Revolving Magnetic Field
Any polyphase system, by virtue of the time displacement of the currents in the phases, makes it possible to easily generate a magnetic field that revolves at the line frequency. Such a revolving magnetic field makes polyphase induction motors possible. Indeed, where induction motors must run on single-phase power (such as is usually distributed in homes), the motor must contain some mechanism to produce a revolving field, otherwise the motor cannot generate any stand-still torque and will not start. The field produced by a single-phase winding can provide energy to a motor already rotating, but without auxiliary mechanisms the motor will not accelerate from a stop when energized.
A rotating magnetic field of steady amplitude requires that all three phase currents are equal in magnitude and accurately displaced one-third of a cycle in phase. Unbalanced operation results in undesirable effects on motors and generators.
Read more about this topic: Three-phase
Famous quotes containing the words revolving, magnetic and/or field:
“Ah, woe is me! Winter is come and gone,
But grief returns with the revolving year.”
—Percy Bysshe Shelley (1792–1822)
“We are in great haste to construct a magnetic telegraph from Maine to Texas; but Maine and Texas, it may be, have nothing important to communicate.”
—Henry David Thoreau (1817–1862)
“Swift blazing flag of the regiment,
Eagle with crest of red and gold,
These men were born to drill and die.
Point for them the virtue of slaughter,
Make plain to them the excellence of killing
And a field where a thousand corpses lie.”
—Stephen Crane (1871–1900)