Home⇒ Engineering⇒
Polyphase induction motors
| 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 ⇒ A 3-phase 440 V, 50 Hz induction
motor has 4% slip. The frequency of
rotor e.m.f. will be 2 Hz [other wrong options] [Discuss in forum] |
| Q2 ⇒ The shaft, on which the rotor of an
induction motor is mounted is made of mild steel [other wrong options] [Discuss in forum] |
| Q3 ⇒ The direction of rotation of a 3-phase
induction motor can be reversed by interchanging any two phases [other wrong options] [Discuss in forum] |
| Q4 ⇒ The starting torque of the slip ring induction
motor can be increased by adding resistance to the rotor [other wrong options] [Discuss in forum] |
| Q5 ⇒ A 3-phase induction motor is running
at a load of the rated torque. What
happens when one of the outer mains
is interrupted while the motor is running
? The motor keeps on running but draws more current [other wrong options] [Discuss in forum] |
| Q6 ⇒ The induction motors which are provided
with open slots have more break down torque [other wrong options] [Discuss in forum] |
| Q7 ⇒ If single phasing occurs when ihe motor
is running, it should not be loaded
beyond 50 per cent of rated load [other wrong options] [Discuss in forum] |
| Q8 ⇒ The speed of a three-phase cage-rotor
induction motor depends on number of poles and frequency of the supply [other wrong options] [Discuss in forum] |
| Q9 ⇒ The most important factor in motor
maintenance is to keep it clean and free from foreign materials [other wrong options] [Discuss in forum] |
| Q10 ⇒ Which of the following component is
usually fabricated out of silicon steel ? Stator core [other wrong options] [Discuss in forum] |
| Q11 ⇒ An induction motor with 1000 r.p.m.
speed will have 6 poles [other wrong options] [Discuss in forum] |
| Q12 ⇒ It is advisable to avoid line-starting of
induction motor and use starter because motor takes five to seven times its full load current [other wrong options] [Discuss in forum] |
| Q13 ⇒ In a three-phase induction motor, the
number of poles in the rotor winding is
always equal to number of poles in stator [other wrong options] [Discuss in forum] |
| Q14 ⇒ A 3-phase induction motor stator delta
connected, is carrying full load and one
of its fuses blows out. Then the motor will continue running burning its one phase [other wrong options] [Discuss in forum] |
| Q15 ⇒ Which type of bearing is provided in
small induction motors to support the
rotor shaft ? Ball bearings [other wrong options] [Discuss in forum] |
| Q16 ⇒ In three-phase induction motors sometimes
copper bars are placed deep in the
rotor to improve starting torque [other wrong options] [Discuss in forum] |
| Q17 ⇒ In the squirrel-cage induction motor the
rotor slots are usually given slight skew to reduce the magnetic hum and locking tendency of the rotor [other wrong options] [Discuss in forum] |
| Q18 ⇒ In an induction motor if air-gap is increased the power factor will be low [other wrong options] [Discuss in forum] |
| Q19 ⇒ The purpose of using short-circuit gear
is to short circuit the rotor at slip rings [other wrong options] [Discuss in forum] |
| Q20 ⇒ The starting torque of a three phase
induction motor can be increased by both (a) and (b) [other wrong options] [Discuss in forum] |
| Or |