Alternating-current motors defined

Alternating-current motors are of three general types, induction, synchronous, and series, and are defined as follows ... 

This is a very good motor for direct connection to certain loads, particularly where constant speed is required. NEMA defines it as a synchronous machine which transforms electrical power from an alternating-current system into mechanical power. It usually has direct-current field excitation by a separately driven direct-current generator or one directly connected to the motor. This motor remains synchronous with the supply frequency and is not affected by the load. Proper application requires consideration of the following ... 

Rectification — is defined as the conversion of -> alternating current, AC, into pulsating -> direct current, DC, by any means other than the use of a motor-generator. That is, the AC is primarily converted by use of a -> rectifier into (unfiltered) unidirectional half-cycles. The percentage ratio of the DC output voltage to the peak AC input voltage of a certain rectifier device is called rectification efficiency. A circuit containing parallel -> capacitance, sometimes in combination with series inductance, is afterwards frequently applied as rectification filter in order to smooth the ripple in the DC current output. A combined device of rectifier and filter is called rectifier-filter system. 

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