Question: The armature current of the synchronous motor:

• 1. has large values for low excitation i niy
• 2. has large values for high excitation only
• 3. has large values for low and high excitation
• 4. any of the above

Question: Exciters of synchronous machines are______________?

• 1. d.c. series machines
• 2. d.c. shunt machines
• 3. d.c. compound machines
• 4. any of the above

Question: The duration of sudden snort-circuit test on a synchronous motor is usually about_____________?

• 1. one hour
• 2. one minute
• 3. one second
• 4. none of the above

Question: The maximum value of torque that a synchronous motor can develop without losing its synchronism, is known as_____________?

• 1. slip torque
• 2. pull-out torque
• 3. breaking torque
• 4. synchronising torque

Question: Which of the following motors is non-self starting ?

• 1. DC series motor
• 2. synchronous motor
• 3. Squirrel cage induction motor
• 4. Wound round induction motor

Question: The magnitude of field flux in a 3-phase synchronous motor?

• 1. varies with power factor
• 2. varies with speed
• 3. varies with the load
• 4. remains constant at all loads

Question: The ratio of starting torque to running torque in a synchronous motor is____________?

• 1. zero
• 2. one
• 3. two
• 4. infinity

Question: The induced e.m.f. in a synchronous motor working on leading power factor will be_____________?

• 1. more than the supply voltage
• 2. less than the supply voltage
• 3. equal to the supply voltage
• 4. None of these

Question: Which of the following resistances can be measured by conducting insulation resistance test on a synchronous motor ?

• 1. Phase to phase winding resistance
• 2. Stator winding to earthed frame
• 3. Rotor winding to earthed shaft
• 4. All of the above

Question: The speed of a synchronous motor:

• 1. increases as the load increases
• 2. decreases as the load decreases
• 3. always remains constant
• 4. none of the above