updated 2026-10-22
Frequency
grid frequency · system frequency · hertz · 주파수
Frequency is how fast alternating current changes direction; it signals whether supply and demand balance. It falls when supply is short and rises when there is a surplus.
Korea's standard frequency is 60 Hz, with a tolerance of ±0.2 Hz.
Korea's electricity is alternating current, so the direction of the current keeps changing. How fast it changes is called frequency, measured in Hz (hertz). The national grid runs at a single frequency, so frequency is the fastest indicator of supply-demand balance.
The Electric Utility Act requires electricity businesses to maintain power quality, and the reliability standard requires KPX to keep grid frequency within a set range through dispatch instructions. There are also standards for how quickly frequency must recover after a generator failure. For this, generators on automatic generation control and governor-free operation, energy storage and others stand by as reserves.
News-reading tip: stories about a large power plant tripping suddenly usually mention a 'frequency drop'. If frequency falls below the standard, some load is automatically disconnected according to plan to prevent a larger blackout.