Problem 9 Two identical synchronous machines, cach rated 60 MVA, 15 kV, with a subtransient reactance of 0.1 pu, are connected through a line of reactance 0.1 pu on the base of the machine rating. One machine is acting as a synchronous generator, while the other is working as a motor drawing 40 MW at 0.8 pf leading with a terminal voltage of 14.5 kV, when a symmetrical three-phase fault occurs at the motor terminals. Deter- mine the subtransient currents in the generator, the motor, and the fault by using the internal voltages of the machines. Choose a base of 60 MVA, 15 kV in the generator circuit.

Problem 9 Two identical synchronous machines, cach rated 60 MVA, 15 kV, with a subtransient reactance of 0.1 pu, are connected through a line of reactance 0.1 pu on the base of the machine rating. One machine is acting as a synchronous generator, while the other is working as a motor drawing 40 MW at 0.8 pf leading with a terminal voltage of 14.5 kV, when a symmetrical three-phase fault occurs at the motor terminals. Deter- mine the subtransient currents in the generator, the motor, and the fault by using the internal voltages of the machines. Choose a base of 60 MVA, 15 kV in the generator circuit.

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 350 V, 50 Hz, Y-connected, eight poles synchronous generator has the OCC given in tabular form below (Phase Voltage versus the field current). The generator has a per-phase synchronous reactance of 3.2 Q, and an armature resistance of 0.6 Q. The machine supplies a 20 KVA load, at 0.8 PF lagging. How much field current must be supplied to the generator to keep the terminal voltage at 350 V? EA. (V) 65 125 260 290 320 350 380 420 450 470 IF, (A) 0.00 0.5 1.0 2.0 2.25 2.55 2.7 3.0 3.7 4.1 4.25 Select one: O a. If = 2.7 A O b. IF = 2.25 A O c. None O d. Ip = 2.55 A Clear my choice
Help soon.thanks.
True or False When synchronous machines are operated as motors, peak voltages increase in case of inductive loading.
A 150 MVA, Synchronous generator has a moment of inertia 47000 Kg-m2 and Kinetic Energy 1600 MJ. The synchronous speed of generator is
q1 c
a syn A: A sylienfonotus generator of 100 MVA, 22 kV, and 0.25 pu transient reactance supplies a motor of 50 MVA, 22 kV, and 0.2 pu transient reactance. The motor is drawing 40 MW at 0.8 power factor leading and terminal voltage of 21.9 kV. The line connecting them has a reactance of 0.05 pu on a base of 100 MVA. Find the transient currents in the generator, the motor, and the fault when a 3-ph fault occurs at the motor terminals. Take SB = 100 MVA, VB = 22 kV, and use the internal voltages %3D %3D of the machines method.
A 10 KVA, 400 V, 3 phase, star cónnected synchronous generator has an armature resistance of 0.80 per phase and synchronous reactance of 1.5 Q per phase. The voltage regulation at a power factor 0.6 lagging is
A generator is connected through a transformer to a synchronous motor as shown in the following figure. (All values in this problem are per unit.) Before the fault V,=0.9,1=1 with power factor 0.8 lagging. jX, P + jX ds jX" dm + E. E The reactances are Xd=0.15 , X,=0.1 , X âm=0.35. A symmetric fault occurs at P. Find the per-unit current magnitudes in the fault, the generator and the motor (a) using subtransient voltages. (b) using a Thevenin equivalent.
"During loss of prime mover, the alternator runs as synchronous motor " True False
Three identical steam-turbine generators G1, G2, and G3 are operating in parallel. Each generator is: 7.2 KV, 25.4 MVA, 60 Hz, 0.77 PF lagging, 4-poles, Y-connected, with synchronous reactance of 2 Q and an armature resistance of 0.05 Q. Each of generators G¡ , and G2 has a characteristic power-frequency slope of 5.8 MW/Hz, and no-load frequency of 62.5 Hz. Generator G3 has a characteristic power-frequency slope of 6.0 MW/Hz. Find the no-load frequency of generator G3 for which all generators supply a load of 38.5 MW, at fsys = 60 Hz. Select one: O a. fsys = 62.5 Hz O b. fsys = 61.85 Hz O c. None O d. fsys = 61.58 Hz Clear my choice
60 – MVA,15 – kV Problem 4 (Questions 21 through 23)-Two identical synchronous machines, each rated with a subtransient reactance of 0.1 py, are connected through a line of reactance 0.1 pu on the base of the machines rating. One machine is acting as a synchronous generator, while the other is working as a motor drawing 45-MW at 0.80 PF leading with a terminal voltage 14.5-kV. A symmetrical three-phase fault occurs at the motor bus. Calculate the following: 21. The generator fault current contribution (Ru.) is 22. The motor fault current contribution (p.u.) is 23. The total fault current is