Delta connected unbalanced load

Discussion in 'Homework Help' started by peeka, Aug 7, 2009.

  1. peeka

    Thread Starter Member

    Apr 25, 2009
    21
    0
    the following is a delta connected load,connect to a 3phase 240 volt 60 supply

    a-b coil Z = 12 ohm pf = .7
    b-c coil z = 20 ohm pf = .8
    c-a coil z = 24 ohm pf = .7

    calculate total active power of the load. (answer is 7344)

    now ive found the current per phase by Z X pf = A

    i just have no idea ....well i forget how to add them all together to give me the total....
     
  2. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,157
    what did you figure for the power in each phase?

    I don't think you found the current per phase with that formula.
     
  3. peeka

    Thread Starter Member

    Apr 25, 2009
    21
    0
    i got a few answers for the power of each phase,
    ab - 2040
    bc - 3840
    ca - 4032
     
  4. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,157
    you might want to expand your answers, specifically,
    • write the formula you used
    • write the numbers you used
    That way we can diagnose the source of your error.

    Only do the ab portion, as bc and ca are just replicates of ab.
     
  5. peeka

    Thread Starter Member

    Apr 25, 2009
    21
    0
    well all i did was workout the line voltage which is given,

    delta 240 VL
    line current for a-b is 34
    phase current for a-b is 20

    etc...same thing for the rest

    then i just did P = root 3 X VL X IL
    then i get no where coz they dont add up lol im thinking i have to add the phase angles via pythagorus...could u jsut work it out coz i need it asap my big exam is in 1 day
     
  6. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,157
    P = (E^2 / Z) * pf

    Try substituting the numbers into that formula then add the resultant powers.
     
Loading...