CHAPTER XIY.

Type of Tesla Single-Phase Motok.

Up to this point, two principal types of Tesla motors havebeen described: First, those containing two or more energizingcircuits through which are caused to pass alternating currentsdiffering from one another in phase to an extent sufficient toproduce a continuous progression or shifting of the poles orpoints of greatest magnetic effect, in obedience to which themovable element of the motor is maintained in rotation ; second,those containing poles, or parts of different magnetic suscepti-bility, which under the energizing influence of the same currentor two currents coinciding in phase will exhibit differences intheir magnetic periods or phases. In the first class of motorsthe torque is due to the magnetism established in different por-tions of the motor by currents from the same or from inde-pendent sources, and exhibiting time differences in phase. Inthe second class the torque results from the energizing effects ofa current upon different parts of the motor which differ in mag-netic susceptibility—in other words, parts which respond in thesame relative degree to the action of a current, not simultaneously,but after different intervals of time.

In another Tesla motor, however, the torque, instead of beingsolely the result of a time difference in the magnetic periods orphases of the poles or attractive parts to whatever cause due, isproduced by an angular displacement of the parts which, thoughmovable with respect to one another, are magnetized simultane-ously, or approximately so, by the same currents. This principleof operation has been embodied practically in a motor in whichthe necessary angular displacement between the points of greatestmagnetic attraction in the two elements of the motor—the arma-ture and field—is obtained by the direction of the lamination ofthe magnetic cores of the elements.

Fig. 62 is a side view of such a motor with a portion of itsarmature core exposed. Fig. 63 is an end or edge view of the