# Y-Δ transform proof using superposition

In the wikipedia page and on every book they proof the transformation by equaling the the equivalent resistance between any pair of terminals while disconnecting the other node.https://en.wikipedia.org/wiki/Y-Δ_transform

Why this should make the two circuits equal? How can we apply superposition here? I have searched everywhere for this answer, In no where anyone explained this. Please explain the principle or this way of proof

anorlunda
Staff Emeritus
In general, when equations are linear you can apply superposition.

In general, when equations are linear you can apply superposition.
Yes I know that but I am asking how you can do that? Like what codition do you put in each situation then sum it up?

In wikipedia they put some conditions on the current in 3 situation but I didnt understand how ?