DOL starting of induction motors is usually restricted to_____________?

Related Mcqs:

1. In squirrel cage induction motors, the rotor slots are usually given slight skew in order to__________?

   A. reduce windage losses B. reduce eddy currents C. reduce accumulation of dirt and dust D. reduce magnetic hum...

2. Star-delta starting of motors is not possible in case of____________?

   A. single phase motors B. variable speed motors C. low horse power motors D. high speed motors...

3. In medium sized induction motors, the slip is generally around___________?

   A. 0.04% B. 0.4% C. 4% D. 14%...

4. In case of the induction motors the torque is___________?

   A. inversely proportional to (Vslip) B. directly proportional to (slip)2 C. inversely proportional to slip D. directly proportional to slip...

5. Which type of bearing is provided in small induction motors to support the rotor shaft ?

   A. Ball bearings B. Cast iron bearings C. Bush bearings D. None of the above...

6. 5 H.P., 50-Hz, 3-phase, 440 V, induction motors are available for the following r.p.m. Which motor will be the costliest ?

   A. 730 r.p.m. B. 960 r.p.m. C. 1440 r.p.m. D. 2880 r.p.m....

7. In three-phase induction motors sometimes copper bars are placed deep in the rotor to___________?

   A. improve starting torque B. reduce copper losses C. improve efficiency D. improve power factor...

8. In case of 3-phase induction motors, plugging means__________?

   A. pulling the motor directly on line without a starter B. locking of rotor due to harmonics C. starting the motor on load which is more than the rated load D. interchanging two supply phases for quick stopping...

9. Blocked rotor test on induction motors is used to find out?

   A. leakage reactance B. power factor on short circuit C. short-circuit current under rated voltage D. all of the above...

10. The starting torque of a 3-phase squirrel cage induction motor is____________?

    A. twice the full load torque B. 1.5 times the full load torque C. equal to full load torque...