No. 714,412. Patented Nov., 1902. C. P. SEN METZ. INDUCTIN MTR. Application filed Mar. 22, 1900.) (No Mode.) 2 Sheets-Sheet. N.W. S. - S N N SS s N N 2 ES Ese V SS His S. NS i SS Sir still All 2 H2SHA S- N coi2s (i. I SN3. i. XSS X9y - - 3. Witnesses G2a4ay (eavia. Inventor Charles? Steinmetz, 2.22% *YAC-4, 2., yatt's
No. 7.f4,412. Patented Nov., 1902. C. P. STEIN METZ. INDUCTIN MTR. 'Application filed Mar. 22, 1900. (No Mode, 2 Sheets-Sheet 2. ld. 622d 0. %e.al- 226, Inventor Charles RSteinmetz by 4.4%W
UNITED STATES PATENT FFICE. CHARLES P. STEINMETZ, F SCHENECTADY, NEW YRK, ASSIGNR T GENERAL ELECTRIC CMPANY, A CRPRATIN F NEW YRK. NDUCT N - MTR. 15 So SPECIFICATIN forming part of Tetters Patent No. 714,412, dated November, 1902. Application filed March 22, 1900, Serial No. 9,66l. (No model.) To all tuh-n, it invazy concer'7. Beit known that I, CHARLES P. STEINMETZ, a citizen of the United States, residing at Schen ectady, in the county of Schenectady and State of New York, have invented certain new and useful Improvements in Induction-Mo tors, (Case No. 1,195,) of which the following is a specification. This invention relates to induction-motors, the object being to permit a safe and effective starting of the motor. The invention relates to induction-motors of that type in which a squirrel-cage winding is employed on the secondary element, the object being to produce an economical and effective starting of the motor by giving the Secondary Winding an increased resistance when the motor is first cut in and then gradu ally decreasing the said resistance as it rises in speed. In starting induction-motors a tre mendous rush of current due to the great slip causes the secondary poles to overpower those of the primary element and gives the motor a low starting torque. In order to prevent this objectionable result, means are commonly provided for cutting resistance into the sec ndary circuit while the motor is starting in order to prevent a blowing out of the primary poles and to increase the starting torque, such resistance being cut out as the motor rises in Speed. I provide for the effective starting of Such motors by mounting on the secondary element a Winding normally kept on closed circuit by means of a high resistance, but capable of being connected up in a series of progressively-decreasing resistance paths as the motor rises in speed. Means have here tofore been provided for effecting a similar result on an induction-motor having a wire Wound secondary, but have usually been com plicated in construction or required rubbing contacts and outside connections. In my organization I employ a high-resistance con nection normally completing the closure of a squirrel-cage winding and which is in circuit at all times and a series of elastically-yield ing conductive disks mounted so as to be shifted to or from the conductors of the wind ing to progressively decrease or increase its resistance. The conductive disks are mount ed on the shaft of the rotary element, so as to turn with the same, but are capable of a sliding movement, and an actuating-lever mounted on the frame of the motor permits them to be pressed toward the winding, pro gressively decreasing its resistance as the pressure increases. The novel features of the invention will be more particularly pointed out hereinafter and will be definitely indicated in the claims. In the accompanying drawings, which illus trate the invention, Figure 1 is a sectional view of a motor embodying my improvements, parts being shown in elevation. Fig. 2 is a detached view showing the arrangement of 65 the squirrel-cage conductors at one end of the secondary element. Fig. 3 is a face view of a resistance-varying disk such as I prefer to employ. Fig. 4 is a detail showing the ar rangement of the secondary conductors and their permanently-connected high-resistance path. The frame of the motor may be of any usual or approved construction, comprising a primary and a secondary core composed of 75 thin laminae of sheet-iron punched interiorly and exteriorly to permit the windings to be mested in grooves in the core and mounted in supporting-frames. 1 and 2 represent these cores, and 3 the primary winding, which may be arranged as usual for the development of a progressive or rotary magnetic field and adapted for connection with an alternating current circuit. I form the secondary wind ing by inserting in the grooves of the core bars of copper or other good conducting metal, as indicated at 4 4, &c. These bars are permanently connected together at ne end of the secondary element by means of a conductive ring 5, permanently fixed in good electrical connection with the ends of the bars, as indicated in Figs. and 2. The other ends of the secondary conductors are bent around the edge of the secondary element and all lie in the same plane. All of these are united electrically by a ring-conductor 6 of relatively high resistance to the conduct ing capacity of the secondary system. This ring-conductor may be let into grooves formed in the elbow of the conductors and connected by a good conductive joint or may be attached thereto, so as to form an effective electrical 95 C
35 2 connection, in any suitable Way. I prefer to constitutes one of the features of my present arrange the conductors so that their ends lie invention, it is evident that in its broader in groups terminating at different radial dis aspect my invention is not limited thereto, tances from the axis, as indicated in Fig. 4. but that I may employ any suitable means n the shaft is mounted a group of dished for successively connecting the armature conductive disks, as indicated at 7 in Fig. 1, conductors in different groups in order to re permanently fixed to a sleeve 8, grooved or duce the effective resistance of the squirrel otherwise constructed, so as to be slid on the cage winding. Moreover, it is to be under shaft to and from the conductors by means stood that in some cases it may be sufficient of a controlling-lever 9, mounted upon or to so arrange the terminals of the armature fixed to the frame of the motor. These disks conductors on the face of the secondary ele constitute a low-resistance connecting device ment that the low-resistance device Will si for the armature-conductors, and they are dished with different degrees of curvature, as indicated in Fig. 1, so that their peripheries lie when not strained at different radial dis tances from the center of the secondary ele ment. The disks are radially slitted, as in dicated in Fig. 3, so as to provide a plurality of peripheral elastic tongues or fingers capa ble of being straightened or flattened out un der a thrust toward the secondary element imparted by the lever 9. The dotted lines at 7 and 7, &c., indicate the normal posi tions of the edges of the several disks-that is to say, when they are not strained by com pression. In the normal position of adjustment when the motor is starting the lever is shifted so as to hold the group of disks out of conductive relation to the secondary winding. In this condition of adjustment the several bars com posing the squirrel-cage winding have a com mon metallic connection at one end to the good conducting-ring 5 and at the other end are connected together by a high-resistance ring 6. This ring is formed of such material or such cross-section as to afford the proper starting resistance for the motor. As the mo tor rises in speed and the slip becomes less relatively to the shifting or rotating magnetic field, the lever 9 may be adjusted so as to bring the cup-shaped disks progressively into engagement with the free ends of the con ductors forming the secondary winding, and as these disks are shifted closer to the wind ing the resistance gradually decreases by a progressively-increasing number of the disks being brought into engaging relation with the group of conductors whose terminals lie nearest the center of the secondary element, and a further decrease of resistance is after Ward produced by cutting in a range or group of conductors or more than one range, if desired, lying farther from the center. Thus by varying the angle of the controlling lever any desired resistance and any desired torque may be effected. The lever may be locked in a number of different positions of adjustment by pressing it into one of the notches in a Serrated bracket 10 and held in its position of maximum torque by a toggle 11. While I have illustrated and described in this case a novel form of low-resistance con necting device for short-circuiting the high resistance connection at the ends of the ar mature - conductors, and while this device 714,412 multaneously connect all of the conductors, and such an arrangement I aim to cover in the claims hereto appended. What I claim as new, and desire to secure by Letters Patent of the United States, is 1. An induction-motor provided with a re volving secondary element having a squirrel cage winding, a high-resistance connection uniting the conductors of the squirrel-cage at one end, terminals connected to said conduc tors and located on the face of the secondary element, and a low-resistance connecting de vice mounted on the motor-shaft and adapted to be moved into engagement with said termi inals. 2. An induction-motor having a squirrel cage winding on its secondary element, per lmanently connected by a low-resistance path at one end and by a high-resistance path at its other end, terminals, in conductive rela tion to the several conductors, on the face of the element at the high-resistance end, and a low-resistance coupler for said terminals. 3. An induction-motor provided on its sec ondary element with a squirrel-cage Winding, the conductors of which are permanently con nected by a good conductive path at one end, and are bent parallel to the face of the ele ment at the other end so as to constitute ter minals therefor, a conducting-ring of high re sistance permanently connected to the con ductors at the latter end of the element, and a low-resistance connecting device movable to and from the face of the movable element during its rotation, and adapted to engage the Said terminals. 4. An induction-motor having a revolving secondary winding provided with a plurality of terminals and a radially-expansible coup ler movable with the winding, adjustable to and from it to vary the resistance of the wind Ing. 5. An induction-motor having a squirrel cage winding on its secondary member pro Vided with groups of terminals, a permanent high-resistance connection to all of said con ductors, and a coupling device for progress ively coupling the groups on short circuit to Vary the torque. 6. An induction-motor having a squirrel cage Winding n its secondary element, and means for coupling the conductors in groups to vary the resistance during the operation of the motor. 7. An induction-motor having a revolving 75 85 II5 I
75. 35 cage winding, a radially-expansible cup-con tact in operative relation thereto, and means for expanding the contact to couple the con ductors and vary the resistance of the wind ing. 8. An induction-motor having a revolving cage winding, a series of terminals therefor on the face of the element arranged in groups at different radial positions, an elastic low resistance coupler, and means for spreading it radially to progressively lower the resist alc6. 9. An induction-motor having a revolving cage winding, terminals, for all of the con ductors of the squirrel-cage, on the face of the element, and a plurality of radially-ex pansible couplers adapted to be brought suc cessively into engagement with the terminals to vary the resistance of the winding. 10. An induction-motor having a secondary element provided with a squirrel-cage wind ing permanently closed by a high resistance, a plurality of conductor-terminals on the face of the secondary element, a cup-shaped elas tic coupler, and a lever for shifting it to cross connect the terminals to provide a low re sistance when the motor rises in speed. 11. An induction-motor having a movable secondary element, terminals for the winding 714,412 of said element to vary its resistance, an elas tic coupler to connect the terminals in differ ent relations, a controlling device on a sta tionary part of the motor to adjust the coup ler, and a lock to secure it in place when ad justed. 12. In an alternating- current induction motor, a squirrel-cage armature-winding com prising a plurality of groups of conductors, a high-resistance connection uniting all of said conductors, and means for successively con necting the conductors of the several groups by a low-resistance connection. 13. In an alternating- current induction motor, a Squirrel-cage armature-winding, hav high-resistance connection, and means for making a low-resistance connection, first be tween a portion only of said conductors, and thereafter between all of said conductors. 14. In an alternating- current induction motor, a squirrel-cage armature-winding hav high-resistance connection, and means for making a low-resistance connection, first be tween alternate conductors and thereafter between the remaining conductors of the said squirrel-cage winding. 15. In an alternating - current induction motor, a Squirrel-cage armature-winding hav high-resistance connection, and a low-resist ance connecting device having a plurality of operative positions in one of which the said device operates to connect a portion only of said conductors, and in the other to connect the remaining conductors. 16. In an alternating- current induction-, motor, a squirrel-cage armature-winding hav high-resistance connection, and a low-resist ance connecting device having a plurality of operative positions in one of which the said device operates to connect together certain of said conductors, and in another to connect together other conductors of the said winding. In witness whereof I have hereunto set my hand this 20th day of March, 1900. CHARLES P. STEINMETZ. Witnesses: BENJAMIN B. HULL, MABEL, E. JACBSN. 3. so 75