Which of the following refers to the increase in the nominal voltage for a duration of 3600 cycles?

A swell is a short-duration increase in RMS voltage lasting between 0.5 cycles and 1 minute, far shorter than the 3600-cycle threshold described.

Overvoltage is classified in IEEE power quality standards as a long-duration RMS voltage increase above nominal levels, typically lasting 1 minute or more - equivalent to roughly 3600 cycles at 60 Hz. This duration threshold separates it from swells, which resolve in under a minute. The sustained nature of overvoltage makes it a distinct category requiring different mitigation strategies than transient or momentary events.

A transient is an extremely brief impulse or oscillatory disturbance lasting less than half a cycle, not a sustained multi-cycle voltage elevation.

A sag is a short-duration decrease in RMS voltage below the nominal level, not an increase.