Electric Drives (3160919) MCQs

MCQs of Scalar control or constant V/f control of induction motor

Showing 1 to 10 out of 52 Questions
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1.

______________ motor is a constant speed motor.

(a)

Synchronous motor
(b)

Schrage motor
(c)

Induction motor
(d)

Universal motor
Answer:

Option (a)

2.

Which feature, while selecting a motor for centrifugal pump, will be of least significance?

(a)

Starting characteristics
(b)

Operating speed
(c)

Horse power
(d)

Speed control
Answer:

Option (d)

3.

Stator voltage control for the speed control of induction motor is suitable for

(a)

Fan and Pump Drive
(b)

Drive of a crane
(c)

Running as the generator
(d)

Constant Load drive
Answer:

Option (a)

4.

In motor, the static frequency changers are used for

(a)

Power factor management
(b)

Improved cooling
(c)

Reversal of direction
(d)

Speed Regulation
Answer:

Option (d)

5.

V/f is maintained constant in the following case of speed control of induction motor

(a)

Below base speed with voltage control
(b)

Below the base speed with frequency control
(c)

Above base speed with frequency control
(d)

None of these
Answer:

Option (b)

6.

Which of the following pair is used for frequency converter?

(a)

Squirrel cage induction motor and Wound rotor induction motor
(b)

Wound rotor induction motor and synchronous motor
(c)

Squirrel cage induction motor and synchronous motor
(d)

Any of these
Answer:

Option (a)

7.

In the case of a 3 phase induction motor, plugging is done by

(a)

Starting the motor on load which is more than the rated load
(b)

Pulling the motor directly on line without a starter
(c)

Interchanging connections of any two phases of the stator for quick stopping
(d)

Locking of the rotor due to harmonics
Answer:

Option (c)

8.

In a 3-phase voltage source inverter used for speed control of induction motor, antiparallel diodes are used across each switching device. The main purpose of diodes is to

(a)

Protect the switching devices against overvoltage
(b)

Provide the path for freewheeling current
(c)

Allow the motor to return energy during regeneration
(d)

Help in switching off the devices
Answer:

Option (c)

9.

In which of the following reason induction motor operation is stable?

(a)

Low Slip region
(b)

High slip region
(c)

Any of the two
(d)

None of the above
Answer:

Option (a)

10.

Rotor resistance speed control method is not applicable in

(a)

Slip Ring induction motor
(b)

Squirrel cage induction motor
(c)

Synchronous motor
(d)

None of the above
Answer:

Option (b)

Showing 1 to 10 out of 52 Questions
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