A. 2 to 3 per cent
B. 10 to 15 per cent
C. 20 to 25 per cent
D. 50 to 75 per cent
Related Mcqs:
- In D.C. machines fractional pitch winding is used__________?
A. to improve cooling
B. to reduce copper losses
C. to increase the generated e.m.f.
D. to reduce the sparking - The purpose of retardation test on D.C. shunt machines is to find out____________?
A. stray losses
B. eddy current losses
C. field copper losses
D. windage losses - Hopkinson’s test on D.C. machines is conducted at_______________?
A. no-load
B. part load
C. full-load
D. overload - According to Fleming’s left-hand rule, when the forefinger points in the direction of the field or flux, the middle finger will point in the direction of_________________?
A. current in the conductor aovtaat of conductor
C. resultant force on conductor
D. none of the above - As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit____________________?
A. a resistance is connected in series with armature
B. a resistance is connected parallel to the armature
C. armature is temporarily open circuited
D. a high value resistor is connected across the field winding - No-load speed of which of the following motor will be highest ?
A. Shunt motor
B. Series motor
C. Cumulative compound motor
D. Differentiate compound motor - The type of D.C. motor used for shears and punches is_____________?
A. shunt motor
B. series motor
C. differential compoutid D.C. motor
D. cumulative compound D.C. motor - 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 - For constant torque drive which speed control method is preferred ?
A. Field control
B. Armature voltage control
C. Shunt armature control
D. Mechanical loading system - In the D.C. motor the iron losses occur in____________?
A. the field
B. the armature
C. the brushes
D. the commutator
