Lect18EEE 2021 AC Circuit Analysis Techniques Dr. Holbert April 7, 2008

Lect18EEE 2022 Introduction Today, we continue to perform AC analyses using phasors and impedances We utilize all our circuit analysis tools to accomplish this –KCL, KVL, Ohm’s Law –Voltage and current division –Superposition, source transformation –Nodal and loop/mesh analyses –Thevenin’s and Norton’s theorems

Lect18EEE 2023 Z eq Series Impedance Z1Z1 Z3Z3 Z2Z2

Lect18EEE 2024 Parallel Impedance Z3Z3 Z1Z1 Z2Z2 Z eq

Lect18EEE 2025 Leading and Lagging Phase x 1 (t) leads x 2 (t) by  -  x 2 (t) lags x 1 (t) by  -  On the following plot, which signals lead and which signals lag?

Lect18EEE 2026 Phase Green leads blue and red Red lags blue and green

Lect18EEE 2027 Circuit Element Phasor Relations (ELI and ICE man) ElementV/I RelationPhasor RelationPhase CapacitorI = C dV/dtI = j ω C V = ω C V  90° I leads V by 90° InductorV = L dI/dtV = j ω L I = ω L I  90° V leads I by 90° ResistorV = I RV = R I = R I  0° V and I are in-phase

Lect18EEE 2028 Class Examples Drill Problems P8-6, P8-9, P8-8