# Solve step by step any 2 examples of the per-unit system preferably one example with the change of bases?

### 2 Answers

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- Ian HLv 71 month ago
The per-unit system is electrical engineering knowledge rather than just maths.

Before going to the second link you might like to watch this short video

reminding you about V, I, R, X, Z and explaining about how you get

Z(base) = [V(base)]^2 / I(base), and so on.

https://www.youtube.com/watch?v=WpU4chWUszY

The aim is to normalise the impedance of components in a power system,

Power and voltage are typically chosen as a base and all quantities are then specified as multiples of those.

This worked example might help you if you are already familiar with, (for example), transformers with 22/220kV voltage rating.

See step 3 for the formula showing how base impedances are calculated

https://peguru.com/2011/06/per-unit-system-practic...

Good luck

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