1 Answer

Answer :

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

Related questions

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

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Last Answer : Series motor has the poorest speed control.

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

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Last Answer : Speed control of three phase induction motor

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

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

Last Answer : Most sensitive galvanometer is spot ballistic galvanometer.

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Last Answer : In case of D.C. shunt motors the speed is dependent on back e.m.f. only because flux is practically constant in D:C. shunt motors.

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Last Answer : The armature voltage control of D.C. motor provides constant torque drive.

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Last Answer : Armature control of DC motor

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Last Answer : Field control of DC motor

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Description : The fall in speed of a dc generator due to increase in load can be corrected by  (1) cooling the armature.. (2) increasing the excitation. (3) reducing the load voltage. (4) increasing the input to the prime mover

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Last Answer : The speed of a D.C. shunt motor can be increased by increasing the resistance in field circuit.

Last Answer : As the load is increased the speed of D.C. shunt motor will reduce slightly.

Last Answer : For the same H.P. rating and full load speed, following motor has poor starting torque differentially compounded.

Last Answer : The speed of a D.C. series motor is inversely proportional to the armature current.

Last Answer : In a D.C. shunt motor, speed is independent of armature current.

Last Answer : When two D.C. series motors are connected in parallel, the resultant speed is normal speed.

Last Answer : Centrifugal switch disconnects the auxiliary winding of the motor at about 70 to 80 percent of synchronous speed.

Last Answer : The speed/load characteristics of a universal motor is same as that of D.C. series motor.

Last Answer : Speed torque characteristic of a repulsion induction motor is similar to that of a D.C. compound motor.

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