Cold load pickup (CLPU) refers to the phenomenon where a significantly higher than normal current is drawn when power is restored to a distribution circuit after an extended outage, or blackout. This inrush current occurs because many loads that are normally operating at steady-state conditions are simultaneously attempting to restart after being de-energized for a prolonged period. These loads include motors, which draw high starting currents, and appliances with heating elements, which have a low resistance when cold. The magnitude and duration of the CLPU current depend on factors such as the duration of the outage, the diversity of the loads, and the ambient temperature. CLPU significantly affects protection schemes during substation restoration by causing ove....
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