Induction Motor MCQ – 1 November 2, 2018December 30, 2018Ajay Sharma 1. In a squirrel cage induction motor, torque with autostarter is ....... times the torque with direct-switching. Where K is the transformation ratio of the autotransformer. K^2 K 1/K^2 1/K Continue >>2. If stator voltage of a squirrel cage induction motor is reduced to 50 per cent of its rated value, torque developed is reduced by ....... per cent of its full-load value. 50 25 75 57.7 Continue >>3. For the purpose of starting an induction motor, a Y-Δ switch is equivalent to an auto-starter of ratio.......per cent. 33.3 57.7 73.2 60 Continue >>4. A double squirrel-cage motor (DSCM) scores over SCIM in the matter of starting torque high efficiency under running conditions speed regulation under normal operating conditions all of the above. Continue >>5. In a DSCM, outer cage is made of high resistance metal bars primarily for the purpose of increasing its starting torque efficiency starting current speed regulation Continue >>6. Which of the following motor is an interesting example of beneficially utilizing a phenomenon that is often considered undesirable ? hysteresis motor reluctance motor shaded-pole motor universal motor Continue >>7. A 6-pole 3-φ induction motor taking 25 kW from a 50-Hz supply is cumulatively-cascaded to a 4-pole motor. Neglecting all losses, speed of the 4-pole motor would be ....... r.p.m. 1500 1000 600 3000 Continue >>8. In the shaded pole squirrel cage induction motor the flux in the shaded part always leads the flux in the unshaded pole segment is in phase with the flux in the unshaded pole segment lags the flux in the unshaded pole segment Continue >>9. When a stationary 3-phase induction motor is switched on with one phase disconnected it is likely to burn out quickly unless immediately disconnected it will start but very slowly it will make jerky start with loud growing noise remaining intact fuses will be blown out due to heavy inrush of current Continue >>10. If single-phasing of a 3-phase induction motor occurs under running conditions, it will stall immediately will keep running though with slightly increased slip may either stall or keep running depending on the load carried by it will become noisy while it still keeps running. Continue >>11. One of the characteristics of a single- phase motor is that it is self-starting is not self-starting requires only one winding can rotate in one direction only. Continue >>12. After the starting winding of a single- phase induction motor is disconnected from supply, it continues to run only on ............winding. rotor field running compensating Continue >>13. The direction of rotation of a single-phase motor can be reversed by reversing connections of both windings reversing connections of starting winding using a reversing switch reversing supply connections. Continue >>14. If a single-phase induction motor runs slower than normal, the more likely defect is improper fuses shorted running winding open starting winding worn bearings. Continue >>15. The capacitor in a capacitor-start induction- run ac motor is connected in series with ...... winding. starting running squirrel-cage compensating Continue >>16. The starting torque of a capacitor-start induction-run motor is directly related to the angle α between its two winding currents by the relation cos α sin α tan α sin α/2. Continue >>17. In a two-value capacitor motor, the capacitor used for running purposes is a/an dry-type ac electrolytic capacitor paper-spaced oil-filled type air-capacitor ceramic type. Continue >>18. If the centrifugal switch of a two-value capacitor motor using two capacitors fails to open, then electrolytic capacitor will, in all probability, suffer breakdown motor will not carry the load motor will draw excessively high current motor will not come upto the rated speed Continue >>19. Each of the following statements regarding a shaded-pole motor is true except its direction of rotation is from un- shaded to shaded portion of the poles it has very poor efficiency it has very poor p.f. it has high starting torque. Continue >>20. Compensating winding is employed in an ac series motor in order to compensate for decrease in field flux increase the total torque reduce the sparking at brushes reduce effects of armature reaction Continue >>21. A universal motor is one which is available universally can be marketed internationally can be operated either on dc or ac supply runs at dangerously high speed on no-load. Continue >>22. In a single-phase series motor the main purpose of inductively-wound compensating winding is to reduce the reactance emf of commutation rotational emf of commutation transformer emf of commutation none of the above. Continue >>23. A repulsion motor is equipped with a commutator slip-rings a repeller neither (a) nor (b). Continue >>24. A repulsion-start induction-run single- phase motor runs as an induction motor only when brushes are shifted to neutral plane short-circuiter is disconnected commutator segments are short- circuited stator winding is reversed. Continue >>25. If a dc series motor is operated on ac supply, it will have poor efficiency have poor power factor spark excessively all of the above Continue >>26. An outstanding feature of a universal motor is its best performance at 50 Hz supply slow speed at all loads excellent performance on dc. supply highest output kW/kg ratio. Continue >>27. The direction of rotation of a hysteresis motor is determined by the retentivity of the rotor material amount of hysteresis loss permeability of rotor material position of shaded pole with respect to the main pole. Continue >>28. Speed of the universal motor is dependent on frequency of supply proportional to frequency of supply independent of frequency of supply none of the above. Continue >> Induction Motor MCQ – 1Result PLAY AGAIN !Please share it, your one share can change my life.