Q. Show Applications for DC Machines?

Dc motors find wide applications in which control of speed, voltage, or current is essential. Shunt motors with constant speed are used for centrifugal pumps, fans, blowers, and conveyors, whereas shunt motors with adjustable speed are employed in rolling mills and paper mills. Compound motors find their use for plunger pumps, crushers, punch presses, and hoists. Series motors (known as traction motors) are utilized for electric locomotives, cranes, and car dumpers. Universal motors, operating with either dc or ac excitation, are employed in vacuum cleaners, food processors, hand tools, and several other household applications. They are available in sizes of fractional horsepower up to, and well beyond, 1 hp, in speeds ranging between 2000 and 12,000 r/min.

The dc shunt generators are often used as exciters to provide dc supply. The series generator is employed as a voltage booster and also as a constant-current source in welding machines. In applications for which a constant dc voltage is essential, the cumulative-compound generator finds its use. The differential-compound generator is used in applications such as arc welding, where a large voltage drop is desirable when the current increases.