CHAPTER X.
Motor With “Current Lag” Artificially Secured.
One of the general ways followed by Mr. Tesla in developinghis rotary phase motors is to produce practically independentcurrents differing primarily in phase and to pass these through themotor-circuits. Another way is to produce a single alternating-current, to divide it between the motor-circuits, and to effectartificially a lag in one of these circuits or branches, as bygiving to the circuits different self-inductive capacity, and inother ways. In the former case, in which the necessary differ-ence of phase is primarily effected in the generation of currents,in some instances, the currents are passed through the energizingcoils of both elements of the motor—the field and armature ; buta further result or modification may be obtained by doing thisunder the conditions hereinafter specified in the case of motorsin which the lag, as above stated, is artificially secured.
Figs. 42 to 47, inclusive, are diagrams of different ways in whichthe invention is carried out; and Fig. 48, a side view of a fo.imof motor used by Mr. Tesla for this purpose.
a b in Fig. 42 indicate the two energizing circuits of a motor,and c d two circuits on the armature. Circuit or coil a is con-nected in series with circuit or coil c, and the two circuits b d aresimilarly connected. Between coils a and c is a contact-ring e,forming one terminal of the latter, and a brush a, forming oneterminal of the former. A ring d and brush c similarly connectcoils b and d. The opposite terminals of the field-coils connectto one binding post h of the motor, and those of the armaturecoils are similarly connected to the opposite binding post i througha contact-ring f and brush g. Thus each motor-circuit while inderivation to the other includes one armature and one field coil.These circuits are of different self-induction, and may be madeso in various ways. For the sake of clearness, an artificial re-sistance r is shown in one of these circuits, and in the other aself-induction coil s. When an alternating current is passed