1 which of the following load normally need starting torque more than the rated torque a conveyo

Step 1: Calculate the ratio of stalling torque to full load torque when a resistance of 0.2 ohm

Question

1-Which of the following loads normally need starting torque more than the rated torque? (a) Conveyors (b) Blowers (c) Centrifugal pump (d) Air compressor 2-The efficiency of the DC motor at maximum power is (a) 90% (b) 100% (c) Around 80% (d) Less than 50% 3-In which of the following applications is a DC series motor used? (a) Centrifugal Pump (b) Motor Operation in DC and AC (c) Water pump drive (d) Starter for car 4-Which DC motor has the least percentage increase in input current for the same percentage increase in torque? (a) Separately excited motor (b) Series motor (c) Shunt motor (d) Compound motor 5-Counter EMF of the DC motor is (a) Less than the applied voltage (b) More than the applied voltage (c) Equal to the applied voltage (d) None of the above 6-Which DC motor is used for the conveyor? (a) Series motor (b) Cumulative compound motor (c) Differentially compound motor (d) Shunt motor 7-Which DC motor is preferred for machine tools? (a) Series motor (b) Cumulative compound motor (c) Differentially compound motor (d) Shunt motor 8-When the speed of DC motor is increased (a) Back EMF increases and current drawn decreases (b) Back EMF decreases and current drawn increases (c) Back EMF and current drawn both increase (d) Back EMF and current drawn both decrease 9-A 240V DC shunt motor with an armature resistance of 0.1 ohm has a full load current of 40A. Find out the ratio of the stalling torque to the full load torque when a resistance of 0.2 ohm is connected in series with the armature (a) 12 (b) 20 (c) 10 10-A DC Motor is driving a constant load torque having an armature resistance of 0.15 ohm and an armature current of 0.25 A, connected to a voltage of 230 V. Now a resistance of 0.1 ohm is added into the armature circuit. The ratio of their speed will be (a) 0.25 (b) 1.24 (c) 0.62 (d) 0.72 11-220 V, 15 kW, 1000 RPM shunt Motor with an armature resistance of 0.250 ohm has a rated line current of 68 A and a rated field current of 2.2 A. The change in field flux required to obtain a speed of 1600 RPM while drawing a line current of 52.8 A and a field current of 1.8 A (a) 18.18% Increase (b) 36.36% Increase (c) 18.18% Decrease (d) 36.36% Decrease

          1-Which of the following loads normally need starting torque more than the rated torque? (a) Conveyors (b) Blowers (c) Centrifugal pump (d) Air compressor 
    2-The efficiency of the DC motor at maximum power is (a) 90% (b) 100% (c) Around 80% (d) Less than 50% 
    3-In which of the following applications is a DC series motor used? (a) Centrifugal Pump (b) Motor Operation in DC and AC (c) Water pump drive (d) Starter for car 
    4-Which DC motor has the least percentage increase in input current for the same percentage increase in torque? (a) Separately excited motor (b) Series motor (c) Shunt motor (d) Compound motor 
    5-Counter EMF of the DC motor is (a) Less than the applied voltage (b) More than the applied voltage (c) Equal to the applied voltage (d) None of the above 
    6-Which DC motor is used for the conveyor? (a) Series motor (b) Cumulative compound motor (c) Differentially compound motor (d) Shunt motor 
    7-Which DC motor is preferred for machine tools? (a) Series motor (b) Cumulative compound motor (c) Differentially compound motor (d) Shunt motor 
    8-When the speed of DC motor is increased (a) Back EMF increases and current drawn decreases (b) Back EMF decreases and current drawn increases (c) Back EMF and current drawn both increase (d) Back EMF and current drawn both decrease 
    9-A 240V DC shunt motor with an armature resistance of 0.1 ohm has a full load current of 40A. Find out the ratio of the stalling torque to the full load torque when a resistance of 0.2 ohm is connected in series with the armature (a) 12 (b) 20 (c) 10 
    10-A DC Motor is driving a constant load torque having an armature resistance of 0.15 ohm and an armature current of 0.25 A, connected to a voltage of 230 V. Now a resistance of 0.1 ohm is added into the armature circuit. The ratio of their speed will be (a) 0.25 (b) 1.24 (c) 0.62 (d) 0.72 
    11-220 V, 15 kW, 1000 RPM shunt Motor with an armature resistance of 0.250 ohm has a rated line current of 68 A and a rated field current of 2.2 A. The change in field flux required to obtain a speed of 1600 RPM while drawing a line current of 52.8 A and a field current of 1.8 A (a) 18.18% Increase (b) 36.36% Increase (c) 18.18% Decrease (d) 36.36% Decrease

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