SYNCHRONOUS MOTORS QUIZ

In order to to reverse the direction of a synchronous motor, _______

None of the listed here

Reduce dc field excitation to zero

Interchange any two stator lines

Change supply frequency

TRUE ANSWER : ?
YOUR ANSWER : ?

A synchronous motor is cheaper than 3-phase induction motor for _____

High speed, high output

None of the listed here

High speed, low output

Low speed, high output

TRUE ANSWER : ?
YOUR ANSWER : ?

A synchronous motor runs at speed ranging from ______

None of the listed here

3600 to 6000 rpm

1800 to 3600 rpm

150 to 1800 rpm

TRUE ANSWER : ?
YOUR ANSWER : ?

In case one phase of a three-phase synchronous motor is short-circuited the motor will

run with excessive vibrations

run at 2/3 of synchronous speed

take less than the rated load

not start

TRUE ANSWER : ?
YOUR ANSWER : ?

Synchronous motor always run at

None of the listed here

Less than synchronous speed

More than synchronous speed

The synchronous speed

TRUE ANSWER : ?
YOUR ANSWER : ?

The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as

None of these

pull-up torque

pull-out torque

pull-in torque

TRUE ANSWER : ?
YOUR ANSWER : ?

When the field of a synchronous motor is under-excited, the power factor will be

lagging

unity

leading

zero

TRUE ANSWER : ?
YOUR ANSWER : ?

Which of the following motors is non self starting?

Wound rotor induction motor

Dc series motor

Squirrel cage induction motor

Synchronous motor

TRUE ANSWER : ?
YOUR ANSWER : ?

A synchronous motor can operate at

Unity power factor only

Leading power factor

Lagging power factor only

Lagging, leading and unity power factors

TRUE ANSWER : ?
YOUR ANSWER : ?

When a synchronous motor is pulled out of synchronism, the stator current ________

Is decreased too much

Remains unchanged

Become zero

Is increased too much

TRUE ANSWER : ?
YOUR ANSWER : ?

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