AC Motors

Alternating current (AC) motors are a broad category of motors that include single / multiphase, universal, servo, induction, synchronous, and gearmotor types. The magnetic field, generated by AC motors, is produced by an electromagnet powered by the same AC voltage as the motor coil. The coils that produce the magnetic field are traditionally called the "field coils" while the coils and the solid core that rotates is called the "armature.” There are many advantages in the use of ac motors aside from the wide availability of AC power. In general, AC motors cost less than DC motors. Some types of AC motors do not use brushes or commutators. This eliminates many problems of maintenance and wear, and also eliminates the problem of dangerous sparking.  They are also particularly well suited for constant-speed applications. This is because its speed is determined by the frequency of the AC voltage applied to the motor terminals.

There are two distinct types of AC motors, synchronous and induction.  A synchronous motor consists of a series of three windings in the stator section with a simple rotating area. A current is passed through the coil, generating torque on the coil. Since the current is alternating, the motor will run smoothly only at the frequency of the sine wave. This allows for constant, unvarying speed from no load to full load with no slip.

Induction motors are the more common of the two motor types. They use electric current to induce rotation in the coils rather than supplying the rotation directly.  Induction motors use shorted wire loops on a rotating armature and obtain their torque from currents induced in these loops by the changing magnetic field produced in the field coils.

• Replacing Your DC Motors? Think AC
  Alternating-current (AC) and direct-current (DC) motors have traditionally served distinctly different applications due to their construction and inherent operating characteristics. In general, AC...
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• Eliminating Damage from Motor Shaft Currents Through Tachometers and Encoders
  Since the introduction of variable speed electronic controls for DC and AC motors, users have noted a troubling problem; voltage potential is sometimes induced on the shaft of the motor....
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• Reference Guide: Glossary of Terms
  AC Motor - AC Motors may be operated at a constant speed, without variable speed control, or may be furnished with a variable frequency controller for variable speed control. Variable speed AC Motors...
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Part Numbers for AC Motors