1 Answer

Usually wide and sensitive speed control is desired in case of colliery winders.

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Description : The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque  (1) Decreases (2) Increases (3) Remains constant (4) None of the above

Answer : The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque Increases 

Answer : Series motor has the poorest speed control.

Answer : Speed control by Ward Leonard method gives uniform speed variation in both directions.

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Answer : Field control of DC motor Armature control of DC motor

Description : speed control methods of three phase induction motor?

Answer : Speed control of three phase induction motor

Answer : In Ward-Leonard control the lower limit of speed is imposed by residual magnetism of the generator.

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Answer : Speed control of the motor using TRIAC:  This basic phase triggering circuit uses the triac in series with the motor across an AC sinusoidal supply. The variable resistor, VR1 is used ... meaning that it may not trigger at the exact same point for each positive and negative half cycle.

Answer : For constant torque drive armature voltage control speed control method is preferred.

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Answer : In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will run as induction motor.

Answer : The speed of a universal motor is usually reduced by using gearing.

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Answer : Field control of DC motor

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