MCQ

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ELECTRICAL MACHINES

Q1. ________has the least value of starting torque to full load torque ratio.

Q2. The interpoles of a DC machine are normally connected,

Q3. In case the field of a synchronous motor is under excited, the power factor will be

Q4. A four-speed squirrel cage induction motor uses ………… stator windings.

Q5. A 200 V DC machine supplies 20 A at 200 V as a generator. The armature resistance is 0.2 Ω. If the machine is now operated as a motor at same terminal voltage and current but with the flux increased by 10%, the ratio of motor speed to generator speed is

Q6. Dummy coils are provided in d.c. generators

Q7. A shunt generator delivers 195 A at a terminal voltage of 250 V. The armature resistance and shunt field resistance are 0.02 Ω and 50 Ω respectively. The iron and friction losses equal 950 W. What is the total copper loss?

Q8. An induction motor and synchronous motor are connected to a common feeder line. To operate the feeder line at unity pf, the synchronous motor should be

Q9. The no load current in a transformer lags the applied voltage by ?

Q10. Magnetic field in a D.C. generator is produced by