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Showing posts with the label Advantage of field control method

What are the factors that control the speed of a DC motor ?

Factors that control the speed of a DC motor : The speed of a motor is given by the equation S=(V-IaRa)/kɸ It is obvious that the speed can be controlled by varying ·          Flux/pole(ɸ) (Flux control) ·          Resistance Ra of armature circuit(Rheoststic control) ·          Applied voltage V(Voltage control) Advantage of field control method: The advantage of field control method is to increase the speed above the base speed. Disadvantage of field control method: The disadvantage of field control method is excessive sparking at the brushes caused by the distortion of the magnetic field resulting from the weakened shunt field.