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Ac machine
| 1-Dont try to cram or spend more time here just read it fast and cover syllabus then practice MCQ's cheptor of same topic to check your progress. . |
| 2-Wrong options are also given but dont concentrate there, Right answer is in bold format. |
| Q1 ⇒ In a 3-phase induction motor, the stator slots are not exact multiple of rotor slots. [other wrong options] [Discuss in forum] |
| Q2 ⇒ In an induction motor, what is the ratio of rotor copper loss and
rotor input? s [other wrong options] [Discuss in forum] |
| Q3 ⇒ A 3-phase slip-ring induction motor is fed from the rotor side with
stator winding short circuited. The frequency of the currents in the
short-circuited stator is slip frequency [other wrong options] [Discuss in forum] |
| Q4 ⇒ Reactor is introduced in the ignition circuit of a mercury arc rectifier
to limit circuit current. [other wrong options] [Discuss in forum] |
| Q5 ⇒ In 3-phase induction motors, sometitl]es copper bars are placed
deep in the rotor. It is done in order to improve starting torque. [other wrong options] [Discuss in forum] |
| Q6 ⇒ The no-load current in an induction motor is in comparison
to that of a power transformer. much higher [other wrong options] [Discuss in forum] |
| Q7 ⇒ A dual voltage single phase ac motor can he operated on either 115 or 230 V. [other wrong options] [Discuss in forum] |
| Q8 ⇒ In a phase-shift control, the phase shift between anode and grid
voltages can be achieved by means of an induction regulator [other wrong options] [Discuss in forum] |
| Q9 ⇒ During starting of a double cage induction motor, the current
induced in the rotor flows mostly through the upper cage. [other wrong options] [Discuss in forum] |
| Q10 ⇒ An induction motor always operates on lagging power factor.
This is due to all of the above. [other wrong options] [Discuss in forum] |
| Q11 ⇒ An 8-pole single phase induction motor is running at 690 rpm.
What is its slip with respect to forward and backward fields,
respectively'! 0.08, 1.92 [other wrong options] [Discuss in forum] |
| Q12 ⇒ In a transformer, electrical power is transferred from primary to
secondary by magnetic flux. [other wrong options] [Discuss in forum] |
| Q13 ⇒ For high starting torque. the most suitable 3-phase induction motor
is ____ induction motor. slip-ring [other wrong options] [Discuss in forum] |
| Q14 ⇒ Circle diagram is employed to determine the performance of a/an induction motor. [other wrong options] [Discuss in forum] |
| Q15 ⇒ The power factor at which single phase induction motors usually
operate is 0.7 lag. [other wrong options] [Discuss in forum] |
| Q16 ⇒ The core flux in transformer depends mainly on supply voltage and frequency. [other wrong options] [Discuss in forum] |
| Q17 ⇒ If a 3-phase induction motor is started when one of the phases is
not available, then the motor all of the above except (d). [other wrong options] [Discuss in forum] |
| Q18 ⇒ A 3-phase induction motor when started picks up speed but runs
stably at about half the normal speed. This is because of non-sinusoidal nature of the supply voltage. [other wrong options] [Discuss in forum] |
| Q19 ⇒ Capacitor in a single-phase induction motor is uscd for starting the motor. [other wrong options] [Discuss in forum] |
| Q20 ⇒ A 50 Hz transformer having equalhysteresis and eddy current
losses at rated excitation is operated at 45 Hz at 90% of its rated
voltage. Compared to rated operating point, the core losses under
this condition. reduce by 14.5%. [other wrong options] [Discuss in forum] |
| Or |