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9/17/2012 What if resistors are neither in series nor in parallel? Delta--Wye Delta • Many circuits can be simplified using three-terminal equivalent networks. three• These are of the type (Y) wye or tee (T) and the delta (∆ (∆) or pi (π (π) networks. Y - Tee 1 9/17/2012 Delta - Pi Delta to Wye Conversion • Each resistor in the YYnetwork is the product of the resistors in the two adjacent ∆ branches, divided by the sum of the three ∆ resistors. Wye to Delta Conversions • Each resistor in the ∆ network is the sum of all possible products of Y resistors taken two at a time, divided by the opposite resistor. 2 9/17/2012 Delta--Wye Chart Delta Balanced Networks • Y and ∆ networks are said to be balanced when R 1 = R 2 = R 3 = R Y and when R a = R b = R c = R ∆ • Under these conditions, conversion formulas become RY = R∆ 3 R ∆ = 3R Y Transform the delta network to its equivalent wye network. 3 9/17/2012 First, transform your network into its opposite network. Second, calculate the new values for your network. Third, erase the old network. 4 9/17/2012 5