How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask akch2002 Your Own Question

akch2002, Engineer
Category: Homework
Satisfied Customers: 3099
Experience:  Home work expert
Type Your Homework Question Here...
akch2002 is online now
A new question is answered every 9 seconds

Power System Transients Homework Problems

This answer was rated:

* Note - All questions should be answered with Laplace Transforms when possible.




Figure 3P.2 shows two capacitor banks, C1 and C2, in a substation. C1 is energized, but C2 is discharged. The three-phase, 60 Hz rating of the banks are: C1, 5 MVA; C2, 3 MVA, on a 13.8 kV base. The source has a short circuit rating of 20kA rms at 13.8 kV. The inductance of the loop between C1 and C2, represented by L2 is 30μH.


Figure 3.3


Calculate the peak transient voltage that will appear on C2 and the peak transient current that will flow in L1, if the switch S is closed at the peak of the voltage cycle. Point out any assumptions you make.




Figure 3.5


A line to ground fault occurs as indicated in Fig. 3P.4, close to the secondary terminals of a 230/34.5 kV transformer. The transformer has a three-phase rating of 100 MVA; it has 0.1 pu reactance on this base.


a.The fault current

b.The time to peak of the transient recovery voltage when the circuit breaker opens to interrupt the fault current. A value of 12.7nF can be assumed for the effective capacitance per phase of the transformer secondary winding.




Figure 3.12


C1=100μF; C2=40μF; L1=10mH; L2=20mH; C1 and L1 in Fig. 3P.8. are oscillating; C2 and L2 are de-energized. The switch is closed when V(C1 )=0 and I2=500A. Calculate: a.Peak voltage reached on C2 b.Peak current reached in L2 c.Frequency of the current in L1 d.Maximum voltage on C1 prior to closing the switch

Thanks. I will try to upload the answers in 12 hrs or so as communicated in other post.
Customer: replied 4 years ago.

Thank you, XXXXX XXXXX to spend some time now reviewing your other answers in more depth to better my understanding, I may ask a couple of questions later.


Thanks again.

You are most welcome.
I am on your job. Once it is over, I will upload the answers. It may take some more time.
Customer: replied 4 years ago.

No problem, I'm working on a paper for my MBA course right now. It will likely be 2 hours before I get to look at my engr work again.

OK. Thanks.
Customer: replied 4 years ago.

How are the problems coming along?


Sorry for delay. I could solve all the problems. Only typing is left. I will upload the answers today.

Customer: replied 4 years ago.

great, thank you. i'll need to submit the assignment within the next 3 hours.

OK. I will try to upload the answers by that time.
In 3.5, I think there is symmetrical fault. Kindly confirm.
Customer: replied 4 years ago.

It doesn't state explicitly, and I cannot say I understand the concept as well as I would like, but a simple L-G fault would be unsymmetrical, and would only be symmetrical if it were L-L-L-G. L -Line and G -Ground

Had this been asymmetrical fault, then zero sequence of the transformer should also have been given; but zero sequence impedance is not given. Hence, I conclude it to be symmetrical fault. The figure also represents symmetrical fault(LLLG). I am almost sure but I just wanted to confirm as language is confusing.
Customer: replied 4 years ago.

Are you getting close to complete, i'm getting into my last hour to submit.

Here are answers.
word file
Kindly rate the answers. BONUS will be appreciated.
Customer: replied 4 years ago.

After reviewing some of the answers you provided, several do not mesh with solutions i found from another professor. Of which I found the final answers for 3.3 and 3.12


for 3.3.

a) VC2 Max = 14.11 kv

b) IL1 Max = 1747 A


for 3.12

a)4.23 kV

b)204.12 A


d) 5kV (This one matched the other instructor)


Could you review a little further for me?


I can look into these problems tomorrow only. Should I opt out so that some expert may try.
In3.12, frequency should be 159Hz. I a not able to follow how frequency will be 164.74Hz.
Customer: replied 4 years ago.

Not yet, I'm going to look at it a bit further and see if I can find any discrepencies. I feel i have enough information amoung the problems you've answered to really get a fell for the questions. I appreciate your work on this very much.

Actually, there are assumptions in my solutions. I have assumed that direct voltage is applied across L2 and C2 in 3.3 and solved the problem. Actually voltage will vary with time and this assumption may be leading to differences in answers.
In 3.12, L1 and C1 are known, we can calculate the frequency. Had frequency been incorrect, I could not have got correct answer in(d).Hence, frequency as calculated seems to be correct.
Anyway look into the solutions.
Probably we may gave to write loop differential equations and solve them without making any assumptions.

Should I attempt these questions again?
Customer: replied 4 years ago.

that would be appreciated, i am working on it more now.

OK. I will again try. Thanks.
Customer: replied 4 years ago.

I think you are on track, it appears the time variance is likely the issue in 3.3, I've been able to validate your c1 and c2 calculations for positive, but still working on the rest a bit. Thanks for staying with the problem for me.

OK. I will come back to you.
Could you co-relate the answers?
Customer: replied 3 years ago.
,I was looking to mark the last question I asked you as satisfactory, but cannot find a link. The homework came back today finally as correct. Sorry, my comfort level for getting help online is not very strong. I do appreaciate your help and hopefully could utilize you again sometime.

You need to spend $3 to view this post. Add Funds to your account and buy credits.
akch2002, Engineer
Category: Homework
Satisfied Customers: 3099
Experience: Home work expert
akch2002 and other Homework Specialists are ready to help you
Thanks for rating excellent. Kindly mention for 'Ashok Kumar' in the beginning of the question when you wish me to reply your question.
Customer: replied 3 years ago.

I have posted another question but did not mention your name if you would like to look at it.

I will have a look at it.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
< Previous | Next >
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland
  • He answered my question promptly and gave me accurate, detailed information. If all of your experts are half as good, you have a great thing going here. Diane Dallas, TX

Meet The Experts:

  • LogicPro



    Satisfied Customers:

    Expert in Java C++ C C# VB Javascript Design SQL HTML
< Last | Next >
  • LogicPro's Avatar



    Satisfied Customers:

    Expert in Java C++ C C# VB Javascript Design SQL HTML
  • Manal Elkhoshkhany's Avatar

    Manal Elkhoshkhany


    Satisfied Customers:

    More than 5000 online tutoring sessions.
  • Linda_us's Avatar


    Finance, Accounts & Homework Tutor

    Satisfied Customers:

    Post Graduate Diploma in Management (MBA)
  • Chris M.'s Avatar

    Chris M.

    M.S.W. Social Work

    Satisfied Customers:

    Master's Degree, strong math and writing skills, experience in one-on-one tutoring (college English)
  • F. Naz's Avatar

    F. Naz

    Chartered Accountant

    Satisfied Customers:

    Experience with chartered accountancy
  • Bizhelp's Avatar



    Satisfied Customers:

    Bachelors Degree and CPA with Accounting work experience
  • Seanna's Avatar



    Satisfied Customers:

    3,000+ satisfied customers, all topics, A+ work

Related Homework Questions