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A three-phase motor is more compact and less costly than a single-phase motor of the same voltage class and rating, and single-phase AC motors above 10 hp (7.5 kW) are uncommon. Three-phase motors also vibrate less and hence last longer than single-phase motors of the same power used under the same conditions. [26]
Mathematics of three-phase electric power. One voltage cycle of a three-phase system, labeled 0 to 360° (2π radians) along the time axis. The plotted line represents the variation of instantaneous voltage (or current) with respect to time. This cycle repeats with a frequency that depends on the power system.
As an example, consider the use of a 10 hp, 1760 r/min, 440 V, three-phase induction motor (a.k.a. induction electrical machine in an asynchronous generator regime) as asynchronous generator. The full-load current of the motor is 10 A and the full-load power factor is 0.8. Required capacitance per phase if capacitors are connected in delta:
For example; a single-phase motor with 3 north and 3 south poles, having 6 poles per phase, is a 6-pole motor. A three-phase motor with 18 north and 18 south poles, having 6 poles per phase, is also a 6-pole motor. This industry standard method of counting poles results in the same synchronous speed for a given frequency regardless of polarity.
Miniature synchronous motor used in analog clocks. The rotor is made of permanent magnet. A synchronous electric motor is an AC electric motor in which, at steady state, [1] the rotation of the shaft is synchronized with the frequency of the supply current; the rotation period is exactly equal to an integer number of AC cycles.
With increasing power output, three-phase motors have preferable characteristics to single-phase motors; the latter not being available in sizes over 15 hp (11 kW) and, though available, rarely seen larger than 5 hp (3.7 kW). (Three-phase motors have higher efficiency, reduced complexity, with regards to starting, and three-phase power is ...
Motor velocity constant, back EMF constant. is the motor velocity, or motor speed, [2] constant (not to be confused with kV, the symbol for kilovolt), measured in revolutions per minute (RPM) per volt or radians per volt second, rad/V·s: [3] The rating of a brushless motor is the ratio of the motor's unloaded rotational speed (measured in RPM ...
An electric motor is a machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor's shaft. An electric generator is mechanically identical to an electric ...