Electrical Engineering · Question Bank

3P AC Circuits

53 of 71 questions match · page 1 of 3. Answer in your head first, then check the solution.

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TypeAll 53Problem solving 23Objective 30
DifficultyAll 71Easy 53Medium 17Hard 1
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#1📜 EE Pre-Board August 2012📘 PowerhouseEasy
A balanced delta connected load of (4 + j3) ohms per phase, 230 V supply. Find the total kVA.
A19.04 kVA
B37.01 kVA
C31.74 kVA
D25.39 kVA
#2📜 EE Pre-Board March 2013📘 PowerhouseEasy
In two-wattmeter method, the readings of the wattmeter will be identical when
ALoad in one of the phases is zero
BPower Factor in unity
CPower factor is 0.5
DNeutral is earthed
#3📜 EE Pre-Board March 2013📘 PowerhouseEasy
What is the minimum number of wattmeter required to measure unbalanced power for a three phase system?
A2
B3
C4
D1
#4📜 EE Pre-Board August 2013📘 PowerhouseEasy
A 230 V, 3-phase source supplies a balanced delta connected load of 8 − j6 Ω per phase. Find the line current in amperes.
A33.1
B39.8
C26.5
D29.3
#5📜 EE Pre-Board August 2013📘 PowerhouseEasy
A 220 v, 3-phase supply has a balanced delta connected load with impedance of 15 + j20 ohms/phase. What is the total real power of the load in watts?
A5,133.3
B4,122.5
C2,965.6
D3,484.8
#6📜 EE Pre-Board March 2014📘 PowerhouseEasy
A 240 v balanced 3ɸ source supplies a purely resistive impedance of 11.52 ohms per phase. What is the total power drawn if it is Y-connected?
A5 kW
B15 kW
C20 kW
D30 kW
#7📜 EE Pre-Board March 2014📘 PowerhouseEasy
Power in a three-phase delta system with balanced load is equal to
A\(\sqrt{3}V_LI_L\,(pf)\)
B\(\sqrt{3}V_\phi I_\phi\,(pf)\)
C\(3V_\phi I_L\,(pf)\)
D\(3V_LI_L\,(pf)\)
#8📜 EE Pre-Board March 2014📘 PowerhouseEasy
What is the minimum number of wattmeters required to measure unbalanced power for a three-phase system?
A2
B4
C3
D1
#9📜 EE Pre-Board March 2014📘 PowerhouseEasy
In two-wattmeter method, the readings of the wattmeters will be identical when
Aload in one of the phases is zero
Bpower factor is unity
Cpower factor is 0.5
Dneutral is earthed
#10📜 EE Pre-Board March 2014📘 PowerhouseEasy
A balanced delta connected load impedance of 15 + j18 Ω per phase is connected across a 230 v, three-phase source. Find the total power consumed.
A10,580 W
B1,445 W
C4,336 W
D3,527 W
#11📜 EE Pre-Board March 2014📘 PowerhouseEasy
A balanced wye – connected load with resistance of 8 ohms per phase and no reactance is supplied by a 240 v, 3 – phase source. Find the real power of the load in watts.
A6,400
B7,200
C6,800
D7,600
#12📜 EE Pre-Board March 2014📘 PowerhouseEasy
For an unbalanced load which connection is suitable?
A3 – wire open delta connection
B4 – wire wye connection
C3 – wire delta connection
D3 – wire wye connection
#13📜 EE Pre-Board August 2014📘 PowerhouseEasy
Two-wattmeters can be used to measure three-phase power for a
Abalanced and unbalanced load
Bunbalanced load only
Cbalanced load only
Dunity power factor only
#14📜 EE Pre-Board March 2015📘 PowerhouseEasy
For a three phase unbalanced load
AThe power factor of each phase will be proportional to the load
BThe power factor each phase will be the same
CThe power factor of at least one of the phases must be leading
DThe power factor of each phase may be different
#15📜 EE Pre-Board August 2015📘 PowerhouseEasy
Three 40 Ω non-inductive resistances are connected in wye across 200 V, 3-phase lines. If one of the resistors is disconnected, what would be the power taken from the mains?
A3,000 W
B2,000 W
C1,000 W
D500 W
#16📜 EE Pre-Board August 2015📘 PowerhouseEasy
A 220 V, 3-phase supply has a balanced delta connected load with impedance of 15 + j20 Ω/phase. What is the total real power of the load in watts?
A5,133.3
B2,965.6
C4,122.5
D3,484.8
#17📜 EE Pre-Board August 2015📘 PowerhouseEasy
A balanced wye-connected load with resistance of 8 Ω/phase and no reactance is supplied by a 240v, 3-phase source. Find the real power of the load in watts.
A6,400
B7,200
C6,800
D7,600
#18📜 EE Pre-Board March 2016📘 PowerhouseEasy
In a balanced three phase wye connected circuit, the line voltages are equal
ATo the line current
BTo the phase voltage
Cand so are the line currents
Dbut the line currents are unequal
#19📜 EE Pre-Board March 2016📘 PowerhouseEasy
In a wye connected system, line current is
A0.707 times the phase current
B1.732 times the phase current
Cequal to the phase current
D1.414 times the phase current
#20📜 EE Pre-Board March 2016📘 PowerhouseEasy
A balanced delta load of 3+j4 ohms per phase is connected to a balanced 110v source. Find the line current.
A22A
B38.1A
C11A
D19.05A

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