The Attempt at a Solution
a) the question is to transform star to delta ?
Okay, that is correct. But it is important that you can see why the individual impedances are in parallel by considering the circuit diagram. If you can't see it, be sure to ask.I have Y and Δ from the start. I transform Y to Δ and obtain 2 x Δ with ZΔ = 45 + j45 and to get single Δ after your hints I thought I need to combine each 2 impedances in parallel so ZΔ x ZΔ /ZΔ+ZΔ and I need to do that 3x ?
Okay, what leads you conclude that you can combine the Y's in that fashion? I'm not saying it's incorrect for this very special case, but you should be able to justify it. That way you won't inadvertently make the error of trying to do the same thing when the scenario is different and combining them in this fashion would be incorrect.Sorry. after Δ to Y transformation I have 15+j15 for each impedance 2xY and then combine each impedance ZYx ZY/ ZY+ZY as in a)
What do you mean by "add 0 into it"?now I am thinking what happens when I add 0 to it? I wonder if you have any hints...:)
adding 0 I meant c) and connection with star points not sure how can I solve this. Also "special case deduction about the nature of the central nodes" that is another scary thing to me I thought transforming and parallel calculation is enough. I am not very good combinatorist.What do you mean by "add 0 into it"?
The diagram alone doesn't explain why you can combine the like-labeled impedances in parallel. Note that none of those pairs shares two nodes... So you need to make a special case deduction about the nature of the central nodes of each Y...