Three 10 ohm resistances are connected delta on a balanced three phase source. If the equation of the phase voltage is \(V_{an} = 120 \sin \omega t\), what is the equation of the phase a line current?
A\(36 \sin \omega t\)
B\(13.15 \sin(\omega t - 30^\circ)\)
C\(11.22 \sin(\omega t + 30^\circ)\)
D\(11.88 \sin(\omega t - 56.6^\circ)\)
#2📜 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
#3📜 EE Pre-Board August 2012📘 PowerhouseMedium
A 220 V, 3 phase, 4 wire abc system supplies unbalanced wye connected resistances of \(R_a\) = 10 ohms, \(R_b\) = 15 ohms, and \(R_c\) = 20 ohms. Determine the total power of the system.
A3,495 W
B3,385 W
C3,560 W
D3,895 W
#4📜 EE Pre-Board August 2012📘 PowerhouseMedium
Power in a balanced 3 phase system is measured by two wattmeter method and it is found that the ratio of the two wattmeter readings is 2 is to 1. What is the power factor of the system?
A0.9
B0.82
C0.866
D0.707
#5📜 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
#6📜 EE Pre-Board March 2013📘 PowerhouseHard
A 230 V, 3-phase, 3-wire system has two balanced 3-phase loads. One, wye connected, has an impedance of 6 + j8 Ω per phase and the other one, delta connected, has an impedance of 24 + j18 Ω per phase. Find the line current in amperes.
A26.3
B23.9
C28.2
D20.8
#7📜 EE Pre-Board March 2013📘 PowerhouseMedium
An unbalanced wye-connected load connected to a 3-phase, 4-wire abc system consists of \(Z_a = 10 + j5\ \Omega\), \(Z_b = 8 + j4\ \Omega\) and \(Z_c = 20 + j0\ \Omega\). If the line to neutral voltage is 120 V, find the total power in watts.
A4,125
B3,312
C5,520
D2,843
#8📜 EE Pre-Board March 2013📘 PowerhouseMedium
In a 230 V, 3-phase, 3-wire system, two wattmeters are connected to measure the power. The ratio of the readings of the wattmeters is 2.5 is to 1. What is the power factor of the system?
A80.3%
B76.6%
C83.1%
D86.6%
#9📜 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
#10📜 EE Pre-Board August 2013📘 PowerhouseMedium
A 220 V, 3-phase, 4-wire abc system supplies unbalanced wye-connected resistances of \(R_a\) = 10 Ω, \(R_b\) = 15 Ω and \(R_c\) = 20 Ω. Determine the total power of the system in watts.
A3,495
B3,560
C3,385
D3,895
#11📜 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
#12📜 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
#13📜 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
#14📜 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\(3V_LI_L\,(pf)\)
#15📜 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
#16📜 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
#17📜 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
#18📜 EE Pre-Board March 2014📘 PowerhouseMedium
Power in a balanced 3-phase system is measured by the two-wattmeter method and it is found that the ratio of the two wattmeter readings is 2 is to 1. What is the power factor of the system?
A0.9
B0.866
C0.82
D0.707
#19📜 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
#20📜 EE Pre-Board March 2014📘 PowerhouseMedium
Two parallel connected loads A and B are supplied by a 440 v, 3 – phase, 60 Hz generator. Load A draws and apparent power of 100 kVA at 0.80 power factor lagging and load B draws an apparent power of 70 kVA at unity power factor. Determine the feeder current.
