Design of AC Machines (2170909) MCQs

MCQs of Design of Three Phase Induction Motor

Showing 81 to 90 out of 97 Questions
6 7 8 9 10
81.

The dispersion coefficient of an induction motor is the ratio of 

(a)

ideal short circuit current to magnetizing current
(b)

Starot voltage per phase to leakage reactance
(c)

magnetizing current to ideal short circuit current
(d)

None of these
Answer:

Option (c)

82.

With an increase in the number of poles - dispersion coefficient and power factor of three-phase induction motor will __________ & ___________ respectively. 

(a)

increases,     increase
(b)

decreases,     decrease
(c)

decrease,       increases
(d)

increases,     decrease
Answer:

Option (d)

83.

With the increase in the number of poles - pole pitch and slot per pole per phase of three-phase induction motor will __________.

(a)

increase
(b)

decrease
(c)

remains the same
(d)

cant predict from this data only
Answer:

Option (b)

84.

How we can decrease the value of the dispersion coefficient in a three-phase induction motor?

(a)

By increasing the length of air gap
(b)

By decreasing the length of the air gap
(c)

By increasing the numbers of pole
(d)

By decreasing the pole pitch
Answer:

Option (b)

85.

Why we cant reduced the length of the air gap beyond a certain value in three-phase induction motor design?

(a)

the zigzag reactance will be increased
(b)

to avoid Collision between stator and rotor
(c)

to reduced magnetic locking
(d)

the zigzag reactance will be increased & to avoid Collision between stator and rotor
Answer:

Option (d)

86.

What will be the value of the Maximum power factor if the value of the dispersion coefficient is 0.25?

(a)

0.6
(b)

0.7
(c)

0.8
(d)

1
Answer:

Option (a)

87.

What will be the value of the Over Load Capacity if the value of the dispersion coefficient is 0.25?

(a)

1
(b)

1.1
(c)

1.2
(d)

1.25
Answer:

Option (d)

88.

With an increase in the length of the air gap in a three-phase induction motor, which of the following remains constant?

(a)

ideal short circuit current
(b)

maximum power output
(c)

maximum torque
(d)

All of these
Answer:

Option (d)

89.

Change in frequency without altering the number of poles keeps dispersion co-efficient ____________. 

(a)

pulsating
(b)

impulsive
(c)

unchanged
(d)

all of these
Answer:

Option (c)

90.

If the frequency is reduced and the same number of poles are used, then the full load input of the three-phase induction motor is __________. 

(a)

increase
(b)

reduced
(c)

remain unchanged
(d)

cant say anything
Answer:

Option (b)

Showing 81 to 90 out of 97 Questions
6 7 8 9 10