Fundamentals of Electric Circuits
6th Edition
ISBN: 9780078028229
Author: Charles K Alexander, Matthew Sadiku
Publisher: McGraw-Hill Education
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Textbook Question
Chapter 12.7, Problem 7PP
Calculate the line current required for a 30-kW three-phase motor having a power factor of 0.85 lagging if it is connected to a balanced source with a line voltage of 550 V.
Answer: 37.05 A.
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A generator is rated 100 MW, 13.8 kV and 90% power. A wye-connected alternator was tested for its effective resistance. The ratio of the effective resistance to ohmic resistance was previously determined to be 1.35. A 12 V battery was connected across two terminals and the ammeter read 120 amperes. What is the per phase effective resistance of the alternator?
An AC motor is connected to a 560-V, 60-Hz line. The motor has a current draw at full load of 53 A. A wattmeter indicates a true power of 18,700 W. Find the power factor of the motor and the amount of capacitance that should be connected in parallel with the motor to correct the power factor to 100%, or unity.
5 kVA at 60 Hz
Primary
2400 V
ellele
Secondary
Given the transformer in Volts rms,
what is the maximum theoretical
120 V
current rating of the Secondary (in
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Select one:
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OB. 12.78 A
OC. 25.4 A
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Chapter 12 Solutions
Fundamentals of Electric Circuits
Ch. 12.2 - Given that Vbn=22030V, find Van and Vcn, assuming...Ch. 12.3 - A Y-connected balanced three-phase generator with...Ch. 12.4 - One line voltage of a balanced Y-connected source...Ch. 12.5 - A positive-sequence, balanced -connected source...Ch. 12.6 - In a balanced -Y circuit, Vab=44015 and ZY = (12 +...Ch. 12.7 - For the Y-Y circuit in Practice Prob. 12.2,...Ch. 12.7 - Calculate the line current required for a 30-kW...Ch. 12.7 - Assume that the two balanced loads in Fig....Ch. 12.8 - The unbalanced -load of Fig. 12.24 is supplied by...Ch. 12.8 - Find the line currents in the unbalanced...
Ch. 12.9 - Prob. 11PPCh. 12.9 - For the unbalanced circuit in Fig. 12.32, use...Ch. 12.10 - Repeat Example 12.13 for the network in Fig. 12.24...Ch. 12.10 - Let the line voltage VL = 208 V and the wattmeter...Ch. 12.10 - If the load in Fig. 12.35 is delta-connected with...Ch. 12 - What is the phase sequence of a three-phase motor...Ch. 12 - If in an acb phase sequence, , then Vcn is:Ch. 12 - Which of these is not a required condition for a...Ch. 12 - Prob. 4RQCh. 12 - Prob. 5RQCh. 12 - In a Y-Y system, a line voltage of 220 V produces...Ch. 12 - In a - system, a phase voltage of 100 V produces a...Ch. 12 - When a Y-connected load is supplied by voltages in...Ch. 12 - Prob. 9RQCh. 12 - Prob. 10RQCh. 12 - If Vab = 400 V in a balanced Y-connected...Ch. 12 - What is the phase sequence of a balanced...Ch. 12 - Given a balanced Y-connected three-phase generator...Ch. 12 - A three-phase system with abc sequence and VL =...Ch. 12 - For a Y-connected load, the time-domain...Ch. 12 - Using Fig. 12.41, design a problem to help other...Ch. 12 - Obtain the line currents in the three-phase...Ch. 12 - In a balanced three-phase Y-Y system, the source...Ch. 12 - A balanced Y-Y four-wire system has phase voltages...Ch. 12 - For the circuit in Fig. 12.43, determine the...Ch. 12 - In the Y- system shown in Fig. 12.44, the source...Ch. 12 - Using Fig. 12.45, design a problem to help other...Ch. 12 - In the balanced three-phase Y- system in Fig....Ch. 12 - Obtain the line currents in the three-phase...Ch. 12 - The circuit in Fig. 12.48 is excited by a balanced...Ch. 12 - A balanced delta-connected load has a phase...Ch. 12 - A positive sequence wye-connected source where ,...Ch. 12 - If Van = 22060 V in the network of Fig. 12.49,...Ch. 12 - For the - circuit of Fig. 12.50, calculate the...Ch. 12 - Prob. 20PCh. 12 - Three 440-V generators form a delta-connected...Ch. 12 - Find the line currents IaA, IbB, and IcC in the...Ch. 12 - A balanced delta connected source is connected to...Ch. 12 - A balanced delta-connected source has phase...Ch. 12 - In the circuit of Fig. 12.54, if , , , find the...Ch. 12 - Using Fig. 12.55, design a problem to help other...Ch. 12 - A -connected source supplies power to a...Ch. 12 - The line-to-line voltages in a Y-load have a...Ch. 12 - A balanced three-phase Y- system has V rms and Z =...Ch. 12 - In Fig. 12.56, the rms value of the line voltage...Ch. 12 - A balanced delta-connected load is supplied by a...Ch. 12 - Design a problem to help other students better...Ch. 12 - A three-phase source delivers 4.8 kVA to a...Ch. 12 - A balanced wye-connected load with a phase...Ch. 12 - Three equal impedances, 60 + j30 each, are...Ch. 12 - A 4200-V, three-phase transmission line has an...Ch. 12 - The total power measured in a three-phase system...Ch. 12 - Given the circuit in Fig. 12.57 below, find the...Ch. 12 - Find the real power absorbed by the load in Fig....Ch. 12 - For the three-phase circuit in Fig. 12.59, find...Ch. 12 - A balanced delta-connected load draws 5 kW at a...Ch. 12 - A balanced three-phase generator delivers 7.2 kW...Ch. 12 - Refer to Fig. 12.48. Obtain the complex power...Ch. 12 - A three-phase line has an impedance of 1 + j3 per...Ch. 12 - A balanced wye-connected load is connected to the...Ch. 12 - A three-phase load consists of three 100-...Ch. 12 - The following three parallel-connected three-phase...Ch. 12 - A balanced, positive-sequence wye-connected source...Ch. 12 - Each phase load consists of a 20- resistor and a...Ch. 12 - A balanced three-phase source with VL = 240 V rms...Ch. 12 - Consider the wye-delta system shown in Fig. 12.60....Ch. 12 - A four-wire wye-wye circuit has...Ch. 12 - Using Fig. 12.61, design a problem that will help...Ch. 12 - A balanced three-phase Y-source with VP = 880 V...Ch. 12 - A three-phase supply, with the line-to-line...Ch. 12 - Using Fig. 12.63, design a problem to help other...Ch. 12 - Determine the line currents for the three-phase...Ch. 12 - Solve Prob. 12.10 using PSpice or MultiSim. For...Ch. 12 - The source in Fig. 12.65 is balanced and exhibits...Ch. 12 - Use PSpice or MultiSim to determine Io in the...Ch. 12 - Given the circuit in Fig. 12.67, use PSpice or...Ch. 12 - Using Fig. 12.68, design a problem to help other...Ch. 12 - Use PSpice or MultiSim to find currents IaA and...Ch. 12 - For the circuit in Fig. 12.58, use PSpice or...Ch. 12 - A balanced three-phase circuit is shown in Fig....Ch. 12 - A three-phase, four-wire system operating with a...Ch. 12 - As shown in Fig. 12.72, a three-phase four-wire...Ch. 12 - Meter readings for a three-phase wye-connected...Ch. 12 - A certain store contains three balanced...Ch. 12 - The two-wattmeter method gives P1=1200W and...Ch. 12 - In Fig. 12.73, two wattmeters are properly...Ch. 12 - If wattmeters W1 and W2 are properly connected...Ch. 12 - For the circuit displayed in Fig. 12.74, find the...Ch. 12 - Predict the wattmeter readings for the circuit in...Ch. 12 - Prob. 75PCh. 12 - Show that the I2R losses will be higher for a...Ch. 12 - A three-phase generator supplied 10 kVA at a power...Ch. 12 - Prob. 78CPCh. 12 - A balanced three-phase generator has an abc phase...Ch. 12 - A balanced three-phase source furnishes power to...Ch. 12 - A professional center is supplied by a balanced...Ch. 12 - A balanced three-phase system has a distribution...Ch. 12 - A commercially available three-phase inductive...Ch. 12 - Figure 12.76 displays a three-phase...Ch. 12 - Design a three-phase heater with suitable...Ch. 12 - For the single-phase three-wire system in Fig....Ch. 12 - Consider the single-phase three-wire system shown...
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- A three-phase, wye-connected induction motor is supplied by a three-phase and four-wire system with line-to-line voltage of 220 V and the impedance of the motor is 6.3 + j3.052 per phase. Determine the following: (a) The magnitude of the line current (b) The power factor of the motor (c) The three-phase average power consumed by the motor (d) The current in the neutral wire. 2.1arrow_forwardplase answer five a quesion option corrctly 9.In AC circuits, power consumed is A.it depends on the supply voltage B.product of voltage and current C.it depends on the power factor (p.f.) of the circuit in addition to voltage and current D.it depends on the magnitude of the circuit current 10A potential transformer is a A.transformer used with an AC ammeter B.transformer used with an AC voltmeter C.transformer used with a DC voltmeter D.transformer used with a DC ammeter 11. Define Per Unit Quantity A/ Xp.u = x base / x actual per unit B/ Xp.u = X actual / x base per unit C/ Xp.u = x actual / x unit per unit 12./ VS= 1200<0º V ZL= 50 + j60 ohm ZS= j25ohm By taking Zbase = 100 ohm, find Vs (p.u), Zs(p.u), ZL(p.u) A. Vs (p.u) = 1 < 00 p.u Zs(p.u) = j0.20 p.u ZL(p.u) = 66.42<390 p.u B. Vs (p.u) = 1 < 00 p.u Zs(p.u) = j0.25 p.u ZL(p.u) = 42.96<730 p. C. Vs (p.u) = 1 < 00 p.u Zs(p.u) = j0.25 p.u ZL(p.u) = 0.781<50.20 p.u 13. Which of…arrow_forwardA three-phase star-connected alternator working at a speed of 750 rpm is required to generate a line voltage of 450 V on an open circuit. The stator has 3 slots per pole per phase and 4 conductors per slot. (Use the standard frequency of supply in Oman). Calculate a) Number of poles b) Slot angle c) Distribution factor d) Useful flux per pole a) b) c) d)arrow_forward
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