Basic AC circuit - Find current in every branch, reactive, active and full power, and power coeffici

Thread Starter

Karalis Artūrs

Joined Apr 17, 2016
I've run into a bit of trouble with an assignment in AC Circuits, could someone point me in the right direction?

Here is the circuit:

The task is to find current in every branch, reactive, active and full power as well as the power coefficient. And construct the current and voltage vector.
The values are:

I've already done a similar task, but without the Z1.
In such case I first got the power and phase shift angles, then get the active and reactive conduction of each branch. Then the full conduction of each branch. And from that I get the power in each branch. From that it's easy to get the powers and coefficient. Something like this:

But in this task I'm a bit confused due to the Z1 and the values of X2 and R3 (which are zeros) - I somehow end up at a formula where something has to be divided by 0. And also in that task the U value was given.

Thanks in advance for any tips.


Joined Jun 17, 2014
Hello there,

If you have already solved a circuit just like this but without Z1, then that probably means you have used a voltage U as the voltage at node 1 in the new circuit so all you have to do then is FIRST calculate what U is in the new circuit, then you can do it the same way. Of course U may be complex in the new circuit that's about the only difference then.

I you need to include Z1 in your analysis then you just need to lump the whole network first into one impedance then go from there.


Joined Mar 31, 2012
In the first case, you have the voltage U12. Can you find the current in branch 2? Can you find the current in branch 3? If so, then can you find the current in branch 1? If so, then if you know U12, the current in branch 1, and the value of Z1, can you find U?