Electrical Engineering · Question Bank

3P AC Circuits

53 of 71 questions match · page 3 of 3. Answer in your head first, then check the solution.

Study the lessons
TypeAll 53Problem solving 23Objective 30
DifficultyAll 71Easy 53Medium 17Hard 1
✕ Clear filters
#41📜 EE Pre-Board August 2018📘 PowerhouseEasy
In a delta connected circuit of three equal resistors, when one resistor is open, the power will be
Aunaltered
Breduced to 1/9
Creduced to 1/16
Dreduced by 1/3
#42📘 EE Pocket Reviewer RojasEasy
What is the advantage of a star-connected system over a delta connected system?
AHigher current
BHigher voltage
CHigher current and voltage
DHigher power
#43📘 EE Pocket Reviewer RojasEasy
How is the power in a delta-connected system related to the power in a wye-connected system if both line current and line voltage are the same?
APower in delta = power in wye
BPower in delta = 3 times power in wye
CPower in delta = \(\sqrt{3}\) times power in wye
DPower in delta = 1/3 times power in wye
#44📘 EE Pocket Reviewer RojasEasy
For the same power rating, what is the physical size of a three-phase ac motor in comparison to a single-phase ac motor?
AThe three-phase motor is bigger in size
BThe three-phase motor is smaller in size
CBoth motors are of the same in size since power ratings are the same
DEither A or B, depending on applications
#45📘 EE Pocket Reviewer RojasEasy
Which of the following unbalanced three-phase loads is the hardest to deal with?
AFour-wire star connected unbalanced load
BUnbalanced delta-connected load
CUnbalanced three-wire, wye-connected load
DNone of these
#46📘 EE Pocket Reviewer RojasEasy
In a “n-phase electrical system”, what is the phasor displacement between the phase voltages?
A0°
B90°
C180°/n
D360°/n
#47📘 EE Pocket Reviewer RojasEasy
Which of the following three-phase systems is used to supply both light and power?
AThree-phase open-delta systems
BThree-phase closed delta systems
CThree-phase star with a neutral wire
DThree-phase star without a neutral wire
#48📘 EE Pocket Reviewer RojasEasy
The zero sequence component of the unbalanced 3-phase system of vectors \(V_a\), \(V_b\) and \(V_c\) is equal to ____ of their vector sum.
A1/3
B1/4
C1/2
D2/3
#49📘 EE Pocket Reviewer RojasEasy
In a three-phase star-connected system, how does the line current related to the phase current?
ALine current is \(\sqrt{3}\) times the phase current
BLine current is \(1/\sqrt{3}\) times the phase current
CLine current is 3 times the phase current
DLine current is equal to the phase current
#50📘 EE Pocket Reviewer RojasEasy
What is the advantage of star-connected system compared to other system?
AThe phase sequence can be easily change
BTwo voltages can be used
CLine current is equal to phase current
DIt is a simple arrangement
#51📘 EE Pocket Reviewer RojasEasy
In a balanced star-connected system, what is the phasor angle between the line voltage and the phase voltage?
A30°
B45°
C60°
D120°
#52📘 EE Pocket Reviewer RojasEasy
In a balanced wye-connected system, which of the following is true about the relation between line voltage and phase voltage?
ALine voltage is equal to the phasor difference between two phase voltages
BLine voltage is equal to the phasor sum between two phase voltages
CLine voltage is equal to 3 times the phase voltage
DLine voltage is equal to the phase voltage
#53📘 EE Pocket Reviewer RojasEasy
When can you tell that a three-phase load is a balanced load?
AThe power factor are the same
BThe impedance are the same
CThe impedance and power factor are the same
DThe resistance and reactance are equal

More Electrical Engineering topics