Is it true that a blackout usually occurs instantly?

A blackout typically does not occur instantly; it is often the result of a series of cascading failures in the electrical grid. When a significant event, such as a fault or an equipment failure, occurs, the system's protective measures may involve gradual disconnection or isolation of affected sections to stabilize the remainder of the grid. This can take time, leading to a more gradual loss of power rather than an instantaneous event.

Factors such as operator responses, system resilience, and the extent of the fault all contribute to the time it takes for a blackout to manifest. In some cases, the situation can progress from minor disturbances to full blackouts over a period of significant seconds to minutes, rather than occurring in an instantaneous manner. Such dynamics highlight the complexity of power systems and the importance of monitoring and managing grid conditions effectively.