US1160674A - System of control for electric motors. - Google Patents

Description

1. F. 1mm; SYSTEM OF CONTROL FOR ELECTRIC MOTORS.

APPLICATION FILED DEC.26, I913.

I/YZ'TNESSES fxz YEN TUE I 35y TEZ' T LE,

H's JET :zwzzzwaxv SYSTEM OF CONTROLFOR ELE CTRXC MOTORS.

APPLiCATlON FILED DEC.26, 19134 Patentd Nov. 16, 1915.

2 SHEETS*$HEET 2.

I/YZTNES'SEE ff WAX/6 I YENT UH flan-1N F TH Z'TL E Hrs AT TI'IRNEX' UNITED STATES PATENT OFFICE.

JOHN F. TRITLE, OF SCHENECTADY, YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented Nov. 16, 1915.

Application filed December 26, 1916. Serial No. 808,701.

1 '0 all whom it may concern Be it known that 1, JOHN F. TRITLE, a citizen of the United Statcs,-residing at Schenectady, of New York, have invented certain new and useful Improvements in Systems of Control for Electric Motors, of which the following is a specification.

This invention relates to the control of electric motors, and especially to a plurality of railway motors.

The object of the invention is to provide a semi-automatic system for controlling a railway car equipment comprising tour ino tors, said system requiring a controller having but three positions, one for the series connection of said motors, one for connecting them in series parallel, and one for their parallel connection. F or each position of the controller, three successive changes occlir in the cin lit connections due to the automatic features of the system, as will hereinafter fully appear. I

In the accompanying drawings, Figures 1 to 9 inclusive are diagrams showing the sue-- the switch arm of the line contactor L. The

current flowing to the four motors A, B, C and D is controlled by eight electromagnetic switches or contactors 11 to 18. The last six. are of any simple construction, those shown conventionally in the drawing having a single solenoid winding acting upon a movable core attached to the switch arm. The first two contactors, however, are of a type which do not respond to aheavy current but close only when said current has been reduced to a predetermined strength. This contactor is not of my invention, and is only conventionally shown in Fig. 10. It has an electroinagnet provided with a winding 19 in series with the line, a two-armed pivoted armature having two air gaps 20, 21, and amagnetic shunt 22, these parts being so adjusted that a heavy current will niagnetize electroniagnet to such an eX- county of Schenectady, State holds this element stationary. But when the current is cut down, the magnetic shunt carries so much larger proportion of the flux that the flux across the air gap at the end of the longer arm of the armature is no longer sullicient to hold said arin against the pull of the flux across the other air gap, and consequently the, armature is turned on its pivot and the movable contact 2- carried by said armature is closed upon. the stationary contact These contactors will he hereinafter referred to as series 'contactors. The winding 19 of series contactor 11 is in series with a resistor R and is connected to the switch arm of the contactor 17. The contact 2i is also connected to the winding 19 so that when it closes upon contact a shunt is established around the resistor R. From an intermediate point on the winding of series contactor 11 a lead runs through a sec ond resistor R to the winding of the series contactor l2, and thence to the switch arm of contactor 15. An intermediate point on the winding of series contactor 12- is connected to the switch arm of contactor 13. The contacts of the contactor 12 short circuit the resistor R One terminal of motor A is connected to the fixed contact of cont-actor 13 and the switch arm of contactor 1% whose fixed contact is grounded. motors A and B are connected to the fixed contact of contactor l5. Adjacent terminals oi motors B and G are connected to the fixed contact of contactor i7 and the switch arm of contactor 18, whose fixed contact is grounded. The adjacent terminals of mo tors C and D are connected to the fixed contact of contactor 16; while the other terminal of motor D is grounded.

mechanical interlock 26 between the two series contactors prevents the second one from operating until the first one has closed. Electrical interlocks a to m arealranged in the various control circuits and are operated by the several contactors (ex- Adjacent terminals of.

. tends across positions 11 and III and cooperates with finger 8 connected to a conductor s which runs to contacts of the single interlocks e' and m and the double interlook i; while segment p occupies position 111 only and cooperates with finger 7) connected by conductor ,2) with an upper'contact of double interlock f. The three positions of the controller correspond with the series, series parallel and parallel connections of the motors, the sei'eral eontactors operating automatically to effect the proper circuit changes when the controller is turned to the position selected.

The operation is as follows:

Position I series.--Contactor L and contactor 13 pick up, closing the line upon the resistor R, part of winding of series contactor 11, resistor R part of winding ofseries contactor 12 and the four motors, all in series. As the motors .speed up, their counterelectromotive force cuts down the current to a point where series contactor 11 will close and shunt the resistor B. This increases the current somewhat, so that the motors mustattain a higher speed before their counterelectromotive force will be sufticient to weaken the current to a point where the series contactor 12 will close and shunt the resistor Ri'learing the motors directly across the line. -When contactor 12 closes, contactor 11 will open again because its winding has been shunted by contactor 12. These steps are shown in Figs. 1, 2 and 3. The circuit through the contactor 13 is by way of the lower contacts of double interlocks and Zr Contactor 13 when closed, opens single interlock (Z in the circuit of contactor 11. Series contactor 1-1 when closed shifts double interlock a from the upper to the lower of its two pairs of contact-s. Series contactor 12 closes both the single interlocks 7) and c, the latter serving to keep the circuit ot contactor 13 closed irrespective of interlock 70.

Position I I series paruZZcZ.-Current flows from segment 8'' to finger s, thence by conductor s and interlock m to contactor 17 and thence by single interlock g to interlock I) (closed by the series contactor 12) and interlock 1/. to ground. The energizing of contactor 17 closes the upper pair of contacts in the interlock Z: and establishes a holding circuit for the contactor 17 through the interlocks Z; and h. The switch arm of contactor 17 closes a shunt around the motors A and I3 through the resistor R and a portion of the windingo't' contactor 1-1 in parallel with resistor F, the combination being in series with the remaining portion of the winding of the contactor-s 11, Fig. 4. The current now has two paths, one through contactors 12 and 13 and the other through the multiple shunt. he small amount of current flowing through this shunt, causes series contactor 11 to close, (Fig. 5), whichdeenergizes series contactor 12 and causes it to open. This breaks the holding circuit of contactor 13, and when its switch arm drops the interlock d becomes closed. This energizes contactor 14 because the upper pair of contacts of interlock i were previously closed when contactor 17 was energized. The closing of contactor 11 grounds one terminal ofthe pair of motors A, B, reversing the direction of current through them and putting them in series parallel with the pair of motors C, D. (Fig. 6).

Position. I l I parallels-To go into parallel, the motorman turns the controller to position III, bringing segment 72 into contact with finger p, and energizing conductor p. The previous closing of contactor 14: has closed the upper pair of contacts of the interlock 7, so that current can now flow to the contactors 15 and 16. Contactor 15 shunts motor B through resistor R and the winding of series contactor 12 and contactor 16 shunts motor-"C through resistor R (Fig.

holding. circuit of contactor 17 at the interlock it, but said circuit is maintained by way of the lower contacts of interlock a which were closed when the series contactor 11 closed in Fig. 5. The small amount of current flowing through the resistor R and the winding of contactor 12 by way of contactor 15 now causes contactor 12 to close (Fig. 8). This short circuits cont-actor 11 and allows it to open, which breaks the holding circuit of contactor 17 at the interlock a. When the switch arm of contactor 17 drops, it closes vides for the successive changes in circuit connections required to place four motors in series, series parallel and parallel, with only three control conductors, three positions on the controller, and two resistors.

In accordance with the provisions of the patent statutes, 1 have described the principle of operation of my invention together with the apparatus which now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be "arried out by other means.

\Vhat I claim as new and esire to secure by Letters Patent ot' the United States, is

1. The method of controlling a plurality of electric motors. which consists in connecting them in series through two resistors and two contactors, automatically shunting the first resistor, and then automatically shunting the first contactor and both resistors.

12. The method oi. controlling a plurality of electric motors, which consists in connecting them in series with two resistors, and with two contactors responsive to a weak ened current only, said contactors closing in succession and each acting when closed to shunt one of said resistors.

3. The method of controlling a plurality of electric motors, which consists in connecting them in series through two resistors, and with two contactors responsive to a weakened current only, short circuiting two of said motors by a shunt around one of said resistors and contactors, thereby causing the first contactor to clos and send an increased current through the second contactor, which thereupon opens, automatically disconnecting said second contactor from the short circuited pair of motors, and automatically grounding one terminal of said pair and thereby reversing the current through them.

4. The method of controlling a plurality of electric motors, which consists in connect ing them in series through two resistors and two contactors responsive to a weakened current only, short circuiting two of said motors by a shunt around one of said resistors and contactors, thereby causing the lirst contactor to close and send an increased current through the second contactor which thereupon opens, autoniatically disconmcting said second contactor from the short circuited pair of motors, automatically grounding one terminal of said pair, closing two shunts respectively around two of said motors, through the second resistor, one shunt including the second contactor, and thereby weakening the current through the second contactor to such an extent that it closes, and then tllll()llltltl(itlll grounding a point between the two pairs of motors.

Means for controlling tour electric motors, comprising two series contactors re sponsive to a weakened current only, a resistor in shunt to the contacts 01' each contactor, six contactors having switch arms controlling the terminals of said motors and two ground connections, single interlocks actuated by the third, fourth, sixth, seventh and eighth of said contactors, double interlocks controlled by the first, fourth, sixth, and seventh contactors, two single interlocks controlled by the second cont-actor, a, controller having three positions and circuit connections between said contr ller and said contactors and interlocks.

6. The method of controlling four or more electric motors which consists in connecting them in series with two resistors, short circuiting said resistors in succession, connecting the two resistors in parallel with the two of said motors in series, connect-ing this latter combination in series with the other two motors, and then short circuitingthe first two motors, thereby connecting the other two motors across the line.

7. The method of controlling four or more. electric motors which consists in connecting them in series with two resistors, short circuiting said resistors in succession, connecting the two resistors in parallel with the two of said motors in series, connecting this latter combination in series with the other two motors, short circuitfng the firs two motors thereby connecting the other two motors across the line, pening the short circuit and connecting to ground thereby placing the two groups of motors in series parallel relation, then shunting one of each group of motors with one of said resistors, short circuiting saidresistors, then opening the short circuit and' connecting to ground thereby placing, all the motors in parallel.

In witness whereof, I have hereunto set my hand this 23rd day of December 191.3. JOHN F. TRlTLE. ll'itnesses: Bnxaamx B. HULL, MAnoAnn'r la. Woman-2y.

Images