Synchronous Motors MCQ Questions & Answers | Electrical Engineering

A. supplied with unbalanced voltage

B. under-loaded

C. over-loaded

D. none of the above

A. The increased load has to take more current

B. The rotor by shifting its phase backward causes motor to take more current

C. The back e.m.f. decreases causing an increase in motor current

D. The rotor strengthens the rotating field causing more motor current

A. stator supply is relieved of responsibility of producing magnetic field

B. mechanical load on the motor can be adjusted

C. synchronous motor runs at synchronous speed

D. synchronous motor has large air gap

A. its power factor may be varied at will

B. its speed is independent of supply frequency

C. its speed may be controlled more easily

D. none of the above

A. Not start

B. Run at $$\frac{2}{3}$$ of synchronous speed

C. Run with excessive vibrations

D. Take less than the rated load

A. Fluctuating loads

B. Variable speed loads

C. Low torque loads

D. Power factor corrections

A. When supply voltage fluctuates

B. When load varies

C. When power factor is unity

D. Motor is under loaded

A. d.c. source

B. armature input

C. motor input

D. supply lines

A. no-load and greatly over-excited fields

B. no-load and under-excited fields

C. normal load with minimum excitation

D. normal load with zero excitation

A. flux density

B. horse power rating

C. speed

D. all of the above