Answered: A 3-phase 33 kV, 37.5 MVA alternator is…

A 3-phase 33 kV, 37.5 MVA alternator is connected to a earth fault on one phase at the remote end. The positive of the alternator are 0.18, 0.12 and 0.1 per unit of its ratin

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

Chapter9: Unsymmetrical Faults

Section: Chapter Questions

Problem 9.7MCQ

See similar textbooks

Related questions

Q: A three-phase Y-connected synchronous generator is rated at 100 MVA, 12.5 kV, 0.85 PF leading and 50…

Q: Question: Find out the appropriate protection schemes for stator winding protection of alternator.…

A: The most common system used of the protection of stator winding foults in the differential…

Q: The zero sequence current of a generator for line to ground faults is į 3.0 p.u. Then the current…

A: Given, For the line to ground fault, the zero-sequence current, I0=j3.0 pu

Q: The negative sequence current of a solidly grounded generator for single line to ground fault is j…

A: Given that negative sequence current of SLG fault is Ia2 =j2.5 pu. Although for single line to…

Q: Loss of excitation is one of the stator faults of alternator which is operational at power station O…

A: 1)Loss of excitation is one of the fault on rotor. 2)Loss of excitation is a very common fault in…

Q: A 30 kv, 50 Hz, 50 MVA generator has the positive, negative, and zero sequence reactances of 0.25…

A: Evaluating the value of the fault current for the single line to ground fault:

Q: Q5: A generator is connected through a transformer to a synchronous motor. Reduced to the same base,…

Q: A 30 MVA 11 kV generator has a reactance of 0.10p.u.on its own base. Determine the per-unit…

A: Given: For the generator Sbold=30 MVAVbold=11 kVXpuold=0.1 puSbnew=50000 KVA=50 MVAVbnew=33 kV

Q: Problem #2: A transformer is fed from a generator via a 5-cycle breaker. Generator reactance are:…

Q: (b) A three-phase A-connected synchronous generator is rated at 120 MVA, 10.5 kV, 0.85 PF leading…

Q: Q1/ Two generators are interconnected by a reactor of I Ohm reactance per phase. The estimated short…

A: multiple questions As per our guidlines we are supposed to do the first question if a student asks…

Q: A three-phase A-connected synchronous generator is rated at 120 MVA, 10.5kV, 0.85 PF leading and 60…

Q: 9. Two alternators each having 4% speed regulation are working in parallel. Alternator 1 is rated 12…

A: Given that two alternators are in parallel. Speed regulation of alternator is 0.04. R in pu=0.04 For…

Q: A 25 MVA, II kV generator has X"d=0.2 p.u. X2 = 0.3p.u. and X0=0.1 p.u. Tht neutral of generator is…

Q: Distribution transformers are generally protected from damage due to excessive internal…

A: Ans: Option C is correct. Distribution transformers are generally protected from damage due to…

Q: 64. A 50 Hz, 11 kV, 3-phase alternator with earthed neutral has a reactance of 5 ohms per phase and…

A: Given, A 50 Hz, 11 kV, 3-phase alternator with earthed neutral has Reactance = 5 ohms per phase The…

Q: positive, negative, and zero sequence reactances of 0.25 pu, 0.15 pu, and 0.05 pu, respectively. The…

A: The expression for single line to ground fault current is given as:

Q: A 12 MVA, 132/6.6 kV, transformer having a reactance of 0.15 pu is fed from an infinite bus. The…

A: The components given in the circuit will be replaced by per unit reactance respectively. The…

Q: The positive, negative and zero sequence reactances of a 15 MVA, 11 kV three-phase wye-connected…

A: In this question, We need to determine the fault current If if single line to ground fault…

Q: A 3 phase, 50 Hz, 50 MVA, 11 kV, alternator has a solidly grounded neutral with zero, positive,…

A: In this question, Find the ohmic value of neutral reactance if double line to ground fault current…

Q: For the same alternator, the ratio of rated KVA, when connected as 3-phase winding alternator to…

A: During the 3-phase connection, the value of the phase spread will be ϕ=π3 Thus, the value of the…

Q: The fault current level of a circuit breaker used in a transmission line with phase voltage 3.3 kV…

A: Given Phase voltage = 3.3kv S = 60 MVA FIND CURRENT

Q: In which portion of the transmission system is the occurrence of faults more common a alternator B…

A: Answer:C transmission line

Q: The reactance of the synchronous generator after few cycles of short circuit is The sequence…

A: Zph''< zph'< Zph Positive < negative< zero sequence imedances

Q: A 30-MVA alternator with 15% reactance is connected to a bus bar. A second alternator rated 25-MVA…

A: The solution is given below

Q: A three-phase 50 MVA 10 kV generator has a reactance of 0.2 pu per phase. Hence the per-unit value…

Q: or A 25 MVA, 13.2 KV, alternator with solidly grounded neutral has a sub transient reactance of…

A: Given: A alternator in which S=25MVAVl=13.2KVXd''=0.025puX2=0.35puX0=0.10puZf=0pu Fault current is…

Q: How to control on the generated emf of 3 phase synchronous generators.

A: Three-phase synchronous generators are mainly used in windmill turbines.Due to the change in wind…

Q: The severity of line-to-ground and 3-phase faults at the terminals of an unloaded star connected…

A: Given, Terminal voltage, E = 1 pu Positive, negative, and zero sequence reactance is X1=X2=j0.35 pu…

Q: Three 6.6 kV altenators of ratings 8 MVA, 2 MVA and 5 MVA have per unit reactances of O.16, 0.08 and…

A: Given:3, 6.6 kV alternator1st generator rating=8MVA, Xpuold1=0.16 pu2nd generator rating=2MVA,…

Q: The base current and base voltage of a 345 kV system are chosen to be 3000A and 300kV respectively.…

A: The solution is given below

Q: 36 slot 4 pole 3 phase alternator winding pg7 slot electrical angle by which the winding is quality…

A: Electrical machines can be either generator, transformer or motors. They can be either Ac machines…

Q: (b) A three-phase A-connected synchronous generator is rated at 120 MVA, 10.5 kV, 0.85 PF leading…

Q: What is the negative sequence component

Q: "A 3-phase, 23 kv, 60 Hz synchronous generator is connected in star and its neutral point is earthed…

A: As per the guidelines we need to solve only first three sub part of given question. we need to…

Q: Which of the following is the severest and has the lowest percentage of occurrence? DLG L-L 3-Phase…

Q: A 39.6 kV, 6 MVA star connected alternator has a reactance of 1.5 ohm per phase and negligible…

A: % of winding unprotected is given by =I'RV×100where,I' = Operational current limit…

Q: A synchronous generator has a constant mechanical input power of Po. In the fault followed by the…

A: Given A1=1.6 A2=0.4

Q: For the same alternator the ratio of rated kva, when connected as a three phase winding alternator…

A: Solution: When connected to single-phase winding, Let the number of turn/Phase=N Phase Spread…

Q: Which of the following is not a boundary condition for an SLG fault on phase 'a' of a power system?…

A: Solution: Single line to ground fault (SLG fault) is the fault that occurs in the transmission line…

Q: Single line to ground fault of a solidly grounded generator positive sequence current is j2.5 p.u,…

A: Choose the correct option Positive sequence current= j2. 5 puri Then current flow in neutral?

Q: A 12 MVA, 132/6.6 kV, transformer having a reactance of 0.15 pu is fed from an infinite bus. The…

A: We will replace the components given in the circuit with per unit reactance respectively. The…

Q: sunny Note: - You are attempting question 4 out of 12 A three phase,20 MVA, 33 kV alternator having…

A: In this question we need to choose a correct option.

Q: 9. Four identical alternators each rated for 20 MVA, 11 KV have a subtransient reactance of 164 are…

Q: The reactance of the synchronous generator after sometime of the fault cleared is ............

A: The reactance of the synchronous generator before fault is Xb During fault reactance is less than…

Q: A generator is rated 800kVA, 2400, 60Hz, 3-phase, 6-poles, and Y-connected has 10% synchronous…

A: In this question, We need to determine the three phase fault current if three phase fault occur.…

Q: Draw and explain the phasor diagram for two transformers in parallel

Q: A 3-phase star connected alternator is rated 30 MVA, 13.8 kV and has the following sequence values…

A: A 3-ph star connected alternator has, Rating (S)= 30 MVA Line voltage (VL)= 13.8 kV Positive…

Concept explainers

Fault Analysis

In an electrical engineering system, a fault is an abnormal electric current flowing through the system, and fault analysis is the study of these faults. For instance, a short-circuit is a fault where the live wire touches the ground or neutral wire. If a circuit is interrupted by a failure of a current-carrying wire then an open circuit fault occurs. The open-circuit faults are also called series faults. One or more phases or ground may be involved in a three-phase fault or may occur only between two phases. Current flows into the earth in case of a ground fault or earth fault. For most situations, the prospective short circuit current of a fault that is predictable can be calculated. To limit the loss of service because of a failure, the protective devices can detect fault conditions and operate circuit breakers and also other devices. All phases equally can be affected in a poly-phase system which is known as symmetric electrical fault. The asymmetric fault becomes more complicated to analyze if only some phases are affected. By using methods such as symmetrical components, the power system analysis of these types of faults is often simplified. The main objective of power system protection is to design, detect, and interrupt power system faults.

Question

A 3-phase 33 kV, 37.5 MVA alternator is connected to a 33 kV overhead line which develops an
earth fault on one phase at the remote end. The positive, negative and zero sequence reactances
of the alternator are 0.18, 0.12 and 0.1 per unit of its rating while those of the line are 6.3, 6.3 and
12.6 ohm per conductor. Find (a) fault current (b) line to neutral voltages at alternator terminals.
= 13 20KV
an
(a) I 1.555 kA (b) V
[Von = 18 -119.16° kV, V, = 18 119.16° kVJ
%3D
%3D
en

Expert Solution

This question has been solved!

Explore an expertly crafted, step-by-step solution for a thorough understanding of key concepts.

This is a popular solution!

SEE SOLUTION Check out a sample Q&A here

Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

Trending now

This is a popular solution!

Step by step

Solved in 6 steps with 6 images

SEE SOLUTION Check out a sample Q&A here

Knowledge Booster

Learn more about

Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, electrical-engineering and related others by exploring similar questions and additional content below.

Similar questions

A three-phase circuit breaker has a 15.5-kV rated maximum voltage, 9.0-kA rated short-circuit current, and a 2.50-rated voltage range factor. (a) Determine the symmetrical interrupting capability at 10-kV and 5-kV operating voltages. (b) Can this breaker be safely installed at a three-phase bus where the symmetrical fault current is 10 kA, the operating voltage is 13.8 k V, and the (X/R) ratio is 12?
At the general three-phase bus shown in Figure 9.7(a) of the text, consider a simultaneous single line-to-ground fault on phase a and line-to-line fault between phases b and c, with no fault impedances. Obtain the sequence-network interconnection satisfying the current and voltage constraints.
Thévenin equivalent sequence networks looking into the faulted bus of a power system are given with ?1=?0.15 , ?2=?0.15 , ?0=?0.2and ?1=1∠0°per unit. Compute the fault currents and voltages for the followingfaults occurring at the faulted bus: (a) Balanced three-phase fault (b) Single line-to-ground fault (c) Line-line fault (d) Double line-to-ground fault Which is the worst fault from the viewpoint of the fault current?
For the radial power system shown in Figure 3, calculate the line-to-ground fault current flowing in each of the circuit breakers for faults at bus 1, bus 2 and bus 3. Also determine the corresponding faulted phase voltage, assuming that the generator is ideal, with a terminal voltage of 1.0 pu. *positive sequence impedance = negative sequence impedance
A 10 MVA, 6.9 kV alternator has a positive, negative andzero sequence per unit reactance components of 0.30, 0.25 and 0.05 respectively. If the neutral of the generator isgrounded through a reactor of 0.48 ohms, determine the fault current during a single line to ground fault.
Given the network shown, for a solid three-phase fault on bus 2 (a) find the sub transient current in per unit from generator 1 and in line 1-2; (b) find the voltages at bus 1 and bus 3. Assume that no current is flowing prior to the fault and that the pre fault voltage at bus 2 is 1.0 per unit. Show your solution.
A 3-phase, 13.8 kV, 10 MVA alternator has positive,negative and zero sequence reactances of 0.20, 0.020 and0.10 pu. Determine the fault current if a double line toground fault occurs.
n a power system what happens to phase voltages for a single line-to-ground fault as fault reactance value is increased from 0pu to 2pu?
Given the 4 bus network shown below, assume that there are no loads and all buses are at the rated voltage and all have the same phase angles. Assume that shunt capacitances are neglected. The relevant transient reactances for the generators and the reactances for the transformers are shown. Solve for the fault current through the fault impedance for a fault at bus 4 with a fault impedance of j0.1 pu. HINT: Use Delta to Wye conversion.