Connect with us

multiple choice questions regarding electrical systems,,help!!!

Discussion in 'Electronics Homework Help' started by aabbddlah, Nov 8, 2012.

Scroll to continue with content
  1. aabbddlah

    aabbddlah

    1
    0
    Nov 8, 2012
    i v got a quiz and i m unable to find answers for these ,, i will appreciate it if u would assist me gents





    q1-Which of the following is NOT an approved transformer configuration by ANSI in regard to voltage phase shift between primary and secondary windings?

    a-Delta-Wye with thirty degrees lagging shift at the secondary

    b-Wye-Wye with zero phase shift

    c-Wye-Delta with thirty degrees lagging shift at the primary

    d-Delta-Delta with zero phase shift

    q2-What components of the fault current shall be considered during the first half cycle of the short circuit and for what purpose?

    a-Transient asymmetrical fault for interrupting rating of the circuit breakers.
    b-Sub-transient asymmetrical fault for Close and Latch rating of the circuit breakers.
    c-Transient symmetrical fault for Close and Latch rating of the circuit breakers.
    d-Sub-transient asymmetrical fault for interrupting rating of the circuit breakers.


    q3-Which of the following is NOT true in regard to fault levels in balanced three phase powewr systems?

    a-Arcing faults are higher than three phase bolted faults.

    b-Ground fault equals approximately the ground resistor current rating fault in resistive grounded systems.

    c-Phase to phase fault equals 0.867 of the three phase bolted fault.

    d-Ground fault equals approximately three phase bolted fault in solidly grounded systems.


    q4-An unbalanced wye with grounded neutral load consists of a 4 + j3 Ohm impedance connected to phase A, a 3 + j3 Ohm impedance connected to phase B, and a 4 + j5 Ohm impedance connected to phase C. The power source is balanced and the sequence is ABC with VAB = 208 at an angle of 0°. Assuming all currents are flowing from the source to the load, calculate the value of I(B) [where I(B) is the phase B current].??

    A~ 28.3 A at an angle of 165°
    B~ 49.0 A at an angle of -175°
    C ~28.3 A at an angle of -145°
    D ~28.3 A at an angle of -175°





    q5-which of the following statements is incorrect?

    a-Normal capacitive currents of the three phases of an ungrounded power system are unequal and hence they do not sum to zero.

    b-Phase reversal is a fundamental negative sequence harmonic.

    c-Phase to ground fault in an ungrounded balanced system will result in three times the single phase normal capacitive current.

    d-Harmonics of triple multiples of the fundamental are zero sequence while harmonics of double multiples of the fundamental are negative sequence.
     
  2. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    u nd 2 do yr own hmwrk... May I sugest u *t W elimination d options/answers uno r false, thN @ dat point progress 2 researchn d remaining answers 1 @ a tym 'til u narrow it dwn... n wen u myt narrow it dwn 2 2 options n r 404, thN ask 4 direction n we myt B abL 2 provide it...
     
    Last edited: Nov 8, 2012
  3. Yoa01

    Yoa01

    214
    0
    Jun 18, 2012
    You, sir, are a genius.
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    11,824
    2,756
    Nov 17, 2011
    Rotfl :D
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-