Low voltage at motor terminals is due to____________?

Related Mcqs:

1. Size of a high speed motor as compared to low speed motor for the same H.P. will be__________?

   A. bigger
   B. smaller
   C. same
   D. any of the above

2. The low power factor of induction motor is due to___________?

   A. rotor leakage reactance
   B. stator reactance
   C. the reactive lagging magnetizing current necessary to generate the magnetic flux
   D. all of the above

3. A pump induction motor is switched on to a supply 30% lower than its rated voltage. The pump runs. What will eventually happen ? It will____________?

   A. stall after sometime
   B. stall immediately
   C. continue to run at lower speed without damage
   D. get heated and subsequently get damaged

4. A change of 4% of supply voltage to an induction motor will produce a change of approximately ________?

   A. 4% in the rotor torque
   B. 8% in the rotor torque
   C. 12% in the rotor torque
   D. 16% in the rotor torque

5. Slip ring motor is preferred over squirrel cage induction motor where___________?

   A. high starting torque is required
   B. load torque is heavy
   C. heavy pull out torque is required
   D. all of the above

6. Reduced voltage starter can be used with_____________?

   A. slip ring motor only but not with squirrel cage induction motor
   B. squirrel cage induction motor only but not with slip ring motor
   C. squirrel cage as well as slip ring induction motor
   D. none of the above

7. In case the air gap in an induction motor is increased____________?

   A. the magnetising current of the rotor will decrease
   B. the power factor will decrease
   C. speed of motor will increase
   D. the windage losses will increase

8. It is advisable to avoid line-starting of induction motor and use starter because__________?

   A. motor takes five to seven times its full load current
   B. it will pick-up very high speed and may go out of step
   C. it will run in reverse direction
   D. starting torque is very high

9. The power factor of an induction motor under no-load conditions will be closer to_____________?

   A. 0.2 lagging
   B. 0.2 leading
   C. 0.5 leading
   D. unity

10. The torque of a rotor in an induction motor under running condition is maximum__________?

    A. at the unit value of slip
    B. at the zero value of slip
    C. at the value of the slip which makes rotor reactance per phase equal to the resistance per phase
    D. at the value of the slip which makes the rotor reactance half of the rotor