Electrical Engineering · Question Bank

3P Induction Motors

115 of 135 questions match · page 6 of 6. Answer in your head first, then check the solution.

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TypeAll 115Problem solving 27Objective 88
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#101📘 EE Pocket Reviewer RojasEasy
In an induction motor, in terms of the slip s, the rotor reactance per phase is proportional to
As
B\(s^2\)
C\(1/s^2\)
D1/s
#102📘 EE Pocket Reviewer RojasEasy
Which of the following is true in a three-phase squirrel-cage induction motor?
AThe rotor conductors are left open
BThe rotor conductors are short circuited through the slip rings
CThe rotor conductors are short circuited through a commutator and sets of brushes
DThe rotor conductors are short circuited through the end rings
#103📘 EE Pocket Reviewer RojasEasy
The “crawling” in an induction motor is caused by which one?
AHigh loads
BLow supply voltage
CIncorrect phase sequence of the supply emf
DHarmonics developed in the motor
#104📘 EE Pocket Reviewer RojasEasy
Reduced voltage starter can be used with which type of induction motors?
ASlip ring type only
BSquirrel-cage type only
CBoth slip ring and squirrel-cage types
DNeither of these
#105📘 EE Pocket Reviewer RojasEasy
The shaft of an induction motor is made from which of the following materials?
ACarbon steel
BCast iron
CStainless steel
DHigh speed steel
#106📘 EE Pocket Reviewer RojasEasy
The frame of an induction motor is usually made from which materials?
ASilicon steel
BCast iron
CAluminum alloys
DPhosphor bronze
#107📘 EE Pocket Reviewer RojasEasy
In a squirrel cage induction motor, why are the rotor bars usually given a slight skew?
ATo reduce the rotor currents
BTo reduce windage losses
CTo reduce the magnetic hum
DTo reduce the eddy currents
#108📘 EE Pocket Reviewer RojasEasy
The starting torque of the slip ring induction motor can be increased by which of the following methods?
ABy adding resistance in the rotor circuit
BBy adding resistance in the stator circuit
CBy adding resistances in the stator and rotor circuits simultaneously
DNone of these
#109📘 EE Pocket Reviewer RojasEasy
“DOL” starting of an induction motor is usually restricted to which of the following?
AHigh speed motors
BVariable speed motors
CHigh horsepower motors
DLow horsepower motors
#110📘 EE Pocket Reviewer RojasEasy
The speed of a squirrel cage induction motor can be controlled by all of the following EXCEPT
AChanging winding resistance
BChanging number of poles
CChanging supply frequency
DReducing supply voltage
#111📘 EE Pocket Reviewer RojasEasy
In a three-phase induction motor, what does the term “plugging” means?
APutting the motor directly on line without a starter
BLocking of rotor due to harmonics
CStarting the motor on load which is more than its capacity
DInterchanging two supply phases for quick stopping
#112📘 EE Pocket Reviewer RojasEasy
In squirrel-cage induction motors which of the following methods of starting cannot be used?
AResistance in rotor circuit
BResistance in stator circuit
CAutotransformer starting
DStar-delta starting
#113📘 EE Pocket Reviewer RojasEasy
Which of the following method of starting a three-phase induction motor needs six terminals?
AStar-delta starting
BAutotransformer starting
CPart-winding starting
DResistance starting
#114📘 EE Pocket Reviewer RojasEasy
Which of the following happens when a star-delta starter is used?
AStarting voltage will reduce
BStarting current will reduce
CStarting torque will rise
DBoth A and B
#115📘 EE Pocket Reviewer RojasEasy
Which one refers to repeated starting and stopping of a motor?
AStepping
BJogging
CPhasing
DPlugging

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