US1686666A - Motor-control system - Google Patents

Description

H. 1:). JAMES- uo'ron conrho'il SYSTEM Filed Aug. 25, 1925 INVENTOR flew/"y 0. Jam es WITNESSES:

TTOERNEY Patented Oct. 9, 1928.

UNITED STATES PATENT OFFICE.

HENRY D. JAMES, OF EDGEWOOD, PENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

MOTOR-CONTROL SYSTEM.

Application filed August 25, 1925. Serial No. 52,290.

' the thermal element to the desiredtemperature Without waste of energy. 'In accordance with my invention, the thermal elements are heated by transformer action. In the preferred form of my invention, a heating coil is mounted on the same core member as the operating coil of the line switch and also of certain accelerating switches. The heating coil is thereby inductively related to the operating coil and receives its energy therefrom.

My invention will be best understood by reference to the accompanying drawing, in which Fig. 1 is a diagrammatic view of circuits and apparatus embodying my invention,

conductors 3, 4-. and 5, through a three-pole electromagnetic switch 6. The motor is provided with starting and accelerating means comprising a plurality of resistor sections 7,

8 and 9, which are connected in the secondary circuit in a familiar manner. The resistor sections are adapted to be successively shunted by a plurality of pairs of accelerating switches 11, 12 and 13 of the electromagnetic type. 3 I

As illustrated in Fig. 2, each of thefelcctromagn'etic switches comprises an armature member 14 that is pivotally mounted on a lower bearin 15 in accordance with. con- YQ tiOILal design. The illustrated core ember 16 is preferably of U-shape; upon one leg thereof is mounted the operating coil 17 and upon another leg thereof is mounted the secondary coil or heating coil 18. Similarly, the accelerating switches 11, 12 and 13 are provided with operating coils 21, 22 and 23, respectively, and with corresponding secondary coils 24 and 25. The last accelerating switch 13, of course, does not require a secondary coil.

The line switch 6, for example, is provided with a bimetallic thermal element 26 that is preferably of V-shape so that it may be readily connected across the terminals of the heating coil 18, as illustrated in Fig. 3. The bimetallic element, when heated, warps from its initial position to make or break a control circuit, in accordance with a familiar practice. In accordance with my invention, when the primary or operating coil 17 is energized, the armature 14: is attracted by the core member 16 to the position illustrated.

in Fig. 2. Therefore, by transformer action, the secondary coil 18 is energized and current will traverse the thermal element 26.

For controlling this element I preferably employ a current of at least and a very low electroinotive force, for example, one volt. i

The system is conveniently controlled by means of a starting switch or push button 27 and a stop button 28.

When reference to Fig. 1, the apparatus is illustrated in its inoperative condition, and the motoris started by operating switch 27, whereby a circuit is established for the operating coil 17 of line switch 6 extending from line conductor 4 through operating coil 17, conductor 31, thermal element 26, stationary contact member 30, conductor 32, switches 27 and 28 and conductor 83 to line conductor 5. No current traverses coil 18 since it is short-c-ircuited. Line switch 6 is thereupon closed to supply energy to the primary windings 2 of the induction motor.

When the line switch 6 is closed, it is maintained closed, independently of the start button 27, by means of an electrical interlock and in accordance with a familiar practice. This interlock is designated as (i-in, that is to say, the intfirlock is closed when 50 amperes the contactor 6 is energized. This holding circuit extends from line conductor 4 through operating coil 17, interlock 6-in, stop switch 28 and conduct 33 to line conductor 5.

Since the secondary or heating coil 18 is inductively related to the primary coil 17, current traverses the winding 18 and the thermal element 26, which are connected in a closed or loop circuit. When the element 26 is sufiiciently heated, it is warped to the right-hand circuit-closing position to engage contact member 34, thereby establishing a circuit for the operating coil 21 of the first accelerating switch 11 extending from line conductor 4 through conductor 35, operating coil 21, conductor 36, contact member 34, thermal element 26, conductor 31, interlock 6-in, switch 28 and conductor 33 to line conductor 5.

Accelerating switch 11 then closes and heating coil 24 is inductively energized from coil 21 to efiect the operation of the associated thermal element 37. When this element operates to its closed position, a circuit is established for the operating coil 22 of the next accelerating switch 12, extending from line conductor 4 through condifctor 35, coil 22 and thermalelement 37 to conductor 36, whence the circuit is completed as previously traced. Similarly, thermal element 38, of.

switch 12 is heated by coil 25 to establish a circuit for the operating coil 23 of the last accelerating switch 13 extending from line conductor 4 through conductor 35, coil 23 and thermal element 38 to conductor 36.

In order that the thermal elements may be quickly cooled and restored to their initial positions, during the period that the motor 1 is operating, it may be desirable to inerrupt the closed circuits of coils 18, 24, and 25 upon the closure of the last accelerating switch 13, or by any other suitable means readil employed by one skilled in the art. It is elieved to be unnecessary to further complicate the drawing by illustrating any such well-known circuit-interrupting means.

It is believed that the advantages of my system will be apparent to one skilled in the art, since a relatively high current is required to heat the thermal elements andv preferably a relatively low voltage is employed. In ordinary commercial systems of distribution, this low voltage and necessary heating current is not readily obtainable from an independent source without an undue waste of energy. In accordance with my invention, no independent source of energy is required and I obtain the required result in a simple and effective manner, as previously described.

I have illustrated my invention in a preferred and diagrammatic form, but various modifications thereof will naturally occur to one skilled in the art, and I desire that my invention shall be limited only in accordance with the scope of the appended claims.

I claim as my invention 1. The combination with a motor and a starting resistor therefor, of a switch for controlling said motor comprising an operating electromagnet and temperature-controlled means comprising a winding inductively related to said electromagnet for controllingsaid resistor.

2. The combination with a motor and electromagnetically operated controlling means therefor, of temperature-controlled means comprising a winding inductively related to said electromagnetically operated controlling means for further controlling said motor.

3. The combination with a translating device and temperature-controlled means for controlling said device provided with an energizing winding, of electro-responsive means having an operating winding inductively related to the energizing winding of said temperature-controlled means for controlling said translating device.

4. The combination with a motor and electro-responsive controlling means therefor, of thermostatic means for controlling the acceleration of said motor, a winding for supplying current for heating said thermosatic means, said winding being inductively related to said electro-responsive means.

5. The combination with a motor and a starting resistor therefor, of a plurality of magnetically operated switches for controlling the starting resistor, a plurality of temperature-controlled devices, and means inductively related to the magnets of said switches for energizing said temperaturecontrolled devices to eifect serial operation thereof.

6. The combination with a motor and a starting resistor therefor, of a plurality of magnetic switches for controlling the starting resistor, operating windings for actuating said switches, a plurality of thermostatic members for efiecting energiz'ation of said switches, and means directly associated with said switches and inductively energized in accordance with the energization of said operating windings for effecting operation of said thermostatic members in a predetermined sequence.

7 The combination with a motor and starting resistor therefor, of a plurality of electromagnetically operated switches for controlling the starting resistor, a plurality of thermostatic members for effecting serial operation of said switches, and means for efi'ecting operation of said thermostatic electromagnetically operated switches for controlling the resistor and provided with operating windings, a plurality of thermostatic members for efiecting energization of said switches serially, and means inductively associated with the respective operatin windings of. said switches and energized simultaneously therewith for efiecting operation of said thermostatic members. 1

In testimony whereof, I have hereunto I subscribed my name this 4th day of August, 1925.

HENRY D. JAMES-

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