It will be further noted that the circuit through the selector switch 56 and the operating relay 47, governing the operation of a given motor, comprises a single wire terminating in the supply conductors 18 and 19. This circuit is always energized with one polarity only, it being unnecessary to reverse the direction of current flow therethrough to govern the motors.

While my invention has been described as applied to the operation of soaking pit covers, it is apparent that it may have many other applications such, for example, as the operation of doors on reheating and open hearth furnaces. It may also be found convenient, in certain cases, to mount both the selector switch station and the master switch station in stationary positions.

Many modificationsmay be made in the circuits and apparatus disclosed in this application within the spirit of my invention, and I do not wish to be limited other than by the scope of the appended claims.

I claim as my invention:

1. In a control system, a plurality of groups of work devices. a conveyor for handling material to and from said work devices, motive devices for said work devices, and means for operating said motive devices from said conveyor.

2. In a control system, a plurality of groups of work devices, a conveyor for supplying material to said devices, motive devices for said work devices, and means on said conveyor for selectively operating said motive devices.

. 3. In a control system, a plurality of groups of work devices, a crane for supplying material to said devices, motors for said devices, and means for selectively controlling the operation of the motors of any group from said crane when said crane is in a position to sup ply material to said group.

4. In a control system, a plurality ofgroups of work devices, a crane for supplying material to said devices, a plurality of motors for said devices, a master switch for controlling the operation of each motor, and a selector switch on said crane for selectively controlling the operation of any of said motors.

5. In a control system, a plurality of groups of work devices,a conveyor for supplying material to said devices, a motor associated with each of said devices, a master switch for controlling the operation of each motor, a plurality of groups of collector rails corresponding to said groups of work devices, and means on said conveyor for selectively energizing any one of the collector rails of a group for controlling the operation of the corresponding motor. v

6. In a control systenna plurality of groups of work devices, motors for said devices. a

crane for supplying material to said devices, a selector switch on said crane for selectively controlling the operation of the motors of any group when the crane is within a predetermined working zone with respect to the group, and means for automatically interrupting the control of said selector switch when the crane moves from said working zone.

7. In a control system, a plurality of work devices, motive devices for actuating said work devices. a conveyor for supplying materialto said work devices. a selector switch for selectively controlling the operation of said motive devices, a master switch associated with each motive device for controlling the operation thereof. and means associated with each master switch for rendering the selector switch inoperative for controlling the associated motor.

8. In a control system, a plurality of closure devices, motive devices for opening and closing said closure devices, a master switch associated with each motive device for controlling the operation thereof, a selector switch for selectively controlling the operation of said motive devices, means effective upon the operation of said selector switch to open one of said closure devices and for preventing closing of that closure device by the associated master switch until the selector switch has been returned to the off position.

9. In a control system, a work'device, a conveyor for handling material to and from said work device, a motive device for said work device, and means for operating said motive device from said conveyor.

In testimony whereof, I have hereunto subscribed my name this 19th day of December, 1925.

PHELAN MoSHANE.

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