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However, 130/225 V, three-wire, two-phase electric power discontinued systems called B1 are used to run old installations in small groups of houses when only two of the three-phase high-voltage conductors are used. The phase shift in Europe is 120°, as is the case with three-phase current.
Most of the Americas use 60 Hz AC, the 120/240 volt split-phase system domestically and three phase for larger installations. North American transformers usually power homes at 240 volts, similar to Europe's 230 volts. It is the split-phase that allows use of 120 volts in the home. Japan's utility frequencies are 50 Hz and 60 Hz.
One voltage cycle of a three-phase system. A polyphase system (the term coined by Silvanus Thompson) is a means of distributing alternating-current (AC) electrical power that utilizes more than one AC phase, which refers to the phase offset value (in degrees) between AC in multiple conducting wires; phases may also refer to the corresponding terminals and conductors, as in color codes.
Both three-phase and single split-phase power can be supplied from a single transformer bank. Where the three-phase load is small relative to the total load, two individual transformers may be used instead of the three for a full delta or a three-phase transformer, thus providing a variety of voltages at a reduced cost.
Voltages in this article are the nominal single-phase supply voltages, or split-phase supply voltages. Three-phase and industrial loads may have other voltages. All voltages are root mean square (RMS) voltage; the peak AC voltage is greater by a factor of 2 {\displaystyle {\sqrt {2}}} , and the peak-to-peak voltage greater by a factor of 2 2 ...
From there they pass through the wall of the house to the electric panel and Main Fuses or Circuit Breakers inside. In North America, the 120/240 V split phase system is used for residential service drops. [3] [4] A pole-mounted single phase distribution transformer usually provides power for one or two residences. The secondary winding of the ...
In the United States it is not usually used for three phase power but for the high leg delta wiring of split-phase electric power (unknown in Europe). This allows one to choose single-phase AC power at either 110–120 volts between phase and neutral or 220–240 volts between phase and phase.
The 2 × 25 kV autotransformer system is a split-phase electric power system which supplies 25 kV power to the trains, but transmits power at 50 kV to reduce energy losses. It should not be confused with the 50 kV system. In this system, the current is mainly carried between the overhead line and a feeder transmission line instead of the rail.