Direct-current motor speed regulation

Direct-Current Motor Control Control for dc motors runs the gamut from simple manual line starters to elaborate regulating systems. Only the starting problems are considered here since variable-speed drives and regulating systems are discussed elsewhere. 

Speed Regulation of Direct-Current Motors. The speed regulation of a direct-current motor is the difference between the steady no-load speed and the steady rated-load speed, expressed in percent of rated-load speed. 

Steam compressor (reciprocating compressor with speed regulated direct current motor) Steam saturator A Live steam B Contaminated vapor C Contaminated condensate D Condensate/feed water E Low-pressure steam F Recovered steam... 

DC drive (direct-current drive) n. A machine drive, particularly that of an extruder, powered by a direct-current motor. The availability of economical solid-state rectifiers, and the good torque-versus-speed characteristic and tight speed regulation of DC drives have made them the most popular choice today for variable-speed service. 

Hybrid thermal vehicles are more expensive than traditional vehicles, because they include more than one energy source on board. However, there are some components of traditional vehicles which are not required for hybrid vehicles and can be made some savings. For instance, in the series conhguration there is no need for the gear box because the electric drive regulates the motor speed electronically, transmission is simplihed and differential is useless if the motors are directly connected to the wheels. The starter can be eliminated in both series and parallel conhguration since electric machines do not need any specihc devices to start. Many hybrid vehicles are currently on the market and this sector is growing rapidly worldwide. 

Extruder motors are usually electric, but some systems utilize hydraulic motors. For example, injection molding machines use hydraulics to develop clamp tonnage. Electric motors may be of the direct current (DC) or alternating current (AC) types. Traditionally, DC motors, which regulate speed through voltage control, have been more popular because they could provide the necessary power at a lower cost. However, recent advances in frequency control - the technique used to regulate speed in AC motors - have caused this type of motor to become more widely used. 

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