19EE2151 CT U5 REVISION

A polyphase system is generated by______

• Having two or more generator windings separated by equal electrical angle.
• Having generator windings at equal distances
• Having generator windings not equal distances
• None of the options are correct

In a three phase AC circuit, the sum of all three generated voltages is _______

• Infinite (∞)

• Zero (0)

• One (1)

• All the options are correct

For a star connected three phase AC circuit is

• Phase voltage is equal to line voltage and phase current is three times the line current

• Phase voltage is square root three times line voltage and phase current is equal to line current

• Phase voltage is equal to line voltage and line current is equal to phase current

• None of the options are correct

In a three phase circuit, delta connection is

• Line voltage is equal to phase voltage
• Line voltage and line current is zero
• Line voltage and line current are Equal
• None of the options are correct

In a balanced three-phase system-delta load, if we assume the line voltage is VRY = V∠0⁰ as a reference phasor. Then the source voltage VYB is?

• V∠180⁰

• V∠120⁰

• V∠-180⁰

• V∠-120⁰

In a balanced three-phase system-delta load, if we assume the line voltage is VRY = V∠0⁰ as a reference phasor. Then the source voltage VBR is?

• V∠-180⁰

• V∠240⁰

• V∠-240⁰

• None of the options are correct

In a delta-connected load, the relation between line voltage and the phase voltage is?

• line voltage > phase voltage

• line voltage = phase voltage

• line voltage < phase voltage

• All the options are correct

In a balanced three-phase load, each phase has

• An equal amount of power
• Unequal amount of power
• Two-thirds of total power
• None of the options are correct

In a three-phase system, the voltages are separated by

• 45°

• 120°

• 180°

• All the options are correct

In a three-phase system, where the three voltage sources are, connected to feed a three-phase load, the phase sequence is important for rotating machinery, because the:

• direction of rotation will be affected
• power factor will be leading instead of lagging
• Magnitude of current flow will increase
• None of the options are correct