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Electrical engineering, made easy

Plain-English guides to power systems, with animated diagrams. For students and working engineers.

Start with the basicsSee the latest guides →
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Learning paths

Read in order, one step at a time

Each track starts simple. Every guide builds on the one before.

Power system basics

Start here · 6 guides
  1. Power system fundamentals
  2. Resistance, inductance and capacitance
  3. What is reactive power?
  4. The per-unit method
  5. Z bus and Y bus
  6. ABCD parameters of a line

Machines and generation

Next step · 5 guides
  1. How a synchronous generator works
  2. Synchronous and asynchronous machines
  3. How induction motors work
  4. DC motor fundamentals
  5. AC vs DC vs servo motors

Protection and safety

Core skills · 5 guides
  1. Overload, short circuit and earth fault
  2. Short circuit analysis and X/R ratios
  3. How a surge arrester works
  4. What 5P10 and 5P20 mean on a CT
  5. REF protection in transformers

Grid control

Advanced · 5 guides
  1. What is a FACTS device?
  2. Static VAR compensators
  3. How a STATCOM works
  4. HVDC transmission
  5. Microgrid components and topology
Tools

Try it with your own numbers

Small calculators that go with the guides.

Learn power systems

Interactive lessons

Power calculator

kW, kVA, kvar and power factor

Y bus and Z bus

Build the matrices step by step

ABCD parameters

See how a line behaves

Latest

New guides

A new explainer every few days.