The power mentioned on the name plate of an electric motor indicates____________?
(A) the power drawn in kW
(B) the power drawn in kVA
(C) the gross power
(D) the output power available at the shaft
The current drawn by the armature of D.C. motor is directly proportional to__________?
(A) the torque required
(B) the speed of the motor
(C) the voltage across the terminals
(D) none of the above
In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to
(A) 100% of the previous value
(B) 50% of the previous value
(C) 25% of the previous value
(D) 10% of the previous value
(D) none of the above
The speed of a D.C. series motor is_____________?
(A) proportional to the armature current
(B) proportional to the square of the armature current
(C) proportional to field current
(D) inversely proportional to the armature current
Three point starter can be used for______________?
(A) series motor only
(B) shunt motor only
(C) compound motor only
(D) both shunt and compound motor
Which D.C. motor is generally preferred for cranes and hoists ?
(A) Series motor
(B) Shunt motor
(C) Cumulatively compounded motor
(D) Differentially compounded motor
In D.C. machines the residual magnetism is of the order of_________________?
(A) 2 to 3 per cent
(B) 10 to 15 per cent
(C) 20 to 25 per cent
(D) 50 to 75 per cent
For which of the following applications a D.C. motor is preferred over an A.C. motor ?
(A) Low speed operation
(B) High speed operation
(C) Variable speed operation
(D) Fixed speed operation
The condition for maximum power in case of D.C. motor is______________?
(A) back e.m.f. = 2 x supply voltage
(B) back e.m.f. = | x supply voltage
(C) supply voltage = | x back e.m.f
(D) supply voltage = back
(D) m.f
The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is______________?
(A) 4.0
(B) 2.0
(C) 1.0
(D) 0.5