POL YPHASE CURRENTS.

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two coils 11 ; but as the coil b' moves from the position indicatedit generates less current, while coil b, moving into the held, gen-erates more. The current from coil b passes through the devicesand wires designated by the letters d , o, o' f, f' k, s .j, i, i/, d, a',a, and g , and the position of the poles of the motor will be dueto the resultant effect of the currents in the two sets of coils—that is, it will be advanced in proportion to the advance or for-ward movement of the armature coils. The movement of thegenerator-armature through one-quarter of a revolution will ob-viously bring coil b' into its neutral position and coil b into itsposition of maximum effect, and this shifts the poles ninety de-grees, as they are fixed solely by coils b. This action is repeatedfor each quarter of a complete revolution.

When more than one motor or other device is employed, theymay be run either in parallel or series. In Fig. 23 the formerarrangement is shown. The electrical device is shown as a con-verter, l, of which the two sets of primary coils p r are con-nected, respectively, to the mains f e, which are electrically con-nected with the two coils of the generator. The cross-circuitwires l m, making these connections, are then connected to thecommon return-wire d. The secondary coils p’ p" are in circuitsn o, including, for example, incandescent lamps. Only one con-verter is shown entire in this figure, the others being illustrateddiagrammatically.

When motors or converters are to be run in series, the twowires e f are led from the generator to the coils of the firstmotor or converter, then continued on to the next, and so onthrough the whole series, and are then joined to the single wiren, which completes both circuits through the generator. This isshown in Fig. 24, in which j i represent the two coils or sets ofcoils of the motors.

There are, of course, other conditions under which the sameidea may be carried out. For example, in case the motor andgenerator each has three independent circuits, one terminal ofeach circuit is connected to a line-wire, and the other three ter-minals to a common return-conductor. This arrangement willsecure similar results to those attained with a generator and motorhaving but two independent circuits, as above described.

When applied to such machines and motors as have three ormore induced circuits with a common electrical joint, the threeor more terminals of the generator would be simply connected