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## Homework Statement

## Homework Equations

## The Attempt at a Solution

a) the question is to transform star to delta ?

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- Thread starter M P
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a) the question is to transform star to delta ?

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attempt:The question asks you to find a single Δ-connected load that is equivalent to total of the two loads shown.

90+90j for single delta ?

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Can you justify adding them? How do the voltage sources "see" them when you combine them?

angle is changing ? on the other connection V ∠0 ∠-120 ∠-240 thank you for the interest.

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gneill

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attempt: ZΔ x ZΔ /ZΔ+ZΔ and then x3 ?

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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 ?Can you elaborate?

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Can you elaborate?

An thank you for the prompt reply

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gneill

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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 ?

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I will improve I promise.

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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.

So similar to b) with 2 x Y at 15+j15 and ZYx ZY/ ZY+ZY

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gneill

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Okay, what leads you conclude that you can combine the Y's in that fashion? I'm not saying it's incorrect for

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now I am thinking what happens when I add 0 to it? I wonder if you have any hints...:)

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gneill

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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...:)

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...

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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...

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.

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gneill

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It's part (c) that asks you to combine two identical Y loads. A very important fact to note is that they are identical. When driven in parallel by the same sources you can be sure that they will behave identically as well. That lets you say something about their center nodes.

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