Three Phase Systems in Power Applications Objective Test - ObjectiveBooks
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# Practice Test: Question Set - 03

1. In a ∆-connected generator, all of the phase voltages are
(A) Zero
(B) Equal in magnitude
(C) One-third of total
(D) One-sixth of total

2. A three-phase generator is connected to three 90 Ω load resistors. Each coil generates 120 V ac. A common neutral line exists. How much current flows through the common neutral line?
(A) 0 A
(B) 1.33 A
(C) 3.99 A
(D) 2.66 A

3. In a ∆-connected source driving a ∆-connected load, the
(A) Load voltage and line voltage are one-third the source voltage for a given phase
(B) Load voltage and line voltage are two-thirds the source voltage for a given phase
(C) Load voltage and line voltage cancel for a given phase
(D) Load voltage, line voltage, and source phase voltage are all equal for a given phase

4. A simple three-phase generator consists of three conductive loops separated by 120°.
(A) True
(B) False

5. The stator is the rotating assembly in a generator or motor.
(A) True
(B) False

6. In a three-phase system, when the loads are perfectly balanced, the neutral current is
(A) Zero
(B) One-third of maximum
(C) Two-thirds of maximum
(D) At maximum

7. In a certain Y-Y system, the source phase currents each have a magnitude of 9 A. The magnitude of each load current for a balanced load condition is
(A) 3 A
(B) 6 A
(C) 9 A
(D) 27 A

8. A balanced load is one in which all the impedances are equal.
(A) True
(B) False

9. A single-phase sinusoidal voltage of 120 V is connected to a 90 Ω load. Current in the circuit is
(A) 13.3 mA
(B) 133 mA
(C) 1.33 A
(D) 6.2 A

10. A constant load power means a uniform conversion of
(A) Mechanical to electrical energy
(B) Electrical to mechanical energy
(C) Current to voltage
(D) Voltage to current

11. In a Y-connected circuit, between each line voltage and the nearest phase voltage, there is a phase angle of
(A) 0°
(B) 30°
(C) 60°
(D) 120°

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