Fundamentals of Electric Circuits
6th Edition
ISBN: 9780078028229
Author: Charles K Alexander, Matthew Sadiku
Publisher: McGraw-Hill Education
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Chapter 12, Problem 55P
A three-phase supply, with the line-to-line voltage of 240 V rms, has the unbalanced load as shown in Fig. 12.62. Find the line currents and the total complex power delivered to the load.
Figure 12.62
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there is a three-phase transformer that supplies 12 kW to a neighborhood supermarket, the same is in the standards and is considered a balanced three-phase load with inductive power factor of 0.8. If the supermarket at the supply input is star connected, fed with four conductors and operating at a phase-neutral voltage equal to 200 V. What is the line current with this load?
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 balanced delta connected load draws 10 Amp line current and 3 kW at 220V. The impedance of each phase of the load in ohms is...arrow_forwarda. Y-Connected b. В 100kW Source 0.9 LAG 80KVA 0.8 LAG Figure 1 80kW 0.85 LAGarrow_forwardThe following three-phase circuit is symmetrical, with line voltage 220 V, 60 Hz, direct phase sequence, isolated neutral and the value of the impedances of the loads in the three phases are: Zan = 10 ohms Zbn = -10j ohm Zcn = -10j Ohm Find:a) Phase voltages on the load;b) Line and phase currents;c) The power supplied to the load. Consider the phase voltage in the reference(Va voltage angle equal to 0)arrow_forward
- 12. A certain load takes 300 kW at 400 V. A three phase capacitor bank rated 15 kVA per phase is connected in parallel with the load to raise the power factor of the system to 90% lagging. What is the power factor of the load before correction? c. 92% d. 88% a. 99% b. 95% 13. A 132 kV line three phase system delivers 70.7 MVA on a balanced delta connected load of a power factor 70.7% lagging. Determine the reactance necessary to attain unity power factor. a. 1 092 ohms c. 1142 ohms d. 1 045 ohms b. 965 ohms 14. A 150 kVA transformer bank will serve a load expected to draw 135 kW at 0.80 lagging power factor. Solve for the size of the capacitor bank needed to be added in order to prevent overloading of the transformer bank. a 40.391 KVAR d. 28.266 KVAR a. 32.506 KVAR b. 35.866 KVARarrow_forward1. What is the main direct cause of reactive power in AC system? A. Resistance of transmission lines B. Inductance and capacitance in the loads C. Ideal transformer connected in the system D. Power produced by generator 2. "Reactive power in a system is dissipated generally as thermal energy?" A. TRUE B. FALSE 3. Which of the following statements are correct for three phase circuit: A. Sum of all the three phase currents is zero in unbalanced network B. Total power transfer to load is constant with time C. Neutral conductor is same size in terms of material used as in single phase conductors D. Net apparent power consumed is equal to real powerarrow_forwardAnswer all 1.) In a three phase Delta-Wye connection a.) What is the relationship between the line to line voltage at the source and the load? b.) What is the relationship between the Phase to Phase voltage at the load and source? c.) What is the relationship between the line Currents and phase currents going into the load? d.) What is the relationship between the power being dissipated as seen from the source compared to the load?arrow_forward
- Find the line currents in the unbalanced three-phase circuit of Fig. 12.26 and the real power absorbed by the load. 220-120° rms V Figure 12.26 220/0° rms V 220/120⁰ rms V b -j5Q B A www j1092 1092 Carrow_forwardUnder balanced operating conditions, consider the 3-phase complex power delivered by the 3-phase source to the 3-phase load. Match the following expressions, those on the left to those on the right. 0) Real power, Py (ii) Reactive power, Qu (ii) Total apparent power Sy (iv) Complex power, Sy (a) (V3 VLL. IL)VA (b) (V3 Vu sng) var (e) (V3 VLL. IL cos ø) W (d) Py +Qy Note that VLL is the rms line-to-line voltage, IL is the ms line current, and o is the power-factor angle.arrow_forwardTwo balanced three-phase loads that are connected in parallel are fed by a three-phase line having a series impedance of (0.4 + j2.7) N per phase. One of the loads absorbs 560 kVA at 0.707 power factor lagging, and the other 132 kW at unity power factor. The line-to-line voltage at the load end of the line is 2200 V3 V. Compute (a) the line-to-line voltage at the source end of the line, (b) the total real and reactive power losses in the three-phase line, and (c) the total three-phase real and reactive power supplied at the sending end of the line. Check that the total three-phase complex power delivered by the source equals the total three-phase com- plex power absorbed by the line and loads.arrow_forward
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