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Which of the following motors is preferred for driving compressors, variable-head centrifugal pumps, rotary presses, circular saws and elevators?

Which of the following motors is preferred for driving compressors, variable-head centrifugal pumps, rotary presses, circular saws and elevators? Correct Answer DC cumulative compound motor

Applications of different DC motors are given below.

Series wound motor: It has very high starting torque. Hence it is used for heavy duty applications such as electric railways, mine hoists, continuous conveyors cranes, rolling mills, metallurgical works etc.

Shunt wound motor: This is almost constant speed motor and its torque varies nearly as the current. Hence, it is used for driving constant speed line shafts, lathes, constant speed head centrifugal pumps, fans wood working machines, reciprocating pumps, laundry washing machines, milling machines, grinders, small printing presses, paper making machines, metal cutting machines etc.

Cumulative compound motor: It has high starting torque and has varying speed within limits i.e. it has self-adjustable speed with changing load. Hence, it is used for driving compressors, pressure blowers, door lifts, circular saws, passenger elevators, freight elevators etc.

Differentially compound motor: It has low starting torque and has constant speed, but dangerously high speed at no load under the circumstances it is seldom used.

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