Protection
15% of exam
Overcurrent, protective relaying, fuses/breakers/reclosers, coordination.
4 concepts
Exam areas
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Overcurrent, protective relaying, fuses/breakers/reclosers, coordination.
4 concepts
Set 50/51 pickup and time dial with the IEEE C37.112 curve family, choose CT ratios that will not saturate, and apply residual ground elements.
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Master ANSI device numbers, percentage-restraint differential, distance zones, and pilot schemes — the relaying vocabulary the exam assumes you know.
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Fuse classes and I²t let-through, breaker interrupting vs close-and-latch duty, and recloser/sectionalizer schemes — the hardware that clears faults.
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Stack TCC curves so the nearest device always wins: CTI margins, the 75% fuse rule, recloser-fuse k factors, and the transformer damage curve.
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