What occurs when no movement is detected for 20 seconds?

The correct selection refers to a state known as "pre alert mode." This is typically a feature designed to enhance safety and efficiency in various systems, especially in emergency equipment or machinery. When no movement is detected for a specified duration—like 20 seconds—the system activates pre alert mode to indicate that it may need attention or that a user might not be actively monitoring it. This serves as a warning that conditions might not be ideal, helping to prevent potential hazards or malfunctions by prompting a check on the equipment.

Pre alert mode can function as a kind of intermediate state, indicating readiness to enter a more significant shutdown or power-saving mode if inaction continues. The response is proactive rather than reactive, promoting safety protocols by notifying the user before a more drastic measure is taken, such as shutting down entirely or entering a less active state.

In contrast, other modes such as emergency shutdown mode or power-saving mode imply a degree of cessation of function that is not merely a warning, but a follow-up action based on prolonged inactivity. Normal operation mode indicates that everything is functioning as intended, meaning that the system is active and moving, which does not occur when no movement is detected for a period.