Two-phase electrical power was used in some early 20th century factories and the distribution systems that served them. It utilized two phases, 90° apart, and was usually supplied using four wires, two for each phase. Less frequently, three wires were used, with a common wire with a larger-diameter conductor. (19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999 in the... A factory (previously manufactory) is a large industrial building where goods or products are manufactured. ...

Induction motors designed for two-phase operation use the same winding configuration as capacitor start single-phase motors. Electric motors of various sizes. ... Electric motors of various sizes. ...

Three-phase electric power provides smoother operation and requires smaller conductors for the same voltage and overall amount of power. It has all but replaced two-phase power. Three-phase power transformer which is the sole transfer point for electricity to a suburban shopping mall in Canada. ...

Two-phase power can be derived from a three-phase source using two transformers in a Scott connection. 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 3-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.

Three-wire, 120/240 volt single phase power used in the USA is sometimes incorrectly called "two-phase". The proper term is 3-wire single phase. A split phase electricity distribution system is a 3-wire single-phase distribution system, commonly used in North America for single-family residential and light commercial (up to about 100 kVA) applications. ...

See also

Polyphase system Polyphase electrical systems supply alternating current electrical power in overlapping phases. ...