3.45 Figure 3.39 shows a oneline diagram of a system in which the three-phasegenerator is rated 300 MVA, 20 kV with a subtransient reactance of 0.2 perunit and with its neutral grounded through a 0.4-2 reactor. The transmis-sion line is 64 km long with a series reactance of 0.5 Q/km. The three-phasetransformer T, is rated 350 MVA, 230/ 20 kV with a leakage reactance of0.1 per unit. Transformer T, is composed of three single-phase transform-ers, each rated 100 MVA, 127/13.2 kV with a leakage reactance of 0.1 perunit. Two 13.2-kV motors M, and M, with a subtransient reactance of0.2 per unit for each motor represent the load. M, has a rated input of200 MVA with its neutral grounded through a 0.4-N current-limiting reac-tor. M, has a rated input of 100 MVA with its neutral not connected toground. Neglect phase shifts associated with the transformers. Choosethe generator rating as base in the generator circuit and draw the posi-tive-sequence reactance diagram showing all reactances in per unit.(20 kV)T,(13.8 kV)FIGURE 3.39T2M,p(230 kV)Problems 3.45k 3E !m3E nM2and 3.46

Answered: 3.45 Figure 3.39 shows a oneline…

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

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Find the elements of the equivalent circuit relative to the secondary of a single-phase transformer. The no- load voltages in the primary and secondary circuit are 200 and 400 volts, respectively, and at a frequency of 50 Hz. The primary no-load current at a voltage of 200 volts is 0.7 amps and the losses in the core are 70 watts. The resistance and reactance of the primary are 3.2 and 1.25 ohms, respectively. Secondary resistance and reactance 6. 0, 0.07 ohms, respectively. Draw the equivalent circle, showing the values of its elements.
A short transmission line connects a step-up transformer on the source side with a series impedance of j0.5 ohms (referred to the primary) to a step-down transformer on the load side with a series impedance of 50 ohms (referred to the primary). The turn ratio of the step-up transformer is 1:14 and a no-load primary voltage of 17 (line-to-line) kV. The step- down transformer has a turn ratio of 18:1 and it has a Y-connected, balanced load of 0.463 +j 0.0772 ohms connected to its secondary side. A capacitor bank of -j0.324 ohms is added parallel to the load. Assuming an ideal transmission line, the effective impedance (per phase) of the system seen by the source would be: O A. 0.292 + j0.375 O B. None of the other choices are correct O C. 0.584 + j0.750 O D.0.196 + j0.158 O E. 5.84 + j7.5
2.5.3 A three phase power system has two generator connected in parallel to a transformer and subsequently to a 230 kV transmission line. The ratings for the components are given as below: Generator 1:10 MVA, reactance of 12%. Generator 2: 5 MVA, reactance of 8%. Transformer: 15 MVA, reactance of 6% Transmission line: impedance of 4+j60 2, for which the reactances in percentage are based on the ratings of the respective components. Obtain the reactance and impedance values of the components in the system in percentage, based on 15 MVA and rated voltage of the components.
No-load operation and short circuit tests were performed on three-phase, 50 Hz 480/220 delta / Y connected transformer. In these testsThe line voltage, line current and three-phase total power have been measured from the high voltage windings and the test results are below.pictures. 100 A DC current when 1.08 V DC voltage from non-transferable software is applied to the low voltage windingshas attracted.Find the single phase equivalent circuit parameters of this transformer.idle test:Voltage: 480V Power:114w current: 0.71Ashort circiut test:V: 10v P: 78w c: 18.3a
3) A three-phase transformer of 60 kVA (three-phase power), 13200/480 V (line A line) in delta-strella connection has a resistance of 0.02 PU and a reactance of 0.08 PU. For this transformer, calculate: a) The voltage regulation at full load and F.P. 0.85 in delay. (b) The regulation of voltage voltage to full cargo and F.P. Unitarian. c) The voltage regulation at full load and F.P. 0.85 in advance.
2. Given three identical ideal single-phase transformers with each rated at 100KVA and 7kV/3.5kV, they are connected as a three-phase transformer bank. The three-phase transformer has high voltage side connected in delta and the low voltage side is connected in wye. A three-phase 200KVA, wye connected load is connected at the low voltage side of the transformer. Calculate the following: a. Rated line-to-line voltage on each side b. Line current on each side of the transformer
When the transformer is loaded in a balanced fashion up to its nominal rating (10 MVA), calculate the high side line-to-line phasor voltages (ab, bc, ca). and low side phasor voltages both line-to-line and line-to-neutral (ab, bc, ca, a, b,c). as a reference for calculations the low side A line to neutral voltage is 7620V at an angle of 0 degrees when the transformer is at rated power. The transformer has the following characteristics: V: 138kV delta high side/ 13.2 kV wye low side 9% impedance X/R ratio of 20
a single-phase transformer serves a 7.2kw resistive loadlocated 200 ft from the transformer. each conductor from the transformer to load has an impedence of (0.78+j0.052) ohms per 1000ft. if the voltage at the load terminal is 240v, the magnitude of the voltage (v) at the transformer secondary is most nearly:
The Y/Y connected 3-phase step-up transformer has a rating of 1200 MVA, operating at 33 kV/340 kV and 60 Hz. Its impedance is characterized solely by a reactance of 11.5 percent. Its purpose is to increase the voltage from a generating station in order to supply power to a 340 kV transmission line. Answer the following questions: a) Draw and determine the equivalent circuit of this transformer, per phase, in per-unit. b) Using the per-unit method, determine the generator terminal voltage when the high-voltage (HV) side of the transformer supplies 800 MVA at a power factor of 0.90 with a lagging angle, and the voltage is 360 kV. Hint: Select the nominal voltage as a base voltage, and the nominal power rating as a base power.
A 10 MVA three phase load is to be served by a three phase transformer at aline voltage of 13.8 kV. The supply side voltage(line-line) is 138 kV. Varioussingle phase transformers are available in the warehouse but all havewindings with voltage ratings under 100 kV and current ratings under 250 A.Is it possible to serve the load using only three single phase transformers? Ifso, specify the three phase connections and the low and high voltage ratingsof the single phase transformers.
A short transmission line connects a step-up transformer on the source side with a series impedance of j0.5 ohms (referred to the primary) to a step-down transformer on the load side with a series impedance of 50 ohms (referred to the primary). The turn ratio of the step-up transformer is 1:10 and a no-load primary voltage of 23 (line-to-line) kV. The step-down transformer has a turn ratio of 35:2 and it has a Y-connected, balanced load of 0.490 +j 0.0816 ohms connected to its secondary side. A capacitor bank of -j0.171 ohms is added parallel to the load. Assuming an ideal transmission line, the load voltage (line-to-neutral) would be: O A. 7360 V O B. 6.2 kV O C. 12750 V O D. 4806 V O E. None of the other choices are correct
In a transformer that has 10 times more turns on the secondary side (side 2) than on the primary side (side 1), the magnitude of the voltage/EMF across the windings on the secondary side, E₂ will be... O a.... 10 times lower than the voltage/emf on the primary side, E₁. O b.... the same as the voltage/emf on the primary side. O c.... always zero regardless of the voltage on the primary side, E₁. O d.... 10 times higher than the voltage/emf on the primary side, E₁.

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