THREE PHASES MULTIPLE CHOICE QUESTIONS
00:30:00
to be answered :
15
Question 1
In a Y-connected circuit, between each line voltage and the nearest phase voltage, there is a phase angle of
A
90°
B
0°
C
60°
D
30°
Question 2
Polyphase generators produce simultaneous multiple sinusoidal voltages that are separated by
A
certain constant frequencies
B
certain constant voltages
C
certain constant voltages
D
certain constant frequencies
Question 3
A constant load power means a uniform conversion of
A
electrical to mechanical energy
B
voltage to current
C
mechanical to electrical energy
D
current to voltage
Question 4
If in a Y-connected ac generator, each phase voltage has a magnitude of 90 V
RMS
, what is the magnitude of each line voltage?
A
0 V
B
90 V
C
156 V
D
180 V
Question 5
In a Y-connected circuit, the magnitude of each line current is
A
one-third the phase current
B
three times the corresponding phase current
C
equal to the corresponding phase current
D
zero
Question 6
The most common type of ac motor is the
A
single-phase induction motor
B
two-phase induction motor
C
three-phase induction motor
D
two-phase squirrel-cage motor
Question 7
In a Y-Y source/load configuration, the
A
phase current, the line current, and the load current are 120° out of phase
B
line current and the load current are in phase, and both are out of phase with the phase current
C
phase current, the line current, and the load current are all equal in each phase
D
phase current and the line current are in phase, and both are 120° out of phase with the load current
Question 8
In a three-phase system, the voltages are separated by
A
120°
B
90°
C
45°
D
180°
Question 9
In a three-phase system, when the loads are perfectly balanced, the neutral current is
A
one-third of maximum
B
at maximum
C
zero
D
two-thirds of maximum
Question 10
In a certain three-wire Y-connected generator, the phase voltages are 2 kV. The magnitudes of the line voltages are
A
6,000 V
B
666 V
C
2000 V
D
3464 V
Question 11
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
9 A
C
27 A
D
12 A
Question 12
In a two phases generator, electrical displacement among two phases or windings is ….. electrical degrees.
A
120°
B
90°
C
180°
D
None of the above
Question 13
The benefit of star-connected supply system is that...
A
Line current is equal to phases current
B
Two voltage can be used
C
Phase sequence can be easily changed
D
It is a simple arrangement
Question 14
If a balanced delta load has an impedance of 6+j9 ohm per phase, then, impedence of every phase of equivalent star load is…
A
6+j9 ?
B
2+j3 ?
C
12+j18 ?
D
3+j45 ?
Question 15
The algebraic sum of instantaneous phase voltage in a a three-phase circuit is equivalent to
A
Zero
B
Line voltage
C
Phase voltage
D
None of the above
At the end of the test, press the 'CHECK' button