# Thread: Need help with this question of AC circuit..urgent?

1. ## Need help with this question of AC circuit..urgent?

a potential difference of 200 /__ 30 deg is applied to two circuits connected in parallel. the current in the respective branches are 20 /__ 60 deg and 40 /__ 3 deg. Find:

1) Active power consumed by each branch and whole circuit
2) Reactive power in each branch and in the whole circuit

i thought it would b solved in the following way. is it correct?
since power =VI

for active power in branch 1
I=I(1) cos 60
V= v cos 30

for reactive power in branch 1
I= I (1) sin 60
V=v sin 30

for total active power
I=i(1)cos60+i(2)cos3
V=vcos 30

2. ## Re: Need help with this question of AC circuit..urgent?

The KVA of the first branch is KVA=E*I =(200 * 20) / 1000 = 4 KVA
The power factor is the cosine of 60 degrees = 0.5
The KW of this branch is KW=KVA*PF = 4 * 0.5 =2KW
The reactive power in the first branch is KVAR=Tan60degrees*2 = 1.732*2 = 3.464 KVAR

The KVA of the second branch is KVA=E*I =(200 * 40) / 1000 = 8 KVA
The power factor is the cosine of 3 degrees =0.998629535
The KW of this branch is KW=KVA*PF = 8 * 0.998629535 =7.989 KW
The reactive power in the second branch is KVAR=Tan3degrees*7.989 = 0.0524*7.989 = 0.4186 KVAR

The total power consumed in whole circuit is 2 = 7.989 = 9.989 KW
The KVAR of the whole circuit is 3.464 + 0.4186 = 3.8826 KVAR

I wonder if the phase angle in branch 2 was 3 or 30 degrees. I worked it as 3 degrees.

3. ## Re: Need help with this question of AC circuit..urgent?

girls are always intelligent.... congrats saloni.....

4. ## Re: Need help with this question of AC circuit..urgent?

Thanks saloni for helping out...keep it up..

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