A 10,000 kVA, 6.9 kV generator has percentage reactance to positive, negative and zero sequence currents 10%, 7% and 3% respectively and its neutral is grounded solidly. The generator is open circuited and excited to its rated voltage. Calculate the line currents (a) when a single line to ground fault develops on phase 'a' of the generator and (b) when the generator phases b and c are shorted.

A 10,000 kVA, 6.9 kV generator has percentage reactance to positive, negative and zero sequence currents 10%, 7% and 3% respectively and its neutral is grounded solidly. The generator is open circuited and excited to its rated voltage. Calculate the line currents (a) when a single line to ground fault develops on phase 'a' of the generator and (b) when the generator phases b and c are shorted.

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 500 kVA, 6.6 kV star connected alternator has a synchronous reactance of 1.0 per phase and negligible resistance. The differential relay operates if the out of balance current through it exceeds 30% of the normal full load current of the alternator. The star point of the alternator is earthed through a resistance of 5 2. What percent of the stator winding is left unprotected ? Show that the effect of the alternator reactance can be neglected.
Consider a single phase transformer of rating 150 KVA, 1500/150, 50 Hz. Let the series resistance due to windings be 0.2 ohm and 0.002 ohm on the HV and LV sides, respectively. Let the series reactance due to leakage flux be j0.45 ohm and j0.0045 ohm on the HV and LV sides, respectively. While conducting Short Circuit test, the HV side should be excited with Volt Input power factor while conducting Short Circuit test is lagging
The severity of line-to-ground and 3-phase faults at the terminals of an unloaded star connected synchronous generator is to be same. If the terminal voltage is 1 p.u. and X, = X2 = j0.35 p.u., Xgo = j0.05 p.u., for the alternator, then the required inductive reactance for neutral grounding is (a) X = j0.1 p.u. (b) Xn =j0.015 p.u. (c) Xạ =j0.15 p.u (d) Xn =j02 p.u.
2.2 Three 20 MVA, 11/0.66 kV, 50 Hz, 3-phase transformers are connected together to supply a mining load. State the main conditions necessary before these three transformers are connected together. (4) nit%202%20Thre....pdf A Unit%202%20Thre....pdf A Unit%201%20-%2.pdf 40) Show al 9:12 AM 7/24/2021
Q-5-) 60 Hz generator supplies 0.50 Pmax power to a busbar with infinite power over a conveying line. When a fault occurs, the reactance value between the generator and the infinite bus becomes 400% times the value before the fault. When the fault is isolated, the maximum power that can be transferred generator to the endless bus is 75% of the original (initial) maximum value. Accordingly, using t area criterion method, calculate the critical clearance angle of the system. 00
.18 Assume that a 5 mile long feeder is supplying a 2000 kVA load of increasing load density starting at a substation. If the K constant of the feeder is given as 0.00001%VD per kVA-mi, determine the following: (a) The percent voltage drop in the main. (b) Repeat part (a) but assume that the load is a lumped-sum load and connected at the end of the feeder. (c) Repeat part (a) but assume that the load is distributed uniformly along the main.
Solve the problem
B:A 20 MVA transformer which may be called upon to operate at 30% overload, feeds 11 KV busbars through a circuit breaker: other circuit breakers supply outgoing feeders. The transformer circuit breaker is equipped with L000/5 A CTs and the feeder circuit breakers with 400/5 A CTs and all sets of CTs feed induction type over current relays. The relays on the feeder circuits breakers have a 125% plug setting, and 0.3 time setting. If 3 ph fault current of 5000 A flows from the transformer to one of the feeders, find the operating time of the feeder relay, the minimum plug setting of the transformer relay and its time setting assuming a discrimination time margin of 0.5 sec. Relays having the following characteristics for TMS-1 PSM T in sec. 2 3.6 5 10 15 20 10 6 3.9 2.8 2.2 2.1
The 3-φ generator is rated 25 MVA, 13.8 kV. The positive, negative and zero sequence reactances are respectively 0.25, 0.30 and 0.15 pu. The neutral of the generator is grounded with a reactance of 1.5 Ω. Determine the sub-transient current and line to line voltages of the generator when a severe fault occurs among the unsymmetrical faults at the generator terminals with the generator operating unloaded at rated voltage. Neglect resistance.
2A. What is another term for "shunt"? a) in series b) in parallel c) compounded d) none of the above 2B. Which of the following is/are a basic type of DC generator connection? a) series b) shunt c) compound d) all of the above
Figure shows a generator connected to a metropolitan system (infinite bus) through highvoltage lines. The numbers on the figure indicate the reactances in p.u. Breakers adjacent to afault on both sides are arranged to clear simultaneously. Determine the critical clearing anglefor the generator for a 3-phase fault at the point P when the generator is delivering 1.0 p.u.power. Assume that the voltage behind transient reactance is 1.2 p.u. for the generator andthat the voltage at the infinite bus is 1.0 p.u.
A star connected neutral grounded 3-phase synchronous generator consists of 0.1 p.u of sub transient reactance ,0.3 p.u of transient reactance and 0.5 p.u of leakage reactance.The zero sequence reactance of the synchronous reactance is None of the above 0.5 p.u 0.7 p.u 0.6 p.u