US963867A - Electric-control system. - Google Patents

Description

W. M. CHUBB.

ELECTRIC CONTROL SYSTEM. APPLICATION FILED JULY 12, 1909.

963,867, Patented July 12, 1910.

INVENTEIR MLL/fi/Y C/lz/BB WILLIAM M. 'GHUBB, OF SAN FRANCISCO, CALIFORNIA.

ELECTRIC-CONTROL SYSTEM.

Specification of Letters Patent. Patented July 12, 1910.

Application filed July 12, 1909. Serial No. 507,088.

To all whom it may concern:

Be it known that I, WILLIAM M. CHUBB, a citizen of the United States, and a resident of the city and county of San Francisco and State of California, have invented new and useful Improvements in Electric-Control Systems, of which the following is a specification.

The invention relates to improvements in the control of electric apparatus and has reference more particularly to the provision of a system whereby the control and regulation of electrical apparatus can be efi'ected in a cheaper and more effective manner than is now the case.

The invention is particularly applicable for use in the control of motors, are lamps, or other electrical apparatus, that are situated at a distance from the point of control and from which point it is desirable to control the operation thereof.

The object of the invention is to provide a system for controlling the operation of electrical apparatus from a point distant therefrom by a simpler and more economical method than is at present in use.

Another object of the invention is to provide a system whereby electrical apparatus may be controlled from a point distant from the installation thereof by means of a control circuit carrying a very small current.

For the purposes of description and in the drmvings, I'have shown the system applied to an electric motor, but it is understood that I do not confine in self to such use of the system but have escribed and illustrated it as it shows one of the simple forms of use.

In starting or varying the speed of an electric motor, it is the general practice to vary the current throu h the armature by varying the external resistance in the armature circuit, and to control a motor from a distance it is necessary either to run the armature circuit to the desired point and insert a variable resistance, or rheostat, at that point, or to insert a system of contactors and relays in the control circuit. In the former case, the armature current being large it is evident that the wires of the external armature circuit between the motor and the rheostat at thepoint of control would have to be very heavy to make the 1 R loss and the voltage drop proportionately' small. It is the custom at present to that is not always convenient to adopt in practice and the purpose of the present invention is to overcome the objections that pertain to such a method. In the latter case, the system is ver complex and costly, requiring a relay or each variation of the resistance in the armature circuit.

My invention is particularly adapted for use in search light control, both in traversing, elevating and depressing the beam and in the control of the positions of the carbons to produce the desired are or spark gap. It is necessary in this work to have the control station removed a considerable distance from the light, so that the observers can see objects upon which the beam is rejected. The operation of the light is e ected by electric motors and it is desirable to have the operation of the motors under perfect control for starting, stopping and varying the speed and reversing. It is quite important in traversing that the rate of travel of beam can be made identical with that of the moving object at which it is projected and complete control of the electric motors is necessary.

If smaller wires were used in the external armature circuit the drop in potential would be so great that the variable resistance ofthe rheostat at the point of control would hardly be perceptible at the motor, and, owing to the low voltage, the motor would operate very inefficiently and would carry only a small fraction of its rated capacity.

In the present invention I have provided a control circuit extending from the main circuit which not only requires a very small current for its operation, but said current passes only when the resistance in the armature circuit of the motor is being varied.

My invention consists of a circuit. connected to the motor circuit and extending to motor.

The following description explains at length the nature of my said improvements and the manner in which I proceed to ap opened. to stop the motor ply the same in the production of a system of motor control; reference being had to the accompanying drawing,

' Figure 1 is a diagrammatic representation of the systeni'of my invention showing the control circuit in inoperative condition. Fig. '2 is a diagrammatic representation showing the control circuit in operation to vary the external resistance in the armature circuit of the motor,

In the drawings I have shown a shunt wound motor 2, the coil 3 representing the field Winding and the resistance l-5 tie external resistance the armaturecircuit. It is obvious that other types of motors Which are controlled by varying the resistance in either field or armature circuit could also be controlled by this system And T. do not Wish to limit myself tothe control of motors as man other varieties or electrical apparatus can be controlled by the same sys-.,

tern Current is supplied by the mains 6 and 7 that lead from any suitable source of power and from Which the energy is taken to drive the motor The motor is connected on one side directly to themain 7 by the lead 8, and on the other side to the.

main 6 through a variable resistance or rheostatic device 4;5 and the leads 9 and 12., The field Winding 3 is shunted across the 7 Wires 8 and 9, and the external armature re-.

sistance 4-5 is placed between the Wires 9 and 12, but is not connected to-the Wire 12 at 5, so that the armature circuit may be The contact point it on the end of the Wire 12 is movable over'the resistance 4L--5 thereby varying the resistance of the armature circuit according to its position. It is common practice to control the motor by varying the external armature resistance and the motor will be under perfect control from a distant point, provided the contact point .14 can be moved at will over the resistance 4L5 from said distant point. The control circuit extends from the motor to thepoint from which the motor is to be controlled, and consists of the conductors 1516, both of relatively small diameter in proportion to the feed wires 6-7, which are connected to the main feed Wires 6-21'respectively, at the 'motor, across the circuit 1516 at the point of control and a' likeresistance 21-2, is placed across the circuit at the motor. These resistances are made large in proportion to the resistance of the circuit 15l( sothat the greatest percentage of the drop over the line occurs over the resistances not over the circuit Wires,

In the system of my invention I employ the circuits of the ivheatstone bridge in A resistance 1718 is placed cease-r which the current enters at21, and divides at that point, part passing through the circuit 2122 and part through the circuit 21 1718-22, the proportion of current passing through each circuit varying inversely as the resistance thereofi 'Assuming that 21 is the point of higher potential and 22 is the'point or lower potential, it is evident that there is the same drop of potential over each of the circuits 2122 and 21- 171822. 'lherefore there are corresponding points in each circuit Where the potentials are the same and-if these points were connected there would he no current tact points are not on points of the same potential a current will fiowtlirough' the circuit 25-26 from the point of-liigh potential to the oint of low potential and such current Wi 1 flow as long asthere is a difi'erence of potential between the ends, of the circuit.

A polarized relay 2? -is arranged in the circuit 2526 and is actuated when the contact points 2324 are on points of difi'erent potential and a current ispassing through the circuits The arm 28 ofthe relay moves to one side or the other according as the point 23 or 24: isof the higherpotent-iah v The arm 28 of the relay is-connected to the conductor 15 through the-Wire .29 and the outer end of the arm. 28 rests het veenthe' contact points 31 and 32' on the conductors I 33 and 34: respectively; Condensers 35 are placed in these circuits torelieve the relay 27 of any sparking which would occur at the-gap between the arm-and the contact I points 31 and 32. The-current in theconductor 33 passes through the solenoid 36 and through the conductor 37 to the condoctor 16, and the current in the conductor 3% thence through the conductor 37 to the con-. ductor 16. The solenoids are arranged to cause a longitudinal movement of the iron core 38. This iron core is-caused'to move in one direction or other by-one or other of the passes through the solenoid '36 and two solenoids, the circuit of which is closed between the contact point and the arm 28 ofthe relay. A current passing through the solenoid 36 will cause the iron core 38 to movetoward the solenoid 36 and a current'through the solenoid 36 can cause it' to move toward the solenoid The con-- tact point 24 is attached to oneend oft-he 'external armature resistance 4- -5, thereby varying the speed of the motor. Dash-pots and other similar appliances may be used on the iron core 38 to damp its action and prevent it from movingfthe contact points over the resistances too rapidly which would have the effect of varying the armature current too suddenly. A solenoid is energized only when the arm 28 of the polarized relay is in contact with one of the contact points 31 32 and this condition occurs only" when the contact points 23-24 are at different potential, and acurrent is passing through the circuit 25'26. Therelay and the solenoids are arranged so that a current passing from contact 23 as a point of higher potential, through the relay will bring the arm 28 in contact with the contact point 31 which will cause the solenoid 36 to move the iron core 38 toward thev solenoid 36, bringing the contact point 24 nearer the point 21 and also moving the contact point 1a over the resistance 45 with the effect olE-vary- 'ing the resistance of the armature circuit. The iron core will move until the contact point 24 contacts with a point on the resistance 2l22 which is at the same potential as the point 23. When the contact 24 reaches this point there will be no current flowing through the relay circuit and the arm 28 will break contact with the contact 31a-nd the iron core will remain stationary. It is seen, therefore, that any motion of the contact 23 will cause a similar motion of the contact 14 and the armature resistance canbe varied as desired. It is to be understood, however, that I do not limit myself to the use of a solenoid, as it is evident that other means, such as a small motor, canbe used to accomplish the same purpose.

When it is desired to stop the motor, the contact point 23 is moved to the low potential end 18 of the resistance 17-18. This makes contact point 24' the 'point of high potential and causes the current to flow from 24 through the relay, bringing the arm 28 in contact with contact point 32, energizing the solenoid 36 and moving the iron core toward solenoid 36. This moves the contact point 14 past the end 5 of the armature resistance"4-.5, and the armature. circuit is opened stoppin the motor. The iron core,

will remain in t at position until it is again moved by the solenoid 36. I I Fig. 1 shows the contact points 2324 on points of equal potential and Fig. 2 shows contact point 23 on a point of higher potential than 24, the relay closed on contact 31 and the iron core movingthe contact point-2 to a point of the same potential as 23 and contact point 14 varying the resistance of the armature circuit.

When it is desirable to control several motors from one point of control, it is necessary only to insert similar resistances across the circuit 1516 and install a polarized relay and solenoid circuits at the motor, thus necessitating the addition of only one wire similar to conductor 25, extending from the motor to the point of control for eachadditional motor it is desirable to control.

It is understood that I do not limit myself to the control of motors and have referred to them in this specification for purposes of description and application.

I claim:

1. In an electric control system, a divided circuit, a resistance in each circuit, points of equal potential on the resistances, contacts on said points, a conductor connecting the contacts and electromagnetic means in the conductor operated by the movement of one contact to a point of diiierent potential to cause a solenoid to be energized, an iron core in. the solenoid connected with the other contact point and adapted to be moved by the solenoid to cause the contact point to move toa point of like potential.

2. In an electric control system the combination with electric supply mains of a circuit connected to the mains at the apparatus to be controlled and extending to the point of control, a resistance in the circuit at the point of control and a similar resistance across the circuit at the apparatus corresponding points of equal potential on each resistance, contacts engaging said points, a polarized relay in the circuit con-v necting said contacts, an auxiliary circuit connected to the control circuit and governed by the relay, means for moving the contact point on the resistance at the point of control to adiiferent potential and a solenoid in the auxiliar .circuit for moving the contact point on t e resistance at the apparatus to the same different potential and simultaneously vary'the operation of the apparatus to be governed.

3. In an electric control system, the combination with electric supply mains of a circuit connected to the mains at the apparatus to be cont-rolled and extending there- 'from to the pointof control, a resistance in the circuit at the point of control, a similar resistance across the circuit at the apparatus, sliding contacts engaging said resist ances, a .conductor connecting said contacts, a polarized relay in said conductor, an auxiliary circuit closed by said relay, a solenoid in said auxiliar circuit, an iron core in said solenoid a apted to move longitudinally therein as the contact point is moved over the resistance at the control end, insulated .means connecting the contact on the resistance at the apparatus With the iron core, means connected to the iron core for regulating electrical apparatus by the motion thereof, the core moving only When the contact on the control resistance and the contact on the resistance across the circuit at the appara us are on points of ditlerent potential.

4. In a motor control system, the combination with an electric motor, electric supply mains and a rheostatic device" in the armature circuit, of a circuit connected to the supply mains at the motor and extending to the point ofcontrol, a resistance in the circuit at that point, a similar resistance shunted across the circuit at the motor, sliding contacts engaging the resistances, a conductor connecting the contacts, a polarized relay in the conductor, an. auxiliary circuit connected to the control circuit and closed by the relay, current flowing in one direction therethrough for one direction of current in the control circuit and in the opposite direction for a reversal of current in the control circuit, a solenoid in the auxiliary circuit, an iron core in the solenoid adapted to he moved longitudinally in opposite directions for oppositely flowing currents in the circuit, and insulated material connecting one end of the solenoid with the contact point on the resistance across the circuit at the motor and the other end with the rheostatic device in the armature circuit of the motor, the current flow- WILLIAM M. crrnnn.

Witnesses WM. K. WHITE, G. Pnosr.

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