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Aitnesses Jonathan Ewoodbridgeinventor No. 755,824, PATENTED MAR, 29, 1904. J. E. WOODBRIDGE, MEANS FOR STARTING ALTERNATING CURRENT DYNAMO ELECTRIC MACHINES, APPLICATION FILED SEPT, ll l901, . NO MODEL . Aitnesses Jonathan EWoodbridgeInventor No. 755,824, Patented March 29, 1904. UNITED STATES PATENT OFFICE. JONATHAN E. WOODBRIDGE, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK. MEANS FOR STARTING ALTERNATING-CURRENT DYNAMO-ELECTRIC MACH NES, SPECIFICATION forming part of Letters Patent No. 755,824, dated March 29, 1904. Application filed Septemberll, 1901, Serial No. 74,997. (No model.) To all whom it may concern: ducing’ member, has its terminals connected Be it known that I, JONATHAN E. WOOD through switches 11 to the secondary termi BRIDGE, a citizen of the United States, resid nals of the transformer-set 5. The other mem ing at Schenectady, in the county of Schen ber, 12, has its three leads or terminals extend 5 ectady and State of New York, have invented ing through collector-rings 13 and connected certain new and useful Improvementsin Means through a set of switches 14 to the rotary 55 for Starting Alternating-Current Dynamo converter leads or terminals, as shown. Electric Machines, of which the following is Mounted upon the shaft of the frequency a specification. - changer is the armature 15 of a small series O My present invention comprises certainim wound direct-current generator. provements particularly useful for starting al The machine as a whole is connected in se ternating-current machines-such, for exam ries with the field-winding 16 of the rotary ple, as rotary converters or the like. converter, which latter winding derives its It comprises means whereby an electromo current normally from connections across the I5 tive force of gradually-increasing frequency commutator-brushes 17 18 of the converter. may be impressed upon the machine to be Afriction or other suitable brake 19 is ar started and also means whereby the field of ranged to act upon the shaft of the frequency the machine may be excited by direct current. changer. The particular type of brake is The drawing accompanying this specifica wholly immaterial, although for purposes of 2O tion represents diagrammatically one embodi convenience I have in the drawing illustrated ment of my invention, the details of which an ordinary friction-brake of the strap type. The action of the starting device will now followingwill be best description. understood by reference to the be readily understood. In starting the rotary The scope of the invention, both in its converter the frequency-changer is first got 25 broader and more limited aspects, is to be de ten up to speed, and this is done by close-cir termined in the usual manner by consideration cuiting the windings of the induced member 75 of the claims appended hereto. 12, the result being accomplished in the pres Referring to the drawing in detail, the ma ent instance by throwing the set of switches chine (indicated at 1) represents diagrammat 14 onto a corresponding number of electric 3o ically a rotary converter, in this case shown as ally-connected contacts 20. This short-cir of the three-phase type. Three-phase mains cuits the winding 12, which thereupon speeds 2 3 4 represent a source of current to which up until its rate of rotation is nearly synchro it may be desired periodically to connect the nous with the impressed field of the inducing rotary. A set of three-phase step-down trans member 10, to which of course current is as 35 formers 5 serves to reduce the electromotive Sumed to be supplied from the transformer set force of the mains 2 3 4 to a value or values 5. When the frequency-changeristhus revolv adapted to the requirements of the rotary 1, ing at full speed, a current of very low fre while switches 6 78 serve to make or break quency is impressed upon the rotary converter connection between the secondary of the set 1. At the same time the boosting-generator 15, 4o of transformers 5 and the alternating-cur which, it should be mentioned, is connected so rent leads of the rotary. as to add its electromotive force to that sup In order to bring the rotary converter 1 up plied from the commutator of the rotary con to synchronism, so that it may be connected verter, being now run at full speed furnishes to the mains 234, Imake use of a frequency current for exciting the field 16 of the said 45 changer, (indicated at 9.) This frequency rotary converter. The brake 19 is then ap changer closely resembles an ordinary induc plied, so as to gradually reduce the speed of 95 tion-motor, both members of which are pro the rotating member of the frequency-changer vided with definite windings. One of the until it finally comes to rest. Under these con members 10, which may be called the 'in ditions it will be evident that as this rotating 2 755,824 member decreases in speed the frequency of ber of the frequency-changer, connections be current supplied therefrom correspondingly tween said direct-current generator and the increases until when the rotating member is at field of said dynamo-electric machine, and standstill the normal frequency of the mains means for cutting the direct-current generator 234 is impressed upon the rotary converter. out of circuit. While the speed of the rotating member of 4. The combination of a rotary converter, the frequency-changer is gradually being de a frequency-changer for starting said rotary creased, thereby decreasing the electromotive converter, and means for exciting the field of force of the booster 15, the electromotive said rotary converter by the joint action of force furnished by the converter itself gradu the rotary converter itself and a source of ally increases, the decrease in electromotive electromotive force which varies inversely force of the booster being practically com with the variation of frequency of current pensated for by the increase in electromotive supplied to the rotary converter. force of the rotary converter. The result is 5. The combination of a rotary converter, the maintenance of a practically constant a frequency-changer, and a direct-currentgen field excitation for the rotary. When the fre erator adapted to be connected in Series with quency-changer has been brought to stand the field-circuit of the rotary converter. still, the booster 15 ceases to produce any 6. The combination of a rotary converter electromotive force and may therefore be cut provided with a shunt field, a source of vari out of circuit by means of the short-circuiting able electromotive force in series with said switch 21. ' field, and means for cutting said source out of 75 In order to adjust the phase relation of the circuit. rotary with respect to the electromotive force 7. The combination of a rotary converter of the mains 2 3 4, the rotating member of provided with a shunt field, an external source 25 the frequency-changer may be allowed to slip of direct current, and means for connecting slowly until the desired adjustment is attained, the shunt field either directly across the as indicated by any usual synchronism-indi brushes of the rotary converter or so as to in cating means. When the desired adjustment clude said source of direct current in series is secured, the switches 6 78 may be thrown, therewith. connecting the rotary to the supply-mains, 8. The combination of a rotary converter, after which the frequency-changer or starting means for starting the rotary converter from device may be cut out of circuit. the alternating-current side, and means for What I claim as new, and desire to secure by Letters Patent of the United States, is supplying current to the field of the rotary 35 1. The combination of an alternating-cur converter from the rotary converter itself rent dynamo-electric machine, a frequency both while it is coming up to speed and after changer for supplying current to said dynamo it is in normal operation. electric machine for starting the same, a di 9. The combination of a rotary converter, rect - current generator driven by the fre a frequency-changer for supplying starting quency-changer, and means for initially ex current to the rotary converter, a direct-cur citing the field of said dynamo-electric ma rent generator driven by the frequency 95 chine from said direct-current generator. changer, and connections whereby the field of 2. The combination of an alternating-cur the rotary converter is excited by the joint rent dynamo-electric machine, means for im action of the rotary converter itself and said 45 direct-current generator. pressing upon said machine an electromotive 10. The combination with a rotary con od force of gradually-increasing frequency, and verter provided with a shunt field, of a source means for exciting the field of said dynamo of variable electromotive force, and a circuit electric machine by the resultant effect of two connecting said source in Series with said electromotive forces one of which decreases shunt field. while the other increases. 3. The combination of an alternating-cur In witness whereof I have hereunto set my Io5 rent dynamo-electric machine, a frequency hand this 9th day of September, 1901. changer, a direct-current generator driven by JONATHAN E. WOODBRIDGE. the frequency-changer, means for restraining Witnesses: 55 MASEL H. EMERSON, the tendency to rotation of the movable mem G. C. HollISTER. .
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