The Tesla Self-Starting Alternating Motor System

Saturday, July 6, 1889
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VOL- XIV~ NO- 1--JULY 0. 1989-J 9 THE -ELECTRICAL VVORLD. The Tesla Self-Starting Alternating Motor System. As is well known, certain forms of alternating current machines have the property, when connected in circuit with an alternating current generator, of running as a motor in synchronism therewith; but, while the alternat- ing current will run the motor after it has attained a rate of speed synchronous with that of the generator, it will not start it; hence, where these “ x-ynchronizing mo- tors,” as they are termed, have been run, some means have been employed to bring the motors up to synchronism with the generator before the alternating current of the generator isapplied to drive them. In some instances mechanical appliances have been utilized for this purpose. In others, special forms of motor have been constructed. With the object of eiiecting the starting of the alter- nating motor and bringing it to synchronism without ex- ternal aid, Mr. Nikola Tesla has devised a. simple system in which he employs an earth return during the period of starting only. For this purpose he constructs a generator with two coils or sets of coils and a motor with corres- ponding energizing coils or sets of coils. By means ot two linewires, one terminal _ of each generator coil is connected to one terminal of its corresponding motor-coil while the opposite terminals of the generator- coils are joined together, and likewise those of the motor. To start the motor an electrical connection is tempor- arily established between the points ol connection between the coils in the generator and those in the motor, so that the system becomes sn ordinary double-circuit system. \Vhen by this plan of connection the motor has attained the desired speed, the earth connection is severed, by which means the system becomes an ordinary single-cm cuit syixchronizing system. The accompanying diagram shows the manner in which this is accomplished, G repre- senting an ordinary alternating current generator ha , ing four held poles A; mngnetized by a continuous current, and an armature wound with two coils C connected toge- ther in series. M represents an alternating-current motor with, say, four poles D, the coils on which are connected in pairs and the pairs connected in series. The motor- armature should have polar projections and closed coils E. Froin the common joint or union between the two coils of both the generator and motor an earth-connection F is established, while the terminals or ends of the coils which they form are connected to the line-conductors. Assuming that the motor is a. synchronizing motor, or one that has the capability of running in synchronism with the generators, but not of starting, it may he started by the above~described plan by closing the ground-com nection from both generator and motor. The system thus becomes one with a two-circuit generator and motor, the ground forming a common return for the currents in the two line wires. When by this arrangement of circuits the motor is brought to speed, the ground connection is broken between the generatornr motor, or both, and ground switches K K being employed for this purpose. The motor then runs as a synchronizing motor. 1: -ff" H <’§\\ vi ii " hi ll] ` - ~ ‘Joni L54 ta g; iii #1 _ I P _ , TESLA SELF-STARTING ALTERNATINQ MOTOR