A central supervisory control system is characterized by which description?

• A. All decisions are made at a single central computer.
• B. Decision making equipment is located in various locations and the system enables/disables local controllers.
• C. It provides only data logging without real-time control.
• D. It uses open-loop control at field devices.

Answer: (B)

Central supervisory control coordinates several local controllers rather than letting one computer make every decision. In this setup, the central supervisor oversees the overall operation, collects data, and issues high-level instructions, while decision making and actuation are distributed to local controllers at various sites. The supervisor can enable or disable these local controllers as needed, allowing scalable, responsive control across the entire system. Real-time control emerges from the closed-loop actions of the local controllers acting on field-device feedback, guided by the central supervision. The other descriptions don’t fit because they either place all decisions in one place, limit the system to data logging, or rely on open-loop action without feedback.