Theory and calculation of alternating current phenomena . Thus the three-phase system, consisting of three equal by one-third of a period, is a symmetrical system. Thequarter-phase system, consisting of two equal displacedby 90°, or one-quarter of a period, is an unsymmetrical 267. The power in a single-phase system is pulsating; that is,the watt curve of the circuit is a sine wave of double frequency,alternating between a maximum value and zero, or a negativemaximum value. In a polyphase system the watt curves of thedifferent branches of the system are pulsat
Theory and calculation of alternating current phenomena . Thus the three-phase system, consisting of three equal by one-third of a period, is a symmetrical system. Thequarter-phase system, consisting of two equal displacedby 90°, or one-quarter of a period, is an unsymmetrical 267. The power in a single-phase system is pulsating; that is,the watt curve of the circuit is a sine wave of double frequency,alternating between a maximum value and zero, or a negativemaximum value. In a polyphase system the watt curves of thedifferent branches of the system are pulsating also. Their sum,however, or the total power of the system, may be either con- 396 GENERAL POLYPHASE SYSTEMS 397 slant or pulsating. In the first case, the system is called abalanced sijstem, in the latter case an unbalanced system. The three-phase system and the quarter-phase system, withequal load on the different branches, are balanced systems; withunequal distribution of load between the individual branchesboth systems become unbalanced Fig. 192. The different branches of a polyphase system may be eitherindependent from each other, that is, without anj^ electrical inter-connection, or they may be interlinked with each other. In thefirst case the polyphase system is called an mdependent system,in the latter case an interlinked system. The three-phase system with star-connected or ring-connectedgenerator, as shown diagrammatically in Figs. 192 and 193, is aninterlinked system.
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