27:
144:: One transformer primary is connected across two phases of the supply. The second transformer is connected to a center-tap of the first transformer, and is wound for 86.6% of the phase-to-phase voltage on the three-phase system. The secondaries of the transformers will have two phases 90 degrees apart in time, and a balanced two-phase load will be evenly balanced over the three supply phases.
124:
Two-phase circuits typically use two separate pairs of current-carrying conductors. Alternatively, three wires may be used, but the common conductor carries the vector sum of the phase currents, which requires a larger conductor. The vector sum of balanced three-phase currents, however, is zero,
120:
requires less conductor mass for the same voltage and overall power, compared with a two-phase four-wire circuit of the same carrying capacity. It has replaced two-phase power for commercial distribution of electrical energy, but two-phase circuits are still found in certain control systems.
128:
While both two-phase and three-phase circuits have a constant combined power for an ideal load, practical devices such as motors can suffer from power pulsations in two-phase systems. These power pulsations tend to cause increased mechanical noise in transformer and motor laminations due to
125:
allowing for the neutral wires to be eliminated. In electrical power distribution, a requirement of only three conductors, rather than four, represented a considerable distribution-wire cost savings due to the expense of conductors and installation.
108:
Two-phase circuits also have the advantage of constant combined power into an ideal load, whereas power in a single-phase circuit pulsates at twice the line frequency due to the zero crossings of voltage and current.
48:
differing by one-quarter of a cycle, 90°. Usually circuits used four wires, two for each phase. Less frequently, three wires were used, with a common wire with a larger-diameter conductor. Some early two-phase
92:
in 1918 that polyphase power systems had a convenient mathematical tool for describing unbalanced load cases. The revolving magnetic field produced with a two-phase system allowed electric motors to provide
61:
systems eventually replaced the original two-phase power systems for power transmission and utilization. Active two-phase distribution systems remain in
88:, it was easier to analyze and design two-phase systems where the phases were completely separated. It was not until the invention of the method of
615:
359:
101:(without an additional starting means). Induction motors designed for two-phase operation use a similar winding configuration as
53:
had two complete rotor and field assemblies, with windings physically offset to provide two-phase power. The generators at
19:
This article is about electric systems with 90° phase difference. For systems with two opposite (180°) live wires, see
324:
293:
795:
352:
105:
single-phase motors. However, in a two-phase induction motor, the impedances of the two windings are identical.
102:
744:
529:
258:
Blalock, T.J. (March 2004). "The first polyphase system a look back at two-phase power for AC distribution".
877:
887:
600:
573:
231:
164:
81:
897:
892:
345:
174:
169:
117:
58:
20:
57:
installed in 1895 were the largest generators in the world at that time, and were two-phase machines.
972:
590:
568:
62:
333:, copyright American Technical Book Company 1897, published by P. F. Collier and Sons New York, 1902
695:
942:
1003:
882:
433:
705:
610:
539:
89:
85:
836:
700:
438:
418:
398:
69:
831:
724:
473:
448:
8:
937:
640:
635:
380:
41:
962:
856:
811:
749:
719:
673:
496:
483:
50:
1008:
922:
826:
754:
546:
534:
524:
320:
289:
872:
84:
was that it allowed for simple, self-starting electric motors. In the early days of
977:
967:
907:
851:
821:
769:
665:
655:
645:
595:
458:
428:
368:
267:
159:
154:
141:
130:
38:
912:
26:
952:
902:
764:
585:
563:
551:
519:
423:
98:
927:
947:
846:
816:
678:
630:
578:
506:
443:
386:
312:
271:
218:
68:, where many commercial buildings are permanently wired for two-phase, and in
997:
957:
625:
54:
45:
982:
917:
605:
65:
759:
690:
137:
44:
electric power distribution system. Two circuits were used, with voltage
650:
620:
491:
453:
932:
685:
463:
337:
714:
558:
514:
136:
Two-phase power can be derived from a three-phase source using two
97:
from zero motor speed, which was not possible with a single-phase
790:
785:
468:
392:
94:
133:
and torsional vibration in generator and motor drive shafts.
75:
616:
Dual-rotor permanent magnet induction motor (DRPMIM)
112:
208:Figure 1253 from the 1917 Hawkins Electrical Guide
319:, Eleventh Edition, McGraw-Hill, New York, 1978,
288:, Eleventh Edition, McGraw Hill, New York (1987)
80:The advantage of two-phase electrical power over
995:
30:A simplified diagram of a two-phase alternator
353:
217:Company advertising services for two-phase:
219:http://www.phillyfacility.com/two_phase.htm
360:
346:
317:Standard Handbook for Electrical Engineers
331:Recent Types of Dynamo-Electric Machinery
253:
251:
284:Terrell Croft and Wilford Summers (ed),
229:
25:
257:
232:"A Tale Of Two Phases And Tech Inertia"
996:
329:Edwin J. Houston and Arthur Kennelly,
248:
367:
341:
13:
76:Comparison with single-phase power
16:Electric power distribution system
14:
1020:
113:Comparison with three-phase power
745:Timeline of the electric motor
286:American Electricans' Handbook
278:
260:IEEE Power and Energy Magazine
223:
211:
202:
1:
530:Dahlander pole changing motor
181:
7:
574:Brushless DC electric motor
230:Williams, Al (2018-03-15).
165:Single-phase electric power
147:
10:
1025:
175:Three-phase electric power
170:Split-phase electric power
118:Three-phase electric power
37:was an early 20th-century
35:Two-phase electrical power
21:split-phase electric power
18:
865:
804:
778:
733:
664:
591:Switched reluctance (SRM)
569:Brushed DC electric motor
505:
482:
407:
375:
272:10.1109/MPAE.2004.1269626
779:Experimental, futuristic
696:Variable-frequency drive
796:Superconducting machine
434:Coil winding technology
296:page 3–10, figure 3–23
90:symmetrical components
86:electrical engineering
31:
837:Power-to-weight ratio
701:Direct torque control
70:Hartford, Connecticut
29:
832:Open-loop controller
725:Ward Leonard control
449:DC injection braking
315:and H. Wayne Beaty,
735:History, education,
381:Alternating current
194:Specific references
42:alternating current
898:Dolivo-Dobrovolsky
857:Voltage controller
812:Blocked-rotor test
750:Ball bearing motor
720:Motor soft starter
674:AC-to-AC converter
535:Wound-rotor (WRIM)
497:Electric generator
304:General references
32:
991:
990:
827:Open-circuit test
666:Motor controllers
547:Synchronous motor
369:Electric machines
1016:
842:Two-phase system
822:Electromagnetism
770:Mouse mill motor
737:recreational use
611:Permanent magnet
540:Linear induction
393:Permanent magnet
362:
355:
348:
339:
338:
297:
282:
276:
275:
255:
246:
245:
243:
242:
227:
221:
215:
209:
206:
160:Rotary converter
155:Polyphase system
142:Scott connection
131:magnetostriction
1024:
1023:
1019:
1018:
1017:
1015:
1014:
1013:
994:
993:
992:
987:
861:
800:
774:
765:Mendocino motor
738:
736:
729:
660:
520:Induction motor
501:
478:
424:Braking chopper
412:
410:
403:
371:
366:
336:
301:
300:
283:
279:
256:
249:
240:
238:
228:
224:
216:
212:
207:
203:
184:
179:
150:
115:
103:capacitor start
99:induction motor
78:
24:
17:
12:
11:
5:
1022:
1012:
1011:
1006:
1004:Electric power
989:
988:
986:
985:
980:
975:
970:
965:
960:
955:
950:
945:
940:
935:
930:
925:
920:
915:
910:
905:
900:
895:
890:
885:
880:
875:
869:
867:
863:
862:
860:
859:
854:
849:
847:Inchworm motor
844:
839:
834:
829:
824:
819:
817:Circle diagram
814:
808:
806:
805:Related topics
802:
801:
799:
798:
793:
788:
782:
780:
776:
775:
773:
772:
767:
762:
757:
755:Barlow's wheel
752:
747:
741:
739:
734:
731:
730:
728:
727:
722:
717:
712:
711:
710:
709:
708:
706:Vector control
703:
688:
683:
682:
681:
679:Cycloconverter
670:
668:
662:
661:
659:
658:
653:
648:
643:
638:
633:
628:
623:
618:
613:
608:
603:
598:
593:
588:
583:
582:
581:
576:
571:
566:
556:
555:
554:
549:
544:
543:
542:
537:
532:
527:
511:
509:
503:
502:
500:
499:
494:
488:
486:
480:
479:
477:
476:
471:
466:
461:
456:
451:
446:
444:Damper winding
441:
436:
431:
426:
421:
415:
413:
409:Components and
408:
405:
404:
402:
401:
395:
389:
387:Direct current
383:
376:
373:
372:
365:
364:
357:
350:
342:
335:
334:
327:
313:Donald G. Fink
309:
308:
307:
305:
299:
298:
277:
247:
222:
210:
200:
199:
198:
197:
195:
191:
190:
188:
183:
180:
178:
177:
172:
167:
162:
157:
151:
149:
146:
114:
111:
77:
74:
15:
9:
6:
4:
3:
2:
1021:
1010:
1007:
1005:
1002:
1001:
999:
984:
981:
979:
976:
974:
971:
969:
966:
964:
961:
959:
956:
954:
951:
949:
946:
944:
941:
939:
936:
934:
931:
929:
926:
924:
921:
919:
916:
914:
911:
909:
906:
904:
901:
899:
896:
894:
891:
889:
886:
884:
881:
879:
876:
874:
871:
870:
868:
864:
858:
855:
853:
850:
848:
845:
843:
840:
838:
835:
833:
830:
828:
825:
823:
820:
818:
815:
813:
810:
809:
807:
803:
797:
794:
792:
789:
787:
784:
783:
781:
777:
771:
768:
766:
763:
761:
758:
756:
753:
751:
748:
746:
743:
742:
740:
732:
726:
723:
721:
718:
716:
713:
707:
704:
702:
699:
698:
697:
694:
693:
692:
689:
687:
684:
680:
677:
676:
675:
672:
671:
669:
667:
663:
657:
654:
652:
649:
647:
644:
642:
641:Piezoelectric
639:
637:
636:Electrostatic
634:
632:
629:
627:
624:
622:
619:
617:
614:
612:
609:
607:
604:
602:
599:
597:
594:
592:
589:
587:
584:
580:
577:
575:
572:
570:
567:
565:
562:
561:
560:
557:
553:
550:
548:
545:
541:
538:
536:
533:
531:
528:
526:
523:
522:
521:
518:
517:
516:
513:
512:
510:
508:
504:
498:
495:
493:
490:
489:
487:
485:
481:
475:
472:
470:
467:
465:
462:
460:
457:
455:
452:
450:
447:
445:
442:
440:
437:
435:
432:
430:
427:
425:
422:
420:
417:
416:
414:
406:
400:
396:
394:
390:
388:
384:
382:
378:
377:
374:
370:
363:
358:
356:
351:
349:
344:
343:
340:
332:
328:
326:
325:0-07-020974-X
322:
318:
314:
311:
310:
306:
303:
302:
295:
294:0-07-013932-6
291:
287:
281:
273:
269:
265:
261:
254:
252:
237:
233:
226:
220:
214:
205:
201:
196:
193:
192:
189:
186:
185:
176:
173:
171:
168:
166:
163:
161:
158:
156:
153:
152:
145:
143:
139:
134:
132:
126:
122:
119:
110:
106:
104:
100:
96:
91:
87:
83:
73:
71:
67:
64:
60:
56:
55:Niagara Falls
52:
47:
43:
40:
36:
28:
22:
841:
330:
316:
285:
280:
266:(2): 63–66.
263:
259:
239:. Retrieved
235:
225:
213:
204:
138:transformers
135:
127:
123:
116:
107:
82:single-phase
79:
66:Philadelphia
34:
33:
760:Lynch motor
525:Shaded-pole
411:accessories
63:Center City
59:Three-phase
998:Categories
656:Axial flux
646:Ultrasonic
621:Servomotor
601:Doubly fed
596:Reluctance
492:Alternator
484:Generators
454:Field coil
439:Commutator
399:commutated
397:SC - Self-
241:2023-02-04
182:References
51:generators
973:Steinmetz
888:Davenport
686:Amplidyne
586:Universal
564:Homopolar
552:Repulsion
464:Slip ring
39:polyphase
1009:AC power
978:Sturgeon
908:Ferraris
893:Davidson
715:Metadyne
631:Traction
579:Unipolar
559:DC motor
515:AC motor
419:Armature
236:Hackaday
148:See also
968:Sprague
963:Siemens
938:Maxwell
903:Faraday
852:Starter
791:Railgun
786:Coilgun
626:Stepper
474:Winding
958:Saxton
943:Ørsted
928:Jedlik
923:Jacobi
913:Gramme
878:Barlow
866:People
691:Drives
606:Linear
507:Motors
469:Stator
323:
292:
95:torque
46:phases
983:Tesla
953:Pixii
918:Henry
883:Botto
873:Arago
459:Rotor
429:Brush
391:PM -
385:DC -
379:AC -
187:Notes
140:in a
948:Park
933:Lenz
651:TEFC
321:ISBN
290:ISBN
268:doi
1000::
262:.
250:^
234:.
72:.
361:e
354:t
347:v
274:.
270::
264:2
244:.
23:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
