POWER SYSTEM ANALYSIS+DESIGN-EBK >I<
6th Edition
ISBN: 9781337259170
Author: Glover
Publisher: INTER CENG
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Textbook Question
Chapter 3, Problem 3.20P
Using base values of 20 kVA and 115 volts in zone 3, rework Example 3.4.
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Three single-phase two-winding transformers, each rated 3 kVA, 220/110volts, 60 Hz, with a 0.10 per-unit leakage reactance, are connected as athree-phase extended D autotransformer bank, as shown in Figure 3.36 (c).The low-voltage D winding has a 110-volt rating. (a) Draw the positive sequencephasor diagram and show that the high-voltage winding has a479.5-volt rating. (b) A three-phase load connected to the low-voltageterminals absorbs 6 kW at 110 volts and at 0.8 power factor lagging. Drawthe per-unit impedance diagram and calculate the voltage and current atthe high-voltage terminals. Assume positive-sequence operation.
HOME WORK: Per-unit circuit: three-zone single-phase network
determine the per-unit impedances and the per-unit source voltage. Then cal-
culate the load current both in per-unit and in amperes. Transformer winding
resistances and shunt admittance branches are neglected.
Zone 1
Vs = 220/0° volts i
Three zones of a single-phase circuit are identified in Figure 3.10(a). The zones
are connected by transformers T₁ and T₂, whose ratings are also shown. Using
base values of 30 kVA and 240 volts in zone 1, draw the per-unit circuit and
T₁
30 kVA
240/480 volts
Xeq = 0.10 p.u.
V sp.u. =
0.9167/0° p.u.
Zoase
Zone 2
Xune 20
(a) Single-phase circuit
I'spu i Xtio.u
Zone 1
Vbase1 = 240 volts
(240)²
30,000
Spase = 30 kVA
= 1.92
T₂ Zload = 0.9 +0.2
20 KVA
460/115 volts
Xea = 0.10 p.u.
jXunepu
j0.10 p.u. j0.2604 p.u.
Zone 2
Vbase2 = 480 volts
Zbase2 =
Zone 3
(480)²
30,000
¡XT2pu hoadp.u.
= 7.68
(b) Per-unit circuit
/0.1378
p.u.
Zone 3
Vbase3= 120 volts
Zbase3 =
base3 =
Zoadp.u. =
1.875+ 0.4167 p.u.…
Discuss causes of insulation failures in high voltage engineering.
High voltage engineering
Chapter 3 Solutions
POWER SYSTEM ANALYSIS+DESIGN-EBK >I<
Ch. 3 - The Ohms law for the magnetic circuit states that...Ch. 3 - For an ideal transformer, the efficiency is (a) 0...Ch. 3 - For an ideal 2-winding transformer, the...Ch. 3 - An ideal transformer has no real or reactive power...Ch. 3 - For an ideal 2-winding transformer, an impedance...Ch. 3 - Consider Figure 3.4. For an ideal phase-shifting...Ch. 3 - Consider Figure 3.5. Match the following, those on...Ch. 3 - The units of admittance, conductance, and...Ch. 3 - Match the following: (i) Hysteresis loss (a) Can...Ch. 3 - For large power transformers rated more than 500...
Ch. 3 - For a short-circuit test on a 2-winding...Ch. 3 - The per-unit quantity is always dimensionless. (a)...Ch. 3 - Consider the adopted per-unit system for the...Ch. 3 - The ideal transformer windings are eliminated from...Ch. 3 - To convert a per-unit impedance from old to new...Ch. 3 - In developing per-unit circuits of systems such as...Ch. 3 - Prob. 3.17MCQCh. 3 - Prob. 3.18MCQCh. 3 - With the American Standard notation, in either a...Ch. 3 - Prob. 3.20MCQCh. 3 - In order to avoid difficulties with third-harmonic...Ch. 3 - Does an open connection permit balanced...Ch. 3 - Does an open- operation, the kVA rating compared...Ch. 3 - It is stated that (i) balanced three-phase...Ch. 3 - In developing per-unit equivalent circuits for...Ch. 3 - In per-unit equivalent circuits of practical...Ch. 3 - Prob. 3.27MCQCh. 3 - Prob. 3.28MCQCh. 3 - For developing per-unit equivalent circuits of...Ch. 3 - Prob. 3.30MCQCh. 3 - Prob. 3.31MCQCh. 3 - Prob. 3.32MCQCh. 3 - The direct electrical connection of the windings...Ch. 3 - Consider Figure 3.25 of the text for a transformer...Ch. 3 - (a) An ideal single-phase two-winding transformer...Ch. 3 - An ideal transformer with N1=1000andN2=250 is...Ch. 3 - Consider an ideal transformer with...Ch. 3 - A single-phase 100-kVA,2400/240-volt,60-Hz...Ch. 3 - Prob. 3.5PCh. 3 - Prob. 3.6PCh. 3 - Consider a source of voltage v(t)=102sin(2t)V,...Ch. 3 - Prob. 3.8PCh. 3 - Prob. 3.9PCh. 3 - A single-phase step-down transformer is rated...Ch. 3 - For the transformer in Problem 3.10. The...Ch. 3 - Prob. 3.12PCh. 3 - A single-phase 50-kVA,2400/240-volt,60-Hz...Ch. 3 - A single-phase 50-kVA,2400/240-volt,60-Hz...Ch. 3 - Rework Problem 3.14 if the transformer is...Ch. 3 - A single-phase, 50-kVA,2400/240-V,60-Hz...Ch. 3 - The transformer of Problem 3.16 is supplying a...Ch. 3 - Using the transformer ratings as base quantities,...Ch. 3 - Using the transformer ratings as base quantities....Ch. 3 - Using base values of 20 kVA and 115 volts in zone...Ch. 3 - Prob. 3.21PCh. 3 - A balanced Y-connected voltage source with...Ch. 3 - Figure 3.32 shows the oneline diagram of a...Ch. 3 - For Problem 3.18, the motor operates at full load,...Ch. 3 - Consider a single-phase electric system shown in...Ch. 3 - A bank of three single-phase transformers, each...Ch. 3 - A three-phase transformer is rated...Ch. 3 - For the system shown in Figure 3.34. draw an...Ch. 3 - Consider three ideal single-phase transformers...Ch. 3 - Reconsider Problem 3.29. If Va,VbandVc are a...Ch. 3 - Prob. 3.31PCh. 3 - Determine the positive- and negative-sequence...Ch. 3 - Consider the three single-phase two-winding...Ch. 3 - Three single-phase, two-winding transformers, each...Ch. 3 - Consider a bank of this single-phase two-winding...Ch. 3 - Three single-phase two-winding transformers, each...Ch. 3 - Three single-phase two-winding transformers, each...Ch. 3 - Consider a three-phase generator rated...Ch. 3 - The leakage reactance of a three-phase,...Ch. 3 - Prob. 3.40PCh. 3 - Consider the single-line diagram of the power...Ch. 3 - For the power system in Problem 3.41, the...Ch. 3 - Three single-phase transformers, each rated...Ch. 3 - A 130-MVA,13.2-kV three-phase generator, which has...Ch. 3 - Figure 3.39 shows a oneline diagram of a system in...Ch. 3 - The motors M1andM2 of Problem 3.45 have inputs of...Ch. 3 - Consider the oneline diagram shown in Figure 3.40....Ch. 3 - With the same transformer banks as in Problem...Ch. 3 - Consider the single-Line diagram of a power system...Ch. 3 - A single-phase three-winding transformer has the...Ch. 3 - The ratings of a three-phase three-winding...Ch. 3 - Prob. 3.52PCh. 3 - The ratings of a three-phase, three-winding...Ch. 3 - An infinite bus, which is a constant voltage...Ch. 3 - A single-phase l0-kVA,2300/230-volt,60-Hz...Ch. 3 - Three single-phase two-winding transformers, each...Ch. 3 - A two-winding single-phase transformer rated...Ch. 3 - A single-phase two-winding transformer rated...Ch. 3 - Prob. 3.59PCh. 3 - PowerWorid Simulator case Problem 3_60 duplicates...Ch. 3 - Rework Example 3.12 for a+10 tap, providing a 10...Ch. 3 - A 23/230-kV step-up transformer feeds a...Ch. 3 - The per-unit equivalent circuit of two...Ch. 3 - Reconsider Problem 3.64 with the change that now...Ch. 3 - What are the advantages of correctly specifying a...Ch. 3 - Why is it important to reduce the moisture within...Ch. 3 - What should be the focus of transformer preventive...
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- Consider the oneline diagram shown in Figure 3.40. The three-phase transformer bank is made up of three identical single-phase transformers, each specified by X1=0.24 (on the low-voltage side), negligible resistance and magnetizing current, and turns ratio =N2/N1=10. The transformer bank is delivering 100 MW at 0.8 p.f. lagging to a substation bus whose voltage is 230 kV. (a) Determine the primary current magnitude, primary voltage (line-to-line) magnitude, and the three-phase complex power supplied by the generator. Choose the line-to-neutral voltage at the bus, Va as the reference Account for the phase shift, and assume positive-sequence operation. (b) Find the phase shift between the primary and secondary voltages.arrow_forwardFigure B2 shows an HVDC system connecting the 400 kV electricity networks of two countries (System A and System B) through a 400 km submarine link, capable of transferring up to 600 MW. Each cable has a dc voltage rating of 300 kV, and a resistance of 0.01 /km. (i) (ii) The primaries of the transformers at each end of the link are connected to the 400 kV ac network. Calculate the highest value for the transformer secondary line voltages. Is it the best option to select this highest value for the transformer secondary line voltage, and why? αд and ag are the delay angles of the converters at System A and System B respectively. 600 MW is to be transferred from System A to System B. Calculate ag if aд is 5 degrees. Two big power stations in System A are closed for maintenance, so 600 MW now needs to be transferred from System B to System A. (i) Explain how this would be achieved. How would this affect: (ii) (!!!) the direction of current flow in the cables; the voltage polarity of the…arrow_forwardThree zones of a single-phase circuit are identified in the figure. The zones are connected by transformers T₁ and T2, whose ratings are also shown. Using base values of 100 kVA and 240 volts in zone 1, draw the per-unit circuit and determine the per-unit impedances and the per-unit source voltage. Then calculate the load current both in per-unit and in amperes. Transformer winding resistances and shunt admittance branches are neglected. Zone 1 Zone 2 Vs = 220/0° volts 3---38 T, 30 KVA 240/480 volts M 0.10 p.u. Xoa Xune = 2 fl T T₂ 20 kVA 460/115 volts Xeg = 0.10 p.u. Zone 3 ww Zload = 0.9 - 10.20arrow_forward
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