How long can a swell last in high voltage events?

A swell in electrical terms refers to a temporary increase in voltage that can occur during high voltage events, such as voltage sags or swells. The typical duration of a swell is usually in the range of a few milliseconds to tens of milliseconds. The correct duration for a swell, particularly in high voltage scenarios, is around 8 milliseconds.

This timeframe is significant because it is long enough to potentially impact sensitive equipment but short enough that it typically doesn't lead to permanent damage unless the equipment is not designed to handle such fluctuations. Understanding the duration of swells is crucial for the design of protective devices and ensuring that systems can cope with transient phenomena like swells that can occur in electrical networks.

Other options like 1 millisecond are generally too brief for a swell, as they often pertain to transient events. Longer durations such as 1 minute or greater than 1 minute indicate sustained overvoltage conditions rather than the brief spikes associated with a swell. Hence, while considering the standard operational definitions, the 8 milliseconds duration accurately reflects the expected behavior of voltage swells in high voltage environments.