An alternator and a synchronous motor are rated 44.1 MVA, 14.8 kV and each has a subtransient reactance of 19.9 %. The line connecting them has a reactance of 19.2% on the base of the machine ratings. The motor is drawing 54.8 MW at 0.67 power factor leading and a terminal voltage of 14.9 kV when a symmetrical bolted three phase fault occurs at the motor terminals. Calculate the rms value in Ampere of subtransient current in the alternator during the fault.

An alternator and a synchronous motor are rated 44.1 MVA, 14.8 kV and each has a subtransient reactance of 19.9 %. The line connecting them has a reactance of 19.2% on the base of the machine ratings. The motor is drawing 54.8 MW at 0.67 power factor leading and a terminal voltage of 14.9 kV when a symmetrical bolted three phase fault occurs at the motor terminals. Calculate the rms value in Ampere of subtransient current in the alternator during the fault.

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.21MCQ: In order to avoid difficulties with third-harmonic exciting current, which three-phase transformer...

See similar textbooks

Similar questions

The reactance of the synchronous generator after few cycles of short circuit is The sequence components have same voltage magnitude.
A generator is having an impedance of 0.93 p.u., before fault occurs in it. What is the possibility of impedance during fault?
A 12 MVA, 132/6.6 kV, transformer having a reactance of 0.15 pu is fed from an infinite bus. The transformer feeds two motor each 6 MVA, 6.6 kV. Each motors has a transient reactance of 0.14 pu and a subtransient reactance of 0.30 pu based on its own rating. A three phase balanced fault occurs at the terminals of one motor as shown in the figure below. Find the subtransient fault current and subtransient current in breaker. M1) 132/6.6 KV СВ 38 CB Infinite Bus M2 Fault
7. An inductive load is shared by two identical synchronous generators A and Bequally, if the excitation of alternator A is increased. (a) Alternator A will deliver more current and alternator B will deliver less current. (b) Alternator B will deliver more current and alternator A will deliver less current. (c) both will continue to deliver same current. (d) both will deliver more current.
A 100-MVA synchronous generator supplies 62.5 MVA of power at 0.8 lagging power factor. The reactance between the load and the generator is normally 1.0 pu, but it increases to 3.0 pu because of a sudden three-phase short circuit. The fault is subsequently cleared and the generator then supplies 43.75 MVA at 0.8 lagging power factor. Determine the critical clearing angle. Select one: a. 88.58 b. None c. 78.58 d 68.58
The primary is 3000 turns, while the secondary is 6000 turns a. single-phase b. double-phase c. step-up d. step-down
The impedance value of a generator is 0.2 pu on a base value of 11 KV, 50 MVA. The impedance value for a base value of 22 KV, 150 MVA is?
(iv) none of above 64. A 50 Hz, 11 kV, 3-phase alternator with earthed neutral has a reactance of 5 ohms per phase and is connected to a bus-bar through a circuit breaker. The distributed capacitance upto circuit breaker between phase and neutral is 0.01 µF. The peak re- striking voltage across the contacts of the breaker is
In order to avoid difficulties with third-harmonic exciting current, which three-phase transformer connection is seldom used for step-up transformers between a generator and a transmission line in power systems. (a) Y- (b) -Y (c) Y-Y
For the same alternator the ratio of rated kva, when connected as a three phase winding alternator to when connected as a single phase alternator by using all the coils is
In large transformers, the total copper losses may vary from % of the rated output. O 0.2 to 0.6 O 0.8 to 1.5 O 0.4 to 1 O 0.5 to 1
A parallel connection of a RL branch with a C branch is connected across a 100V AC mains. At first R = 10 ohms, L = 20mH and frequency of 1000rad / s, the current measured is 2.2361A at 89.44 leading power factor. A) Determine the initial capacitance. B) However, a fault occurs on the capacitor branch making its capacitance 20% lower and a resistance of 5 ohms is detected. If this faulty circuit is rerun but at a frequency of 500 rad / s, determine the new current that will flow through the circuit