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Generator labLab
← Generator lab

Part 1 · The idea

  1. 1Split any three
  2. 2Three circuits

Part 2 · Faults in real systems

  1. 3The four faults
  2. 4Grounding
  3. 5Transformers & the line

Part 3 · Protecting the system

  1. 6The fault recorder
  2. 7What relays see
  3. 8Clear it in time

Teacher guide

Teacher guide

Lesson plans, common mix-ups and exercises for the eight chapters of the faults course. Every answer here is worked out by the same model the chapters use, so it matches what learners see.

Answers stay hidden here until you press Show answers, and the worksheet never prints them. The chapters show live numbers, so open an exercise’s setup, or a mix-up, after the class has tried.

How to use the course

  • Each chapter is a playground: a picture, the controls under it, Try this ideas that set it up and say where to look, and What you’re seeing, which explains whatever is on screen and what your last change did. Nothing is locked or graded.
  • Ask first, then try. Read a Check yourself question to the class, let them agree on an answer, then press Set it up or the matching Try this idea. Each chapter below lists its questions, with the answers hidden.
Links, storage and the numbers
  • “Open this setup” links (…#try=<idea>&…&from=teacher&ex=<id>) set up the idea and its values. The chapter shows a note with the exercise and a link back here. It also shows the result, so open it once the class has worked the question.
  • In a learning platform, add &embed to any chapter link (for example faults.html#try=lg&embed) to hide the header and footer inside a frame.
  • Nothing is stored about the learner except their settings (with the idea and extras they had open), their display choices (slow motion, Describe figures in words), which first-visit hints and notes they have seen, and the protection game’s streak, and only in their own browser.
  • **What the numbers are.** Currents and voltages show in [[pu|per-unit (pu)]] first, then in amps or kV at that place. [[X120|X1, X2 and X0]] are the reactances that positive-, negative- and zero-sequence current meet. [[3I0|3I0 (three times I0)]] is the current in a neutral or in the ground. Fault values are initial symmetrical ([[subtransient]]) values; AC decrement is not modelled.

Chapters and lesson plans

Open a chapter for its 10- and 20-minute plans, the questions to ask first, the mix-ups it clears up and three exercises.

Answer key

Worked out when this page opens, from the same model blocks as the chapters; a test checks every value, so the key can’t go stale.

The answers are hidden.

Accessibility notes

  • Keyboard. Every playground works from the keyboard: Tab reaches the picture’s handles, then the controls, the guide and the extras; arrow keys move sliders and handles. “Skip to the picture” is the first Tab stop.
  • Describe figures in words. The ⋯ menu has a switch that puts a short description under every figure. Screen readers get the description either way.
  • Reduced motion. When the device asks for less motion, the pictures start paused and nothing slides or pulses; Play still works. The ⋯ menu also has three slow-motion speeds.
  • Colour is never the only cue. Phases carry their letter and a shape marker; sequences carry a line style: solid for positive, dashed for negative, dotted for zero.
  • Explanations are never hidden behind a question. What you’re seeing explains the picture whatever the learner has done; the questions are optional.
  • High contrast and Windows forced colours are supported, and every lamp, breaker and outcome is also written as text.