Three single-phase step-up transformers rated at 50 MVA, 13.2 kV/80 kV are connected in delta-wye on a 13.2 kV transmission line. If they feed a 120 MVA load, calculate the following: a. The secondary line voltage b. The currents in the transformer windings c. The incoming and outgoing transmission line currents

Three single-phase step-up transformers rated at 50 MVA, 13.2 kV/80 kV are connected in delta-wye on a 13.2 kV transmission line. If they feed a 120 MVA load, calculate the following: a. The secondary line voltage b. The currents in the transformer windings c. The incoming and outgoing transmission line currents

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...

See similar textbooks

Similar questions

A 600 kVA, 1-phase transformer has an efficiency of 92 % both at full-load and half- load at unity power factor. Determine its efficiency at 60 % of full-load at 0.8 power factor lag.
A low voltage distribution transformer feeds two different loads with a three-phase line. The nominal voltage of the line is 400 Volt. The total length of the feeder is 500 m. The distance from the transformer to these loads is 140 m and 340 m, respectively. Their consumption is 11 kVA with a 0.8 lagging power factor and 10 kW with a 0.8 lagging power factor, respectively. The feeder's cross-section is 15 mm2 and the feeder's conductivity is 56 m/ohm.mm2. Find the following information. The distance from the transformer to the maximum voltage drop point is m The maximum voltage drop is Volt The power loss between the transformer and 11 kVA load is Watt.
A three-phase Y-Y transformer is rated at 25 MVA, 13.8-kV:69-kV and has a single-phase equivalent series impedance 62 + j388 mΩ referred to the low-voltage winding.a. A three-phase short circuit is applied to the low-voltage winding. Calculate the voltage applied to the high-voltage winding which will result in rated current into the short circuit.b. The short circuit is removed and a three-phase load is connected to the low-voltage winding. With rated voltage applied to the high-voltage winding, the input power to the transformer is observed to be 18 MW at 0.75 power-factor lagging. Calculate the line-line terminal voltage at the load.
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 13.2 (line-to-line) kv. The step-down transformer has a turn ratio of 15:1 and it has a Y-connected, balanced load of 0.667 +j 0.111 ohms connected to its secondary side. A capacitor bank of -j0.239 ohms is added parallel to the load. Assuming an ideal transmission line, the effective impedance of the system (per phase) seen by the source would be: O A. 0.093 + j0.249 O B. 0.372 + j0.996 OC.3.72 + j9.96 O D. None of the other choices are correct O E. 0.186 + j0.498
3.8. Three identical 9-MVA, 7.2-kV/4.16-kV, single-phase transformers are con- nected in wye on the high-voltage side and delta on the low voltage side. The equivalent series impedance of each transformer referred to the high-voltage side is 0.12 + j0.82 S per phase. The transformer supplies a balanced three- phase load of 18 MVA, 0.8 power factor lagging at 4.16 kV. Determine the line-to-line voltage at the high-voltage terminals of the transformer.
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.
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.
Two single-phase transformers, having equal turns ratio, in parallel supply a secondary load of 1,000 A at 0.8 pf lagging. For each transformer the secondary emf on open circuit is 3,300 V and their total leakage impedances referred to secondary are (0.10 + j0.20) ohms and (0.05 + j0.040) ohm, respectively. Determine the output current on each transformer.
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 13.2 (line-to-line) kV. The step-down transformer has a turn ratio of 15:1 and it has a Y-connected, balanced load of 0.667 +j 0.111 ohms connected to its secondary side. A capacitor bank of -j0.239 ohms is added parallel to the load. Assuming an ideal transmission line, the load voltage (line-to-neutral) would be: A. 5118 V B. 6.2 kV C. 8865 V D. None of the other choices are correct E. 4225 V
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.
It is bartleybe's policy that if questions objective than you need to solve at least first 3 questions.
In the system shown in Figure 1, the transformers are connected star-star with both star points grounded and the generator is connected in star with its star points grounded. The per unit impedances of each element on a 40 MVA base are given in Table 1 and the voltage levels are given in Table 2. Z [p.u.] 0 2 tööt Generator 0.01 +j0.08 p.u. L Figure 1: A section of the distribution system Transformer T1 Line V BASE [KV] 0.04 + j 0.03 + j 0.15000000000000002 0.06000000000000000 Generator Table 1: Sequence impedances (p.u. on 40 MVA base) 3 T2 181. Line 3 10 Table 2: Voltage bases (kV) Load 1 Transformer T2 Load Current A load current of 11.316 kA is flowing with a lagging power factor of 90 %. Convert this to a current vector in per-unit. IL = 0.04 + j 0.06000000000000000