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 9RQ
To determine
Choose the correct option to check whether the statement “Total instantaneous power of balanced three-phase circuit is equal to the average power of the circuit” is true or false.
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A synchronous generator has been
synchronized to an infinite grid of 13.8 kV
and 60 Hz. The generator prime mover C/C
is such that the no-load frequency is 62.5
Hz and the power slope is 1 MW/Hz. The
AVR C/C (The reactive power against the
terminal voltage C/C) is such that the zero
reactive power voltage is 14.6 kV, while the
slope is 0.4 MVAR/kV. Calculate:
(a) the kVA loading of the generator and its
power factor.
(b) the settings of the prime mover and AVR
such that the generator delivers 3 MW at
0.85 lagging power factor.
There is an installation with two equal triphasic loads of 300 kVA each and a power factor of 0.9 lagging. When connecting a pure reactive element in parallel, the reactive power at the entrance of the installation is 150 kVARS, with a lagging power factor. We can say that:
a) A bank of reactors was connected and the fp deteriorated.
b) A capacitor bank was connected and the pf deteriorated.
c) A bank of reactors was connected and the fp improved.
d) A capacitor bank was connected and the pf improved.
e) None of the above
Three-phase electricity is delivered to a factory 7 km from a distribution company. The
factory receives a total of 2000 kW of power at a voltage of 10.98 kV (rms) per phase.
If the transmission cable in each phase has a resistance of 1.8 per 10 km, then the
total power lost in the cables of this three-phase system is
(a) 4.645 W
(b) 13.93 W
(c) 4.645 kW
(d) 13.93 kW
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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