How do transient voltages differ from voltage sags and voltage swells?

Transient voltages are characterized by their brief and unpredictable nature, which aligns with the concept of being more erratic. These voltage spikes occur suddenly and typically last for only a very short period, often milliseconds. Unlike voltage sags or swells, which involve prolonged decreases or increases in voltage levels, transient voltages can be seen as sharp, momentary fluctuations that may result from events such as lightning strikes, switching operations in power lines, or other sudden electrical disturbances.

The erratic behavior of transient voltages makes them distinct from voltage sags, which are gradual reductions in voltage lasting from a few cycles to several seconds, and voltage swells, which are short-term increases in voltage, lasting a similar duration. Understanding the fleeting nature of transients helps in effectively designing protective measures and improving system resilience against such unpredictable shifts in voltage.