A synchronous and synchronous motors are the two main categories of ac motors. The induction motor is a common form of asynchronous motor and is basically an ac transformer with a rotating secondary.

Note: This article is based on the 2011 NEC. Article 430 provides the requirements for electric motors while Art. 440 offers amended and additional requirements for hermetic motors, such as those used ...

THE first edition of this work appeared in 1904. Since then remarkable advances have been made in electrical engineering. A foremost place in this progress must be given to electric motors, and more ...