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3-Phase Motor Starters: MCQs & Answers

The document discusses types of starters used for three phase induction motors, including stator resistance starters, autotransformer starters, star-delta starters, rotor resistance starters, and direct online starters. It provides 11 multiple choice questions with answers about the characteristics and applications of these different starter types. For example, it notes that star-delta starters are the cheapest option and have advantages of being both cheap and maintenance free.

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192 views3 pages

3-Phase Motor Starters: MCQs & Answers

The document discusses types of starters used for three phase induction motors, including stator resistance starters, autotransformer starters, star-delta starters, rotor resistance starters, and direct online starters. It provides 11 multiple choice questions with answers about the characteristics and applications of these different starter types. For example, it notes that star-delta starters are the cheapest option and have advantages of being both cheap and maintenance free.

Uploaded by

पंकज काळे
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Types of Starters in Three Phase Induction Motor

Q1. While using stator resistance starter with 3 phase induction motor, the resistances of the starter are
kept at

a. Maximum
b. Minimum
c. Half of the maximum value
d. None of these

View Answer / Hide Answer


ANSWER: a. Maximum

Q2. When stator resistances are starter is used, the factor by which stator voltage reduces is say x. If
x<1, then due to stator resistance starter, the starting torque

a. Increases by fraction x
b. Reduces by fraction x ∧ 2
c. Reduces by fraction x
d. Increases by fraction x ∧ 2

View Answer / Hide Answer


ANSWER: b. Reduces by fraction x ∧ 2

Q3. An autotransformer starter is suitable for

a. Star connected induction motor


b. Delta connected induction motor
c. Both (a) & (b)
d. None of these

View Answer / Hide Answer


ANSWER: c. Both (a) & (b)

Q4. The cheapest starter for induction motor is

a. Stator resistance starter


b. Autotransformer starter
c. Star-delta starter
d. Rotor resistance starter

View Answer / Hide Answer


ANSWER: c. Star-delta starter

Q5. Windings of star-delta starter while starting and during running are connected in

a. Star, delta
b. Delta, delta
c. Star, star
d. Delta, star

View Answer / Hide Answer


ANSWER: a. Star, delta
Q6. The advantages of star-delta starter over other types of starter is

a. Cheapest of all
b. Maintenance free
c. Both (a) & (b)
d. None of these

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ANSWER: c. Both (a) & (b)

Q7. When rotor resistance starter is used with induction motor then

a. Only starting current is limited


b. Only starting torque is limited
c. Both starting current and starting torque are limited
d. Neither starting current nor starting torque is limited

View Answer / Hide Answer


ANSWER: c. Both starting current and starting torque are limited

Q8. Direct online starter also called D.O.L. starter is used for motors having capacity

a. Less than 5 h.p.


b. Less than 10 h.p.
c. Greater than 10 h.p.
d. For any capacity motor

View Answer / Hide Answer


ANSWER: a. Less than 5 h.p.

Q9. The NO contact and NC contact of D.O.L. starter is normally

a. Open, closed
b. Closed, open
c. Open, open
d. Closed, closed

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ANSWER: a. Open, closed

Q10. A 3 phase induction motor in a short circuit current is equal 3 times of the full load current. If the
full load slip is 2%, then the starting torque as a percentage of full load torque is

a. 6% of full load torque


b. 18% of full load torque
c. 36% of full load torque
d. None of these

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ANSWER: b. 18% of full load torque

Q11. In textile machines, to avoid breaking of threads, soft starters are used. The commonly used
method in soft starter is

a. Direct online method


b. Star-delta method
c. Thyristor voltage controller method
d. Thyristor current controller method

View Answer / Hide Answer


ANSWER: c. Thyristor voltage controller method

Discussion
RE: Types of Starters in Three Phase Induction Motor - MCQs with Answers -Jayendra
(12/28/15)

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