iPhone, iPad & Mac · shown as “Grid Prep”

Power Grid Operator Exam Prep

An independent trainer for the four NERC System Operator Certification examinations — written from the freely published primary sources, and scored the way the examination is. Formerly System Operator Prep.

One bank, four credentials

All four examinations are drawn from the same six content domains and the same 31 knowledge areas. What differs between them is only how many scored questions each area contributes — and NERC publishes that table for every credential.

So the app carries one question bank and one progress record, and the credential picker re-weights everything: your readiness estimate, the order of your weak areas, and the way a mock paper is sampled. An answer counts towards all four.

A count, not a percentage

NERC passes candidates on an absolute cut score, so the headline figure is a projected score out of the paper — "88 of 120" says something "73%" does not. Weak areas are ranked by scored questions at risk: how far below full marks you are, times what the area is worth on the credential you picked. Area Control Error costs a BI candidate four questions and a TO candidate one.

What is inside

• 1,224 original questions across the 31 knowledge areas, each carrying NERC's own cognitive level — recall, application or analysis.
• Mock papers sampled to the published outline — exactly the number of questions listed for each knowledge area, three hours, no feedback until you submit.
• A six-bus one-line with its flows, ratings and an N-1 contingency analysis report, rebuilt from scratch every time you open it.
• A Balancing Authority AGC control board — frequency, interchange, bias, reserve and the units on AGC, with the ACE left for you to calculate.
• Twenty calculation drills with worked solutions: ACE, governor droop, frequency response, rate of change of frequency, three-phase power, the power triangle, per unit, line losses, post-contingency margin and load relief.
• 31 reference cards — seven must-know numbers and a short essay each.
• Spaced repetition, and it all works offline. No account, no sign-in, no data collected.
• Free to try — 50 practice questions, one full mock paper and the whole Library. Full Access is one in-app purchase, no subscription, on iPhone, iPad and Mac.

Where the content comes from

Written from the sources NERC publishes free of charge for candidate use, read rather than recalled: the four Certification Examination Content Outlines, the Exam Resource Materials, the System Operator Certification Program Manual, the Glossary of Terms, and 60 currently enforceable Reliability Standards. No commercial prep product and no past examination was used — NERC publishes no official question bank.

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