MindTap Engineering, 1 term (6 months) Printed Access Card for Glover/Overbye/Sarma's Power System Analysis and Design, 6th
6th Edition
ISBN: 9781305636323
Author: Glover, J. Duncan, Overbye, Thomas, Sarma, Mulukutla S.
Publisher: Cengage Learning
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Chapter 3, Problem 3.40P
To determine
To draw:
Per unit equivalent circuit.
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Three 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 - 10.20
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.…
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.
Chapter 3 Solutions
MindTap Engineering, 1 term (6 months) Printed Access Card for Glover/Overbye/Sarma's Power System Analysis and Design, 6th
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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