Definition
The very large current that flows through the power system during a short-circuit fault — potentially tens or hundreds of times normal operating current — driven by full system voltage across the very low impedance of the fault path. Fault currents are limited primarily by the impedance between the source and the fault location; as more generation is added to a system, fault current levels increase. All switchgear — circuit breakers, disconnect switches, and busbars — must be rated to withstand and interrupt the maximum available fault current at the installation point as a core safety requirement.
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Topic Deck
Electrical Engineering Fundamentals
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Source
FERC Pro Forma OATT / LGIP