Master Electrical Engineering from Zero to Pro

Chapter 1: DC Circuit Analysis

DC circuit analysis forms the foundation of all electrical engineering. Understanding how current flows, how voltage distributes, and how resistance affects a circuit is essential before studying any advanced topic.

Ohm's Law

Ohm's Law states that current through a conductor is directly proportional to the voltage and inversely proportional to resistance, provided temperature remains constant.

Kirchhoff's Laws

KCL (Current Law): The algebraic sum of all currents entering and leaving a node equals zero. Current in = Current out.

KVL (Voltage Law): The algebraic sum of all voltages around any closed loop equals zero.

Thevenin's Theorem

Any linear circuit with voltage/current sources can be replaced by a single voltage source (Vth) in series with a single resistance (Rth) from the perspective of any two terminals.

Mesh & Node Analysis

Mesh analysis applies KVL to each independent loop. Node analysis applies KCL at each node. For circuits with n nodes, node analysis gives (n−1) equations; for m meshes, mesh analysis gives m equations. Choose based on which gives fewer equations.

Chapter 2: AC Circuits & Phasors

Alternating current circuits involve sinusoidally varying voltages and currents. Phasor analysis converts differential equations into algebraic ones, making AC circuit analysis tractable.

Sinusoidal Signals

A sinusoidal voltage is represented as v(t) = Vm sin(ωt + φ), where Vm is peak voltage, ω is angular frequency, and φ is phase angle.

Impedance

Impedance (Z) is the AC equivalent of resistance. Resistors have real impedance; inductors and capacitors have imaginary (reactive) impedance.

Power Factor

Power factor (PF) is the cosine of the phase angle between voltage and current. Unity PF means all power is real (resistive load). Capacitors are used to correct lagging PF in inductive loads.

Chapter 3: Transformers

Transformers are static electromagnetic devices that transfer electrical energy between circuits through magnetic induction. They are fundamental to power transmission and distribution systems.

EMF Equation

The EMF induced in a transformer winding depends on the number of turns, core cross-section, flux density, and frequency.

Efficiency & Regulation

Transformer efficiency is the ratio of output power to input power. Voltage regulation is the change in secondary terminal voltage from no-load to full-load conditions.

Tests on Transformers

Open Circuit Test: Conducted on LV side with HV open. Determines core loss (iron loss) and no-load current.

Short Circuit Test: Conducted on HV side with LV shorted. Determines copper loss and equivalent impedance at full load.