It will be out of phase with the main magnetic field because the increased resistance alters the supply phase. The starter winding uses smaller diameter wire and fewer turns than the stator winding, giving it more resistance. Split-phase motors implement an auxiliary winding outside the stator coil to provide the initial phase difference needed for rotation. This article will specify the different types of single phase motors, so that general principles can be applied to these specific designs. Many of the specifications for other AC motors apply when selecting a single phase motor, and these can be found in our articles on induction motors and AC motors. Types of Single Phase MotorsĪ single phase motor only refers to the type of input power supply used, and not the specific stator-rotor-starter arrangement. More information on these starters can be found in our article on motor starters. Motor starters solve this issue by adding an out-of-phase influence (auxiliary windings, capacitors, etc.), which then creates a simulated rotating magnetic field to start the motor. The stationary rotor will not feel any effects from this pulsating, “up-down” magnetic field if it not already moving, as the up-down magnetic forces cancel each other out perfectly. These motors must be given an initial “shove”, or feel a force “out-of-phase” with the stator phase in order for initial movement of the rotor to occur. This approximates a rotating field, but not completely. In three-phase motors, the 120 degrees of phase separation between the three AC currents running through the stator windings produces a rotating magnetic field however, the magnetic field made by only a single phase “pulsates” between 2 motor poles, as there is only one AC current producing two possible magnetic field states (the AC current has two sinusoidal peaks, where the magnetic fields will be equal but opposite in orientation, or “up-down”).
Single-phase motors use both stators and rotors like other AC motors, though they work much differently. They also require a starter, as using only one phase of input power provides zero starting torque at rest. Single-phase motors contain both stators and rotors like most electric motors, but they only use one winding in their stator which carries only one AC current, and their rotors tend to be more basic than those of other designs. They are commonly found in induction motors, but can also be synchronous. “Single-phase” only refers to the input power, so there are many types of motors that use single phase inputs. They operate in much the same way that squirrel cage, wound rotor, and other polyphase motors work, except they are somewhat simplified (more information on these motors can be found in our articles on squirrel cage, wound rotor, and induction motors). Single phase motors are a type of AC motor that uses electromagnetic principles to create useful rotational energy. This motor, its operating principles, and its specifications will be discussed to help designers understand the benefits of single phase motors, as well as when to use them. This article will look at single phase industrial motors, a mainstay the modern world that provides power to many useful tools. These motors use AC current and the physics of electromagnetism to generate rotational power, and come in many types depending upon the application. There are many types of electric motors, yet the AC motor remains commonplace in industry thanks to its elegance and its tried-and-true performance.
These machines have given us everything from lighting to refrigeration to even superfast electric vehicles, all by transforming electrical power into mechanical motion. Where would we be without the electric motor?