Unit-5 Part-3

1. How many electrical degrees separates from the other two phases phase voltage on the balance three-phase supply?

• 60˚

• 90˚

• 120˚

• 180˚

1. what degree does the arrow of the magnetic field points straight downward from N to S in the figure

• 120

• 360

• 300

• 180

what is the position of phase “C” current at 60˚ degrees

• Half negative

• Half positive falling

• Full negative

• Half positive rising

which phrases will be meeting at 120 degrees?

• Phase C and D

• Phase C and A

• Phase A and B

• Phase B and D

what is the position of phase “A” current at 240 degrees?

• Half positive decline

• Maximum positive

• Half negative on rise

• Half negative decline

which direction is the rotor turning?

• Clockwise

• Counter clockwise

• Forward

• Downward

As shown in the picture the motor runs counter clockwise. What will happen if you connected L1 to T3 and L2 to T2 and L3 to T1

• Motor will run in the same direction

• Motor will run in opposite direction

• Motor windings will be shorted

• Motor will be overloaded

As shown in the picture what will happen if you connect L3 to T3 and L2 to T2 and L1 to T1

• motor will overheat

• motor will run clockwise

• motor will run counter clockwise

• motor winding will be shorted

As shown in the picture what will happen if you connect L3 to T3 and L2 to T2 and L1 to T1

• motor will overheat

• motor will run clockwise

• motor will run counter clockwise

• motor winding will be shorted

What is synchronous speed?

• the speed of the rotating magnetic field

• the number of pole pairs on the rotor

• the difference between the rotating magnetic field and rotor

• the speed measured using the ammeter