Electrical Machines Practice Test 6

1. If the load angle is increased till 135°, the consequence will be ___________

no alternation of synchronism

increase in stability limit

loss of synchronism

reduction in stability limit

2. The satisfactory operation of the synchronous machine means ___________

none of the mentioned

mechanical speed of rotor is equal to stator field speed

stator field is stationary

mechanical speed is zero

3. Synchronous compensators are ________

under excited synchronous motor with no mechanical load

normally excited synchronous motor with no mechanical load

over excited synchronous motor with no mechanical load

over excited synchronous motor with mechanical load

4. The phasor addition of stator and rotor mmfs in a cylindrical rotor synchronous machine, is possible because __________

mmfs are rotating in same direction at different speeds

mmfs are stationary with respect to each other

mmfs are rotating in opposite direction

one mmf is stationary and the other mmf is rotating

5. The short circuit load losses is/are ______________

stray load losses

direct load loss and stray load losses

direct load loss

field current loss

6. The magnetization current drawn from an AC supply a synchronous motor is used to _________

all of the mentioned

set up magnetizing armature reaction

compensate core losses

set up flux in magnetic circuit of device

7. When an alternator is loaded suddenly the torque produced in damper is?

Induction motor

Synchronous generator

Induction generator

Synchronous motor

8. Auxiliary method of starting is not possib1e due to the fact that ____________

it can not be started under load

all of the mentioned

it can be only started under load

it is less efficient

9. Which one of the following is the base reason to place field on rotor in the alternator?

Large current in the stator

Insulation of high voltage is made easy on stator than on rotor

Small power in field circuit

Huge power in stator

10. Consider the following statements and mark appropriately.

 I. In a cylindrical-rotor synchronous machine, armature flux is in phase with armature current.
 II. In salient pole machine, armature flux lags the armature current.

I and II are true

None of them are true

I is true

II is true