# 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
3,311
1,108
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
3,311
1,108
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
3,311
1,108
P = (E^2 / Z) * pf

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